METHOD FOR DETERMINING TOTAL ALDEHYDE IN ONE OR MORE CRUDE 2,5-FURANDICARBOXYLIC ACID (FDCA), CRUDE TEREPHTHALIC ACID (TPA) AND THEIR ESTERS

Abstract

A process is described for the determination of soluble aldehydes in a composition comprising one or more of (a) 2,5-furandicarboxylic acid (FDCA), (b) terephthalic acid (TPA), (c) esters of 2,5-furandicarboxylic acid and (d) esters of terephthalic acid. The process may indicate the presence in the composition of even very low levels of soluble aldehydes that have been associated with unacceptable color development in a) the composition, b) a portion of the composition or c) a prepolymer, oligomer or polymer made, directly or indirectly, of at least a portion of the composition or portions of the composition, so that mitigating or corrective measures can be taken in response.

Description

The present invention relates, from one perspective, to a process for the manufacture of 2,5-furandicarboxylic acid (FDCA) and its esters, such as its dimethyl ester derivative (FDME), and to polymers that can be prepared from these materials. From another perspective, the present invention relates to the manufacture of conventional petroleum-based terephthalic acid (TPA) for which FDCA has been proposed as a renewable, plant-based alternative and to polymers that can be prepared from it. Background of the Invention The depletion of fossil fuels has created a significant incentive to seek alternative sources of petroleum-based carbon, synthesizing so-called platform molecules that can serve as building blocks for commercially significant products. Biomass is currently viewed as a potential substitute from which many high-value chemicals can be derived, but developing sustainable technologies for producing these chemicals from renewable resources remains a significant challenge. The bio-based monomers, 2,5-furandicarboxylic acid (FDCA) and its dimethyl ester derivative, 2,5-furandicarboxylic acid dimethyl ester (FDME) are recognized as important starting materials in the production of poly(alkylene furan dicarboxylic acid) polymers that can substitute for the well-known and mass-produced petroleum-derived analogs, namely poly(alkylene terephthalate) polymers, such as polyethylene terephthalate (PET). A prominent example of a poly(alkylene furan dicarboxylic acid) polymer is poly(ethylene furan dicarboxylic acid), or PEF, which is obtained by the reaction of FDCA or FDME with ethylene glycol. The bio-based polymer (bio-plastic) PEF exhibits superior properties in several respects, relative to the petroleum-derived analog PET, particularly in the area of ​​packaging.For example, blends of PEF and PET can provide better barrier properties with respect to CO2 and O2, extend shelf life compared to pure PET, and produce acceptable containers for products such as beer that are susceptible to oxidative degradation. Other packaging applications of PEF include films used to make bags, wraps, and heat shrink materials that have high mechanical strength and are recyclable. In general, FDCA and FDME are useful platform molecules in the production of polyamides, polyurethanes, and polyesters, which have diverse applications such as plastics, fibers, coatings, adhesives, personal care products, and lubricants. The commercial significance of these molecules is demonstrated, for example, in a 2004 study by the US Department of Energy, identifying FDCA as one of twelve priority chemicals for building a future green chemistry industry. Due to its structural similarity to terephthalic acid (TPA), FDCA's potential as a substitute monomer for synthesizing polyesters has been recognized since at least 1946, for example in GB621971A, and a number of parties have invested significant efforts over several years to achieve a commercially viable process for producing FDCA. In the case of FDCA synthesis from bio-based starting materials, an advance is described in US Patent 10,538,499, according to which a feedstock comprising six-carbon sugar units (e.g., fructose) is subjected to integrated processing steps, the first of which is a dehydration step to produce 5-hydroxymethylfurfural (HMF) and / or certain HMF derivatives, such as ester or ether derivatives thereof. The dehydration product comprising the material is then oxidized to the desired FDCA, according to a similar type of Medieval oxidation as used for the oxidation of p-xylene to produce TPA, using a homogeneous catalyst system including cobalt, manganese, and bromine components. US 9,029,580 discloses a process for producing a dry purified carboxylic acid product that includes furan-2,5-dicarboxylic acid (FDCA). The process includes oxidizing at least one oxidizable compound such as 5-(hydroxymethyl)furfural (5-HMF) to produce a product containing a reduced amount of 5-formyl furan-2-carboxylic acid (FFCA). US Pub 20190352784 discloses a process for treating a furan-2,5-dicarboxylic acid composition by using an electrochemical cell to electrochemically reduce carbonyl groups such as aldehyde groups in the same impurity, 5-formyl-furan-2-carboxylic acid (FFCA). Tachibana et al., Plant-based Poly(Schiff-Base) Composed of Bifurfural, ACS Omega, 2018 May 18, 3(5): 5336-45, revealed the formation of poly(Schiff base) composed of bifurfural and diamine as the desired polymer product. A method for the quantitative determination of aldehydes in oxidized oil based on the reaction of N,N-dimethyl-pphenylenediamine (DPPD) with aldehydes in the presence of acetic acid was disclosed by Miyashita et al., Journal of the American Oil Chemist's Society (JAOCS), Vol. 68, no. 10, p. 748-751 (Oct. 1991). This method uses benzene as a solvent for aldehyde solutions, and the lowest amount of aldehyde is determined down to ppm. WO 2019 / 014382 discloses a process for producing a purified 2,5-furandicarboxylic acid (FDCA) pathway product that includes: contacting an FDCA pathway product that includes FDCA and 5-formyl-furan-2-carboxylic acid (FFCA) with hydrogen in the presence of a heterogeneous reduction catalyst and a solvent under conditions sufficient to form a reaction mixture to reduce FFCA to hydroxymethylfurancarboxylic acid (HMFCA), and producing a purified FDCA pathway product; wherein the purified FDCA pathway product includes FDCA, HMFCA, less than 10 mole percent of a remaining FFCA impurity, less than 10 mole percent of 5-methyl-2-furoic acid (MFA), and less than 10 mole percent of tetrahydrofuran-2,5-dicarboxylic acid (THFDCA); wherein the solvent is a multi-component solvent that includes water and a water-miscible aprotic organic solvent;and wherein the heterogeneous reduction catalyst includes a solid support and a metal selected from the group including Cu, Ni, Co, Pd, Pt, Ru, Ag, Au, Rh, Os, Ir, and any combination thereof.; Despite extensive efforts, commercial production of FDCA has not been realized and improved bio-based synthetic routes for FDCA and its derivatives continue to be sought, in an effort to establish economic viability at a commercial scale. Brief Description of the Invention In a first aspect, the present invention relates to a process for determining soluble aldehydes in a composition, wherein the composition includes one or more of (a) 2,5-furandicarboxylic acid (FDCA), (b) terephthalic acid (TPA), (c) an ester of 2,5-furandicarboxylic acid and (d) an ester of terephthalic acid, and wherein the process itself includes combining one or more diamine salts with the composition under suitable conditions to cause the soluble aldehydes present in the composition to react with the added diamines and form one or more imines, and then analyzing the composition for imines. In another aspect, the present invention relates to the use of an analytical process for monitoring the presence of an amount of soluble aldehyde in a composition that exceeds a certain threshold value associated with unacceptable color development in a) the composition, b) a portion of the composition or c) a prepolymer, oligomer or polymer made, directly or indirectly, at least in part of the composition or a portion of the composition, and when the threshold value is exceeded, making a change to the manner in which the composition or portion of the composition is formed, the processing of the composition or portion of the composition or making both a change to the manner in which the composition or portion of the composition is formed and a processing of the composition or portion of the composition, to prevent such unacceptable color development.In certain embodiments, these remedial measures may include one or more of changing the manner of oxidizing one or more FDCA or TPA oxidation precursors to form FDCA or TPA, respectively, treating the composition or a portion thereof by introducing one or more color stabilizing additives thereto and hydrogenating the composition or a portion thereof. In this regard, processes for producing TPA or esters from TPA have long been known to require conditions conducive to the formation of problematic byproducts, including labile aldehydes known as color formers. A prime example of a known color former that must be addressed in the production of TPA or esters from TPA is 4-carboxybenzaldehyde (hereafter, 4-CBA). However, labile aldehydes are also problematic for the production of FDCA or esters from FDCA. For example, one aldehyde in particular, 5-formyl-2-furancarboxylic acid methyl ester (FFME), can be present in amounts above 1% by weight in the raw mixture from the Medieval-type oxidation of one or more FDCA furanate precursors obtained from the acid-catalyzed dehydration of hexoses (e.g., fructose) and has nearly identical physical properties to FDME, thus posing a purification challenge. Furthermore, in controlled experiments in which FFME was spiked into the FDME mixture at low ppm amounts,Substantial color is observed within a short time interval at temperatures just above the melting point of FDME. Instrumental methods, such as GC-FID, GC / MS, LC-PDA and LC / MS are certainly capable of measuring known organic compounds, including aldehydes, at low ppm levels, but these methods cannot accurately account for all the variety of unknown molecular species that have been produced with 5-formyl-2-furandicarboxylic acid in recent attempts to develop a commercially viable process for producing FDCA and / or FDME with monomer purity; the present invention can thus be broadly understood as relating in the first aspect by providing a method that can rapidly account for the presence of very small amounts of known and unknown aldehydes that may be found in compositions that include one or more of FDCA, esters of FDCA with alcohols, TPA and esters of TPA with alcohols,and in a second aspect by taking corrective action efficiently and effectively when the analytical methods of the present invention indicate such corrective action is necessary to prevent the development (or eventual development) of undesirable color in the composition or in materials or articles made from the composition., In this embodiment, the composition analyzed or monitored is a crude FDCA product from the oxidation of one or more FDCA furanate precursors. In another embodiment, the composition analyzed or monitored is the crude TPA product from the oxidation of p-xylene. In yet another embodiment, the composition analyzed or monitored is a mixed monomer composition comprising FDCA and TPA from the oxidation in the same or different reactors of one or more furanate precursors of FDCA and pxylene, respectively. In certain embodiments, the mixed monomer composition is one formed by the co-oxidation in the same reactor under a unitary set of reaction conditions of one or more furanate precursors of FDCA and pxylene, as described in the generally designated Patent Cooperation Agreement Application Series No. PCT / US21 / 31969, filed on May 12, 2021 for Co-Production Of Monomers, Including At Least One Bio-Based Monomer (969 PCT application) and claiming priority from United States Provisional Patent Application Series No. 63 / 025,345 filed May 15, 2020 and from European Patent Application No. 20196216.4 filed September 15, 2020. In yet another embodiment, the composition to be analyzed or monitored is that resulting from the esterification with one or more alcohols of a crude FDCA product from the oxidation of one or more furanate precursors of FDCA, of a crude TPA product from the oxidation of p-xylene or a combination of FDCA and TPA from the oxidation in the same or different reactors of one or more furanate precursors of FDCA and p-xylene. In the esterification of such a combination of FDCA and TPA, in certain embodiments, the combination to be esterified is a mixed monomer composition formed by the simultaneous oxidation in the same reactor under a set of reaction conditions of one or more furanate precursors of FDCA and p-xylene, as described in the '969 PCT application. In certain embodiments, analysis or monitoring is performed in real time with in-process materials from the synthesis of one or more of FDCA, TPA, an ester or esters of FDCA and an ester or esters of TPA. In certain embodiments, the analysis or monitoring is performed in real time with the materials in the process and the making of changes to the method of formation of the composition or part of the composition, the treatment of the composition or part of the composition or the carrying out of either the change in the method of formation of the composition or part of the composition or the treatment of the composition or part of the composition also occurs in real time in accordance with the results of the analysis or monitoring. These and other related aspects, manifestations and advantages will become clear from the following Full Description. Complete Description of the Invention The terms wt%, wt-ppm, and wt-ppm, as used herein, are used to denote percentage by weight, parts per million by weight, and parts per billion by weight, respectively. The term mol-% is used to denote molar percentage. Unless otherwise stated, the phrase being (or) substantially free from, may mean, in various embodiments, having (or having) less than 5 wt% of, having (or having) less than 1 wt% of, or having (or having) less than 1 wt% of. In the case of references to by-products such as aldehyde by-products in particular, and color-forming by-products in general, these may be referred to as contaminants or impurities, for example in the subject matter incorporated by reference. The term FDCA stands for 2,5-furandicarboxylic acid (FDCA). An esterified derivative of FDCA means a derivative in which one or both of the carboxylic acid groups of the compound are ester groups, such as alkyl ester groups or aryl ester groups, with methyl ester groups, ethyl