Process for preparation of diamines

Abstract

This document describes a process for preparing diamine compounds from aldehyde compounds. The process can include reacting a dialdehyde, a diacetal of a dialdehyde, or a combination of both with a source of hydrogen and a source of ammonia in the presence of a heterogeneous catalyst, a solvent, and optionally a promoter under reaction conditions to obtain its corresponding diamine in a desired yield.

Description

Methods for preparing diamines Technical Field

[0001] This document relates to a method for preparing diamines from aldehyde compounds. Specifically, this document relates to a method for the reductive amination of a diacetal substrate to its corresponding diamine in high yield over a heterogeneous catalyst. Background Technology

[0002] Nylon is a family of synthetic polyamide polymers used in a variety of industries, including textiles, automotive, machine parts, packaging, and consumer goods. Nylon is readily processed into fibers, granules, molded shapes, and films that exhibit excellent strength and compatibility across a range of temperatures and environments. The most commonly used nylons are nylon-6 (polycaprolactam) and nylon-6,6 (polyhexamethylenediamine adipamide). Adipaldehyde, also known as 1,6-hexanal, is an industrial intermediate used, for example, in the production of caprolactone (CPLN), adipic acid (AA), 1,6-hexanediol (HDO), and other chemicals found to have applications in nylon (or polyamide) manufacturing processes. For example, adipic acid (AA) is one of two monomers used to prepare nylon-6,6. Chemicals such as 1,6-hexanediol (HDO) can be converted into its corresponding diamine, 1,6-hexanediamine (HMD), another monomer used to prepare nylon-6,6. Summary of the Invention

[0003] This document describes a method for preparing a diamine; the method includes the following steps: in a reaction zone, contacting an acetal compound with a hydrogen source and an ammonia source in the presence of a heterogeneous catalyst, a solvent, and optionally a promoter. Specified reaction zone conditions can be maintained for a specified time period, and the specified time period can be selected to substantially convert the acetal compound into at least one diamine compound. The reaction zone effluent can be recovered to obtain the diamine compound. In one example, the acetal is formed as a reaction product of an aldehyde compound. The aldehyde compound may be selected from one or more of the following compounds: R1-CHO, HCO-R1-CHO, wherein R1 is selected from C4-C6. 12 Hydrocarbon group. In one example, the acetal can be the reaction product of at least one aldehyde compound selected from the group consisting of: butyraldehyde, n-pentanaldehyde, hexanal, succinaldehyde, glutaraldehyde, and hexadaldehyde.

[0004] The acetal may be selected from one or more compounds having the following molecular structures:

[0005]

[0006] Here, R2 can be selected from C2-C. 12The hydrocarbon groups A1, A2, A3, and A4 can each be independently selected from C1-C5 alkyl groups, and A5 and A6 can each be independently selected from C2-C4 alkyl groups. In one example, the acetal can be selected from the group consisting of: diethylene glycol acetal of butyraldehyde, diethylene glycol acetal of pentanaldehyde, diethylene glycol acetal of hexadial, 1,3-propanediol acetal of butyraldehyde, 1,3-propanediol acetal of pentanaldehyde, 1,3-propanediol acetal of hexadial, glycerol acetal of butyraldehyde, glycerol acetal of pentanaldehyde, and glycerol acetal of hexadial.

[0007] Reaction zone conditions may include temperatures ranging from about 45 degrees Celsius (°C) to about 150°C, from about 45°C to about 125°C, or from about 50°C to about 100°C. For example, the reaction temperature may be in the range of ≥ about 55°C to ≤ about 75°C. Reaction zone conditions may include pressures ranging from about 10 psi (Psig) to about 4500 Psig, from about 50 Psig to about 4000 Psig, or from about 100 Psig to about 4000 Psig. For example, the reaction pressure may be in the range of ≥ about 200 Psig to ≤ about 500 Psig. One atmosphere (atm.) is equal to about 14.7 Psig. Reaction zone conditions may include a specified residence time, selected to convert at least a portion of the acetal compound into at least one diamine compound. In one example, the specified residence time in the reaction zone may be quantified as the time when the reaction zone pressure no longer drops below a specified threshold pressure.

[0008] In one example, ammonia can be at least one of ammonia gas, an aqueous solution of ammonia, or an amine. In one example, the heterogeneous catalyst may include a sponge metal catalyst. For example, such a suitable sponge metal catalyst may contain at least one of nickel and cobalt, such as Raney... ® Nickel or Raney ® The sponge metal is at least one of cobalt. In one example, the solvent may include at least one of an oxygen-containing compound or water. For example, the oxygen-containing compound may include at least one of an alcohol or ester. For example, the alcohol solvent may include at least one of methanol, ethanol, propanol, and butanol. Such an alcohol solvent may be obtained via processes such as hydrocarbon-based synthesis processes, by-product or co-product alcohols from chemical synthesis processes, biomass-derived processes, fermentation processes, or combinations thereof. In one example, water may be the solvent.

