Preparation method of polymuconate salts and polymuconic acid derivatives

Abstract

This invention relates to a preparation process of polymuconate salts and polymuconic acid derivatives in aqueous solution, wherein said process comprises the following steps: (a) reacting muconic acid precursor with aqueous basic solution to obtain muconate salt; and (b) adding an initiator to the muconate salt solution obtained from step (a) and operating at the determined temperature to obtain polymuconate salts.

Description

[0001] Preparation method of polymuconate salts and polymuconic acid derivatives

[0002] Technical Field

[0003] The present invention relates to the preparation method of polymuconate salts and polymuconic acid derivatives.

[0004] Background of the Invention

[0005] Muconic acid or 2,4-hexadienedioic acid is a chemical having a conjugated double bond and carboxylic group, which can be divided into three isomers: cis,cis-muconic acid, cis,trans- muconic acid, and trans, trans-muconic acid.

[0006] At present, muconic acid can be prepared by using biocatalysts produced from natural processes. From this reason, muconic acids have been widely studied for using as a precursor in the preparation of polymer by condensation polymerization such as the conversion into adipic acid and terephthalic acid to replace the polymers obtained from petroleum. Moreover, muconic acid can also be used to produce polymuconate by topochemical polymerization and radical polymerization.

[0007] The production process of polymuconate by topochemical polymerization is the polymerization process employing radiation to the monomer crystal having proper alignment to initiate the polymerization as described in the following examples.

[0008] US7388064B2 discloses the use of muconate ester as the monomer for the preparation of polymuconate using topochemical polymerization by light or heat.

[0009] US20060154999A1 discloses the method that uses the muconic acid ammonium salt as the precursor. By radiation, the topochemical polymerization is induced resulting in an ammonium salt of polymuconate. Then, the ammonium salt is converted to alkaline salt and silver, respectively. Finally, the polymers containing distributed metal particles are produced by the reduction process. However, the synthesis of polymuconate from muconic ester crystal ester provides high yield in short period but for polymuconate salt, it is needed to take 72 hours to provide only 30 % yield. Nevertheless, topochemical polymerization needs to use monomer having proper crystal alignment which is not suitable for the preparation of polymuconate in the industrial scale.

[0010] The production process of polymuconate by radical polymerization has limitation in the long reaction time which is not suitable for the preparation of polymuconate in the industrial scale as described in the following examples.

[0011] Minoura et., al. studied the use of muconic acid and muconate ester to synthesis the polymuconic acid and polymuconate respectively (J. Polym. Sci. Polym. Chem. Ed. 1977, 15, 1917-1926.). The study found that the polymerization process of muconic acid using azobisisobutyronitrile as the initiator and dimethyl sulphate as the solvent. The reaction was operated at 100 °C for 50 hours. This could produce polymuconic acid at only 30 % yield.

[0012] Matsumoto et., al. studied the muconic ester derivatives to produce polymuconate in the condition without solvent to increase the reaction rate Macromolecules 1996, 29, 423-432.). This study found that the trans, trans-muconic acid isomer gave higher yield than cis,trans-muconic acid and cis,cis-muconic acid, respectively.

[0013] Quin tens et., al. studied the reversible addition-fragmentation chain transfer polymerization (RAFT polymerization) of trans, trans-muconic ester (Polym. Chem., 2019,10, 5555-5563.) and was able to control the molecular weight of the polymer.

[0014] From all above, there is no disclosure on the preparation method of polymuconate salts and polymuconic acid derivatives using polymerization of muconate salt as the precursor. The process disclosed in this patent can be prepared in aqueous solution which is not toxic to the environment and can be applied in many industries such as superabsorbent polymer, binder, etc. of the Invention

[0015] This invention relates to the preparation process of polymuconate salts and polymuconic acid derivatives in aqueous solution, wherein said process comprises the following steps:

[0016] (a) reacting muconic acid precursor with aqueous basic solution to obtain muconate salt; and

[0017] (b) adding an initiator to the muconate salt solution obtained from step (a) and operating at the determined temperature to obtain polymuconate salts.

[0018] Detailed

[0019] The present invention discloses the preparation method of polymuconate salts and polymuconic acid derivatives in aqueous solution.

[0020] Any aspect demonstrated herein is meant to include the other application of this invention unless stated otherwise.

[0021] Technical terms or scientific terms used here have definitions as by a person skilled in the art unless stated otherwise.

[0022] Any tools, equipment, methods, or chemicals named herein mean tools, equipment, methods, or chemicals being used commonly by a person skilled in this art, except being stated as the special tools, equipment, methods, or chemicals that specific to this invention.

