Phosphate esters with very low triphenyl phosphate content

Abstract

The composition comprises phosphate esters, such as alkyl and aryl phosphate esters, which have a very low or no triphenyl phosphate (TPP) content. Additionally, a method for synthesizing phosphate esters is also disclosed, which aims to control the TPP content to less than 0.1% in order to drastically reduce the potential toxicity of products containing phosphate esters.

Description

Technology Field

[0001] This application claims priority to U.S. Provisional Application No. 63 / 620,943, filed January 15, 2024. Such prior application is incorporated herein by reference. Background Technology

[0002] Phosphate esters are widely used due to their flame-retardant properties, along with their primary use as additives in wire and cable formulations. Phosphate esters can be non-halogenated, and these types are growing to replace brominated flame retardants.

[0003] Triphenyl phosphate (CAS No. 115-86-6) is a well-known phosphate ester flame retardant, but it is a substance for which the regulatory framework is expanding. European regulatory authorities strengthened its risk assessment in 2017. In May 2023, France published a conclusion document indicating that triphenyl phosphate (TPP) should be classified as Category 1 for endocrine disruption, and it was recommended that it be added to the SVHC (Substances of Very High Concern) list. This is the first step toward restricting the substance for commercial use. TPP was officially listed on the SVHC list by European authorities in early November 2024.

[0004] Even if not intentionally present in products, TPP is a byproduct generated during the synthesis of other phosphate esters. It is difficult or impossible to remove using the technologies adopted after synthesis. means of solving the problem

[0005] The following is a brief summary of the subject matter to be described in more detail in this specification. This summary is not intended to limit the scope of the claims.

[0006] The present specification discloses compositions comprising phosphate esters, such as alkyl and aryl phosphate esters, which have a very low or no triphenyl phosphate (TPP) content. Methods for synthesizing phosphate esters are also disclosed, which aim to drastically reduce the potential toxicity of these products and control TPP to less than 0.1%.

[0007] In some embodiments, the descriptions in this specification relate to compositions comprising phosphate ester compounds of Formula 1, Formula 2, and Formula 3.

[0008]

[0009]

[0010]

[0011] Herein, R1 and R2 are independently selected from the group consisting of C4-C18 branched or linear alkyl groups, C4-C18 branched or linear alkenyl groups, C4-C18 branched or linear alkoxy groups, C4-C18 branched or linear hydroxyalkyl groups, branched or linear C4-C18 alkyl ether groups, or mixtures thereof; Formula 1 is at least 75% by weight of the total weight of all phosphate esters in the composition; and Formula 3 is less than 0.1% by weight of the total weight of all phosphate esters in the composition. Or the descriptions in this specification relate to compositions comprising phosphate ester compounds of Formula 4, Formula 5, and Formula 3.

[0012]

[0013]

[0014] Here, R3 and R4 are independently selected from the group consisting of C1-C10 branched or linear alkyl groups, C1-C10 branched or linear alkenyl groups, C1-C10 branched or linear alkoxy groups, C1-C10 branched or linear hydroxyalkyl groups, branched or linear C1-C10 alkyl ether groups, or mixtures thereof, and Formula 3 is less than 0.1 weight% relative to the total weight of all phosphate esters in the composition.

[0015] In some embodiments, the techniques described herein relate to compositions in which R1 and R2 are independently selected from branched or linear C4-C18 alkyl groups or branched or linear C4-C18 alkyl ether groups; or R4 and R5 are independently selected from branched or linear C4-C18 alkyl groups or branched or linear C4-C18 alkyl ether groups.

[0016] In some embodiments, the techniques described herein relate to compositions in which R1 and R2 are 2-ethylhexyl.

[0017] In some embodiments, the techniques described herein relate to compositions in which R1 and R2 are linear or branched C10 alkyl groups.

[0018] In some embodiments, the techniques described herein are linear or branched -C 10 H 21 , -C 12 H 25 , -C 14 H 29 , or -C 16 H 33 It relates to a composition independently selected from a group consisting of groups.

[0019] In some embodiments, the descriptions in this specification relate to compositions in which the structure of Formula 2 is present in an amount of 20% by weight to 1% by weight relative to the total weight of all phosphate esters in the composition.

[0020] In some embodiments, the descriptions in this specification relate to compositions in which the structure of Formula 3 is present in an amount of 0.01% to 0.05% by weight relative to the weight of the total compounds.

[0021] In some embodiments, the techniques described herein relate to compositions in which R3 and / or R4 are t-butyl groups.

[0022] In some embodiments, the technologies described herein relate to a polymer composition comprising (a) a polymer selected from the group consisting of polyvinyl chloride (PVC), polyurethane, polyvinyl acetate, polyvinyl butyral, polystyrene, nitrocellulose, nitrile rubber, ABS, polycarbonate, polyamide, polyester, epoxy, and combinations thereof; and (b) a polymer composition comprising a phosphate ester composition comprising phosphate ester compounds of Formula 1, Formula 2, and Formula 3 as listed above, wherein R1 and R2 are independently selected from the group consisting of C4-C18 branched or linear alkyl groups, C4-C18 branched or linear alkenyl groups, C4-C18 branched or linear alkoxy groups, C4-C18 branched or linear hydroxyalkyl groups, branched or linear C4-C18 alkyl ether groups, or mixtures thereof; Formula 1 is 75% by weight of the total weight of all phosphate esters in the composition; and Formula 3 is less than 0.1% by weight of the total weight of all phosphate esters in the composition. Or comprises phosphate ester compounds of Formula 4, Formula 5, and Formula 3 as listed above, wherein Formula 3 is less than 0.1% by weight of the total weight of all phosphate esters in the composition.

[0023] In some embodiments, the techniques described herein relate to compositions in which the polymer is selected from the group consisting of PVC and polyurethane.

[0024] In some embodiments, the techniques described herein relate to compositions in which R1 and R2 are independently selected from branched or linear C4-C18 alkyl groups or branched or linear C4-C18 alkyl ether groups; or R4 and R5 are independently selected from branched or linear C1-C10 alkyl groups or branched or linear C1-C10 alkyl ether groups.

[0025] In some embodiments, the techniques described herein are such that R1 and R2 are 2-ethylhexyl, linear or branched -C 10 H 21 , -C 12 H 25 , -C 14 H 29 , or -C 16 H 33 The invention relates to a composition in which the groups are independently selected from a group consisting of groups; or in which R3 and / or R4 are t-butyl groups.

[0026] In some embodiments, the techniques described herein relate to a method for preparing a phosphate ester having a low triphenyl phosphate content, wherein the method comprises the step of reacting an alcohol having the formula R0OH with POCl3 to produce a reaction mixture having an intermediate; said alcohol having the formula R0OH is provided in a molar ratio of 1.10:1 or greater with respect to POCl3; said R0 is an alkyl group selected from the group consisting of C4-C18 branched or linear alkyl groups, C4-C18 branched or linear alkenyl groups, C4-C18 branched or linear alkoxy groups, C4-C18 branched or linear hydroxyalkyl groups, branched or linear C4-C18 alkyl ether groups, or mixtures thereof; and said intermediate is reacted with a phenate compound to form a composition comprising a phosphate monoester having an alkyl group corresponding to R0; Alternatively, the method comprises the step of reacting a substituted phenol with POCl3, wherein the phenol is substituted with substituents R3 and / or R4; wherein the molar ratio of the substituted phenol to POCl3 is 1.65:1 or greater; and R3 and R4 are independently selected from the group consisting of C1-C10 branched or linear alkyl groups, C1-C10 branched or linear alkenyl groups, C1-C10 branched or linear alkoxy groups, C1-C10 branched or linear hydroxyalkyl groups, branched or linear C1-C10 alkyl ether groups, or mixtures thereof.