ester groups, or phenyl ester groups being specific examples. In the case of methyl ester groups, the desired esterified derivative of FDCA for use in forming polyesters such as with ethylene glycol (PEF) is 2,5-furandicarboxylic acid, dimethyl ester (FDME). As will be apparent from the foregoing summary and from the following description, while the terms soluble aldehyde, aldehyde, labile aldehyde, aldehyde derivative and the like are all used herein, one skilled in the art will understand that all of these essentially refer comprehensively to compounds having at least one aldehyde group present therein to react with a diamine salt in the inventive method (or even with the aldehyde functional group itself), to give at least one corresponding imine group that can be found analytically as described herein. An aldehyde derivative of FDCA, for example, means a derivative in which one of the carboxylic acid groups of the compound is not an aldehyde group, such as a formyl group bonded directly to a furan ring or a formylalkyl group bonded through an intervening alkyl group, with a formyl group, a formylmethyl group, or a formylethyl group being specific examples. In terms of the formyl group, the aldehyde derivative of FDCA that is most typical and primarily of interest to the present invention is 5-formyl-2-furancarboxylic acid (FFCA), although other lower aldehyde derivatives that may not be identified (to the practitioner) will certainly also be of interest for the formation of undesirable colors by the aldol condensation process (as described above). An aldehyde derivative of an esterified derivative of FDCA means an esterified derivative of FDCA as defined above, wherein one of the ester groups of this derivative is an aldehyde group, such as a formyl group directly bonded to a furan ring or a formylalkyl group bonded through an intervening alkyl group, with a formyl group, a formylmethyl group, or a formylethyl group being specific examples. In the case of a formyl group, and an esterified derivative of FDCA being FDME, the aldehyde derivative of FDME that is particularly and primarily of interest for the purposes of the present invention is 5-formyl-2-furancarboxylic acid methyl ester (FFME), although again, possibly unidentified aldehyde derivatives of other esterified derivatives of FDCA would also be of interest for the formation of undesirable colors by aldol condensation. The present invention as summarized above principally relates to processes for the preparation of 2,5-furandicarboxylic acid (FDCA), although in certain embodiments FDCA is prepared in combination with other monomers, such as terephthalic acid (TPA). Some of these processes in turn explicitly include esterifying FDCA or combined dicarboxylic acids (FDCA and TPA) to form ester derivatives of FDCA or FDCA and TPA, wherein one or preferably both of the carboxylic acid groups of these dicarboxylic acids are instead ester groups, such as alkyl ester groups (in the case of mono- or dialkyl ester derivatives) or aryl ester groups (in the case of mono- or diaryl ester derivatives), with methyl ester groups, ethyl ester groups, or phenyl ester groups being specific examples.In terms of methyl ester groups, the preferred ester derivative of FDCA is 2,5-furandicarboxylic acid, dimethyl ester (FDME) and the ester derivative of TPA is dimethyl terephthalate (DMT), which can be formed by the reaction of FDCA and TPA, respectively, with sufficient amount of methanol. Real-Time Quantitation of Aldehydes and Aldehyde Derivatives When considering the use of these materials to make various polymers, as previously indicated, color—or rather the absence of color—is an important attribute with respect to the commercial acceptability of these materials and the polymers made from them, for a number of applications. For example, PET is widely used in the manufacture of carbonated soft drink bottles, and it is understood that bottles prepared at least in part from PEF must be substantially colorless to be an acceptable, at least partially plant-based alternative to the PET bottles they are accustomed to.As related above, we have found that very small amounts of various materials containing aldehyde groups (and combinations (including dimers, trimers, etc.) of these materials formed by aldol condensation) including, but not limited to, FFCA / FFME prepared in the various processes described in the art for preparing FDCA (or FDME) may contribute to the development of unacceptable color in the FDCA / FDME and in polymers (such as PEF) prepared therefrom.Therefore, in one aspect of the present invention, a novel process has been developed and disclosed herein that allows all aldehyde and aldehyde derivative byproducts to be quantitatively quantified, for example, in a composition containing FDCA from the oxidation of one or more oxidative precursors of FDCA, in a composition containing FDCA esters from subsequent esterification of the same FDCA-containing composition, in a composition containing TPA from the oxidation of p-xylene, in a composition containing TPA esters from subsequent esterification of the same TPA-containing composition, a mixed monomer composition including FDCA and TPA or a composition including ester products from esterification carried out on a mixed monomer composition. The process provided herein includes a highly sensitive protocol that utilizes a diamine, such as N,N'dimethylphenylenediamine (DPPD), as an agent that reduces virtually all aldehydes to stable, long-wavelength absorbing imines that can be detected by UV-Vis analysis in sub-ppm (nanomolar) amounts, and that can be performed and provide quantitative results in a sufficiently rapid manner that the method can be used in real time and for online process control or real-time mitigation of excess aldehydes (as precursors to color formation, where aldehydes are again broadly understood to mean aldehyde derivatives including, for example, FDCA, esters of FDCA, TPA and esters of TPA) found in the composition being analyzed or monitored.In one particular embodiment, the process disclosed herein may be used to determine the presence of total aldehydes in excess of 30 ppm in a crude 2,5-furandicarboxylic acid composition, wherein the composition is formed by the oxidation of one or more furanic precursors of 2,5-furandicarboxylic acid. In another embodiment, the process may be used to determine the presence of total aldehydes in excess of 10 ppm in a crude 2,5-furandicarboxylic acid composition. In still another embodiment, the process may be used to determine the presence of total aldehydes in excess of 30 ppm in a crude 2,5-furandicarboxylic acid composition. The following chemical equation shows the imine addition formation of N,N'-Dimethyl- -p-Phenylenediamine (DPPD) that occurs with aldehydes in compositions according to the process of the present invention: FFME ® θ nh3hso / SonikasLrt DPPD in 96% MeOH / 4% Iminium hydrogen sulfate Anilium hydrogen sulfate P«a pKa 5-6 Adducts are Schiff base salts, are highly colored, and absorb strongly at long wavelengths. The following are diamine salts (formulas i to x) which may also be used in accordance with the present invention, to produce UV-Vis detectable imines: N,N'-dimethyl-p-phenylenediamine sulfate (DPPD sulfate); '2HCI N,N'-dimethyl-p-phenylenediamine dihydrogen chloride (DPPD dihydrogen chloride); C2H2O4 N,N'-dimethyl-p-phenylenediamine oxalate (DPPD oxalate); N,N'-dimethyl-p-phenylenediamine hydrogen chloride (DPPD hydrogen chloride); v) N,N'-dimethyl-o-phenylenediamine dihydrogen chloride (DOPD dihydrogen chloride); vi) N,N'-dimethyl-o-phenylenediamine sulfate (DOPD sulfate); vii) N,N'-dimethyl-o-phenylenediamine hydrogen chloride (DOPD hydrogen chloride); viii) N,N'-dimethyl-p-phenylenediamine dihydrogen chloride dihydrogen chloride); W z^nh2ήο ix)Z'---4 3---4 N,N'-dimethyl-p-phenylenediamine hydrogen chloride hydrogen chloride); x)nn·· ^5°4 N,N'-dimethyl-p-phenylenediamine sulfate (DPBD sulfate). Diamine salts i-vii are commercially available. Diamines viii, ix, x can be prepared easily. For example, which is not limiting for the preparation of diamine salts viii, (DPBD (DPBD Salts of methods ix, and x and are given below, together with comments regarding subsequent iminization with aldehydes that may be present in the composition to be analyzed quantitatively in accordance with the present invention. Subsequent derivatization of these UV-Vis-detectable imines can be easily performed at room temperature. We have found that certain solvents are preferred for the reaction, while other commonly used industrial solvents—namely, benzene, toluene (producing a greenish color), xylene, ethyl acetate, acetone, THF (producing a purple color), acetonitrile, methanol, and ethanol—are not preferred for use. Methylene chloride and chloroform in particular appear to work very well. Preparation of Diamine Salt viii)y N, N ' -dimethyl-pphenylenediamine dihydrogen chloride (DPBD dihydrogen chloride) from DPBD ► Cl +NH λ Cl Regional People's Representative Council (DPBD) DPBD dihydrogen chloride Procedure: DPBD is converted to DPBD dihydrogen chloride as follows. mL round-bottom flask equipped with a PTFE-coated magnetic stir bar was filled with 1 g of N,N'-dimethyl-pphenylenediamine (4.70 mmol) and 100 mL of a 0.1 molar solution of HC1 ethanolate. The resulting mixture was stirred vigorously overnight, and then excess solvent was removed under pressure, first by rotary evaporation (50°C, 25 torr), then under high vacuum (<1 torr) for two days, yielding 1.3 g of DPBD dihydrogen chloride as a crystalline solid. Immunization with FEME: A rapid reaction occurs when FFME and DPBD dihydrogen chloride are mixed, producing the adduct listed below (formula xi). This species will exhibit an Xmax >500 nm (Spectroscopy Letters (1998), 31(5), 1107-1122), which is advantageous because it can be clearly distinguished from any soluble furan oligomer in the mixture that has an Xmax approaching 400 nm (approximating the DPPD adduct). O Preparation of Diamine Salt ix)y N, N ' -dimethyl-pphenylenediamine hydrogen chloride (DPBD hydrogen chloride) from DPBD Regional People's Representative Council (DPBD) DPBD dihydrogen chloride Procedure: DPBD is converted to DPBD hydrogen chloride as follows. A 50 mL round-bottom flask equipped with a PTFE-coated magnetic stir bar was charged with 1 g of N,N'-dimethyl-pphenylenediamine (4.70 mmol) and 100 mL of a 0.047 molar ethanolic HCl solution. The resulting mixture was stirred vigorously overnight, and then excess solvent was removed under pressure, first by rotary evaporation (50°C, 25 torr), then under high vacuum (<1 torr) for two days, yielding 1.2 g of DPBD hydrogen chloride as a crystalline solid. Immunization with FFME: A rapid reaction occurs when FFME and DPBD hydrogen chloride are mixed, producing the adduct listed below (formula xii). This species will exhibit an Xmax>500 nm (Spectroscopy Letters (1998), 31(5), 1107-1122), which is advantageous because it distinguishes it significantly from the soluble furan oligomers in the mixture which have exhibited Amax close to 400 nm (near the DPPD adduct). xii) Preparation of Diamine Salt x) - N,N'-dimethyl-p-phenylenediamine sulfate (DPBD sulfate) from DPBD DPBD DPBD sulfate Procedure: DPBD is converted to sulfate DPBD as follows. A 50 mL round-bottom flask equipped with a PTFE-coated magnetic stir bar was charged with 1 g of N,N'-dimethyl-pphenylenediamine (4.70 mmol) and 100 mL of a 0.047 molar H2SO4ethanolic solution. The resulting mixture was stirred vigorously overnight, and then excess solvent was removed under pressure, first by rotary evaporation (50°C, 25 torr), then under high vacuum (<1 torr) for two days, yielding 1.5 g of DPBD sulfate as a crystalline solid. Immunization with FFME: A rapid reaction occurs when FEME and DPBD sulfate are mixed, producing the adduct listed below (formula xiii). This species will exhibit an Amax >500 nm (Spectroscopy Letters (1998), 31(5), 1107-1122), which is advantageous because it distinguishes it significantly from the soluble furan oligomers in the mixture that have exhibited Amax near 400 nm (near the DPPD adduct). Those in the field who benefit from this disclosure will find that other diamine salts can be prepared and used in the methods disclosed herein. These other diamine salts will differ solely by the type and position of their substituents, while maintaining both the ortho and para amine groups to each other. Following are the FDCA and FDME formulas. HO. Z\ / OH Π0Π O o 2,5-furandicaboxylic acid (FDCA) CKO OCHo O o dimethyl ester furandicarboxylate (FDME) The undesirable color-forming carbonyl compounds (aldehydes) in the compositions of FDCA and FFME are shown in the formulas below. oo 1 A. JHO'L / 5-formyl-2-furancarboxylic acid (FFCA) Methyl-5-formyl-2-furandicaboxylate (FFME) 2,5-diformylfuran (DFF) Following are the TPA and DMT formulas. Terephthalic acid (TPA) Dimethyl terephthalate (DMT) The undesirable color-forming aldehydes in the TPA and DMT compositions are shown in the formulas below. 