[0009] In one example, the promoter can be a metal hydroxide, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, or a combination thereof.

[0010] In one example, the method may include recovering reaction zone effluent to obtain a diamine, including a solids separation step to recover the reaction zone effluent from a heterogeneous catalyst. For example, the solids separation step may include pressure filtration, vacuum filtration, centrifugation, membrane separation, distillation, scraped membrane evaporation, decantation, gravity settling, or a combination thereof.

[0011] Alternatively or otherwise, methods for preparing 1,6-hexanediamine may involve mixing the diacetal of hexanedialdehyde with a hydrogen source and an ammonia source in a reaction zone in the presence of a heterogeneous catalyst, a solvent, and optionally a promoter. Here, the method may include controlling the reaction zone conditions for a specified period of time to convert the diacetal of hexanedialdehyde to 1,6-hexanediamine. The method may also include recovering the reaction zone effluent to obtain 1,6-hexanediamine.

[0012] Alternatively or otherwise, methods for preparing 1,6-hexanediamine may involve mixing adipaldehyde with a hydrogen source and an ammonia source in a reaction zone in the presence of a heterogeneous catalyst, a solvent, and optionally a promoter. Here, the method may include controlling the reaction zone conditions for a specified period of time to convert the adipaldehyde to 1,6-hexanediamine. The method may also include recovering the reaction zone effluent to obtain 1,6-hexanediamine. Detailed Implementation

[0013] Some industrial-scale processes for the production of adipic acid and 1,6-hexanediamine can be capital-intensive, involving several complex conversion steps and unit operations. For example, one method for producing adipic acid involves the oxidation of cyclohexane and may involve the use of nitric acid, which tends to produce nitrous oxide. This approach may involve challenges, such as potential carbon emissions. One method for producing 1,6-hexanediamine involves the catalytic hydrogenation of 1,6-hexanonitrile (or adiponitrile, which may be referred to herein as ADN). Adiponitrile can be prepared, for example, via the dihydrocyanation of 1,3-butadiene, acrylonitrile coupling, or adipic acid ammoniation. Such methods may involve challenges, such as dependence on hydrogen cyanide sources. Additionally, some adipic acid ammoniation methods may rely on corrosive catalysts and may involve special, expensive, or rare metallurgical materials. Furthermore, acrylonitrile coupling may involve relatively energy-intensive industrial-scale electrochemical processes.

[0014] One method for producing diamines is described in Chinese Publication Serial No. 114426502, which involves mixing an aldehyde compound (i.e., an aldehyde, acetal, or a combination thereof), ammonia, an oxidant, a catalyst, and a promoter and heating the mixture to yield a nitrile. However, it is desirable to produce diamines more directly from diacetals. Another method for producing diamines is described in US Patent Serial No. 10941092, which involves a two-stage hydroformylation of butadiene. For example, the hydroformylation process may involve the synthesis of adipic acid, 1,6-hexanediamine, and 1,6-hexanediol via the bipositive selective hydroformylation of 1,3-butadiene, for example, involving an intermediate of adipic acid aldehyde diacetal. Here, a diamine, such as 1,6-hexanediamine (HMD), can ultimately be produced. For example, 1,6-hexanediol (HDO) can be produced from the diacetal of adipic acid (approximately 68% yield), which can then be converted to HMD (approximately 81% yield). A potential challenge with this method of preparing diamines is the relatively low overall yield of HMD, such as less than about 55%.

[0015] Another method for producing diamines is described in U.S. Patent No. 6,696,609, such as that relating to dialdehydes. However, this method faces challenges in terms of selectivity and yield of the desired diamine product.

[0016] A method for producing acetals is described in U.S. Patent Application Publication No. 5,312,996, which relates to a hydroformylation process for producing 1,6-hexanedialdehyde. This method may involve reacting butadiene with hydrogen and carbon monoxide in the presence of rhodium to achieve the conversion of butadiene to 1,6-hexanedialdehyde. Here, the acetal may be formed via the reaction of an aldehyde with 1,2-diol, 1,3-diol, or 2,4-diol, such as in the presence of an acetalization catalyst (e.g., sulfuric acid, phosphoric acid, etc.).