[0027] In some embodiments, the techniques described herein relate to a method for preparing a phosphate ester having a low triphenyl phosphate content, wherein the method comprises the step of reacting an alcohol having the formula R0OH with POCl3 to produce a reaction mixture having an intermediate; wherein the alcohol having the formula R0OH is provided in a molar ratio of 1.10:1 or greater with respect to POCl3; wherein R0 is an alkyl group selected from the group consisting of C4-C18 branched or linear alkyl groups, C4-C18 branched or linear alkenyl groups, C4-C18 branched or linear alkoxy groups, C4-C18 branched or linear hydroxyalkyl groups, branched or linear C4-C18 alkyl ether groups, or mixtures thereof; and wherein the intermediate is reacted with a phenate compound to form a composition comprising a phosphate monoester having an alkyl group corresponding to R0; Alternatively, the method comprises the step of reacting a substituted phenol with POCl3, wherein the phenol is substituted with substituents R3 and / or R4; wherein the molar ratio of the substituted phenol to POCl3 is 1.65:1 or greater; and R3 and R4 are independently selected from the group consisting of C1-C10 branched or linear alkyl groups, C1-C10 branched or linear alkenyl groups, C1-C10 branched or linear alkoxy groups, C1-C10 branched or linear hydroxyalkyl groups, branched or linear C1-C10 alkyl ether groups, or mixtures thereof.

[0028] In some embodiments, the techniques described herein relate to a method in which a composition comprises less than 0.1 weight percent of triphenyl phosphate relative to the total weight of the phosphate esters.

[0029] In some embodiments, the techniques described herein relate to a method of maintaining the reaction for longer than 15 minutes after the step of reacting an alcohol having the formula R0OH with POCl3, and after all the alcohol and POCl3 have been added, before proceeding to the step of reacting the intermediate with a phenate compound.

[0030] In some embodiments, the techniques described herein relate to a method of maintaining the reaction at a temperature of 1°C to 20°C after the step of reacting an alcohol having the formula R0OH with POCl3.

[0031] In some embodiments, the techniques described herein relate to a method of reacting an alcohol having the formula R0OH with POCl3, wherein the temperature of the step is maintained at 1 to 20°C.

[0032] In some embodiments, the techniques described herein relate to a method in which the step of reacting an alcohol having the formula R0OH with POCl3 is performed under partial vacuum, or a method in which partial vacuum is applied after adding a substituted phenol.

[0033] In some embodiments, the techniques described herein relate to a phosphate ester composition comprising phosphate ester compounds of Formula 1, Formula 2, and Formula 3, wherein R1 and R2 are independently selected from the group consisting of C4-C18 branched or linear alkyl groups, C4-C18 branched or linear alkenyl groups, C4-C18 branched or linear alkoxy groups, C4-C18 branched or linear hydroxyalkyl groups, branched or linear C4-C18 alkyl ether groups, or mixtures thereof; Formula 1 is 75% by weight relative to the total weight of the phosphate ester compounds in the composition; and Formula 3 is less than 0.1% by weight relative to the total weight of the phosphate ester compounds in the composition; or comprising phosphate ester compounds of Formula 4, Formula 5, and Formula 3, wherein Formula 3 is less than 0.1% by weight relative to the total weight of the phosphate ester compounds in the composition.

[0034] In some embodiments, the techniques described herein relate to a method in which a substituted phenol reacts with POCl3, the molar ratio of the substituted phenol to POCl3 is 1.75:1 to 2.5:1, and the order of addition is to add the substituted phenol to POCl3.

[0035] The foregoing summary presents a simplified overview to provide a basic understanding of some aspects of the systems and / or methods discussed herein. This summary is not a comprehensive overview of the systems and / or methods discussed herein. It is not intended to identify the key or decisive elements of such systems and / or methods or to describe their scope. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed descriptions to be provided later. Specific details for implementing the invention

[0036] Various techniques related to triphenyl phosphate with very low triphenyl phosphate (TPP) content are now described. In the following description, numerous specific details are presented for illustrative purposes to provide a thorough understanding of one or more embodiments. However, it may be apparent that such embodiment(s) can be practiced without these specific details.

[0037] As used herein, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless otherwise specified or the context makes clear, the phrase “X uses A or B” is intended to mean any of the natural inclusive permutations. That is, the phrase “X uses A or B” is satisfied by any of the following cases: X uses A; X uses B; or X uses both A and B. Furthermore, the articles “one” and “one” used in this application and the appended claims should generally be interpreted to mean “one or more” unless otherwise specified or the context makes clear that they indicate the singular form.

[0038] For example, if the molecular weight of a polymer is provided, it should be understood as the average molecular weight unless otherwise specified or understood from the context.

[0039] Triphenyl phosphate (TPP) is a byproduct in most commercial alkyl aryl phosphates and triaryl phosphate products. Some commercial products have been tested in this specification by gas chromatography methods to determine the weight percent of TPP. For products on the market, the amount of TPP varies from 40% to about 1%. Considering that the TPP percentage is sufficient for addition to the SVHC list, it was determined that it is necessary to reduce the weight percent of TPP in alkyl aryl phosphates and triaryl phosphates.

[0040] The phosphate ester compositions disclosed in this specification may include various alkyl aryl phosphate esters. In one embodiment, the phosphate ester comprises one or more of the compounds of structures 1 and 2.

[0041] [Structure 1]

[0042]

[0043] [Structure 2]

[0044]

[0045] [Structure 3](TPP)

[0046]

[0047] In structures 1 and 2, R1 and R2 are independently selected from the group consisting of C4-C18 branched or linear alkyl groups, C4-C18 branched or linear alkenyl groups, C4-C18 branched or linear alkoxy groups, C4-C18 branched or linear hydroxyalkyl groups, branched or linear C4-C18 alkyl ether groups, or mixtures thereof. The C4-C18 alkyl groups, C4-C18 alkenyl groups, C4-C18 alkoxy groups, and C4-C18 hydroxyalkyl groups may be selected from, for example, C5-C16, C6-C14, or C8-C12.

[0048] In certain embodiments, R1 and R2 are independently selected from C4-C18 alkyl groups or C4-C18 alkyl ether groups. In other embodiments, R1 and R2 are independently selected from linear or branched C8 groups, such as 2-ethylhexyl, or C10 groups, such as isodecanol. In other embodiments, R1 and R2 are independently selected from the group consisting of linear or branched C12, C14, or C16 groups, or R1 and R2 are 2-ethylhexyl, linear or branched -C 10 H 21 , -C 12 H 25 , -C 14 H29 , or -C 16 H 33 It is independently selected from a group of groups; or R3 and / or R4 are t-butyl groups.