4-carboxybenzaldehyde (4-CBA) Terephtaldehyde (also known as 1,4-formylbenzene) Methyl-4-formylbenzoate (also known as 4-carbomethoxybenzaldehyde) Disclosed here is a rapid and feasible technique for determining very low levels of such problematic aldehydes; in certain embodiments using methylene chloride or chloroform, the presence of carbonyl compounds in excess of 30 bpm can be determined. Without being bound by theory, it is expected that the total time for derivatization of a diamine (e.g., DPPD) is actually much shorter than indicated in the illustrative procedure above alone, because the reaction to make the imine is a fast reaction. After determination of total aldehydes in the subject composition, appropriate approaches can be taken to reduce color formation and / or increase color stability in the subject composition. Aldehyde Mitigation in Response to Quantitation Above Threshold Value As previously indicated, where excessive levels of aldehydes in TPA or its esters as well as in FDCA or its esters are found in a composition monitored or analyzed through the formation and quantitation of imines thereof by UV-Vis spectroscopy, responsive initiation and use of mitigating measures, such as hydrogenation or other derivatization of the aldehydes in the composition to prevent the formation of body color by aldol condensation and / or the use of stabilizing additives to the composition, are contemplated by the present invention although a specific object of the present invention in certain embodiments is to provide sufficient real-time determination of the total aldehydes in a composition (such as a composition including FDCA, esters of FDCA, TPA, esters of TPA, both of FDCA and TPA or esters of both FDCA and TPA) to allow for the reduction of cumulative low aldehydes as such composition is produced through changes to the process that produces the composition,and thereby reduce the frequency and / or duration (and associated additional costs) of these mitigation measures. In embodiments, the process modification involves changing the manner in which such oxidation to produce FDCA, TPA, or a combination of FDCA and TPA is carried out. In other embodiments, the subject composition undergoes further, or additional, oxidation to oxidize additional portions of the aldehyde. Such additional oxidation may be achieved in a secondary oxidation zone. If the aldehydes defined by the present invention are such, either in quantity and / or character (e.g., having a greater proportion of condensed aldehydes approaching the size to prove color in a composition, an oligomer or a polymer made from such composition), that mitigation measures are desirable to prevent the development of undesirable color in the monomer, mixed monomer composition or polymer made from the monomer or combination of monomers related to the present invention, one mitigation measure that may be taken would involve low temperature hydrogenation of a composition requiring mitigation. We have found that through low-temperature hydrogenation using certain catalysts as described herein, the problematic aldehyde derivatives related to the present invention can, even when present in small concentrations, be selectively hydrogenated so that the desired monomers (e.g., FDCA, esters of FDCA, TPA and esters of TPA) in the composition remain largely or almost entirely unreacted. This is surprising considering that at least the monomers have unsaturated furan rings (FDCA and its esters), since these unsaturated furan rings would be expected to be susceptible to hydrogenation and thus the formation of undesirable by-products (e.g., tetrahydrofuran derivatives) that can no longer be economically utilized in the production of bio-based polymers.Without being bound by theory, favorable results are obtained using the hydrogenation conditions and catalysts described here, due to the effective conversion of not only small amounts of aldehyde derivatives, but also small amounts of degradation products that may have aldehyde groups and / or may have conjugated double bonds. These aldehyde derivatives and their degradation products may cause early color loss and decreased color stability. Selective hydrogenation results in these aldehyde groups being converted to hydroxyalkyl groups. For example, in the case of any aldehyde derivative of FDCA or its esterified derivatives as described above, the formyl group directly attached to the furan ring can be converted to a hydroxymethyl group directly attached to the furan ring, the formylmethyl group can be converted to a hydroxyethyl group, or the formylethyl group can be converted to a hydroxypropyl group. In the case of contaminants that are aldehyde derivatives of FDCA or esterified derivatives of FDCA, where the aldehyde group is a formyl group, the contaminant can be selectively hydrogenated to its hydroxymethyl derivative. For example, in the case of FFCA (an aldehyde derivative of FDCA), this contaminant can be selectively hydrogenated to its hydroxymethyl derivative, 5-hydroxymethyl-2-furancarboxylic acid (HMFCA).In the case of FFME (an aldehyde derivative of FDME, which is an esterified derivative of FDCA), this contaminant can be selectively hydrogenated to its hydroxymethyl derivative, 5-hydroxymethyl-2-furancarboxylic acid methyl ester (HMFME). A representative hydrogenation method includes contacting a monomer composition requiring mitigation with hydrogen in the presence of a catalyst and under sufficiently mild hydrogenation conditions (in particular at sufficiently low temperatures) so that contaminants associated with color formation or with color instability are selectively hydrogenated, and in the case of a composition including FDCA or an ester of FDCA, without simultaneously reducing the unsaturated furan ring in the FDCA or an esterified derivative of FDCA to a substantial degree, e.g., retaining at least 99.5 percent of the FDCA or esterified derivative of FDCA originally found in the composition, and in other embodiments, at least 99.6, 99.7, 99.8 and 99.9 percent of FDCA or esterified derivatives of FDCA, intact in hydrogenated composition. The hydrogenation catalyst is typically in solid form and in certain embodiments will include at least a first noble metal, and in other embodiments preferably includes a first noble metal and a second noble metal, in all embodiments, however, of such a type that under mild hydrogenation conditions (usually meaning at temperatures of 120 degrees Celsius or less) the catalyst is sufficiently active to hydrogenate the aldehyde derivatives found in the untreated composition but is not so active as to simultaneously reduce the unsaturated furan rings in said compositions that include FDCA or esterified derivatives of FDCA to a substantial extent. Noble metal in this case is understood to refer to a class of metallic elements that are resistant to oxidation. In a representative embodiment, the first noble metal, and preferably both the first and second noble metals, may be selected from the group including platinum (Pt), rhodium (Rh), ruthenium (Ru), palladium (Pd), silver (Ag), osmium (Os), iridium (Ir), and gold (Au), with the term comprising being used solely to indicate the member of the group, according to the particular embodiment, from which the noble metal is selected, but not precluding the addition of other noble metals and / or other metals in general. Therefore, a hydrogenation catalyst that includes a noble metal includes a catalyst that includes at least two noble metals, as well as a catalyst that includes at least three noble metals, and similarly a catalyst that includes two noble metals and a third, non-noble metal such as a promoter metal (e.g., a transition metal).Representative promoter metals can be selected from Groups 12-14 of the Periodic Table, such as from Group 13 or Group 14 of the Periodic Table. Preferred promoter metals are selected from the group that includes zinc (Zn), gallium (Ga), germanium (Ge), indium (In), and tin (Sn), with Sn being preferred. One or more promoter metals can be present in amounts, or combined amounts, generally from 0.3 wt% to 10 wt%, and typically from 0.5 wt% to 3 wt%, based on the weight of the catalyst. According to preferred embodiments, one or more noble metals and / or one or more promoter metals are present in amounts, or combined amounts, generally from 0.1 wt% to 10 wt%, and typically from 0.5 wt% to 5 wt%, based on the weight of the catalyst. Regardless of the amount, the hydrogenation catalyst may be a solid-supported noble metal-containing catalyst, meaning that the noble metal and optionally the promoter metal are placed on a solid support, which may be substantially refractory (inert) under the hydrogenation conditions, or which may function by itself (e.g., in terms of providing acid or base sites to provide or enhance catalytic activity). Carbon, including activated carbon, is an exemplary solid support. In the case of at least two, or only two, noble metals being present, they may each be freely present in amounts from 0.05 wt% to 5 wt%, or from 0.3 wt% to 3 wt%, based on the weight of the catalyst.For example, a representative hydrogenation catalyst may include two noble metals, Pt and Ru, which may be freely present in amounts within this range (e.g., from 0.05 wt% to 5 wt%). That is, Pt may be present in that amount, Ru may be present in that amount, or both Pt and Ru may be present in that amount. The hydrogenation catalyst may include either or both of these noble metals, or other noble metals, in specific amounts, or in combined amounts, as described above. A preferred hydrogenation catalyst will primarily include the noble metals Pt and Ru, together with the promoter metal Sn, with these metals present in amounts as described above. The hydrogenation catalyst, according to certain embodiments, includes from 0.1 wt% to 1 wt% (preferably from 0.3 wt% to 1 wt%) Pt, from 0.5 wt% to 5 wt% (preferably from 1 wt% to 3 wt%) Ru, and from 0.5 wt% to 5 wt% (preferably from 1 wt% to 3 wt%) Sn. In a representative embodiment, a single noble metal (e.g., Pt or Ru), or alternatively two noble metals (e.g., both Pt and Ru) may be the only noble metals present in the hydrogenation catalyst, such that, for example, the other noble metals are / are present in an amount or combined amount of less than 0.1% by weight, or less than 0.05% by weight, based on the weight of the hydrogenation catalyst. In a further representative embodiment, a single noble metal (e.g., Pt), or two noble metals (e.g., both Pt and Ru), and optionally a promoter metal (e.g., Sn) are substantially the only metals present in the hydrogenation catalyst, with the exception of metals that may be present in the solid support (e.g., such as aluminum present in the solid support as aluminum oxide).Therefore, in the case of a support comprising substantially all carbon, a single noble metal, or two noble metals, and an optional promoter metal, may be substantially the only metals present. For example, other metals, in addition to the single noble metal, or two noble metals, the optional promoter metal, and the solid support metal (if present), may be present in an amount or combined amount of less than 0.1 wt%, or less than 0.05 wt%, based on the weight of the hydrogenation catalyst. Any metal present in the catalyst, including the noble metal and the optional promoter metal, may have a metal particle size in the range generally from 0.3 nanometers (nm) to 20 nm, typically from 0.5 nm to 10 nm, and frequently from 1 nm to 5 nm. Noble metals and optional promoter metals of a representative hydrogenation catalyst may be disposed of or deposited on a solid support, which is intended to include a catalyst in which the noble metal and optional promoter metal are / are present on the surface of the support and / or within an internal structure of the porous support. Therefore, in addition to said noble metal and optional promoter metal, the representative hydrogenation catalyst may further include a solid support, with the exemplary solid support including carbon and / or one or more metal oxides. The exemplary metal oxides are selected from the group including aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, strontium oxide, tin oxide, etc.The solid support may include all, or substantially all of one or more of such metal oxides, for example such that the one or more metal oxides are present in an amount, or combined amount, of at least about 95% by weight of the solid support. Alternatively, carbon, such as activated carbon, may be present in an amount of at least 95% by weight, or at least 99% by weight, of the solid support. Activated carbon refers to a form of carbon that has undergone one of a number of possible treatments (e.g., high temperature evaporation) to increase porosity. Activated carbon also refers to a form obtained by chemical treatment (e.g., acid or base) to change properties such as the concentration of acid sites. The noble metal and optionally the promoter metal may be incorporated into the solid support according to techniques known for catalyst preparation, including sublimation, impregnation, or dry blending. In the case of impregnation, an impregnating solution of a soluble compound of one or more noble metals and optionally one or more promoter metals in a polar (aqueous) or nonpolar (e.g., organic) solvent may be brought into contact with the solid support, preferably under inert conditions. For example, this contact may be carried out, preferably with stirring, in an ambient atmosphere of nitrogen, argon, and / or helium, or alternatively in a non-inert atmosphere, such as air. The solvent may then be evaporated from the solid support, for example using heating, flowing gas, and / or vacuum conditions, leaving a dry, noble metal-impregnated and optionally promoter-impregnated support.The noble metal and the promoter metal may be impregnated in the solid support, as in the case of two noble metals and the promoter metal being impregnated simultaneously by being dissolved in the same impregnation solution, or alternatively impregnated separately using different impregnation solutions and impregnation steps. In any case, the noble metal impregnated support and the promoter impregnated support may optionally be subjected to further preparation steps, such as washing with a solvent to remove excess noble metal, optional promoter metal, and impurities, further drying, calcination, etc. to produce the hydrogenation catalyst. The solid support itself can be prepared according to known methods, such as extrusion to form cylindrical particles (extrudates) or oil droplets or spray drying to form spherical particles. Regardless of the specific shape of the solid support and the resulting catalyst particles, the amount of noble metal and optional promoter metal present in the hydrogenation catalyst, as described above, refers to the weight of said noble metal and optional promoter metal, on average, in a particular catalyst particle (e.g., of any shape such as cylindrical or spherical), regardless of the specific distribution of the noble metal and optional promoter metal within the particle. In this regard, it is understood that different preparation methods may provide different distributions, such as deposition of the noble metal and optional promoter metal primarily on or near the surface of the solid support or uniform distribution of the noble metal and optional promoter metal throughout the solid support.In general, the weight percentages described herein, which are based on the weight of the solid support or on the weight of the hydrogenation catalyst, may refer to the weight percentage in a single catalyst particle but more specifically refer to the average weight percentage over a large number of catalyst particles, such as the number in a hydrogenation reactor that forms the catalyst bed as used in the stabilization method described herein. Typical hydrogenation conditions include high hydrogen partial pressures, such as at least 2 megapascals (MPa) (291 psi), for example from 2 MPa (291 psi) to 18 MPa (2,611 psi), and more specifically from 2.5 MPa (363 psi) to 10 MPa (1,450 psi). The pressure in a hydrogenation reactor can be generated predominantly or substantially from hydrogen, such that this range of hydrogen partial pressures can relate substantially to the total pressure. However, the presence of