[0023] The use of singular noun or singular pronoun with “comprising” in claims or specification means “one” and “one or more”, “at least”, and “one or more than one”.

[0024] All compositions and / or methods disclosed and claims in this application aim to cover embodiments from any action, performance, modification, or adjustment without any experiment that is significantly different from this invention, and obtain with object with utility and resulted as same as the present embodiment according to a person ordinary skilled in the art although without specifically stated in claims. Therefore, substitutable or similar objects to the present embodiment, including any little modification or adjustment that clearly seen by a person skilled in the art should be construed as remains in spirit, scope, and concept of invention as appeared in appended claims.

[0025] Throughout this application, term “about” means any number that appeared or showed here that could be varied or deviated from any error of equipment, method, or personal using said equipment or method.

[0026] Throughout this application, the concentration of the solution is calculated by molarity (M) or molar which is the concentration of the solution that describes the mole number of the solute in 1 L of the solution unless being stated as other unit.

[0027] The polymuconate salt herein means the polymer having the following structure: wherein M is group 1 of 2 of metal ion or ammonium ion compound.

[0028] The polymuconic acid derivatives may comprise polymuconic acid, polymuconate ester, and polymuconate copolymer.

[0029] Polymuconic acid means the polymer having the following structure:

[0030] Polymuconate ester means the polymer having the following structure: wherein R is alkyl group

[0031] Copolymer of polymuconate means the polymer having some structures similar to polymuconate salt, polymuconic acid, or polymuconate ester.

[0032] The followings demonstrate the embodiments of the invention without any intention to limit the scope of the invention.

[0033] This invention relates to the preparation process of polymuconate salts and polymuconic acid derivatives in aqueous solution, wherein said process comprises the following steps:

[0034] (a) reacting muconic acid precursor with aqueous basic solution to obtain muconate salt; and

[0035] (b) adding the initiator to the muconate salt solution obtained from step (a) and operating at the determined temperature to obtain polymuconate salts.

[0036] In one aspect of the invention, the muconic acid precursor comprises cis, cis- muconic acid, cis,trans-muconic acid, trans, trans-muconic acid, or a mixture thereof.

[0037] In one aspect of the invention, preferably the muconic acid is cis, trans -muconic acid because it has higher solubility in aqueous solution than cis,cis-muconic acid and trans, trans- muconic acid.

[0038] In one aspect of the invention, the base in step (a) is selected inorganic base of hydroxide of alkali metals or alkaline earth metals, or organic base of amine.

[0039] In one aspect of the invention, the base is sodium hydroxide, potassium hydroxide, or a mixture thereof. In one aspect of the invention, the initiator in step (b) is selected from inorganic initiator, or organic initiator of peroxide or persulfate.

[0040] In one aspect of the invention, the initiator is sodium persulfate, potassium persulfate, ammonium persulfate, or a mixture thereof, wherein the concentration of the initiator is in a range of 0.001 - 0.25 M.

[0041] In one aspect of the invention, the concentration of muconate salt solution in step (b) is in a range 1.0 - 6.0 M.

[0042] In one aspect of the invention, the reaction in step (b) is operated at the temperature in a range 90 to 130 °C and pH in a range 5.0 to 14.0.

[0043] In some aspects of the invention include the process for preparing polymuconic acid and its derivatives, said process comprises the following step:

[0044] (a) reacting muconic acid precursor with a base in aqueous solution to obtain muconate salt;

[0045] (b) adding the initiator to the muconate salt solution obtained from step (a) and operating at the determined temperature to obtain polymuconate salts;

[0046] (c) adding the acid to the polymuconate salts from step (b) to obtain polymuconic acid; and

[0047] (d) optionally, adding the esterification catalyst and esterification agent selected from alcohol having 1 to 10 carbon atoms to polymuconic acid in step (c) and operating at the temperature in the range of 60 to 150 °C.

[0048] In one aspect of the invention, the muconic acid precursor comprising cis, cis- muconic acid, cis,trans-muconic acid, trans, trans-muconic acid, or a mixture thereof.

[0049] In one aspect of the invention, the base in step (a) is selected from inorganic base of hydroxide of alkali metals or alkaline earth metals, or organic base of amine. In one aspect of the invention, the base is sodium hydroxide, potassium hydroxide, or the mixture thereof.

[0050] In one aspect of the invention, the initiator in step (b) is selected from inorganic initiator, or organic initiator of peroxide or persulfate.