[0049] Specific examples of phosphate esters corresponding to structure 1 are 2-ethylhexyl diphenyl phosphate (CAS no. 1241-94-7), isodecyl diphenyl phosphate (CAS no. 29761-21-5), and C12-C16 alkyl diphenyl phosphate.

[0050] In one embodiment, the phosphate ester is non-halogenated, such as non-brominated and non-chlorinated. In one embodiment, the phosphate ester has a molecular weight of 650 g / mol to 325 g / mol, e.g., 520 g / mol to 350 g / mol, or 480 g / mol to 390 g / mol.

[0051] In one embodiment, the phosphate ester composition has a content of structure 1 of 75% or more relative to the total weight (or total weight of the composition) of formulas 1, 2, and 3, for example, 76% to 99.9%, 80% to 95%, or 85% to 90% of structure 1. Structure 2 may be present in an amount of 24.999% to 0.0001% by weight, for example 20% to 1%, or 15% to 5% relative to the total weight (or total weight of the composition) of formulas 1, 2, and 3.

[0052] In one embodiment, the phosphate ester comprises one or more substituted triphenyl phosphate compounds of structures 4 and 5, wherein one or two of the phenyl groups are substituted with substituents R3 and R4.

[0053] [Structure 4]

[0054]

[0055] [Structure 5]

[0056]

[0057] In structures 4 and 5, the substituents R3 and R4 are independently selected from the group consisting of C1-C10 branched or linear alkyl groups, C1-C10 branched or linear alkenyl groups, C1-C10 branched or linear alkoxy groups, C1-C10 branched or linear hydroxyalkyl groups, branched or linear C1-C10 alkyl ether groups, or mixtures thereof. The number of carbon atoms in the C1-C10 alkyl groups, C1-C10 alkenyl groups, C1-C10 alkoxy groups, and / or C1-C10 hydroxyalkyl groups may be selected, for example, from C2 to C9, C3 to C7, or C4 to C6. In certain embodiments, R3 and / or R4 are t-butyl groups.

[0058] In one embodiment, the substituted triphosphate ester compound is non-halogenated, non-brominated, or non-chlorinated. In one embodiment, the phosphate ester has a molecular weight of 700 g / mol to 375 g / mol, e.g., 620 g / mol to 400 g / mol, or 450 g / mol to 420 g / mol.

[0059] In one embodiment, the substituted triphenyl phosphate composition has a content of at least 40 wt% of structure 4 relative to the total weight of formulas 4, 5, and 3, and the total weight of all phosphate esters (or the total weight of the composition), for example, 55 wt% to 85 wt%, 60 wt% to 80 wt%, or 65 wt% to 75 wt% of structure 4. Structure 5 may be present in an amount of 60% to 0.0001%, for example 50% to 1%, or 40% to 5%.

[0060] In any composition comprising structures 1 and 2 or structures 4 and 5, phosphate ester compositions have traditionally contained structure 3 (TPP) in an amount of 0.5 to 3%. In contrast, the phosphate ester compositions disclosed herein have a total weight percentage of TPP of less than 0.1 weight% relative to the weight of TPP / total weight of phosphate ester (e.g., each of formulas 1 to 5, or total composition weight), e.g., 0.0001% to 0.09%, 0.001% to 0.08%, 0.01% to 0.05%, or 0.015 to 0.045%.

[0061] The phosphate ester composition may also contain very small amounts of phenol and water, for example, 1 to 500 ppm each, e.g. 10 to 300 ppm.

[0062] Various consumer and industrial products may include phosphate ester compositions as a component. For example, flame-retardant materials utilize phosphate esters as flame retardants, and polymer materials may use phosphate esters as plasticizers. In some applications, phosphate esters act as both plasticizers and flame retardants.

[0063] In particular, non-halogenated phosphate esters are valued for use in flame-retardant materials. Phosphate esters function by causing a coating or suffocating effect on the solid phase of combustible materials. When exposed to heat from a fire, phosphate esters react to form polymeric phosphoric acid. This heat-activated polymeric phosphoric acid forms a char layer that covers the combustible material, blocking contact with oxygen. This slows down or stops the combustion reaction.

[0064] Phosphate esters can be used in polymer compositions such as, for example, polyvinyl chloride (PVC), polyurethane, polyvinyl acetate, polyvinyl butyral, polystyrene, nitrocellulose, nitrile rubber, ABS, polycarbonate, polyamide, polyester, epoxy, and combinations thereof. Phosphate esters provide a plasticizing effect and can also be used to improve the fire resistance and / or smoke suppression properties of the material. Plasticizers can be used to improve the processing properties and end properties of the material. Materials such as wires, cables, flooring, textiles (polymer-coated fabrics), belts, hoses, structural foams, paints, coatings, oils, and lubricants can benefit from the phosphate ester compositions disclosed herein.

[0065] In one embodiment, a phosphate ester composition is included in a material, said material having a total weight percentage of TPP (TPP weight / total phosphate ester weight) of less than 0.1%, for example, 0.0001% to 0.09%, 0.001% to 0.08%, or 0.01% to 0.05% (TPP weight / total phosphate ester weight). Additionally, the total weight percentage of TPP in the polymer material is less than 0.1% (TPP weight / total material weight), for example, 0.0001% to 0.09%, 0.001% to 0.08%, or 0.01% to 0.05% (TPP weight / total material weight).

[0066] In one embodiment, 2-ethylhexyl diphenyl phosphate is synthesized by a three-step reaction. In the first step, the starting materials are POCl3 and 2-ethylhexanol. These fluids are mixed together, and 2-ethylhexanol is provided in an excess of 10% or more. The stoichiometric ratio between 2-ethylhexanol and POCl3 is 1.10 or greater, for example, 1.10 to 2, or 1.11 to 1.5, or 1.2 to 1.3. In one embodiment, the reactants are cooled below room temperature, for example, to 1 to 22°C, for example, 5 to 15°C, or 8 to 12°C. Cooling may be applied during the reaction and / or the reactants may be metered to maintain a low reaction temperature (for example, 1 to 20°C, for example, 8 to 18°C ​​or 12 to 16°C). As the reaction proceeds, a partial vacuum may also be applied to the reaction flask, and a pressure of, for example, 10 to 75 mmHg, 20 to 60 mmHg, or 30 to 50 mmHg may be applied.

[0067] In previous methods for preparing this compound, the ratios were equal or slightly in excess, for example, by multiples of 1.0 to 1.05. Surprisingly, small changes in the ratios of these components resulted in an unexpected improvement, reducing TPP byproducts to less than 0.1 weight%.

[0068] Another unexpected process improvement was achieved by extending the holding time at the end of the Step 1 reaction to more than 15 minutes. This contrasts with previous practices where the holding time was maintained for only 0–5 minutes. Holding time refers to the time after all reactants have been added. Holding may also include mixing or stirring. By extending this step, a reduction in TPP content was observed. After mixing the two components, the reaction can be held for more than 15 minutes, for example, 15.5 to 60 minutes, 16 to 25 minutes, or 17.5 to 22.5 minutes. During the holding time of the reaction mixture, the temperature can be controlled, for example, to 1 to 20°C, for example, 5 to 15°C, or 8 to 12°C. Extending the holding time allows as many POCl3 molecules as possible to react with the alcohol. This reaction is advantageous at lower temperatures, for example, 8 to 18°C ​​or 12 to 16°C. Once POCl3 is reduced to a very small amount, TPP% can be controlled to be less than 0.1%. This is because POCl3 entering the step 3 reaction is believed to be a chemical that reacts to make TPP.