other gas species evaporated from the reaction mixture (e.g., evaporated solvent), can cause the hydrogen partial pressure to decrease relative to this total pressure, so that, for example, the total pressure of a hydrogenation reactor can range from, for example, 2.5 MPa (363 psi) to 20 MPa (2,900 psi), and more specifically from 3 MPa (435 psi) to 12 MPa (1,740 psi). Reaction temperatures typically less than 120 degrees Celsius will be preferred for carrying out hydrogenations, and as shown in the worked examples below, temperatures on the order of 50 or 60 degrees Celsius were found to be sufficient with the exemplary hydrogenation catalysts and with sufficient hydrogen supplied to reduce substantially all of the aldehyde derivatives in the FDCA and FDCA ester-containing compositions tested, while simultaneously leaving the furan ring intact. The reaction time, i.e., the time during which the reaction mixture is maintained under pressure and temperature conditions at any target value or target subrange within any of the pressure and temperature ranges given above (e.g., a target total pressure value of 4.1 MPa (600 psi) and a target temperature of 80°C (176°F), is from 0.1 h to 24 h, and preferably from 0.5 h to 5 h, in the case of batch-by-batch reactions. For continuous processes, this reaction time corresponds to the reactor residence time. An additional parameter relevant for continuous processes is the weight hourly space velocity (WHSV), which in the art is understood as the weight of the feed stream (e.g., monomer composition) to the reactor per hour, divided by the weight of the hydrogenation catalyst. Therefore, this parameter represents the equivalent catalyst base weight of the feed processed per hour, and it is related to the inverse of the reactor residence time.According to a representative embodiment, the hydrogenation conditions include a WHSV generally from 0.01 h1 to 2 0 h 1, and typically from 0.05 h-1 to 5 h-1. These mild hydrogenation conditions, in combination with a judiciously selected, less active hydrogenation catalyst, result in the selective hydrogenation of problematic aldehyde derivatives to the corresponding hydroxyalkyl derivatives. Compositions comprising these aldehyde derivatives, after being introduced into a hydrogenation reactor used to contact this feed and hydrogen in the presence of a hydrogenation catalyst, may be dissolved in a suitable solvent (e.g., an organic solvent including, or comprising, methanol or other alcohol). The untreated composition, optionally together with the solvent, as well as hydrogen, may be added batch-by-batch or continuously to the hydrogenation reactor. For example, in the case of continuous operation, hydrogen may be present in the recycle gas stream and added in molar excess with respect to the aldehyde derivatives present in the monomer composition.In continuous or batch-by-batch operation, the reaction mixture including the composition and solvent may be maintained under hydrogenation conditions as described herein, to produce an aldehyde-mitigated composition for further processing or use. A continuous hydrogenation process can therefore be carried out by continuously feeding the composition requiring mitigation (e.g., in the form of a soluble composition dissolved in a solvent), and hydrogen to a hydrogenation reactor containing a catalyst (e.g., as a fixed bed) and continuously withdrawing, from the reactor, the resultant hydrogenated / aldehyde-reduced composition, optionally following its separation from excess (unreacted) hydrogen. According to some embodiments, the composition in question may be subjected to one or more purification steps prior to hydrogenation, to reduce the amount of aldehyde present and thereby reduce the requirements (e.g., hydrogen consumption, hydrogen partial pressure, and / or temperature) for achieving below a threshold level of a particular color-related aldehyde in the particular composition. For example, a further representative method may include, prior to (e.g., upstream of) contact with hydrogen, crystallizing a crude composition comprising FDCA or one or more esterified derivatives of FDCA, to increase its purity (relative to the crude composition) in the FDCA or one or more esterified derivatives of FDCA before a hydrogenation step is performed on the composition. Consequently and parenthetically, subjecting a composition to hydrogenation as a particular means of mitigating aldehydes present in a composition shall not be considered as another means of mitigating aldehydes by removing a portion of the aldehyde from the composition or by other means cannot also be used; instead, a combination of mitigation steps may be used, including, but not limited to, the exemplary methods described herein. Crystallization may include dissolving the crude composition in a suitable solvent (e.g., an organic solvent including methanol or other alcohol) and then cooling the crude composition / solvent system to crystallize the composition. In certain embodiments, the desired product purity in the crude composition from the previous oxidation step will typically be 85 wt% or less (e.g., from 70 wt% to 85 wt%). As a result of crystallization, the purity of the hydrogenated composition may be increased to 99 wt% or more. For example, in some embodiments, crystallization of the crude composition may achieve a purity specification of at least 99.5 wt%, with in all cases a reduction in the content of the aldehyde derivative. In some embodiments, in fact, crystallization alone may be found to be sufficient as a means of mitigation without further, although it is generally expected that some further mitigation, e.g., by hydrogenation of compositions of the type described above would be desirable. For example, a crystallization step may reduce the b* chromaticity coordinate from a value greater than 5, or greater than 10, to a value less than 5. In general, crystallization of a crude composition including FDCA or an esterified derivative thereof may result in a composition containing a monomer having a b* chromaticity coordinate less than 5, less than 3, or even less than 1. All or primarily all of the color improvement associated with crystallization may be due to a reduction in the amount of aldehyde present in the monomer-containing composition.For example, crystallization of a crude FDCA composition or a crude FDME composition may reduce the amount of the corresponding FFCA or FFME from the values ​​described above (e.g., from 0.3 wt% to 10 wt%, FFCA in the case of an FDCA composition or from 0.1 wt% to 3 wt% FFME in the case of an FDME composition), or optionally from other initial amounts for certain crude compositions that include FDCA or esterified derivatives thereof, to less than 1 wt%, less than 0.5 wt%, or even less than 0.2 wt%, of the corresponding aldehyde derivative. Therefore, while it will be understood from the above that the removal of at least some of the aldehydes, in the initial purification of a crude composition comprising FDCA or its esterified derivatives (e.g., by crystallization), may in itself substantially improve the color and / or color stability of the resulting monomer-containing composition and may provide a high purity material with a substantial reduction in the concentration of aldehydes (color precursors) present, it will be borne in mind that even very small amounts of residual aldehydes and / or other color bodies may cause the resulting composition to fail to meet certain color specifications, such as a b* chromaticity coordinate of less than 0.5, so that some further mitigation e.g., by hydrogenation as described herein will typically also be employed. As described above, the hydrogenation method contemplated herein is selective so that the aldehyde groups present in a composition are effectively neutralized as a source of final color development by molecular weight buildup through aldol condensation. In representative embodiments, either as a result of conversion of the aldehyde groups to something else (by selective hydrogenation or some other means of derivatization), use of crystallization or some other means of removing the aldehyde functionality from the composition or by a combination of removing and changing the aldehyde functionality in a composition, the total amount of aldehyde in combination in a composition will in any case be reduced to less than 500 wt.ppm, less than 200 wt.ppm, or even less than 100 wt.ppm. Other mitigation measures contemplated when excessive levels of aldehydes are indicated to be present in a composition by the quantitative analysis methods of the present invention would involve the addition of one or more color stabilizing additive compounds to the composition, the measures of which are described in the commonly designated WO 2019 / 246034, Color Stabilization of Monomers and Other Reactants for Forming Bio-Based Polymers (application WO'034). As demonstrated in WO'034 and in the examples below reproduced from WO'034, these color stabilizing additive compounds have been demonstrated to be useful for reducing color development in compositions containing FDCA and FDCA esters such as those produced by the Medieval-type oxidation of one or more furanate precursors from the dehydration of hexose sugars (such as fructose). Representative color stabilizer additive compounds taught in WO'034 include substituted phenols, which refer to compounds having at least one phenol group, but possibly two or more phenol groups, where the benzene ring of the moiety or moieties has at least one substituent, in addition to the hydroxyl substituent. Typical examples of such substituents are alkoxy and alkyl substituents, with methoxy and tert-butyl substituents being preferred. Therefore, examples of substituted phenols include alkoxy-substituted (e.g., methoxy-substituted) and alkyl-substituted (e.g., tert-butyl-substituted) phenols, which are compounds having at least one phenol moiety, but possibly two or more phenol moieties, with one or more alkoxy (e.g., methoxy) and alkyl (e.g., tert-butyl) substituents, respectively.In the case of tert-butyl substituted phenols, these compounds are often referred to as hindered phenols, given the steric hindrance resulting from the geometry of this substituent. Substituted phenols include butylated hydroxyanisole (BHA); 2,6-dimethoxyphenol (DMP); 2,6-di-tert-butyl-4-methoxyphenol (DTMP); pentaerythritol tetrakis[3-[3,5-di-tertbutyl-4-hydroxyphenyl]propionate (PETC); 2-tert-butylhydroquinone (TBHQ); ethylenebis(oxyethylene)bis-(3-(5-tert-butyl-4hydroxy-m-tolyl)-propionate); and octadecyl-3-(3,5-di-tertbutyl-4-hydroxyphenyl)-propionate. Of these compounds, (i) BHA, DMP, and DTMP are methoxy-substituted phenols, and (ii) DTMP, PETC, TBHQ, ethylenebis(oxyethylene)bis-(3-(5-tert-butyl-4hydroxy-m-tolyl)-propionate); and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate are tert-butyl-substituted phenols. Other color-stabilizing additives include phenyl-substituted amines (e.g., 4,4'-bis(a,a-dimethylbenzyl) diphenylamine (XDPA)), phosphites (e.g., tris(2,4-di-tertbutylphenyl)phosphite), and antioxidant vitamins (e.g., ascorbic acid).PETC compounds are commercially available as Irganox®1010 (BASF) or Dovernox®10 (Dover Chemical). Corp.); the compound ethylenebis(oxyethylene)bis-(3-(5-tert-butyl-4hydroxy-m-tolyl)-propionate) is commercially available as Irganox®245 (BASF); the compound tris(2,4-di-tert-butylphenyl)phosphite is commercially available as Irgafos®168 (BASF); and the compound octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate is commercially available as Irganox®1076 (BASF) or Dovernox®76 (Dover Chemical Corp.). Certain combinations of compounds and / or classes of compounds as described above are commercially available and can be readily used, if desired. For example, a combination of 50 wt% PETC and 50 wt% tris(2,4-di-tert-butylphenyl)phosphite is commercially available as Irganox®B255 (BASF). 20 wt% octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and 80 wt% tris(2,4-di-tert-butylphenyl)phosphite are commercially available as Irganox®B900 (BASF). A combination of 50 wt% PETC and 50 wt% tris(2,4-di-tert-butylphenyl)phosphite is commercially available as Irganox®B225 (BASF). Color stabilizing additive compounds may be used in compositions requiring mitigation in specific amounts, or combined amounts in the case of combinations, generally from 10 parts per million by weight (wt-ppm) to 1 percent by weight (wt%), typically from 50 wt-ppm to 2,000 wt-ppm, and often from 50 wt-ppm to 1,500 wt-ppm. According to preferred embodiments, BHA additives may be present in the composition in amounts from 100 wt-ppm to 500 wt-ppm, or the additive Irganox®245 may be present in the composition in amounts of 800 weight-bpj to 1,200 weight-bpj. In another preferred embodiment, the additive BHA may be present in the composition in an amount of from 50 wt.ppm to 800 wt.ppm or, more preferably, from 50 wt.ppm to 500 wt.ppm. In another preferred embodiment, the additive DMP may be present in the composition in an amount of from 200 wt.ppm to 1,500 wt.ppm or, more preferably, from 400 wt.ppm to 600 wt.ppm. In another preferred embodiment, the additive DTMP may be present in the composition in an amount of from 50 wt.ppm to 100 wt.ppm. In another preferred embodiment, the additive XDPA may be present in the composition in an amount of from 100 wt.ppm to 1,500 wt.ppm. In another preferred embodiment, the additive PETC may be present in the composition in an amount of from 200 wt.ppm to 1,500 wt.ppm. In another preferred embodiment, the additive Irganox®245 may be present in the composition in an amount of from 50 wt.ppm to 1,500 wt.ppm or, more preferably, from 50 wt.ppm to 100 wt.ppm. In another preferred embodiment, the additive Irganox®B900 may be present in the composition in an amount of from 50 wt.ppm to 1,500 wt.ppm or, more preferably, from 50 wt.ppm to 500 wt.ppm.In another preferred embodiment, the additive Irganox®B225 may be present in the composition in an amount from 1,500 wt.ppm to 1,500 wt.ppm or, more preferably, from 50 wt.ppm to 500 wt.ppm. The following examples illustrate and support various aspects of the present invention as just described: EXAMPLE EXAMPLES 1 — 4 For these examples, a number of solutions of aldehyde derivatives were prepared in methylene chloride, using predetermined amounts of aldehyde derivative impurities associated with the preparation of FDME (FFME), with the preparation of TPA (4-formylbenzoic acid (or 4-carboxybenzaldehyde (4-CBA)) and terephtaldehyde) and with the preparation of DMT (methyl-4-formylbenzoate) and using various volumes of further dilution of methylene chloride. Appropriate amounts of DPPD sulfate