[0017] A scientific journal publication, J. Org. Chem. 1996, 61, 3849-3862, describes examples of reductive amination of aldehydes and ketones, in which acetals do not react under certain conditions.

[0018] The inventors have recognized the advantages of producing one or more industrial intermediates (e.g., adipic acid, adiponitrile (ADN), 1,6-hexanediamine (HMD), hexanediol (HDO), etc.) via less complex alternative production routes and / or using relatively inexpensive starting materials compared to certain other methods (e.g., aldehydes, such as aldehydes, dialdehydes, acetals, or diacetals). The inventors have envisioned a process to address the industrial need for improved production of diamines and their corresponding precursors, exhibiting, for example, desired conversion rates and selectivity. This document describes a technically and economically feasible process for the production of diamines and their corresponding precursors. One example is the production of HMD from adipic acid or its corresponding precursor containing two acetal groups at the first and sixth positions. Another example is the production of cadaverine or 1,5-pentamethylenediamine (also referred to herein as PMD or PMDA) from glutaraldehyde or its corresponding precursor containing two acetal groups at the first and fifth positions.

[0019] This document relates to a first single step in the direct conversion of a diacetate to its corresponding diamine, without prior hydrolysis of the diacetate to a diol. The diacetate can be prepared by reacting its corresponding diacetate with a diol / ethylene glycol (e.g., monoethylene glycol or diethylene glycol, propylene glycol, glycerol, etc.). The document also relates to the reductive amination of the diacetate to its corresponding diamine via a diacetate intermediate. For example, the one-step method described herein can preserve the diacetate substrate, for instance, by reducing or minimizing oligomerization of the diacetate substrate. This one-step method can be carried out under certain “mild” process conditions, such as in terms of temperature and pressure, where the substrate is substantially completely converted and involves relatively high desired product yields.

[0020] Adipaldehyde is a key intermediate in the conversion of cyclohexene to nylon and is prone to self-condensation, such as yielding oligomers, which reduces the yield of the desired product (e.g., 1,6-hexanediamine (HMD)). This self-condensation can be avoided by protecting the dialdehyde to a diacetal. Effective catalysts can facilitate the subsequent indirect reductive amination of the diacetal to its corresponding diamine product. It is desirable that certain catalysts for the reductive amination of the dialdehyde diacetal be alcohol-resistant and substantially unreactive to alcohols, for example, when used as a solvent. For example, sponge nickel (e.g., Raney) ® Nickel can provide an effective heterogeneous catalyst for the direct reductive amination of acetals formed from dialdehydes to diamines. For example, spongy nickel can be used with minimal involvement of catalyst poisoning, oligomerization of dialdehydes, and significant alkylation of the product by the resulting alkanols.

[0021] The technology described herein can help provide a commercially viable route for the preparation of diamines from acetals (derived from aldehyde compounds such as HMD derived from its own dialdehyde; cadaverine derived from glutaraldehyde; and putrescine derived from butanedialdehyde)). Compared to the capital-intensive and low-concentration biosynthetic processes currently used for putrescine and cadaverine, the disclosed one-step method starting from acetals can provide a small-scale, cost-effective, and high-yield option for the production of these diamines. This method may involve a one-step chemical process, using, for example, Raney... ® The optimal conditions are: a sponge-like metal catalyst, a solvent (water, alcohol, ester), a promoter (e.g., caustic alkali), a mild temperature, and moderate pressure. Substrate conversion can be complete, and product yields can be relatively high, thus facilitating the recovery of the desired product from trace impurities. The resulting diamine product can be particularly desirable, for example, for industrial applications. For instance, HMD is a monomer in the production of nylon-6,6, while cadaverine or PMDA is a monomer in the production of nylon-5X.

[0022] Names and abbreviations of materials used in this disclosure :

[0023] 1,6-hexamethylenedialdehyde (H&D)

[0024] AA adipic acid or 1,6-adipic acid;

[0025] ADN adiponitrile or 1,6-adiponitrile;

[0026] BD1,3-butadiene;

[0027] Cadaverine (PMD), 1,5-pentamethylenediamine or 1,5-diaminopentane;

[0028] Glutaraldehyde 1,5-pentamethylenedialdehyde;

[0029] HDO hexanediol or 1,6-hexanediol;

[0030] HMD (HMDA) 1,6-hexamethylenediamine or hexamethylenediamine;

[0031] Putrescine (DAB) 1,4-diaminobutane or 1,4-butanediamine;

[0032] 1,4-Butanedialdehyde;

[0033] The dialdehyde of adipic acid, industrially known as hexanedial / adipaldehyde, 1,6-hexanedialdehyde, adipic aldehyde, or adipic dialdehyde (CAS No. 1072-21-5), is commercially available. The adipical used in the examples was produced by INVISTA and has a purity of 99.9% by weight.