[0069] In some embodiments, the reaction mixture may be maintained for additional times, such as 15.5 to 60 minutes, 16 to 25 minutes, or 17.5 to 22.5 minutes, and / or may be further maintained under partial vacuum at, for example, 28 to 45°C, e.g. 30 to 40°C, or 33 to 38°C. This step is intended to further complete the reaction between all the raw materials. In this step, the mono-ester between POCl3 and the alcohol is the dominant species. Due to the excess of the alcohol, a small amount of di-ester is present. This part at a relatively higher temperature is intended to consume all the raw materials before entering the reaction in step 3.

[0070] Step 1 is depicted in reaction equation (Ia).

[0071] (Ia)

[0072]

[0073] In Step 1, a sufficient excess of alcohol must be provided, and the holding time at the end of Step 1 must be long enough and the temperature sufficiently low to allow POCl3 molecules to react with the alcohol to form mono-esters. Without being bound by theory, it is believed that these reaction conditions facilitate the prevention (removal) of unreacted POCl3 molecules from entering Step 3, where they can react with sodium phenate. Any unreacted POCl3 molecules are likely to react in Step 3 to become TPP.

[0074] If the reaction is raised to a higher temperature too early at the end of Step 1, the already formed mono-esters (i.e., dichloridate) may react further with the free alcohol and be consumed. This deprives the remaining POCl3 molecules of the opportunity to become mono-esters and increases the formation of TPP in Step 3.

[0075] Step 2 is depicted in reaction scheme (Ib). Sodium hydroxide (NaOH) is added to phenol. This produces an intermediate product, sodium phenate compound, and water.

[0076] (Ib)

[0077]

[0078] This reaction can be cooled to, for example, 45°C to 35°C or 42°C to 38°C in order to keep it below 50°C.

[0079] Step 3 is depicted in reaction scheme (Ic). The sodium phenate compound, an intermediate from Step 2, is combined with 2-ethylhexyl dichlorophosphate (Ic), an intermediate product of Step 1. Sodium phenate is provided in a molar ratio of 2:1 with respect to 2-ethylhexyl dichlorophosphate. This produces the final product 2-ethylhexyl diphenyl-phosphate together with the sodium chloride salt. When carried out according to the conditions listed above in relation to an excess of alcohol and / or a long holding time after Step 1, the amount of TPP produced in the final product through these Steps 1 to 3 and reaction schemes (Ia, Ib, Ic) is very small.

[0080] (Ic)

[0081]

[0082] In one embodiment, water and base may be mixed and cooled to 20°C before adding phenol so that the temperature of the reaction in step 3 can be controlled, for example, to be maintained at less than 50°C, e.g., 45°C to 35°C, or 42°C to 38°C.

[0083] In one embodiment, at the end of the reaction in step 3, water may be added and then HCl may be added to adjust the pH of the system to, for example, 9 to 12, e.g., 9.5 to 11.5, or 10 to 11.

[0084] In one embodiment, isodecyl diphenyl phosphate ester is similarly prepared by a three-step reaction. The same temperature ranges listed above for the reaction steps of the 2-ethylhexyl diphenyl phosphate ester embodiment are also applicable to the isodecyl diphenyl phosphate ester embodiment.

[0085] In the first step, the starting materials are POCl3 and isodecanol. These fluids are mixed together, and isodecanol is provided in an excess of 10% or more. The stoichiometric ratio between isodecanol and POCl3 is 1.10 or greater, for example, 1.10 to 2, or 1.11 to 1.5, or 1.2 to 1.3.

[0086] In previous methods for preparing this compound, the ratios were equal or slightly excess (1.0-1.05). Surprisingly, this small change in the ratios of these components resulted in an unexpected improvement, reducing TPP byproducts to less than 0.1 wt%. HCl is produced as a major byproduct.

[0087] After mixing the two components, the reaction is maintained for at least 15 minutes, e.g., 15.5 to 60 minutes, 16 to 25 minutes, or 17.5 to 22.5 minutes. During the time the reaction mixture is maintained, the temperature can be controlled, e.g., 1 to 20°C, e.g., 5 to 18°C, or 12 to 15°C. This produces a first intermediate product. Step 1 is depicted in reaction scheme (IIa).

[0088] (IIa)

[0089]

[0090] Similar to reaction scheme Ia, the process was improved by extending the holding time at the end of the step 1 reaction to more than 15 minutes. By extending this step, an additional reduction in TPP content was observed.

[0091] In Step 1, a sufficient excess of alcohol must be provided, and the holding time at the end of Step 1 must be long enough and the temperature sufficiently low to allow POCl3 to react with the alcohol to form a mono-ester. Without being bound by theory, it is believed that these reaction conditions facilitate the prevention (removal) of unreacted POCl3 molecules from entering Step 3, where they can react with sodium phenate. Any unreacted POCl3 molecules are likely to react in Step 3 to become TPP.

[0092] If the reaction is raised to a higher temperature too early at the end of Step 1, the already formed mono-esters (i.e., dichloridate) may react further with the free alcohol and consume them all. As in the reaction described previously, this is believed to deprive the remaining POCl3 molecules of the opportunity to become mono-esters and increase the formation of TPP in Step 3.

[0093] Step 2 is depicted in reaction scheme (IIb) and is identical to Ib. Sodium hydroxide (NaOH) is added to phenol. This produces a sodium phenate compound and water.

[0094] (IIb)

[0095]

[0096] Step 3 is depicted in reaction scheme (IIc), where the sodium phenate compound from Step 2 is combined with isodecyl dichlorophosphate (IIc), the product of Step 1. This produces the final product isodecyl diphenylphosphate together with the sodium chloride salt. When carried out according to the conditions listed above in relation to an excess of alcohol and / or a long holding time after Step 1, the amount of TPP produced in the final product through these Steps 1 to 3 and reaction schemes (IIa, IIb, IIc) is very small.

[0097] (IIc)

[0098]

[0099] The process steps described above for specific phosphate ester final products may be applied to other embodiments in which the alcohol is added in a molar ratio of 1.10:1 or greater with respect to POCl3 in Step 1, or in other ratios described above. The alcohol (R0OH) may have an R0 group selected from the group consisting of C4-C18 branched or linear alkyl groups, C4-C18 branched or linear alkenyl groups, C4-C18 branched or linear alkoxy groups, C4-C18 branched or linear hydroxyalkyl groups, branched or linear C4-C18 alkyl ether groups, or mixtures thereof. The C4-C18 alkyl groups, C4-C18 alkenyl groups, C4-C18 alkoxy groups, and C4-C18 hydroxyalkyl groups may be selected from, for example, C5-C16, C6-C14, or C8 to C12.

[0100] To continue the synthesis, steps 2 and 3 are performed as described above, and the intermediate product from step 1 is added to the phenate intermediate product of step 2 in step 3 as described above. Bases other than NaOH, for example, KOH, may be used.

[0101] In each of the synthesis steps above, the reaction mixture after step 3 undergoes separation (removal of the oil product layer) and purification steps (e.g., washing) to obtain a phosphate ester composition.