were then added to each of these solutions, in the form of a solution of DPPD sulfate in a solvent comprising 0.3 weight percent acetic acid in methanol.After thirty minutes of stirring to allow for the formation of the desired imine adducts, each solution was then analyzed by UV-Vis spectroscopy to verify the ability of the instrumental method to show proportional absorbance for the amount of relevant aldehyde-derived impurities present in a given solution, generally across a range of wavelengths ranging from 410 nm to 460 nm. The analysis demonstrated that the UV-Vis spectroscopy would be effective for accurately quantifying FFME at levels at least as low as 900 parts per billion by weight, 4-CBA at levels at least as low as 495 parts per billion by weight, terephthaldehyde at levels at least as low as 443 parts per billion by weight and methyl-4-formylbenzoate at levels at least as low as 540 parts per billion by weight. EXAMPLE 5 For an initial example demonstrating hydrogenation as an effective mitigation measure in the determination of excessive amounts of aldehydes, in particular, in compositions including FDCA or esters of FDCA (given that hydrogenation / reduction has previously been known to overcome 4CBA in landfill), a mixture of 3 grams of FDME and 0.5 grams of FFME, dissolved in 20 ml of methanol, was added to a 75 ml high-pressure reactor (Parr Instrument Company). To this solution was added 0.5 grams of solid hydrogenation catalyst particles containing 2 wt% Ru / 2 wt% Sn / 0.5 wt% Pt, supported on carbon. The reactor was pressurized and purged with hydrogen (three times at 500 psi) while continuously stirring the reaction mixture at 800 rpm. The vessel was then pressurized with hydrogen to 600 psi, and the reaction contents were heated to 50°C and maintained at this temperature for 1 h.The reaction mixture was then cooled to room temperature and filtered by vacuum filtration to remove the catalyst. The filtrate was then subjected to rotary evaporation to remove the solvent and yield a white solid. This solid was analyzed by nuclear magnetic resonance (NMR) to resolve the components of the product mixture. This mixture was found to contain 84.9% FDME by weight, or nearly the same content as the initial mixture of FDME and FFME, with the exception of only 3.1% FFME by weight. The hydroxymethyl derivative and hydrogenation product, HMFME, were also present. Therefore, the results indicate that most of the FFME was converted, or partially reduced, to HMFME, without altering FDME. EXAMPLE 6 The Example 5 experiment was repeated, except with a reaction temperature of 60°C instead of 50°C. In this case, the product mixture contained 84.9 wt% FDME, or nearly the same content as the initial mixture of FDME and FFME, with only 4.2 wt% FFME. The hydroxymethyl derivative and hydrogenation product, HMFME, was also present, as well as a small amount (less than 1,000 wt-ppm) of a hydrogenation product containing a (saturated) tetrahydrofuran ring. Again, these results indicate that, even at this higher temperature compared to that used in Example 5 above, most of the FFME was converted, or partially reduced, to HMFME, without changing the FDME. EXAMPLE 7 The Example 5 experiment was repeated, except with a reaction pressure of 1,200 psi instead of 600 psi. In this case, the product mixture contained 84.8% FDME by weight, or nearly the same content as the initial mixture of FDME and FFME, except for only 0.3% FDME by weight. FFME. The hydroxymethyl derivative and hydrogenation product, HMFME, is also present, as are small amounts (less than 1,000 wt.ppm) of hydrogenation products containing a (saturated) tetrahydrofuran ring. By increasing the reaction rate, in this case by increasing the hydrogen pressure, it was observed that FFME was almost completely converted, and still without significant loss of FDME by ring saturation. COMPARISON EXAMPLE 1 The Example 5 experiment was repeated, except with a reaction temperature of 80°C instead of 50°C, and a pressure of 500 psi instead of 600 psi. Also, the catalyst contained 2 wt% Ru / 1 wt% sulfur (S), supported on carbon. Using this catalyst composition, essentially all of the furan rings of the starting mixture were hydrogenated to the corresponding tetrahydrofuran rings, resulting in the loss of the desired FDME. COMPARISON EXAMPLE 2 The experiment of Comparative Example 1 was repeated, except the catalyst contained 2 wt% Ru, supported on carbon. Using this catalyst composition, essentially all of the furan rings of the starting mixture were hydrogenated to the corresponding tetrahydrofuran rings, resulting in the loss of the desired FDME. EXAMPLE 8 The partial hydrogenation of 5-hydroxymethyl furfural (HMF) to produce 2,5-dihydroxymethylfuran was investigated. A 10-gram sample of HMF, dissolved in 90 grams of methanol, was added to a 300-ml high-pressure Parr reactor (Parr Instrument Company). To this solution were added 1.5 grams of solid hydrogenation catalyst particles containing 5 wt% Ru, supported on carbon. The reactor was pressurized and purged with hydrogen (three times at 500 psi pressure) while continuously stirring the reaction mixture at 600 rpm. The vessel was further pressurized with hydrogen to 1,000 psi, and the reaction contents were heated to 100°C and maintained at this temperature for 1 hour. The reaction mixture was then cooled to room temperature and filtered by vacuum filtration to remove the catalyst. The filtrate was then subjected to rotary evaporation to remove the solvent and obtain a light brown oil.This oil was analyzed by nuclear magnetic resonance (NMR) to separate the components of the product mixture containing 2,5-dihydroxymethylfuran. EXAMPLE 9 The partial hydrogenation of 5-acetylmethyl furfural (AcMF) was investigated to produce 2-hydroxymethyl, 5-acetylmethyl furan. A 20-gram sample of AcMF, dissolved in 80 grams of methanol, was added to a 300-ml high-pressure Parr reactor (Parr Instrument Company). To this solution were added 3 grams of solid hydrogenation catalyst particles containing 5 wt% Ru, supported on carbon. The reactor was pressurized and purged with hydrogen (three times at 500 psi) while continuously stirring the reaction mixture at 600 rpm. The vessel was further pressurized with hydrogen to 1,000 psi, and the reaction contents were heated to 100°C and maintained at this temperature for 1 hour. The reaction mixture was then cooled to room temperature and filtered by vacuum filtration to remove the catalyst. The filtrate was then subjected to rotary evaporation to remove the solvent and obtain a light brown oil.This oil was analyzed by nuclear magnetic resonance (NMR) to separate the components of the product mixture, which contained >95% by weight of 2hydroxymethyl,5-acetylmethyl furan. EXAMPLE 10 The color and color stability of samples containing FDME, with FFCA from 100 wt.ppm to 10,000 wt.ppm, were investigated. To prepare the samples, 20 grams of FDME in each box, with the specified proportion of FFCA, were placed into 25 ml headspace vials, each equipped with a magnetic stir bar. The vials were then placed in a heating block preheated to a specified temperature. Complete melting of the samples was observed between 5-10 minutes, and the stirring speed was set at 500 rpm. After the specified time, the samples were removed, cooled to room temperature, and then analyzed for color, specifically the L*a*b* chromaticity coordinates and the APHA color index. The samples used for color analysis contained 6 wt% FDME / FFCA in a 1:1 solvent mixture of acetonitrile / isopropanol. Each measurement was performed in triplicate and averaged. Contaminant concentrations, in addition to the temperature, time, and atmosphere conditions for stability testing, are shown in Table 1 below, along with the results for each sample and a commercial reference sample (Sarchem).Assuming color specifications of L*>99, a*<0.5, b*<0.5, and APHA <10, an indication of whether the sample passes or fails the specification is also included in this table. Table 1—FFCA in FDME, Color Stability Testing Experiment Name Data L*(C) a*(C) b*(C) APHA Specification - IPA-Matrix Acetonitrile 99.98 0.00 0.00 0 - - FDME (Sarchem) 99.82 -0.01 0.02 0 - 1 100 ppm FFCA in FDME, 120oC, 2 hours, N2 99.82 0.00 0.05 1 Pass 2 100 ppm FFCA in FDME, 120oC, 2 hours, Air 99.45 -0.08 0.16 3 Pass 3 100 ppm FFCA in FDME, 200oC, 2 hours, N2 99.72 -0.13 0.54 19 Fail 4 100 ppm FFCA in FDME, 2 0 0oC, 2 hours, Air 99.45 -0.17 1.10 38 Fail 5 1000 ppm FFCA in FDME, 120oC, 2 hours, N2 99.77 0.01 0.11 4 Pass 6 1000 ppm FFCA in FDME, 120oC, 2 hours, Air 99.61 -0.11 0.21 6 Pass 7 1000 ppm FFCA in FDME, 200oC, 2 hours, N2 99.72 -0.26 0.84 26 Fail 8 1000 ppm FFCA in FDME, 200oC, 2 hours, Air 99.45 -0.27 1.43 46 Failed 9 1000 ppm FFCA in FDME, 200oC, 2 hours, N2 99.77 -1.10 3.90 127 Failed 10 1000 ppm FFCA 99.81 -0.92 3.70 122 Failed in FDME, 200oC, 2 hours, Air This example highlights that FFCA leads to color formation, particularly at elevated temperatures, similar to that encountered during esterification. The most easily violated specification is the b* chromaticity coordinate, which is <0.5. Importantly, even a relatively low FFCA level of 100 ppm can result in failure to meet this specification. EXAMPLE 11 The color and color stability of samples containing FDME were investigated, according to the protocol used in Example 10, except that in these samples 100 wt.-ppm to 10,000 wt.-ppm of FFME were used as color formers / contaminants. The contaminant concentrations, in addition to the temperature, time, and atmosphere conditions for stability testing, are shown in Table 2 below, along with the results for each sample and a commercial reference sample (Sarchem). With the same presumptive color specifications of L*>99, a*<0.5, b*<0.5, and APHA <10, an indication of whether the sample passed or failed the specifications is also included in this table. Table 2—FFME in FDME, Color Stability Testing Experiment Name Data L*(C) a*(C) b*(C) APHA Specification - IPA-Matrix Acetonitrile 99.98 0.00 0.00 0 - — FDME (Sarchem) 99.82 -0.01 0.02 0 — 1 100 ppm FFME in FDME, 120oC, 2 hours, N2 99.71 0.00 0.11 2 Pass 2 100 ppm FFME in FDME, 120oC, 2 99.80 -0.03 0.23 4 Pass hours, Air 3 100 ppm FFME in FDME, 200oC, 2 hours, N2 99.63 -0.16 0.63 18 Fail 4 100 ppm FFME in FDME, 200oC, 2 hours, Air 99.58 -0.25 1.31 46 Fail 5 1000 ppm FFME in FDME, 120oC, 2 hours, N2 99.82 0.02 0.16 3 Pass 6 1000 ppm FFME in FDME, 120oC, 2 hours, Air 99.79 0.09 0.31 7 Pass 7 1000 ppm FFME in FDME, 200oC, 2 hours, N2 99.35 -0.22 1.02 33 Failed 8 1000 ppm FFME in FDME, 200oC, 2 hours, Air 99.28 -0.38 1.84 69 Failed 9 1000 ppm FFME in FDME, 200oC, 2 hours, N2 99.92 -1.77 4.82 189 Failed 10 1000 ppm FFME in FDME, 200oC, 2 hours, Air 99.61 -2.02 8.17 256 Failed This example highlights that FFME leads to color formation, particularly at elevated temperatures, similar to that encountered during esterification. As in Example 10, the most easily violated specification 5 is the chromaticity coordinate b*, which is <0.5. Importantly, even a relatively low FFME level of 100 ppm can result in failure to meet this specification. EXAMPLE 12 Samples containing FDME and varying levels of FFME, as shown in Table 3 below, were prepared according to the protocol used in Example 10, and then analyzed for color, and specifically the L* a* b* chromaticity coordinates and the APHA color index. The samples used for color analysis contained 6 wt% FDME / FFME in a 1:1 acetonitrile / isopropanol solvent mixture. These samples were then subjected to a hydrogenation step for stabilization. The color results, both before and after hydrogenation, are also shown. Table 3—FFME in FDME, Color Testing with Hydrogenation Colorimetry: Transmittance, 6% by weight of solids in 1:1 acetonitrile / isopropanol Sample Name Data L*(C ) a*(C ) b*(C ) Hazen / AP HA 99.1 — 1 15% FFME in FDME 1 2.57 7.65 236 99.4 - 2 3% FFME in FDME 7 1.80 5.12 160 99.3 - 3 0.3% FFME in FDME 3 1.68 2.25 97 15% FFME in FDME, Post 99.7 - 4 Hydrogenation 6 0.32 0.98 28 3% FFME in FDME, Post 99.8 - 5 Hydrogenation 7 0.12 0.38 14 0.3% FFME in FDME, Post 99.9 - 6 Hydrogenation 0 0.03 0.10 2 The results showed a strong correlation between the amount of FFME contaminants initially present in the FDME and the resulting sample color. More importantly, however, hydrogenation had a profound impact in terms of color enhancement, and in fact, this improvement was visible even in visual comparisons between samples before and after hydrogenation. EXAMPLE 13 Samples containing FDCA and varying levels of FFCA, as shown in Table 4 below, were prepared according to the protocol used in Example 10, and then analyzed for color, and specifically for the L* a* b* chromaticity coordinates and the APHA color index. The samples used for color analysis contained 1% by weight of FDCA / FFCA in a TEGMME solvent mixture. These samples were then subjected to a hydrogenation (reduction) step for stabilization. The color results, both pre- and post-hydrogenation (reduction) are also shown below in Table 4. Table 4—FFCA in FDCA, Color Test with Hydrogenation to Hazen / APH l Name Data L*(C) a*(C) b*(C) A 1 14% FFCA in FDCA 98.28 -2.58 10.11 334 2 3% FFCA in FDCA 98.47 -2.21 8.73 286 3 1% FFCA in FDCA 99.33 -1.39 4.52 145 4 0.3 % FFCA in FDCA 99.68 -0.62 2.14 67 14% FFCA in FDCA, 5 Post-Reduction 100.01 -0.06 0.07 0 3% FFCA in FDCA, 6 Post-Reduction 99.89 -0.05 0.11 1 1% FFCA in FDCA, 7 Post Reduction 99.96 -0.02 0.07 1 0.3% FFCA in FDCA, 8 Post Reduction 99.99 -0.03 0.09 1 As in Example 12, these results also show a strong correlation between the amount of contaminant, in this case FFCA, initially present in the FDCA, and the resulting sample color. Hydrogenation has a significant impact in terms of color improvement, and this improvement is visible even in a visual comparison between the samples before and after hydrogenation. The FDCA in the samples was essentially left intact, with 99.7 percent of the FDCA remaining after hydrogenation in Samples 1 and 3, 99.8 percent of the FDCA remaining intact in Sample 4 after hydrogenation, and 99.9 percent of the FDCA remaining after hydrogenation in Sample 2. EXAMPLE 14 An FDME sample was crystallized from the mother liquor of the esterification reaction step and determined to have 82.6 wt% FDME (dimethyl ester), with 16.0 wt% monomethyl ester, FDMME, resulting from incomplete esterification. The sample also contained 0.36 wt% starting compound FDCA and 0.58 wt% aldehyde-derived contaminant FFME. The solid material was dissolved in a solvent mixture and analyzed for color according to the procedure in Example 6. The chromaticity coordinates L*, a* and b* were 69.38, 7.02, and 59.12, respectively, indicating a