[0034] The diacetal of adipaldehyde with a purity of 95% by weight was prepared by INVISTA using ethylene glycol and was used in the examples.

[0035] The sponge-like nickel-type catalyst used in the examples (e.g., Raney) ® Nickel), such as Raney ® Ni 2400 and Raney ® Co 2724 is commercially available and is sourced from WR Grace's Davison division. While not mentioned, other Raney... ® Type II catalysts may also be suitable.

[0036] Experimental methods

[0037] All experiments were conducted in a semi-batch mode in a 300 mL high-pressure stirred autoclave, such as the Parr Instrument Company Model 4560, within an explosion-proof barrier. The reactor was equipped with baffles, a hollow-shaft gas entrainment impeller, and was stirred at 2000 RPM to ensure thorough gas-liquid mixing during the reaction. A 1 / 8 HP variable-speed stirrer motor with large pulleys allowed stirring speeds exceeding approximately 1000 RPM, thereby increasing gas entrainment. The reactor was also equipped for, for example, sampling of one or both gas and liquid during operation.

[0038] In one example, the ready-to-use catalyst is washed three times with water and weighed using a hydrostatic bottle method. Then, under argon atmosphere, the slurry, along with the substrate (typically adipaldehyde diacetal) and solvent (water or alcohol), is transferred to the reactor in a glove box. The reactor is then sealed, removed from the glove box, and installed on a heating and stirring system in a fume hood. It is pressure tested with argon and then heated to the desired temperature (typically 75°C). The pressure is increased to the desired level (typically 500 Psig) using cylinders filled with ammonia and hydrogen. The feed cylinder is connected to Brooks mass flow controllers, which operate as flow meters, to maintain pressure by introducing feed gas into the reactor. Liquid phase samples from the reactor are taken for analysis.

[0039] In a stirred autoclave reactor, pre-weighed amounts of catalyst, solvent, promoter (e.g., 50 wt% aqueous sodium hydroxide solution), and substrate (e.g., hexamethylenediacetal) are added. The autoclave reactor is shut off, and the gas phase space is purged three times with argon. The reactor is then pressurized with argon to check for leaks. The argon is then purged, and hydrogen and ammonia are introduced into the gas phase space to bring the pressure to 200 Psig. The reactor is then heated to the desired temperature, and the pressure is subsequently increased to 500 Psig with hydrogen and ammonia, while the stirring speed is set to 2000 RPM. The reaction is allowed to continue under these conditions. The progress of the reaction is monitored, such as by sensing the real-time consumption of hydrogen and ammonia by sensing the decrease in pressure over time. The reaction is considered complete when the pressure no longer decreases further. At this point, the pressure is released while maintaining a sufficiently high temperature to prevent the target diamine product from solidifying.

[0040] The reaction conditions can be maintained for a specified time period, which can be selected to promote the conversion of the substrate to at least one diamine product. The specified time period can be in the range of about 10 minutes to about 10 hours, such as less than about 8 hours, less than about 6 hours, less than about 5 hours, or less than about 4 hours. In one example, the specified time period can be in the range of about 20 minutes to about 5 hours, or in the range of about 30 minutes to about 4 hours, or in the range of about 1 hour to about 5 hours.

[0041] The final mixture is discharged from the reactor and the product is analyzed by gas chromatography.

[0042] Liquid-phase products of each reaction were analyzed on a Hewlett-Packard 7890 GC equipped with a methyl silicone rubber capillary column (DB-5) and a flame ionization detector, and quantified using calibration curves. HMD formation rates were calculated using GC analysis of the liquid phase and / or feed consumption rates measured by a flow meter.

[0043] Data analysis: Hydrogen consumption within the reactor was continuously monitored and downloaded to Excel for analysis. GC analysis was used to determine selectivity.

[0044] GC Analysis: The sample is diluted with ethanol, loaded with an internal standard (diethylacetamide), and analyzed by gas chromatography. In one example, the GC sample is more inert or stable in ethanol than in methanol solution. For example, in methanol, side reactions may occur within several days, which may alter the properties and concentrations of some components in the sample. In ethanol, the sample remains stable for at least two weeks. The sample can be analyzed on a Hewlett-Packard 7890 GC equipped with a methyl silicone capillary column (DB-5) with a 1 μm membrane, which can be pretreated by repeatedly injecting concentrated HMD solution before use. The column carrier gas can be helium (He) at approximately 2 cc / min (constant pressure mode), and the split ratio can be approximately 25:1 after injecting 1 μL. Heating profiles can be: at approximately 60 °C for 1 minute, such as ramping to 275 °C at a rate of 7 °C / min, such as holding for 10 minutes. The GC detector may include a flame ionization detector. In one example, GC analysis may involve an internal standard (0.05 g DEAC dissolved in 5 mL of ethanol).