[0102] In one embodiment, the substituted triphenyl phosphate is synthesized by a two-step single-vessel reaction as illustrated in reaction scheme (III).

[0103] (III)

[0104]

[0105] In the first step, the starting materials are POCl3, aluminum chloride (AlCl3), and p-tert-butyl-phenol (PTBP). POCl3 / AlCl3 is first present in a reaction vessel, followed by the addition of PTBP, which is preferably heated to, for example, 50 to 95°C, e.g. 55 to 85°C, or 65 to 75°C. Aluminum chloride acts as a catalyst and may be provided in small amounts relative to POCl3 in a molar ratio of, for example, 1:100 to 1:10, e.g. 1:80 to 1:20, or 1:40 to 1:60.

[0106] The mixture of POCl3 / AlCl3 is then heated at a second temperature for some time, for example, from 30 minutes to 24 hours, for example, from 1 hour to 4 hours, or from 1.5 hours to 3 hours. The second temperature may be 100 to 200°C, for example, from 110 to 150°C, or from 115 to 135°C.

[0107] After this additional heating, phenol is added to the mixture at a second temperature, and the second temperature is maintained for a set period of time, for example, 1 to 5 hours, e.g., 2 to 4 hours, or 2.5 to 3.5 hours. After this period of time, a partial vacuum may be applied to the reaction flask during the second period of time, for example, at a pressure of 20 to 85 mmHg, 30 to 70 mmHg, or 40 to 60 mmHg. The second period of time may be, for example, 0.25 to 2 hours, e.g., 0.5 to 1.5 hours, or 0.4 to 0.75 hours. The second temperature may be maintained during the second period of time. After this second period of time, the reactants are cooled to a temperature lower than the second temperature, for example, 25 to 100°C, 40 to 90°C, or 50 to 85°C.

[0108] Subsequently, more reactants are added in the second step. First, a caustic base, for example, NaOH or KOH, is added. This base can be diluted with water and its function is to neutralize the aluminum chloride, which acts as a catalyst. Then, optionally, an organic acid such as gluconic acid may also be added to adjust the pH to a neutral level near 7, for example, 6.8 to 7.2. This reaction may proceed for a third time period, and the temperature may be controlled by increasing the temperature, for example, from 40°C to 95°C, for example, from 50°C to 90°C, or from 60°C to 80°C. The third time period may be, for example, from 0.5 to 24 hours, for example, from 0.75 to 5 hours, or from 1 to 3 hours.

[0109] After this, the reaction mixture undergoes separation (removal of the oil product layer) and purification steps (e.g., washing) to obtain a substituted triphenyl phosphate ester composition. Commercially viable yields of more than 75%, e.g. 80 to 98%, or 85 to 95% can be achieved.

[0110] The stoichiometric ratio of p-tert-butylphenol to POCl3 used in the process is 1.65:1 or greater, for example, 1.75:1 to 2.5:1, 1.85:1 to 2.1:1, or 1.9:1 to 2.0:1. As shown in the examples, this molar ratio, along with the order of addition of the alkyl-substituted phenol and POCl3, influences the final product to control the weight% of TPP.

[0111] It should be understood that other substituted phenols may be used instead of p-tert-butylphenol in the method. These include phenols substituted with groups R3 and / or R4 as defined above. That is, these groups may be independently selected from the group consisting of C1-C10 branched or linear alkyl groups, C1-C10 branched or linear alkenyl groups, C1-C10 branched or linear alkoxy groups, C1-C10 branched or linear hydroxyalkyl groups, branched or linear C1-C10 alkyl ether groups, or mixtures thereof. The C1-C10 alkyl groups, C1-C10 alkenyl groups, C1-C10 alkoxy groups, and C1-C10 hydroxyalkyl groups may be selected, for example, from C2-C9, C3-C7, or C4 to C6.

[0112] Examples

[0113] Examples 1 and 2 and Comparative Examples 1 and 2

[0114] In Example 1, the first 2-ethylhexyl diphenylphosphate ester was synthesized as follows.

[0115] Step I.

[0116] Phosphorus oxychloride (153.3 g, 1.00 mol) was added to a 1-L flask and cooled to 10°C. Under vacuum, 2-ethylhexanol (143.3 g, 1.10 mol) was added to the flask at a rate that maintained the temperature below 15°C. Under vacuum of 30-50 mmHg, the mixture was held and stirred for 30 minutes to allow sufficient reaction between 2-ethylhexanol and phosphorus oxychloride at 15°C or below, then heated to 35°C and held under vacuum for 1.5 hours. The vacuum was released, and dichloridate was transferred to an addition funnel.

[0117] Step II / III.

[0118] In another 1-L flask, water (167 g) and 50% NaOH (166.4 g, 2.08 mol) were mixed and cooled to 20°C. Phenol (189.2 g, 2.01 mol) was added to this caustic solution to control the temperature to below 40°C. After cooling the resulting sodium phenate solution to 20°C, the dichloridate (254 g by weight) was added while maintaining the temperature at 25°C. It took 30 minutes to complete this addition. The mixture was stirred at 22 to 25°C for 45 minutes.

[0119] Initial separation.

[0120] The reaction mixture was diluted with water, and 38% HCl (16 g) was added to adjust the pH to 10-11. After stirring at 25°C for 5 minutes, the mixture was allowed to stand to separate the phases: the lower layer is the aqueous layer; and the upper layer is the product. The lower aqueous layer is removed to obtain the upper product layer.

[0121] Washing steps.

[0122] After that, a series of six washes were performed on the oily product, the second wash was a base wash using sodium hydroxide (170 g), and the rest were water washes. After each step, the mixture was allowed to stand and the water layer was removed.

[0123] Steam Stripping Steps.

[0124] In a 1-L flask, the washed oil was steam stripped for 15 minutes at 120-130°C under a vacuum of 80-110 mmHg. Subsequently, the steam was cut off, and the contents were dried for 5 minutes at 120-130°C under a vacuum of 30-50 mmHg. After the contents cooled to 80°C, the vacuum was released. 329 g of product was obtained.

[0125] The composition of the product was analyzed, and 2-ethylhexyl diphenyl phosphate was 90.96%, while triphenyl phosphate was 0.022%, which was well below 0.1%.

[0126] Another example (Example 2) and a comparative example (Comparative Example 1) were attempted using the same process step outline as described in Example 1. The product compositions of these reactions (by GC) and a commercial product manufactured at the production site (Comparative Example 2) are summarized in the table below.

[0127] Table 1 shows the reaction conditions, yield, product distribution and TPP content according to GC area for Examples 1 and 2 and Comparative Examples 1 and 2.

[0128] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Step I: Molar ratio of 2-ethylhexanol to POCl3 1.10 1.15 1.05 1.02 Step 1 Retention time (minutes) at the end of the reaction 30 30 30 4 transference number(%) 90.8 91.1 90.5 N / A 2-Ethylhexyl diphenyl phosphate (weight%) 90.96 87.62 94.67 93.35 TPP (weight%) 0.022 0.017 0.200 0.705

[0129] In Comparative Example 1, when the molar ratio of 2-ethylhexanol to POCl3 was 1.05 and the holding time at the end of Step 1 was 30 minutes, the TPP% of the final composition was 0.200%, which exceeded the threshold of 0.1%. This indicates that increasing the holding time at the end of the Step 1 reaction to 30 minutes and increasing the molar ratio of alcohol to POCl3 to 1.05 alone is not sufficient to lower the TPP% to less than 0.1%.