significant color change, particularly with respect to b*. The analyzed sample was then subjected to a hydrogenation step for stabilization. Analysis of the sample, post-hydrogenation, showed that it had, on a solvent-free basis, 82.9 wt% FDME, 16.1 wt% FDMME, and 0.45 wt% FDCA, and therefore hydrogenation had little impact in terms of converting these desired monomers.However, this sample did not have any detectable FFME, further indicating that hydrogenation is highly selective for aldehyde derivatives. Consistent with these analytical results, the L*, a*, and b* chromaticity coordinates of the post-hydrogenation sample increased significantly, to 99.26, -0.53, and 1.34, respectively. EXAMPLES 15 - 26 For the following example regarding the use of color-stabilizing additives as mitigation measures, color development in FDME was determined during a period of accelerated degradation testing. In each test, 10 grams of FDME sample was placed into a vial containing 20 ml of air headspace. The vial was then placed in a heating block, set to the temperature at which color stability was to be measured. Once the solid had melted and the desired temperature was reached, a timer was activated and, following the predetermined test time period, the vial was removed and allowed to cool to ambient conditions. Approximately 240 mg of the solid was then dissolved in 3.76 grams of a 1:1 (w / w) mixture of isopropanol (IPA) and acetonitrile, the mixture referred to as the matrix below. The solid and matrix were sonicated until completely dissolved, and the color of the solution was determined using a Konica Minolta CM-5 colorimeter. Table 5-7 below shows the results of tests performed on reference compositions, without color-stabilizing additives. APHA color values ​​and chromaticity coordinates L* a* b* were determined for (i) the initial matrix, (ii) the initial FDME, and (iii) the FDME samples, following heating at 120°C (248°F) for 1 hour (Table 5), or at 150°C (302°F) for 15 hours (Table 6), or at 120°C (248°F) for 48 hours (Table 7). Table 5 —FDME Matrix and Color Data, 120°C, 15 hours Data Name [Antioxidant] bpj L*(C ) a*(C ) b*(C ) APH A Targ et 1:1 IPA / Acetonitrile Matrix 0 99.9 8 0 0 0 **** * FDME 0 99.7 9 — 0.01 0.07 1 1 FDME #1, 120oC, 15 hours 0 99.6 6 0.05 0.54 19 2 FDME #2, 120oC, 0 99.4 - 0.56 20 15 hours 3 0.03 3 FDME #3, 120oC, 15 hours 0 99.7 3 - 0.02 0.63 23 4 FDME #4, 120oC, 15 hours 0 99.3 9 - 0.03 0.58 21 5 FDME #5, 120oC, 15 hours 0 99.6 7 - 0.02 0.67 25 **** * Mean 99.5 8 - 0.01 0.60 22 **** * Standard Deviation 0.13 0.03 0.04 2 Table 6 —FDME Matrix and Color Data, 150°C, 15 hours Sample Data Name # L*(C) a*(C) b*(C) APHA Target 1:1 IPA / Acetonitrile Matrix 0 100.1 -0.01 0.02 0 ***** FDME 0 99.79 -0.01 0.07 1 1 FDME #1, 150oC, 15 hours 1 99.74 0.07 0.56 21 2 FDME #2, 150oC, 15 hours 2 99.89 -0.09 0.65 24 3 FDME #3, 150oC, 15 hours 3 99.91 0.03 0.56 20 4 FDME #4, 150oC, 15 hours 4 99.74 0.01 0.58 21 5 FDME #5, 150oC, 15 hours 5 99.76 0.04 0.68 25 ***** Mean 99.81 0.01 0.61 22 ***** Standard Deviation 0.08 0.05 0.05 2 Table 7 —FDME Matrix and Color Data, 120°C, 48 hours Name Data Sample # L*(C) a*(C) b*(C) APHA Target 1:1 IPA / Acetonitrile Matrix 0 99.98 0 0 0 ***** FDME 0 99.79 -0.01 0.07 1 1 FDME #1, 120oC, 48 hours 1 99.99 0.00 0.72 24 2 FDME #2, 120oC, 48 hours 2 99.86 -0.02 0.78 25 3 FDME #3, 120oC, 48 hours 3 99.79 -0.01 0.92 32 4 FDME #4, 120oC, 48 hours 4 99.42 -0.04 0.82 26 5 FDME #5, 120oC, 48 hours 5 99.84 -0.01 0.76 25 ***** Mean 99.78 -0.02 0.8 26 ***** Standard Deviation 0.19 0.01 0.07 3 The initial FDME sample was obtained from a very pure source, as seen from the values ​​in the second row of Table 5-7 above. However, after exposure to all tested temperatures for each of the tested time periods, the APHA color exceeded 10 and the b* chromaticity coordinate exceeded 0.5. The color stabilizing additive compound was then tested for its ability to prevent color development in the FDME samples, during the accelerated degradation test period. The test was performed as described above, except that, prior to heating, each 10 gram FDME sample was filled with a measured amount of the additive into a vial. In the table below, the APHA color values ​​and chromaticity coordinates L* a* b* are shown as determined for (i) the original matrix, (ii) the original FDME, and (iii) the FDME samples, after heating with various weights of ppm of the color stabilizing additive compound. Specifically, the results obtained for the test at 120°C (248°F) for 15 hours with BHA are shown in Table 8. Table 8 — FDME with BHA Additive, 120°C, 15 hours Data Name [BHA] bpj L*(C) a*(C) b*(C) Δb* APHA Δ APHA Target 1:1 IPA / Acetonitrile Matrix 0 100 0 0 ***** 0 ***** ***** FDME 0 99.79 -0.01 0.07 ***** 1 ***** 1 FDME, 0 99.58 -0.01 0.60 ***** 22 ***** 120oC, 15 hours 2 FDME, 50 parts per hour BHA, 120 0.21 15 7 4 FDME, 200 parts per hour BHA, 120oC, 15 hours 200 99.48 -0.03 0.41 0.19 16 6 5 FDME, 300 parts per hour BHA, 120oC, 15 hours 300 99.58 -0.05 0.46 0.14 17 5 6 FDME, 500 ppm BHA, 120oC, 15 hours 500 99.77 -0.06 0.51 0.09 18 4 7 FDME, 1500 parts per hour BHA, 120oC, 15 hours 1,500 99.77 -0.06 0.72 -0.12 23 -1 According to these results, BHA has a color stabilizing effect on FDME, especially considering the decrease in the APHA color chromaticity coordinate b* value, relative to the reference composition in the third row of the table above. At BHA additive amounts of 50-1,500 ppm, the APHA color is reduced to less than 10. At BHA additive amounts of 50-300 ppm, b* is reduced to less than 0.5. The results obtained for testing at 130°C (266°F) for 6 hours with BHA are shown in Table 9. Table 9 — FDME with BHA Additive, 130°C, 6 hours Data Name [BHA] bpj L*(C) a*(C) b*(C) Δb* APHA Δ APHA Target 1:1 IPA / Acetonitrile Matrix 0 99.99 -0.01 0 ***** 0 ***** ***** FDME 0 99.79 -0.01 0.07 ***** 1 ***** 1 FDME, 130oC, 6 hours 0 99.75 -0.03 0.13 ***** 3 ***** 2 FDME, 50 ppm BHA, 130oC, 6 hours 50 99.81 -0.01 0.04 0.09 0 3 3 FDME, 100 parts per hour BHA, 130oC, 6 hours 100 99.76 -0.01 0.06 0.07 1 2 4 FDME, 200 ppm BHA, 130oC, 6 hours 200 99.78 -0.02 0.09 0.04 1 2 5 FDME, 500 parts per hour BHA, 130oC, 6 hours 500 99.79 -0.02 0.11 0.02 2 1 6 FDME, 1000 bpj BHA, 130oC, 6 hours 1,000 99.72 -0.01 0.22 -0.09 10 -7 7 FDME, 500 500 99.78 -0.15 0.42 -0.29 15 -12 bpj TBHQ, 130oC, 6 hours These results further illustrate that BHA has a color stabilizing effect on FDME, particularly considering the decrease in the APHA color values ​​of the chromaticity coordinate b*, relative to the 5 reference compositions in the third row of the table above. The results obtained for testing at 150°C (302°F) for 6 hours with BHA are shown in Table 10. Table 10 — FDME with Additive BHA, 150°C, 6 jam Name Data [Antioxidation n] bpj L*(C ) a*(C ) b*(C ) Δb* APH A Δ APH A Target et 1:1 IPA / Matriks Asetonitr il 0 99,9 9 0,01 — 0,01 **** * 0 *** ** **** * FDME 0 99,7 9 - 0,01 0,07 **** * 1 *** ** 1 FDME, 150oC, 6 jam 0 99,7 1 - 0,08 0,58 **** * 15 *** ** 2 FDME, 50 bpj BHA, 150oC, 6 jam 50 99,7 7 - 0,01 0,05 0,53 1 14 3 FDME, 100 bpj BHA, 150oC, 6 jam 100 99,8 0 - 0,02 0,07 0,51 1 14 4 FDME, 200 bpj BHA, 150oC, 6 jam 200 99,8 2 - 0,04 0,14 0,44 3 12 5 FDME, 300 bpj BHA, 150oC, 6 jam 300 99,7 9 - 0,06 0,16 0,42 4 11 6 FDME, 500 bpj BHA, 150oC, 6 jam 400 99,7 5 - 0,07 0,24 0,34 9 6 7 FDME, 600 bpj BHA, 150oC, 6 jam 600 99,6 0 - 0,10 0,30 0,28 11 4 8 FDME, 1500 bpj BHA, 150oC, 6 jam 1.500 99,5 8 - 0,13 1,10 - 0,52 39 -24 These results further illustrate that BHA has a color stabilizing effect on FDME, particularly considering the decrease in the APHA color value of the chromaticity coordinate b*, relative to the reference composition in the third row of the table above. At BHA additive amounts of 50-800 ppm, b* decreases to less than 0.5. In addition, at BHA additive amounts of 50-500 ppm, the APHA color also decreases to less than 10. The results obtained for testing at 150°C (302°F) for 6 hours with TBHQ are shown in Table 11. Table 11 — FDME with TBHQ Additive, 150°C, 6 hours Data Name [Antioxide n] bpj L*(C ) a*(C ) b*(C ) Δb* APH A Δ APH A Targ et 1:1 IPA / Matri ks Acetonitri il 0 99, 9 9 0.01 - 0.01 **** * 0 *** ** **** * FDME 0 99, 9 7 - 0.01 0.07 **** * 1 *** ** 1 FDME, 150oC, 6 hours 0 99, 7 6 - 0.09 0.55 **** * 18 *** ** 2 FDME, 100 ppm TBHQ, 150oC, 6 hours 0 99, 5 7 - 0.13 0.69 - 0.14 24 -6 3 FDME, 100 parts per hour TBHQ, 150oC, 6 hours 100 99, 2 7 - 0.15 0.78 - 0.23 26 - 8 4 FDME, 200 ppm TBHQ, 150oC, 6 hours 200 99, 6 9 - 0.20 1.17 - 0.62 38 -20 5 FDME, 300 ppm TBHQ, 150oC, 6 hours 300 99, 7 6 - 0.38 1.57 - 1.02 46 -28 6 FDME, 500 ppm TBHQ, 150oC, 6 hours 500 99, 8 5 - 0.43 2.42 - 1.87 60 -42 7 FDME, 1,500 99.9 - 3.46 - 81 -63 1500 ppm TBHQ, 150oC, 6 hours 2 0.44 2.91 The results obtained for testing at 150°C (302°F) for 6 hours with DMP are shown in Table 12. Table 12 — FDME with DMP Additive, 150°C, 6 hours Data Name [Antio ksidan ] bpj L*(C ) a*( C) b*( C) Δb* APH A Δ APH A Tar get 1:1 IPA / Acetonitrile Matrix 0 100, 01 0.0 0 0.0 1 *** ** 0 *** ** *** ** FDME 0 99.7 9 - 0.0 1 0.0 7 *** ** 1 *** ** 1 FDME, 150oC, 6 hours 0 99.7 1 - 0.0 8 0.5 8 *** ** 15 *** ** 2 FDME, 50 bpj DMP, 150oC, 6 hours 50 99.8 0 0.1 5 0.6 6 - 0.0 8 24 -9 3 FDME, 100 ppm DMP, 150oC, 6 hours 100 99.6 5 0.1 9 0.6 1 - 0.0 3 23 - 8 4 FDME, 200 ppm DMP, 150oC, 6 hours 200 99.8 5 0.2 3 0.5 0 0.0 8 20 -5 5 FDME, 300 ppm DMP, 150oC, 6 hours 300 99.4 9 0.0 5 0.3 0 0.2 8 14 1 6 FDME, 500 ppm DMP, 150oC, 6 hours 500 99.8 4 0.0 2 0.1 6 0.4 2 6 9 7 FDME, 1500 bpj DMP, 150oC, 6 hours 1,500 99.7 8 — 0.0 0.2 7 0.3 1 12 3 1 These results illustrate that DMP has a color stabilizing effect on FDME. At DMP additive amounts of 200–1,500 ppm, the b* chromaticity coordinate decreases to less than 0.5. At DMP additive amounts of approximately 500 ppm (e.g., from approximately 400 ppm to approximately 600 ppm), the APHA color also decreases to less than 10. The results obtained for testing at 150°C (302°F) for 6 hours with DTMP are shown in Table 13. Table 13 — FDME with DTMP Additive, 150°C, 6 hours Data Name [Antio ksidan ] bpj L*( C) a*( C) b*( C) Δb* APH A Δ APH A Targ et 1:1 IPA / Acetonitrile Matrix 0 99, 99 0.0 0 0.0 0 *** ** 0 *** ** **** * FDME 0 99, 79 - 0.0 1 0.0 7 *** ** 1 *** ** 1 FDME, 150oC, 6 hours 0 99, 71 - 0.0 8 0.5 8 *** ** 15 *** ** 2 FDME, 50 bpj DTMP, 150oC, 6 hours 50 99, 76 0.0 5 0.4 0 0.1 8 11 4 3 FDME, 100 BPJ DTMP, 150oC, 6 hours 100 99.59 0.1 4 0.3 8 0.2 0 11 4 4 FDME, 200 ppm DTMP, 150oC, 6 hours 200 99.51 0.2 2 0.5 1 0.0 7 15 0 5 FDME, 300 ppm DTMP, 150oC, 6 hours 300 99.95 0.1 8 0.6 3 — 0.0 5 23 -8 6 FDME, 500 ppm 500 99.03 1.1 - 43 -28 DTMP, 150oC, 6 hours 78 0 0 0.5 2 7 FDME, 1500 DTMP, 150oC, bpj 6 hours 1,500 99, 34 0.4 5 1.8 9 - 1.3 1 66 -52 These results illustrate that DTMP has a color stabilizing effect on FDME. At DTMP additive amounts of 50-100 ppm, the chromaticity coordinate b* decreases to less than 0.5. The results obtained for testing at 150°C (302°F) for 6 hours with XDPA are shown in Table 14. Table 14—FDME with XDPA Additive, 150°C, 6 hours Data Name [Antioxide n] bpj L*(C) a*(C ) b*(C ) Δb* APH A Δ APH A Target 1:1 IPA / Matri ks Acetonitr il 0 100.0 1 0 .00 0.01 **** * 0 *** ** ***** FDME 0 99.79 0 - .01 0.07 **** * 1 *** ** 1 FDME, 150oC, 6 hours 0 99.71 0 - .08 0.58 **** * 15 *** ** 2 FDME, 50 parts per hour 150oC, 6 100 99.57 0 .19 0.41 0.17 12 3 4 hours FDME, 200 ppm XDPA, 150oC, 6 hours 200 99.73 0.04 0.33 0.25 11 4 5 FDME, 300 ppm XDPA, 150oC, 6 hours 300 99.64 - 0.04 0.41 0.17 12 3 6 FDME, 500 ppm XDPA, 150oC, 6 hours 500 99.78 - 0.08 0.42 0.16 13 2 7 FDME, 1500 ppm XDPA, 150oC, 6 hours 1500 99.34 - 0.05 0.34 0.24 12 3 These results illustrate that XDPA has a color stabilizing effect on FDME, particularly considering the decrease in the APHA color value of the chromaticity coordinate b*, relative to the 5 reference compositions in the third row of the table above. At XDPA additive amounts of 100-1,500 ppm, b* decreases to less than 0.5. The results obtained for testing at 150°C (302°F) for 6 hours with PETC are shown in Table 15. Table 15 — FDME with PETC Additive, 150°C, 6 hours Data Name [Antioxide n] bpj L*(C) a*(C ) b*(C ) Δb* APH A Δ APHA Tar get 1:1 Science / Matri 0 100.0 1 0.00 0.01 **** * 0 **** * ks Asetonitr il *** ** FDME 0 99.79 - 0.01 0.07 **** * 1 **** * 1 FDME, 150oC, 6 hours 0 99.71 - 0.08 0.58 **** * 15 **** * 2 FDME, 50 bpj PETC, 150oC, 6 hours 50 99.55 0.18 0.87 - 0.29 33 -18 3 FDME, 100 ppm PETC, 150oC, 6 hours 100 99.33 0.20 0.81 - 0.23 31 -16 4 FDME, 200 parts per hour PETC, 150oC, 6 hours 200 99.77 0.11 0.26 0.32 13 2 5 FDME, 300 ppm PETC, 150oC, 6 hours 300 99.50 0.15 0.36 0.22 16 -1 6 FDME, 500 ppm PETC, 150oC, 6 hours 500 99.78 0.12 0.21 0.37 11 4 7 FDME, 1500 ppm PETC, 150oC, 6 hours 1500 99.68 0.11 0.30 0.28 14 1 These results illustrate that PETC has a color stabilizing effect on FDME. At PETC additive amounts of 200–1,500 ppm, the chromaticity coordinate b* decreases to less than 0.5. The results obtained for testing at 150°C (302°F) for 6 hours with Irganox®245 are shown in Table 16. Table 16 — FDME with Irganox®245 Additive, 150°C, 6 hours Data Name [Anti-oxidants] bpj L*( C) a* (C ) b*( C) Δb* APH A Δ APHA Ta rg et 1:1 IPA / Acetonitrile Matrix 0 100 .01 0, 00 0.0 1 *** ** 0 **** * ** ** * FDME 0 99, 79 - 0, 01 0.0 7 *** ** 1 **** * 1 FDME, 150oC, 6 hours 0 99, 71 - 0, 08 0.5 8 *** ** 15 **** * 2 FDME, 50 bpj Irganox 245, 150oC, 6 hours 50 99, 62 0, 08 0.2 2 0.3 6 10 5 3 FDME, 100 ppm Irganox 245, 150oC, 6 hours 100 99.48 0.08 0.3 3 0.2 5 13 2 4 FDME, 200 ppm Irganox 245, 150oC, 6 hours 200 99.65 0.04 0.4 0 0.1 8 16 -1 5 FDME, 500 ppm Irganox 245, 150oC, 6 hours 500 99.43 0.06 0.4 1 0.1 7 17 -2 6 FDME, 1500 ppm Irganox 245, 150oC, 6 hours 1500 99.60 0.01 0.3 0 0.0 8 19 -4 These results illustrate that Irganox®245 has a color stabilizing effect on FDME. At Irganox®245 additive amounts of 50-1,500 ppm, the b* chromaticity coordinate is reduced to less than 0.5. At Irganox®245 additive amounts of 5 to approximately 50 ppm (e.g., from approximately 50 ppm to approximately 100 ppm), the APHA color is also reduced to 10. The results obtained for testing at 150°C (302°F) for 6 hours with Irganox®B900 are shown in Table 17. Table 17 — FDME with Irganox®B900 Additive, 150°C, 6 hours Data Name [Antioxide n] bpj L*(C) a* (C ) b*(C ) Δb* APH A Δ APH A Targ et 1:1 IPA / Matri ks Acetonitri il 0 100.0 1 0.00 0.01 **** * 0 *** ** **** * FDME 0 99.79 - 0.01 0.07 **** * 1 *** ** 1 FDME, 150oC, 6 hours 0 99.71 - 0.08 0.58 **** * 15 *** ** 2 FDME, 50 ppm Irganox B900, 150oC, 6 hours 50 99.66 — 0.02 0.27 0.31 10 5 3 FDME, 100 parts per hour Irganox 100 99.61 - 0.05 0.25 0.33 10 5 B900, 150oC, 6 hours 4 FDME, 200 ppm Irganox B900, 150oC, 6 hours 200 99.29 - 0.03 