[0045] Precautions and Implementation Examples

[0046] Various aspects of this disclosure can be better understood by referring to the following embodiments, which are provided by way of example. This disclosure is not limited to the embodiments given herein.

[0047] Example 1

[0048] Add 4.5g of Raney to a 300mL stirred autoclave reactor. ® Ni 2400, 4.6 g water, 0.5 g caustic soda (50 wt% sodium hydroxide aqueous solution), and 60 g hexamethylenediacetal. The reactor was shut down, and the gas phase space was purged three times with argon. The reactor was then pressurized with argon to check for leaks. The argon was then purged, and hydrogen and ammonia were introduced into the gas phase space to bring the pressure to 200 Psig. The reactor was then heated to 75°C, and the pressure was subsequently increased to 500 Psig with hydrogen and ammonia, with the stirring speed set to 2000 RPM. The reaction progress was monitored by the pressure reduction. The reaction was considered complete when the pressure no longer decreased further. At this point, the pressure was released while maintaining a temperature of 60°C to 80°C to prevent the solidification of the diamine product 1,6-hexamethylenediamine (HMD). The final mixture was discharged from the reactor, and the product was analyzed by gas chromatography.

[0049] Example 2

[0050] Repeat Example 1, except that Raney is used. ® Co 2724.

[0051] Example 3

[0052] Example 1 was repeated, except that adipaldehyde was used instead of adipaldehyde diacetal as the substrate.

[0053] Example 4

[0054] Example 2 was repeated, except that adipaldehyde was used instead of adipaldehyde diacetal as the substrate.

[0055] Example 5

[0056] Repeat Example 1, except that the reaction temperature is lowered to 55°C.

[0057] Example 6

[0058] Repeat Example 1, except that no caustic soda is added to the reaction.

[0059] Example 7

[0060] Repeat Example 1, except that 0.2 g of caustic soda was added to the reaction.

[0061] Example 8

[0062] Repeat Example 7, except that ethanol is added to the reaction instead of water.

[0063] Example 9

[0064] Example 5 was repeated, except that ethanol was added to the reaction instead of water.

[0065] Example 10

[0066] Repeat Example 1, except that ethanol is added to the reaction instead of water.

[0067] Table 1 below summarizes the results of Examples 1 through 10.

[0068] Table 1

[0069]

[0070] †Yield is based on the added substrate (e.g., adipaldehyde diacetal).

[0071] ‡The term "Ad-CHO diacetal" refers to adipaldehyde diacetal;

[0072] GC analysis confirmed that all transformations in the experiments were completed.

[0073] Trace impurities in the product include hexamethyleneimine, diaminocyclohexane, and aminomethylcyclopentamine;

[0074] *The caustic alkali used is a 50% by weight aqueous solution of sodium hydroxide.

[0075] Distilled water was used in the examples.

[0076] The ethanol used has a purity of 99% by weight. .

[0077] Table 1 shows the effects of slurry-type nickel and cobalt catalysts on the yield of HMD produced by the reductive amination of adipaldehyde and adipaldehyde diacetal. In each example, substrate conversion was confirmed by GC analysis.

[0078] It was observed that the reductive amination of diacetal yielded relatively better diamine yields compared to the direct reductive amination of adipaldehyde (Examples 3 and 4). Surprisingly and unexpectedly, diamine yields were observed in the range of 88% to 92% for adipaldehyde substrates, indicating that oligomerization and self-condensation were reduced or minimized during the reaction.

[0079] With all other reaction parameters identical, Examples 1, 6, and 7 demonstrate the effect of the presence (or absence) and total amount of sodium hydroxide added to the reaction on the overall yield of HMD obtained. Example 6 yielded an HMD yield of 92.7% in the absence of caustic alkali, while the HMD yield increased to 95.1% (Example 7; 0.2 g caustic alkali) and 97.1% (Example 1; 0.5 g caustic alkali). In all experiments, the caustic alkali used was a 50% by weight aqueous solution of sodium hydroxide.