[0130] Comparative Example 2 included a production sample of Santicizer® 141 (2-ethylhexyl diphenyl phosphate), with an alcohol-to-POCl3 molar ratio of 1.02 and a retention time of 4 minutes at the end of Step 1 reaction. In this case, the TPP% is 0.705%, which is much higher than the 0.1% threshold.

[0131] Examples 3 and Comparative Examples 3 and 4

[0132] In Example 3, the first isodecyl diphenyl phosphate was synthesized as follows.

[0133] Step I.

[0134] Phosphorus oxychloride (140.0 g, 0.913 mol) was added to a 1-L flask and cooled to 10°C. Under vacuum, isodecanol (160.0 g, 1.004 mol) was added to the flask at a rate that maintained the temperature below 15°C. Under vacuum of 30-50 mmHg, the mixture was held and stirred for 30 minutes to allow sufficient reaction between isodecanol and phosphorus oxychloride, then heated to 35°C over 30 minutes and held at 35°C for 1.5 hours. The vacuum was released, and the dichloridate was transferred to a dropper funnel.

[0135] Step II / III.

[0136] In another 1-L flask, water (152 g) and 50% NaOH (152.0 g, 1.900 mol) were mixed and cooled to 20°C. Phenol (172.7 g, 1.835 mol) was added to this caustic solution to control the temperature to below 40°C. After cooling the resulting sodium phenate solution to 20°C, the dichloridate (254 g by weight) was added while maintaining the temperature at 25°C. It took 27 minutes to complete this addition. The mixture was stirred at 22 to 25°C for 45 minutes.

[0137] Initial separation.

[0138] The reaction mixture was diluted with water (200 g), and 38% HCl (16 g) was added to adjust the pH to 10-11. After stirring at 25°C for 5 minutes, the mixture was allowed to stand to separate the phases: the bottom layer is the aqueous layer; and the top layer is the product. The bottom aqueous layer is removed to obtain the product layer.

[0139] Washing step.

[0140] Six washes were performed on the oily product; the second wash was a basic wash using sodium hydroxide, and all others were water washes. During each wash, the mixture was allowed to stand to separate phases. The aqueous layer was removed.

[0141] Steam stripping.

[0142] In a 1-L flask, the washed oil was steam stripped for 15 minutes at 120-130°C under a vacuum of 80-110 mmHg. Subsequently, the steam was cut off, and the contents were dried for 5 minutes at 120-130°C under a vacuum of 30-50 mmHg. The vacuum was released after the contents cooled to 80°C. 321 g of product was obtained.

[0143] The TPP% of the product was tested and found to be 0.0287% (287 ppm), which was well below the 0.1% threshold.

[0144] A comparative example (Comparative Example 3) was attempted using the same process step outline as described in Example 3. The product compositions of these reactions (by GC) and a commercial product manufactured at the production site (Comparative Example 4) are summarized in the table below.

[0145] Table 2 shows the product distribution according to reaction conditions, yield, and GC area of ​​Example 3, Comparative Example 3, and Comparative Example 4 (production sample).

[0146] Example 3 Comparative Example 3 Comparative Example 4 Santicizer® 148 Step I: Molar ratio of isodecanol to POCl3 1.10 1.10 1.05 Step 1 Retention time (minutes) at the end of the reaction 30 4 4 transference number(%) 90.0 89.7 Not applicable Isodecyl diphenyl phosphate (weight%) 85.42 90.35 91.18 TPP (weight%) 0.0287 0.400 0.673

[0147] In Comparative Example 3, the molar ratio between alcohol and POCl3 is 1.10. However, the retention time at the end of Step 1 reaction was only 4 minutes at approximately 15°C. The TPP% was 0.4%, which is still much higher than the 0.1% threshold. On the other hand, the production sample of Santicizer® 148 (isodecyl diphenyl phosphate) had a ratio of 1.05 and a retention time of 4 minutes at the end of Step 1 reaction, exhibiting a TPP of 0.673%. This demonstrates that only by combining an alcohol-to-POCl3 ratio of 1.10 or higher and extending the retention time at the end of Step 1 reaction to approximately 15°C can POCl3 molecules be provided with sufficient time to become mono-esters (i.e., dichloridate).

[0148] Examples 4 and Comparative Examples 5 and 6

[0149] Under a vacuum of 50 to 250 torr, an alcohol (a mixture of lauryl and tetradecyl alcohols) (164.0 g) was added to phosphorus oxychloride (120.0 g) at 10-15°C. Under a vacuum of 30-50 torr, the mixture was maintained and stirred at 15°C for 30 minutes, then maintained at 35°C for 1.5 hours to obtain a liquid intermediate. While maintaining a temperature of 20 to 25°C, this intermediate was added to a phenate solution prepared with 25% NaOH (262 g) and phenol (147.3 g) according to Step 2 of Example 1. The mixture was stirred at pH >13 at 22 to 25°C for 45 minutes.

[0150] The reaction mixture was diluted with water (180 g), and the product oil (375 g) was separated and subjected to a series of washes including a caustic wash, two diluted HCl washes, and one water wash. The washed oil (346 g) was steam stripped and dried under vacuum at 120-130°C to obtain 316 g of C12-C16 alkyl diphenyl phosphate. The yield was 95.5%, the color was 1 APHA, and the acidity was 6.135 meq. / 100 g. The total GC area for all products was 99.39%, including 0.034% triphenyl phosphate.

[0151] In Comparative Example 5, the molar ratio of starting alcohol to POCl3 was 1.02, and the retention time at the end of Step 1 reaction was 30 minutes.

[0152] Comparative Example 6 was a production sample of Santicizer® 2148, which is chemically a C12-C16 alkyl diphenyl phosphate. When the molar ratio of alcohol to POCl3 was 1.05 and the holding time was 4 minutes, the TPP% was 0.278%.

[0153] Table 3 shows the product distribution according to reaction conditions, yield, and GC area of ​​Example 4, and Comparative Examples 4 and 5.

[0154] Example 4 Comparative Example 5 Comparative Example 6 Santicizer® 2148 Step I: Ratio of alcohol to POCl3 1.10 1.02 1.05 Step 1 Retention time at the end of the reaction 30 30 4 transference number(%) 95.5 93.1 89.9 Alkyl diphenyl phosphate (weight) 87.522 72.91 88.103 Triphenyl Phosphate Content (Weight%) 0.034 0.153 0.278

[0155] According to the data, increasing the molar ratio and increasing the retention time at the end of Step 1 reaction are both effective in reducing TPP% to less than 0.1%.

[0156] Example 5

[0157] In Example 5, an alkyl-substituted triphenyl phosphate ester was synthesized as follows.

[0158] p-tert-butylphenol (262.9 g) was added in portions at 70–95°C to a mixture of phosphorus oxychloride (153.3 g) and aluminum chloride (3.0 g) heated to 70°C. After heating the mixture further at 125°C for 2 hours, phenol (117.6 g) was added in portions at 120–125°C to the same reactor. The mixture was heated continuously at 125°C for 3 hours under atmospheric pressure, followed by heating under vacuum (~50 torr) for 30 minutes. The HCl gas generated during the reaction was absorbed into water.