0.17 0.41 7 8 5 FDME, 500 ppm Irganox B900, 150oC, 6 hours 500 99.74 - 0.04 0.22 0.36 8 7 6 FDME, 1500 ppm Irganox B900, 150oC, 6 hours 1500 99.65 — 0.06 0.33 0.25 13 2 These results illustrate that Irganox®B900 has a color stabilizing effect on FDME, especially considering the decrease in APHA color values, chromaticity coordinates b*, relative to the 5 reference compositions in the third row of the table above. At Irganox®B900 additive amounts of 50-1,500 ppm, b* is reduced to less than 0.5. In addition, at Irganox®B900 additive amounts of 50-500 ppm, APHA color is also reduced to 10 or less. 10 The results obtained for testing at 150°C (302°F) for 6 hours with Irganox®B225 are shown in Table 18. Table 18—FDME with Irganox®B225 Additive, 150°C, 6 hours Data Name [Ant iox idan ] bpj L*( C) a*( C) b*( C) Δb* APH A Δ APH A Ta rg et 1:1 IPA / Acetonitrile Matrix 0 99, 99 0.0 0 0.0 0 *** ** 0 *** ** ** ** * FDME 0 99, 79 - 0.0 1 0.0 7 *** ** 1 *** ** 1 FDME, 150oC, 6 hours 0 99, 71 - 0.0 8 0.5 8 *** ** 15 *** ** 2 FDME, 50 bpj B225, 150oC, Irganox 6 hours 50 99, 76 - 0.0 1 0.1 7 0.4 1 7 8 3 FDME, 100 ppm B225, 150oC, Irganox 6 hours 100 99.58 - 0.0 4 0.1 8 0.4 0 7 8 4 FDME, 200 ppm B225, 150oC, Irganox 6 hours 200 99.81 - 0.0 2 0.2 4 0.3 4 9 6 5 FDME, 500 ppm B225, 150oC, Irganox 6 hours 500 99.85 - 0.0 6 0.2 6 0.3 2 9 6 6 FDME, 1500 ppm B225, 150oC, Irganox 6 hours 1.50 0 99.63 - 0.0 1 0.3 0 0.2 8 12 3 These results illustrate that Irganox®B225 has a color stabilizing effect on FDME, especially considering the decrease in the 5 APHA color chromaticity coordinate b* values, relative to the reference composition in the third row of the table above. At Irganox®B225 additive amounts of 50-1,500 ppm, b* is reduced to less than 0.5. In addition, at Irganox®B225 additive amounts of 50-500 ppm, the APHA color is also reduced to less than 10. The color stabilizing additive compounds were also tested for their ability to prevent color development in FDCA samples, during accelerated degradation testing periods. In the first series of tests, a 300 mg FDCA sample was dissolved in 9700 mg triethylene glycol monomethyl ether (TEGMME) to produce a 3 wt% solution. A reference FDCA composition without any additives was heated to 100°C (212°F) for 2 hours in an air environment, after which the composition was allowed to cool to ambient conditions. Compositions of various color stabilizing additive compounds alone, namely BHA, Irganox®245, Irganox®B900, Irganox®B225, Dovernox®10, and Dovernox®76 were subjected to these heating conditions. Also, each of these additives was combined with a composition that included a 3 wt% FDCA solution as described above, at an addition rate of 100 ppm, and the resulting stabilized compositions were also subjected to these heating conditions. The colors of the reference composition, the additive alone, and the stabilized FDCA composition containing 100 ppm of this additive, were determined using a Konica Minolta CM-5 colorimeter. Table 19 below shows the APHA color values ​​and L* a* b* chromaticity coordinates determined for the samples. Table 19 — FDCA, 3 wt % in TEGMME, Stabilized with Various Additives, 100°C, 2 hours AO FDCA (%wt) AO (ppm) Temperature L*(C) Time (min) Gas L*(C) a* b*(C) APHA - - - - - Air 99.99 0.03 0 0 - - — 100 120 Air 99.86 0.03 0.09 2 - 3 - 100 120 Air 99.54 -0.90 2.11 102 BHA - 100 100 120 Air 100 0.02 0.01 0 BHA 3 100 100 120 Air 99.81 -0.41 0.86 25 Irganox 245 - 100 100 120 Air 99.88 0.03 0.01 1 Irganox 245 3 100 100 120 Air 99.67 -0.44 1.01 31 Irganox 8900 - 100 100 120 Air 99.94 0.06 0.05 2 Irganox B900 3 100 100 120 Air 99.76 -0.33 0.94 27 Irganox B225 - 100 100 120 Air 99.92 0.01 0.03 1 Irganox B225 3 100 100 120 Air 99.89 -0.48 0.79 24 Dovernox 10 - 100 100 120 Air 99.84 0.02 0.01 1 Dovernox 10 3 100 100 120 Air 99.79 -0.61 1.20 45 Dovernox 76 - 100 100 120 Air 99.80 -0.01 0.04 2 Dovernox 76 3 100 100 120 Air 99.91 -0.53 0.68 21 These results illustrate that all tested additives have a color stabilizing effect on FDCA, particularly considering the decrease in the APHA color value of the chromaticity coordinate b*, relative to the reference composition in the third row of the table above. Additional testing was performed according to the procedure described above, but by dissolving 100 mg of FDCA sample in 9,900 mg of propylene glycol (PG) to produce a 10% w / w solution. Variations in the amount of additive were tested for color stabilization FDCA, and APHA color values ​​and chromaticity coordinates L* a* b* are determined as shown in Table 20 below. Table 20 — FDCA, 1% wt in PG, Stabilized with Various Additives, 100°C, 2 hours FDCA (%) 81 - BHA 100 100 120 Water 100 -0.02-0 0 1 BHA 100 100 120 Water 99.87 -0.26-0.49 26 1 BHA 500 100 120 Water 99.69 -0.17-0.33 17 - Irganox 245 100 100 120 Water 99.88 0.02-0 0 1 Irganox 245 100 100 120 Water 99.74 -0.33-0.88 24 1 Irganox 245 300 100 120 Water 99.71 -0.34-0.96 27 1 Irganox 245 600 100 120 Water 99.69 -0.19-0.63 21 1 Irganox 245 1.000 100 120 Water 99.83 -0.08 0.28 11 - Irganox B900 100 100 120 Water 99.91 0, 04 0, 01 1 1 Irganox B900 100 100 120 Water 99.83 -0.05 0.52 18 1 Irganox B900 300 100 120 Water 99.81 -0.11 0.64 20 1 Irganox B900 600 100 120 Water 99.42 -0.18 3.55 145 1 Irganox B900 1000 100 120 Water 99.51 -0.24 4.21 187 - Irganox B225 100 100 120 Water 99.95 0.01 0 0 1 Irganox B225 100 100 120 Water 99.89 0.03 0.54 25 Dovernox 10 100 100 120 Water 99.91 0.01 0.02 1 1 Davernox 10 100 100 120 Water 99.82 -0.14 0.65 20 - Dovernox 76 100 100 120 Water 99.92 0.01 0.03 2 1 Dovernox 76 100 100 120 Water 99.85 -0.11 0.71 27. 1 Dovernox 76 300 100 120 Water 99.81 -0.18 0.56 25 The chromaticity coordinate b* decreases to less than 0.5 at BHA additive amounts of 100-500 ppm and at Irganox®245 additive amounts of about 1,000 ppm (e.g., from about 800 ppm to about 1,200 ppm). ITEM: 1. A process for the determination of soluble aldehydes in a composition, wherein the composition includes one or more of (a) 2,5-furandicarboxylic acid (FDCA), (b) terephthalic acid (TPA), (c) esters of 2,5-furandicarboxylic acid and (d) esters of terephthalic acid, and wherein the process includes combining one or more diamine salts with the composition under suitable conditions to cause the soluble aldehydes present in the composition to react with the added diamine salt or salts and form one or more imines, and then analyzing the imine composition. 2. Process according to item 1, where the analysis step includes ultraviolet-visible spectroscopy. 3. A process according to either item 1 or item 2, wherein any soluble aldehyde present in the composition reacts with the added salt or diamine salts to such an extent that it can be determined whether more than 30 parts per million by weight of the soluble aldehyde is present in the composition prior to reaction with the added salt or diamine salts. 4. The process according to item 3, wherein any soluble aldehyde present in the composition reacts with the added salt or diamine salts to such an extent that it can be determined whether there is more than 10 parts per million by weight of soluble aldehyde in the composition prior to reaction with the added salt or diamine salts. 5. The process according to item 4, wherein any soluble aldehyde present in the composition reacts with the added salt or diamine salts to such an extent that it can be determined whether there is more than 30 parts per billion by weight of soluble aldehyde in the composition prior to reaction with the added salt or diamine salts. 6. Process according to any one of items 1-5, wherein the composition is an in-process material sampled from a process for the manufacture of one or more of FDCA, TPA, esters of FDCA and esters of TPA, after an oxidation step to form one or more of FDCA and TPA. 7. The process according to item 6, further comprising dehydrating the hexose to obtain one or more furanate oxidation precursors of FDCA, oxidizing said one or more furanate oxidation precursors of FDCA to form a crude oxidation product including FDCA, sampling said crude oxidation product in real time after said crude oxidation product is formed and analyzing said crude oxidation product sample by the process according to any one of items 1-5. 8. The process according to item 6, further comprising oxidizing a feed composition including p-xylene to form a crude oxidation product including TPA, sampling the crude oxidation product in real time after said crude oxidation product is formed and then analyzing the sample of said crude oxidation product by a process according to any one of items 1-5. 9. The process according to item 6, further comprising dehydrating the hexose to obtain one or more furanate oxidation precursors of FDCA, combining said one or more furanate oxidation precursors of FDCA with p-xylene, oxidizing the combination of said one or more furanate oxidation precursors of FDCA with p-xylene to form a crude oxidation product including both FDCA and TPA, sampling said crude oxidation product in real time after said crude oxidation product is formed and then analyzing said sample of said crude oxidation product by the process according to any one of items 1-5. 10. The process according to any one of items 6-9, further comprising modifying the process for making one or more FDCA, TPA, esters of FDCA and esters of TPA responsive to the results of the analysis step, processing the composition by selectively hydrogenating dissolved aldehydes in the composition and / or by adding a color stabilizing additive or additives to the composition or both modifying the process for making one or more FDCA, TPA, esters of FDCA and esters of TPA and processing the composition. 11. A process for monitoring soluble aldehydes in a composition comprising (a) crude 2,5-furandicarboxylic acid (FDCA) from the oxidation of one or more furanate precursors of FDCA, (b) crude terephthalic acid (TPA) from the oxidation of p-xylene, (c) either 2,5-furandicarboxylic acid or terephthalic acid, (d) an ester of 2,5-furandicarboxylic acid (e) an ester of terephthalic acid or (f) an ester of either 2,5-furandicarboxylic acid or terephthalic acid, said process comprising the steps of: supplying a diamine salt and combining it with the composition under suitable conditions to cause the soluble aldehyde present in the composition to react with the diamine and form one or more imines; and determining by ultraviolet-visible spectroscopy whether an excess of the soluble aldehyde is present in the composition;and responsive to the detection of excessive levels of soluble aldehydes in the composition, changing the process for manufacturing the composition or processing said composition by selectively hydrogenating the soluble aldehydes in the composition and / or by adding color stabilizing additives or additives to said composition, or both changing the process for manufacturing the composition and processing said composition.; 12. Process according to item 11, wherein the excess soluble aldehyde content is 30 parts per million by weight. 13. Process according to item 12, wherein the excess soluble aldehyde content is 10 parts per million by weight. 14. Process according to item 13, wherein the excess soluble aldehyde content is 30 parts per billion by weight. 15. Process according to any of items 1-14, wherein before or during combination with the diamine salt, the composition is combined with a selected solvent of methylene chloride and chloroform. 16. Process according to item 15, where the solvent is methylene chloride 17. Process according to any one of items 1-16, wherein the diamine salt is selected from at least one of: N,N'-dimethyl-p-phenylenediamine sulfate (DPPD sulfate); N,N'-dimethyl-p-phenylenediamine dihydrogen chloride (DPPD dihydrogen chloride); N,N'-dimethyl-p-phenylenediamine oxalate (DPPD oxalate); N,N'-dimethyl-p-phenylenediamine hydrogen chloride (DPPD hydrogen chloride); N,N'-dimethyl-o-phenylenediamine dihydrogen chloride (DOPD dihydrogen chloride); N,N'-dimethyl-o-phenylenediamine sulfate (DOPD sulfate); N,N'-dimethyl-o-phenylenediamine hydrogen chloride (DOPD hydrogen chloride); N,N'-dimethyl-o-phenylenediamine dihydrogen chloride (DPBD dihydrogen chloride); N,N'-dimethyl-p-phenylenediamine hydrogen chloride (DPBD hydrogen chloride); and N,N'-dimethyl-p-phenylenediamine sulfate (DPBD sulfate). 18. The process according to item 17, wherein the diamine salt is selected from at least one of: N,N'-dimethyl-p-phenylenediamine sulfate (DPPD sulfate); N,N'-dimethyl-o-phenylenediamine dihydrogen chloride (DPBD dihydrogen chloride); N,N'-dimethyl-p-phenylenediamine hydrogen chloride (DPBD hydrogen chloride); and N,N'-dimethyl-p-phenylenediamine sulfate (DPBD sulfate). 19.The process according to item 18, wherein the diamine salt is N,N'-dimethyl-p-phenylenediamine sulfate (DPPD sulfate). 20. The process according to any one of items 11 -19, in. wherein the composition is prepared by selectively hydrogenating the aldehyde dissolved in the composition by reaction with hydrogen in the presence of a hydrogenation catalyst which includes at least a first noble metal. 21. The process according to item 20, wherein the hydrogenation catalyst includes both a first precious metal and a second precious metal. 22. The process according to item 21, wherein said hydrogenation catalyst further includes a promoter metal. 23. The process according to item 22, wherein said hydrogenation catalyst comprises from 0.5% by weight to 5% by weight of ruthenium (Ru), from 0.5 wt% to 5 wt% tin (Sn) and from 0.1 wt% to 1 wt% platinum (Pt) on a solid support containing carbon. 24. Process according to any one of items 11-19, in where the composition is processed by adding a color stabilizing additive in the form of substituted phenol. 25. The process according to item 24, wherein the substituted phenol is a methoxy substituted phenol or a tert-butyl substituted phenol. 26. Process according to any one of items 11-19, wherein said composition is treated by the addition of one or more color-stabilizing additives selected from the group consisting of butylated hydroxyanisole (BHA); 2,6-dimethoxyphenol (DMP); 2,6-di-tert-butyl-4-methoxyphenol (DTMP); pentaerythritol tetrakis[3-[3,5-di-tert-butyl-4hydroxyphenyl]propionate (PETC); 2-tert-butylhydroquinone (TBHQ); 4,4'-bis(a,a-dimethylbenzyl) diphenylamine (XDPA); ethylenebis (oxyethylene) bis-(3-(5-tert-butyl-4-hydroxy-mtolyl)-propionate); tris(2,4-di-tert-butylphenyl)phosphite; octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate and ascorbic acid. 27. The process according to item 26, wherein said color stabilizing additive or additives are added to the composition in an amount of from 50 to 2,000 parts per million by weight (ppm) of said composition as a whole.