[0080] With all other reaction parameters being equal, the effect of reaction temperature is evident in Examples 1 and 5 (water as solvent) and Examples 9 and 10 (ethanol as solvent). Lowering the reaction temperature from 75°C to 55°C resulted in a slight increase in HMD yield; specifically, the yield increased from 97.1% [Example 1] to 98.3% [Example 5] when water was used as the solvent, and from 96.5% [Example 10] to 98.3% [Example 9] when ethanol was used as the solvent.

[0081] Comparisons between Examples 7 and 8; Examples 5 and 9; and Examples 1 and 10 show that changing the solvent from water to ethanol has little effect on the reaction performance.

[0082] Example 11

[0083] Example 1 was repeated, except that diethylene glycol diacetal of succinyl aldehyde was used as the substrate. 1,4-Butanediamine (DAB or putrescine) was obtained in high yield.

[0084] Example 12

[0085] Example 9 was repeated, except that 1,3-propanediol diacetal of glutaraldehyde was used as the substrate. 1,5-Diaminopentane (PMD or cadaverine) was obtained in high yield.

[0086] Example 13

[0087] Example 5 was repeated, except that the diethylene glycol diacetal of 1,9-nonadialdehyde was used as the substrate. 1,9-Diaminononane was obtained with high selectivity and overall yield.

[0088] Example 14

[0089] Example 10 was repeated, except that a diethylene glycol diacetal of 1,12-dodecanedialdehyde was used as the substrate. 1,12-dodecanediamine was obtained in high yield.

[0090] Example 15

[0091] Example 1 was repeated, except that a glycerol diacetal of 1,4-phenylenedialdehyde (terephthalaldehyde) was used as the substrate. p-Phenylenediamine (1,4-phenylenediamine or PPD) was obtained in high yield.

[0092] Similarly, according to the method of Example 1, isomers of p-phenylenediamine, namely o-phenylenediamine (OPD) and m-phenylenediamine (MPD), can be produced in high yields from the diacetals of the corresponding dialdehydes of p-phenylenediamine (i.e., 1,2-phenylenedialdehyde and 1,3-phenylenedialdehyde). Therefore, the disclosed process provides an alternative route for the preparation of such industrially important intermediates with improved selectivity and overall yield. Conventional methods are more complex and require nitrobenzenes produced by benzene dinitration, which are cumbersome to handle.

[0093] Throughout the document, values ​​expressed in this range format should be interpreted flexibly to include not only the values ​​explicitly listed as the upper and lower limits of the range, but also all individual values ​​or subranges covered within that range, just as if each value and subrange were explicitly listed. For example, the range “about 0.1% to about 5%” or “about 0.1% to 5%” should be understood to include not only about 0.1% to about 5%, but also the individual values ​​(e.g., 1%, 2%, 3%, and 4%) and subranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. Unless otherwise specified, the expression “about X to Y” has the same meaning as “about X to about Y”. Similarly, unless otherwise specified, the expression “about X, Y, or about Z” has the same meaning as “about X, about Y, or about Z”.

[0094] In this document, unless the context clearly indicates otherwise, the terms “a,” “an,” or “the / described” are used to include one or more. Unless otherwise specified, the term “or” is used to mean a non-exclusive “or.” The expressions “at least one of A and B” or “at least one of A or B” have the same meaning as “A, B, or A and B.” Furthermore, it should be understood that the wording or terminology used herein, unless otherwise defined, is for illustrative purposes only and not for limitation. Any use of section headings is intended to aid in reading the document and should not be construed as restrictive; information relating to a section heading may appear within or outside that particular section.

[0095] In the methods described herein, these actions can be performed in any order without departing from the principles of the invention, except where the timing or sequence of operations is explicitly stated. Furthermore, specified actions can be performed simultaneously unless the explicit language of the claims states that they can be performed individually. For example, performing the claimed action X and performing the claimed action Y can be performed simultaneously in a single operation, and the resulting process will fall within the literal scope of the claimed process.

[0096] As used herein, the term “about” may allow for a certain degree of fluctuation in a value or range, for example, within 10%, 5%, or 1% of the upper or lower limits of the value or range, and includes the exact value or range stated herein.