[0159] The reaction mixture was cooled to 80°C and treated with a dilute base (430 g prepared with 400 g of water and 30 g of 50% NaOH) and gluconic acid (8.0 g) at 75°C for 1.5 hours.

[0160] The phases were separated, and the oil layer was washed with water three times until the final pH reached 8.

[0161] Washed oil (462 g) was steam stripped and dried under vacuum at 120-130°C to obtain 390 g of the target product.

[0162] The product showed a yield of 91.9%, a color of 55 APHA, and a pH of 0.076 meq. / 100 g. GC analysis of the product composition revealed that TPP was 0.075%, which was below the 0.1% threshold. The remaining product composition included pt-butylphenyl diphenyl phosphate, phenyl di(pt-butylphenyl) phosphate, and some tris(pt-butylphenyl) phosphate.

[0163] Comparative Example 7

[0164] p-tert-butylphenol (225.3 g) was added in portions at 70 to 95°C to a mixture of phosphorus oxychloride (153.3 g) and aluminum chloride (3.0 g) heated to 70°C. After heating the mixture further at 125°C for 2 hours, phenol (141.2 g) was added in portions at 120 to 125°C. The mixture was continuously heated at 125°C for 3 hours under atmospheric pressure, followed by heating under vacuum (~50 torr) for 30 minutes. The HCl gas generated during the reaction was absorbed into water.

[0165] The reaction mixture was cooled to 80°C and treated with a dilute base (500 g prepared with 460 g of water and 40 g of 50% NaOH) and gluconic acid (8.0 g) at 72°C for 1.5 hours.

[0166] The phases were separated, and the oil layer was washed with water three times until the final pH reached 9.

[0167] Washed oil (450 g) was steam stripped and dried under vacuum at 120 to 130°C to obtain 393 g of the target product.

[0168] The product showed a yield of 95.8%, a color of 8 APHA, and a pH of 0.019 meq. / 100 g. GC analysis showed that the TPP was 0.15%, slightly exceeding the 0.1% threshold.

[0169] Comparative Example 8

[0170] p-tert-butylphenol (180.3 g) was added in portions at 50 to 95°C to a mixture of phosphorus oxychloride (153.3 g) and aluminum chloride (3.0 g) heated to 50°C. After heating the mixture further at 125°C for 1.5 hours, phenol (169.4 g) was added in portions at 120 to 125°C. The mixture was heated continuously at 125°C for 2.5 hours under atmospheric pressure, and then heated under vacuum (~50 torr) for 30 minutes. The HCl gas generated in the reaction was absorbed into water.

[0171] The reaction mixture was cooled to 80°C and treated with diluted caustic soda (500 g prepared with 460 g of water and 40 g of 50% NaOH) and gluconic acid (8.0 g) at 72°C for 1.5 hours.

[0172] The phases were separated, and the oil layer was washed with water three times until the final pH reached 9.

[0173] Washed oil (404 g) was steam stripped and dried under vacuum at 120-130°C to obtain 368 g of the target product.

[0174] The yield was 93.5%, the color was 10 APHA, and the acidity was 0.040 meq. / 100 g. GC analysis showed that the TPP was 1.31%, which was well above the 0.1% threshold.

[0175] Comparative Example 9

[0176] Phosphorus oxychloride (153.3 g) was slowly added to a mixture of p-tert-butylphenol (225.3 g) and aluminum chloride (3.0 g) heated to 105°C at 105 to 112°C. After heating the mixture further at 115°C for 1 hour, phenol (141.2 g) was added in portions. The mixture was continuously heated at 125°C for 3 hours under atmospheric pressure, and then heated under vacuum (~50 torr) for 30 minutes. The HCl gas generated during the reaction was absorbed into water.

[0177] The reaction mixture was cooled to 80°C and treated with diluted caustic soda (500 g prepared with 460 g of water and 40 g of 50% NaOH) and gluconic acid (8.0 g) at 70°C for 1.5 hours.

[0178] The phases were separated, and the oil layer was washed with water three times until the final pH reached 9.

[0179] Washed oil (423 g) was steam stripped and dried under vacuum at 120-130°C to obtain 398 g of the target product.

[0180] The product showed a yield of 97.0%, a color of 55 APHA, and a pH of 0.014 meq. / 100 g. GC analysis showed that the TPP was 8.46%, which was significantly higher than the previous two comparative examples.

[0181] All results of Example 5 and Comparative Examples 7-9 are summarized in Table 4 below.

[0182] Example 5 Comparative Example 7 Comparative Example 8 Comparative Example 9 molar ratio of PTBP to POCl3 1.75 1.50 1.20 1.50 Addition order Add PTBP to POCl3 Add PTBP to POCl3 Add PTBP to POCl3 Add POCl3 to PTBP transference number(%) 91.9 95.8 93.5 97.0 TPP% 0.075 0.15 1.31 8.46

[0183] From the above results, it can be seen that in order to achieve less than 0.1% TPP in the target product, the initial molar ratio of PTBP to POCl3 must be 1.65 or higher (e.g., 1.75 or higher), and the order of addition must be the addition of PTBP to POCl3. This synergistically maximizes the opportunity for each POCl3 molecule to react with PTBP first to become a mono-ester. In the step 2 reaction in the same reactor, there is much less unreacted POCl3 when phenol is added. It is believed that POCl3 reacts with phenol to become TPP, and through this approach, the TPP% in the final product can be controlled to less than 0.1%.

[0184] The description above includes examples of one or more embodiments. Of course, it is impossible to describe every possible variation and alteration of the apparatus or methodology to explain the aspects described above, but those skilled in the art will recognize that many additional modifications and substitutions of the various aspects are possible. Accordingly, the described aspects are intended to accommodate all such changes, modifications, and variations that fall within the spirit and scope of the scope of the description. Furthermore, to the extent that the term “includes” is used in the detailed description or claims, it is intended to have a comprehensive meaning similar to how “comprising” is interpreted when used as a transitional phrase in the claims. The term “consisting essentially” as used herein means that which does not substantially affect the specified material or step, and the fundamental and novel properties of the material or method. Unless otherwise specified above, the properties mentioned herein may be determined by applicable ASTM standards, and if no ASTM standard for such properties exists, the most commonly used standard known to those skilled in the art may be used. The articles "hana," "il," and "han" should be interpreted as meaning "more than one" unless the context indicates a contrary meaning.