Claims

1. A process for the determination of soluble aldehydes in a composition, wherein the composition includes one or more of (a) 2,5-furandicarboxylic acid (FDCA), (b) terephthalic acid (TPA), (c) esters of 2,5-furandicarboxylic acid and (d) esters of terephthalic acid, and wherein the process includes combining one or more diamine salts with the composition under suitable conditions to cause the soluble aldehydes present in the composition to react with the added diamine salt or salts and form one or more imines, and then analyzing the imine composition.

2. The process according to claim 1, wherein said analysis step includes ultraviolet-visible spectroscopy.

3. A process according to any one of claim 1 or claim 2, wherein any soluble aldehyde present in said composition reacts with the added salt or diamine salts to such an extent that it can be determined whether more than 30 parts per million by weight of soluble aldehyde is present in said composition prior to reaction with the added salt or diamine salts.

4. The process according to claim 3, wherein any soluble aldehyde present in said composition reacts with the added salt or diamine salts to such an extent that it can be determined whether more than 10 parts per million by weight of soluble aldehyde is present in said composition prior to reaction with the added salt or diamine salts.

5. The process according to claim 4, wherein any soluble aldehyde present in said composition reacts with the added salt or diamine salts to such an extent that it can be determined whether more than 30 parts per billion by weight of soluble aldehyde is present in said composition prior to reaction with the added salt or diamine salts.

6. A process according to any one of claims 1-5, wherein said composition is an in-process material sampled from a process for manufacturing one or more of FDCA, TPA, an ester of FDCA and an ester of TPA, after an oxidation step to form one or more of FDCA and TPA.

7. The process according to claim 6, further comprising dehydrating the hexose to obtain one or more furanate oxidation precursors of FDCA, oxidizing said one or more furanate oxidation precursors of FDCA to form a crude oxidation product including FDCA, sampling said crude oxidation product in real time after said crude oxidation product is formed and analyzing said crude oxidation product sample by the process according to any one of claims 1-5.

8. The process according to claim 6, further comprising oxidizing a feed composition comprising p-xylene to form a crude oxidation product comprising TPA, sampling the crude oxidation product in real time after said crude oxidation product is formed and then analyzing the sample of said crude oxidation product by a process according to any one of claims 1-5.

9. The process according to claim 6, further comprising dehydrating the hexose to obtain one or more furanate oxidation precursors of FDCA, combining said one or more furanate oxidation precursors of FDCA with p-xylene, oxidizing the combination of said one or more furanate oxidation precursors of FDCA with p-xylene to form a crude oxidation product including both FDCA and TPA, sampling said crude oxidation product in real time after said crude oxidation product is formed and then analyzing said sample of said crude oxidation product by the process according to any one of claims 1-5.

10. The process according to any one of claims 6-9, further comprising modifying the process for making one or more FDCA, TPA, esters of FDCA and esters of TPA responsive to the results of the analysis step, processing the composition by selectively hydrogenating dissolved aldehydes in the composition and / or by adding a color stabilizing additive or additives to the composition or both modifying the process for making one or more FDCA, TPA, esters of FDCA and esters of TPA and processing the composition.

11. A process for monitoring soluble aldehydes in a composition comprising (a) crude 2,5-furandicarboxylic acid (FDCA) from the oxidation of one or more furanate precursors of FDCA, (b) crude terephthalic acid (TPA) from the oxidation of p-xylene, (c) either 2,5-furandicarboxylic acid or terephthalic acid, (d) an ester of 2,5-furandicarboxylic acid (e) an ester of terephthalic acid or (f) an ester of either 2,5-furandicarboxylic acid or terephthalic acid, said process comprising the steps of: supplying a diamine salt and combining it with the composition under suitable conditions to cause the soluble aldehyde present in the composition to react with the diamine and form one or more imines; and determining by ultraviolet-visible spectroscopy whether an excess of the soluble aldehyde is present in the composition;and responsive to the detection of excessive levels of soluble aldehydes in the composition, changing the process for manufacturing the composition or processing said composition by selectively hydrogenating the soluble aldehydes in the composition and / or by adding color stabilizing additives or additives to said composition, or both changing the process for manufacturing the composition and processing said composition.; 12. The process according to claim 11, wherein said excess soluble aldehyde content is 30 parts per million by weight.

13. The process according to claim 12, wherein said excess soluble aldehyde content is 10 parts per million by weight.

14. The process according to claim 13, wherein said excess soluble aldehyde content is 30 parts per billion by weight.

15. The process according to any one of claims 1-14, wherein before or during combination with the diamine salt, the composition is combined with a solvent selected from methylene chloride and chloroform.

16. The process according to claim 15, wherein the solvent is methylene chloride.

17. The process according to any one of claims 1-16, wherein the diamine salt is selected from at least one of: N,N'-dimethyl-p-phenylenediamine sulfate (DPPD sulfate); N,N'-dimethyl-p-phenylenediamine dihydrogen chloride (DPPD dihydrogen chloride); N,N'-dimethyl-p-phenylenediamine oxalate (DPPD oxalate); N,N'-dimethyl-p-phenylenediamine hydrogen chloride (DPPD hydrogen chloride); N,N'-dimethyl-o-phenylenediamine dihydrogen chloride (DOPD dihydrogen chloride); N,N'-dimethyl-o-phenylenediamine sulfate (DOPD sulfate); N,N'-dimethyl-o-phenylenediamine hydrogen chloride (DOPD hydrogen chloride); N,N'-dimethyl-o-phenylenediamine dihydrogen chloride (DPBD dihydrogen chloride); N,N'-dimethyl-p-phenylenediamine hydrogen chloride (DPBD hydrogen chloride); and N,N'-dimethyl-p-phenylenediamine sulfate (DPBD sulfate).

18. The process according to claim 7, wherein said diamine salt is selected selected from at least one of: N,N'-dimethyl-p-phenylenediamine sulfate (DPPD sulfate); N,N'-dimethyl-o-phenylenediamine dihydrogen chloride); dihydrogen chloride (DPBD N,N'-dimethyl-p-phenylenediamine hydrogen chloride); and hydrogen chloride (DPBD N,N'-dimethyl-p-phenylenediamine sulfate (DPBD sulfate).

19. The process according to claim 18, wherein said diamine salt is N,N'-dimethyl-p-phenylenediamine sulfate (DPPD sulfate).

20. A process according to any one of claims 11-19, wherein said composition is prepared by selectively hydrogenating a dissolved aldehyde in the composition by reaction with hydrogen in the presence of a hydrogenation catalyst comprising at least a first noble metal.

21. The process according to claim 20, wherein said hydrogenation catalyst includes both a first precious metal and a second precious metal.

22. The process according to claim 21, wherein said hydrogenation catalyst further includes a promoter metal.

23. The process according to claim 22, wherein said hydrogenation catalyst comprises from 0.5 wt% to 5 wt% ruthenium (Ru), from 0.5 wt% to 5 wt% tin (Sn) and from 0.1 wt% to 1 wt% platinum (Pt) on a carbon-containing solid support.

24. Process according to any one of claims 11-19, wherein said composition is treated with the addition of a color stabilizing additive in the form of a substituted phenol.

25. The process according to claim 24, wherein said substituted phenol is a methoxy substituted phenol or a tert-butyl substituted phenol.

26. A process according to any one of claims 11-19, wherein said composition is treated by the addition of one or more color-stabilizing additives selected from the group consisting of butylated hydroxyanisole (BHA); 2,6-dimethoxyphenol (DMP); 2,6-di-tert-butyl-4-methoxyphenol (DTMP); pentaerythritol tetrakis[3-[3,5-di-tert-butyl-4hydroxyphenyl]propionate (PETC); 2-tert-butylhydroquinone (TBHQ); 4,4'-bis(a,a-dimethylbenzyl) diphenylamine (XDPA); ethylenebis(oxyethylene) bis-(3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate); tris(2,4-di-tert-butylphenyl)phosphite; octadecyl-3(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate and ascorbic acid.

27. The process according to claim 26, wherein said color stabilizing additive or additives are added to the composition in an amount of from 50 to 2,000 parts per million by weight (ppm) of said composition as a whole.