[0097] As used herein, the term “substantially” means most or most, such as at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%. As used herein, the term “substantially free” may mean having none or having trace amounts of material such that the amount of material present does not affect the material properties of the composition comprising the material, such that the composition is about 0% to about 5% by weight, or about 0% to about 1% by weight, or about 5% by weight or less, or less than, equal to or greater than about 4.5% by weight, 4% by weight, 3.5% by weight, 3% by weight, 2.5% by weight, 2% by weight, 1.5% by weight, 1% by weight, 0.9% by weight, 0.8% by weight, 0.7% by weight, 0.6% by weight, 0.5% by weight, 0.4% by weight, 0.3% by weight, 0.2% by weight, 0.1% by weight, 0.01% by weight, or about 0.001% by weight or less of the material. The term "substantially free" may mean having trace amounts such that the composition is about 0% to about 5% by weight, or about 0% to about 1% by weight, or about 5% by weight or less, or less than, equal to or greater than about 4.5% by weight, 4% by weight, 3.5% by weight, 3% by weight, 2.5% by weight, 2% by weight, 1.5% by weight, 1% by weight, 0.9% by weight, 0.8% by weight, 0.7% by weight, 0.6% by weight, 0.5% by weight, 0.4% by weight, 0.3% by weight, 0.2% by weight, 0.1% by weight, 0.01% by weight, or about 0.001% by weight or less, or about 0% by weight of material.

[0098] All publications mentioned in this specification, including non-patent literature (such as scientific journal articles), patent application publications, and patents, are incorporated by reference as if each publication were specifically and individually indicated as incorporated by reference.

[0099] It should be understood that the description herein is intended to be exemplary and not restrictive. Many other embodiments will be apparent to those skilled in the art after reading the above description. Therefore, the scope of the invention should be determined by reference to the appended claims and the full scope of their authorized equivalents. In the appended claims, the terms "comprising" and "wherein" are used as common English equivalents of the respective terms "including" and "wherein". Furthermore, the terms "first," "second," "third," etc., are used only as designations and are not intended to impose numerical requirements on their objects.

[0100] As used in this article, the term "dial" is an abbreviation for dialdehyde and is commonly used in industry.

[0101] As used herein, the term "aldehydes" refers to a class of organic compounds and includes aldehydes [R-CHO], dialdehydes [HCO-R-CHO], acetals of aldehydes, or diacetals of dialdehydes. Acetals or diacetals can be produced by reacting a diol or glycol with a suitable aldehyde or dialdehyde. As an example, the diethylene glycol acetal of butyraldehyde can be produced by reacting diethylene glycol [DEG] with butyraldehyde. In another example, the glycerol diacetal of hexamethylenedialdehyde can be produced by reacting glycerol with hexamethylenedialdehyde. These chemical reactions are known in industry.

[0102] Non-limiting examples of suitable dialdehydes may include butyraldehyde, glutaraldehyde, hexadaldehyde, heptadecaldehyde, octanaldehyde, nonanaldehyde, decanedaldehyde, undecanedialdehyde, dodecanedialdehyde, etc. Other examples may include cyclic dialdehydes such as cyclopentyldialdehyde, 1,3-cyclohexyldicarboxaldehyde, 1,4-cyclohexyldicarboxaldehyde, cycloheptyldialdehyde, etc. Some examples of aromatic dialdehydes may include terephthalaldehyde and isophthalaldehyde.

[0103] Low-carbon dialdehydes (such as succinaldehyde and glutaraldehyde) can be produced from biomass-derived raw materials and fermentation processes.

[0104] Higher carbon content dialdehydes can be produced, for example, by hydroformylation of an unsaturated aldehyde having one less carbon atom than the desired dialdehyde or a diene having two less carbon atoms than the desired dialdehyde. Other industrial processes for preparing C6 and higher dialdehydes may include ozone or H2O2 reduction of the corresponding cyclic olefin having the same number of carbon atoms as the desired dialdehyde, or reduction by a dicarboxylic acid having the same number of carbon atoms as the desired dialdehyde.

[0105] In one scenario, adipaldehyde can be produced via ozone reduction of cyclohexene. In another, 1,5,9-cyclododecanetriene (CDDT), commercially produced from the cyclotrimerization of 1,3-butadiene, can be contacted with ozone to produce a dodecyl (or 12-carbon) aldehyde, as disclosed in U.S. Patent No. 4,085,127. Similarly, 1,5-cyclooctadiene (COD), a coproduct of the cyclotrimerization of butadiene, can undergo ozone reduction to provide an octyl (or 8-carbon) aldehyde.

[0106] While the subject matter disclosed herein will be described in detail in conjunction with the enumerated claims, it should be understood that the exemplary subject matter is not intended to limit the claims to the disclosed subject matter.

Claims

1. A method for preparing diamine; the method comprising: In the reaction zone, the acetal compound is brought into contact with a hydrogen source and an ammonia source in the presence of a heterogeneous catalyst and solvent. The reaction zone conditions are controlled for a specified period of time to convert the acetal compound into at least one diamine compound; And to recover the effluent from the reaction zone to obtain the diamine compound.