Claims

Claim 1 In the composition, phosphate ester compounds of Chemical Formula 1, Chemical Formula 2, and Chemical Formula 3, [Chemical Formula 1] [Chemical Formula 2] [Chemical Formula 3] Herein, R1 and R2 are independently selected from the group consisting of C4-C18 branched or linear alkyl groups, C4-C18 branched or linear alkenyl groups, C4-C18 branched or linear alkoxy groups, C4-C18 branched or linear hydroxyalkyl groups, branched or linear C4-C18 alkyl ether groups, or mixtures thereof, wherein Formula 1 is 75 weight% or more of the total weight of all phosphate esters in the composition, and Formula 3 is less than 0.1 weight% of the total weight of all phosphate esters in the composition; or phosphate ester compounds of Formula 4, Formula 5, and Formula 3, [Formula 4] [Chemical Formula 5] A composition comprising: wherein R3 and R4 are independently selected from the group consisting of C1-C10 branched or linear alkyl groups, C1-C10 branched or linear alkenyl groups, C1-C10 branched or linear alkoxy groups, C1-C10 branched or linear hydroxyalkyl groups, branched or linear C1-C10 alkyl ether groups, or mixtures thereof, wherein Formula 3 comprises less than 0.1 weight% relative to the total weight of all phosphate esters in the composition. Claim 2 A composition according to claim 1, wherein R1 and R2 are independently selected from branched or linear C4-C18 alkyl groups or branched or linear C4-C18 alkyl ether groups, or R4 and R5 are independently selected from branched or linear C4-C18 alkyl groups or branched or linear C4-C18 alkyl ether groups. Claim 3 A composition according to claim 1, wherein R1 and R2 are 2-ethylhexyl. Claim 4 A composition according to claim 1, wherein R1 and R2 are linear or branched C10 alkyl groups. Claim 5 In paragraph 1, R1 and R2 are linear or branched -C 10 H 21 , -C 12 H 25 , -C 14 H 29 , or -C 16 H 33 A composition independently selected from a group of groups. Claim 6 A composition according to claim 1, wherein the structure of Chemical Formula 2 is present in an amount of 20% to 1% by weight relative to the total weight of all phosphate esters in the composition. Claim 7 A composition according to claim 1, wherein the structure of Chemical Formula 3 is present in an amount of 0.01% to 0.05% by weight relative to the weight of the total compounds. Claim 8 A composition according to claim 1, wherein R3 and / or R4 are t-butyl groups. Claim 9 A polymer composition comprising: (a) a polymer selected from the group consisting of polyvinyl chloride (PVC), polyurethane, polyvinyl acetate, polyvinyl butyral, polystyrene, nitrocellulose, nitrile rubber, ABS, polycarbonate, polyamide, polyester, epoxy, and combinations thereof; and (b) a phosphate ester composition comprising: phosphate ester compounds of Formula 1, Formula 2 and Formula 3, [Formula 1] [Chemical Formula 2] [Chemical Formula 3] Herein, R1 and R2 are independently selected from the group consisting of C4-C18 branched or linear alkyl groups, C4-C18 branched or linear alkenyl groups, C4-C18 branched or linear alkoxy groups, C4-C18 branched or linear hydroxyalkyl groups, branched or linear C4-C18 alkyl ether groups, or mixtures thereof, wherein Formula 1 is 75% by weight relative to the total weight of all phosphate esters in the composition, and Formula 3 is less than 0.1% by weight relative to the total weight of all phosphate esters in the composition; or phosphate ester compounds of Formula 4, Formula 5, and Formula 3, [Formula 4] [Chemical Formula 5] A composition comprising: wherein R3 and R4 are independently selected from the group consisting of C1-C10 branched or linear alkyl groups, C1-C10 branched or linear alkenyl groups, C1-C10 branched or linear alkoxy groups, C1-C10 branched or linear hydroxyalkyl groups, branched or linear C1-C10 alkyl ether groups, or mixtures thereof, wherein Formula 3 comprises less than 0.1 weight% relative to the total weight of all phosphate esters in the composition. Claim 10 In claim 9, the polymer is a composition selected from the group consisting of PVC and polyurethane. Claim 11 A composition according to claim 9, wherein R1 and R2 are independently selected from branched or linear C4-C18 alkyl groups or branched or linear C4-C18 alkyl ether groups; or R4 and R5 are independently selected from branched or linear C1-C10 alkyl groups or branched or linear C1-C10 alkyl ether groups. Claim 12 In paragraph 9, R1 and R2 are 2-ethylhexyl, linear or branched -C 10 H 21 , -C 12 H 25 , -C 14 H 29 , or -C 16 H 33 A composition independently selected from a group consisting of groups, or R3 and / or R4 being t-butyl groups. Claim 13 A method for preparing a phosphate ester having a low triphenyl phosphate content, comprising the step of reacting an alcohol having the formula R0OH with POCl3 to produce a reaction mixture having an intermediate, wherein the alcohol having the formula R0OH is provided in a molar ratio of 1.10:1 or greater with respect to POCl3, wherein R0 is an alkyl group selected from the group consisting of C4-C18 branched or linear alkyl groups, C4-C18 branched or linear alkenyl groups, C4-C18 branched or linear alkoxy groups, C4-C18 branched or linear hydroxyalkyl groups, branched or linear C4-C18 alkyl ether groups, or mixtures thereof; and the step of reacting the intermediate with a phenate compound to form a composition comprising a phosphate monoester having an alkyl group corresponding to R0. A method comprising the step of reacting a substituted phenol with POCl3, wherein the phenol is substituted with substituents R3 and / or R4, wherein the molar ratio of the substituted phenol to POCl3 is 1.65:1 or greater, and R3 and R4 are independently selected from the group consisting of C1-C10 branched or linear alkyl groups, C1-C10 branched or linear alkenyl groups, C1-C10 branched or linear alkoxy groups, C1-C10 branched or linear hydroxyalkyl groups, branched or linear C1-C10 alkyl ether groups, or mixtures thereof. Claim 14 In claim 13, the method comprises less than 0.1% by weight of triphenyl phosphate relative to the total weight of the phosphate esters. Claim 15 A method according to claim 13, wherein, after the step of reacting the alcohol having the chemical formula R0OH with POCl3, the reaction is maintained for a longer period than 15 minutes before proceeding to the step of reacting the intermediate with the phenate compound after both the alcohol and POCl3 have been added. Claim 16 A method according to claim 13, wherein, after the step of reacting the alcohol having the chemical formula R0OH with POCl3, the reaction is maintained at a temperature of 1°C to 20°C. Claim 17 A method according to claim 13, wherein, in the step of reacting the alcohol having the chemical formula R0OH with POCl3, the temperature of the step is maintained at 1 to 20℃. Claim 18 In claim 13, the step of reacting the alcohol having the chemical formula R0OH with POCl3 is performed under partial vacuum, or a partial vacuum is applied after adding the substituted phenol, in a method. Claim 19 In claim 13, the phosphate ester composition comprises phosphate ester compounds of Formula 1, Formula 2 and Formula 3, [Formula 1] [Chemical Formula 2] [Chemical Formula 3] Herein, R1 and R2 are independently selected from the group consisting of C4-C18 branched or linear alkyl groups, C4-C18 branched or linear alkenyl groups, C4-C18 branched or linear alkoxy groups, C4-C18 branched or linear hydroxyalkyl groups, branched or linear C4-C18 alkyl ether groups, or mixtures thereof, wherein Formula 1 is 75% by weight relative to the total weight of all phosphate esters in the composition, and Formula 3 is less than 0.1% by weight relative to the total weight of all phosphate esters in the composition; or phosphate ester compounds of Formula 4, Formula 5, and Formula 3, [Formula 4] [Chemical Formula 5] A method comprising, wherein the above chemical formula 3 is less than 0.1 weight% relative to the total weight of all phosphate ester compounds in the composition. Claim 20 A method according to claim 13, wherein the substituted phenol reacts with POCl3, the molar ratio of the substituted phenol to POCl3 is 1.75:1 to 2.5:1, and the order of addition is to add the substituted phenol to POCl3.

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