2. The method according to claim 1, wherein the acetal is a reaction product of an aldehyde compound.

3. The method according to claim 2, wherein the aldehyde compound is selected from one or more of the following compounds: R1-CHO, HCO-R1-CHO; wherein R1 is selected from C4-C6. 12 Hydrocarbon group.

4. The method according to any one of claims 1 to 3, wherein the acetal is a reaction product of at least one aldehyde compound selected from the group consisting of: butyraldehyde, n-pentanaldehyde, hexanal, succinaldehyde, glutaraldehyde, and hexadialdehyde.

5. The method according to claim 4, wherein the acetal is selected from the group consisting of: diethylene glycol acetal of butyraldehyde, diethylene glycol acetal of pentanaldehyde, diethylene glycol acetal of hexadaldehyde, 1,3-propanediol acetal of butyraldehyde, 1,3-propanediol acetal of pentanaldehyde, 1,3-propanediol acetal of hexadaldehyde, glycerol acetal of butyraldehyde, glycerol acetal of pentanaldehyde, and glycerol acetal of hexadaldehyde.

6. The method of claim 1, wherein the acetal is selected from one or more compounds having the following molecular structures: in, R2 is selected from C2-C 12 The hydrocarbon groups A1, A2, A3, and A4 are each independently selected from C1-C5 alkyl groups, and A5 and A6 are each independently selected from C2-C4 alkyl groups.

7. The method of claim 1, wherein controlling the conditions of the reaction zone comprises controlling the temperature within a temperature range selected from the group consisting of 45°C to 150°C, 45°C to 125°C, and 50°C to 100°C.

8. The method of claim 1, wherein controlling the reaction zone conditions comprises controlling a pressure range selected from the group consisting of 10 Psig to 4500 Psig, 50 Psig to 4000 Psig, and 100 Psig to 4000 Psig.

9. The method of claim 1, wherein controlling the reaction zone conditions includes determining a specified residence time, the specified residence time being determined to convert at least a portion of the acetal compound into at least one diamine compound when the reaction zone pressure no longer decreases from a specified set pressure value.

10. The method according to claim 1, wherein the ammonia source is selected from ammonia gas, an aqueous solution of ammonia, and an amine.

11. The method according to claim 1, wherein the heterogeneous catalyst is a sponge metal.

12. The method of claim 11, wherein the sponge metal comprises at least one of nickel and cobalt.

13. The method of claim 11, wherein the sponge metal is selected from Raney. ® Nickel and Raney ® cobalt.

14. The method of claim 1, wherein the solvent comprises an oxygen-containing compound.

15. The method of claim 14, wherein the oxygen-containing compound is selected from water, alcohols, and esters.

16. The method of claim 15, wherein the alcohol is selected from methanol, ethanol, propanol and butanol.

17. The method of claim 15, wherein the alcohol is obtained from a process selected from the group consisting of: hydrocarbon-based synthesis processes, by-product or co-product alcohols from chemical synthesis processes, biomass-derived processes, and fermentation processes.

18. The method of claim 1, wherein the contact is further carried out in the reaction zone in the presence of a promoter.

19. The method of claim 18, wherein the promoter is a metal hydroxide.

20. The method according to claim 19, wherein the metal hydroxide is selected from sodium hydroxide, potassium hydroxide, calcium hydroxide and barium hydroxide.

21. The method of claim 1, wherein recovering the reaction zone effluent to obtain the diamine compound further comprises a solid separation step to recover the reaction zone effluent from the heterogeneous catalyst.

22. The method of claim 21, wherein the solid separation step is selected from the group consisting of: pressure filtration, vacuum filtration, centrifugation, membrane separation, distillation, scraped membrane evaporation, decantation, and gravity sedimentation.

23. A method for preparing 1,6-hexanediamine; the method comprising: In the reaction zone, the diacetal of adipaldehyde is mixed with a hydrogen source and an ammonia source in the presence of a heterogeneous catalyst and solvent; the reaction zone conditions are controlled for a sufficient time to efficiently convert the diacetal of adipaldehyde into 1,6-hexanediamine; and the effluent from the reaction zone is recovered to obtain 1,6-hexanediamine.

24. A method for preparing 1,6-hexanediamine; the method comprising: In the reaction zone, adipaldehyde is mixed with a hydrogen source and an ammonia source in the presence of a heterogeneous catalyst and solvent; the reaction zone conditions are controlled for a sufficient time to efficiently convert adipaldehyde into 1,6-hexanediamine; and the effluent from the reaction zone is recovered to obtain 1,6-hexanediamine.

25. The method according to claim 23 or 24, wherein the reaction zone further comprises a promoter.

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