[0051] In one aspect of the invention, the initiator is sodium persulfate, potassium persulfate, ammonium persulfate, or the mixture thereof, wherein the concentration of the initiator is in the range of 0.001 - 0.25 M.

[0052] In one aspect of the invention, the concentration of muconate salt solution in step (b) is in the range of 1.0 - 6.0 M.

[0053] In one aspect of the invention, the reaction in step (b) is operated at the temperature in the range of 90 to 130 °C and pH in the range of 5.0 to 14.0.

[0054] In one aspect of the invention, the acid in step (c) is selected from sulfuric acid, hydrochloric acid, or acetic acid.

[0055] In one aspect of the invention, the esterification catalyst is selected from acid or alkoxide metal.

[0056] In one aspect of the invention, the esterification catalyst is sulfuric acid and p- toluenesulfonic acid.

[0057] In one aspect of the invention, the esterification agent in step (d) is methanol, propanol, and butanol.

[0058] In some aspects of the invention, the process for preparing polymuconate copolymer, wherein said process comprises the following steps: (a) reacting the muconic acid precursor and comonomer selected from acrylic derivatives, methacrylic derivatives, and styrene derivatives with base in aqua solution to obtain the mixture of muconate salt and comonomer; and

[0059] (b) adding the initiator to solution comprising the mixture of muconate salt and comonomer from step (a) to obtain the polymuconate copolymer.

[0060] In one aspect of the invention, the comonomer is sodium acrylate salt, sodium methacrylate salt, or a mixture thereof.

[0061] The muconic acid precursor comprises cis, cis- muconic acid, cis,trans-muconic acid, trans, trans-muconic acid, or the mixture thereof.

[0062] In one aspect of the invention, the base in step (a) is selected from inorganic base of hydroxide of alkali metals or alkaline earth metals, or organic base of amine.

[0063] In one aspect of the invention, the base is sodium hydroxide, potassium hydroxide, or the mixture thereof.

[0064] In one aspect of the invention, the initiator in step (b) is selected from inorganic initiator, or organic initiator of peroxide or persulfate.

[0065] In one aspect of the invention, the initiator is sodium persulfate, potassium persulfate, ammonium persulfate, or the mixture thereof, wherein the concentration of the initiator is in the range of 0.001 - 0.25 M.

[0066] In one aspect of the invention, the concentration of muconate salt solution in step (b) is in the range of 1.0 - 6.0 M and the concentration of comonomer is in the range of 1.0 - 6.0 M.

[0067] In one aspect of the invention, the reaction in step (b) is operated at the temperature in the range of 90 to 130 °C and pH in the range of 5.0 to 14.0. In some aspects of the invention, the preparation process of polymuconate salts and polymuconic acid derivatives can be done in one pot synthesis.

[0068] The following are demonstrations of this invention by referring to the experimental examples. However, the aspects of the invention described in these examples are not intended to limit the scope of this invention.

[0069] Preparation of muconate salt of sample 1

[0070] 1 M of cis,trans-muconic acid precursor was added to 2 M sodium hydroxide to obtain the solution having pH 5. Then the solution was filtered and dried to obtain sodium cis,trans-muconate salt as the white solid. The production yield was 98 %. Preparation of muconate salt of sample 2 - 6

[0071] The samples were prepared by the same method in the preparation of sample 1 using the muconic acid precursor, base, and pH according to table 1.

[0072] Table 1 : The preparation of muconate salt from muconic acid precursor at different base and pH Preparation of polymuconate salts and polymuconic acid derivatives

[0073] Preparation of comparative sample 1

[0074] 2.5 M of cis,trans-muconic acid precursor was added to the reactor equipped with magnetic stirrer. The pH of the mixture was adjusted to be lower than 4. Sodium sulfate was added to the solution until the concentration of the initiator was 0.025 M. Nitrogen gas was blown before closing the lid. Then, the mixture was heated up to 100 °C for 24 hours and reduced to 25 °C. The obtained polymuconic acid was white solid. The production yield was 8.6 %. The production yield of muconolactone, muconodilactone, and levulinic acid were 61.9, 23.2, and 6.3 % respectively.

[0075] Preparation of polymuconate salts and polymuconic acid derivatives

[0076] Preparation of the sample according to the invention 1

[0077] 1 M of cis,trans-muconic acid precursor was added with 2 M sodium hydroxide to obtain the solution having pH 5. Then the solution was filtered and dried to obtain sodium cis,trans- muconate salt as the white solid. The production yield was 98 %.

[0078] 4 M of sodium cis,trans-muconate salt was added to sodium persulfate until the concentration of the initiator was 0.04 M. Nitrogen gas was blown before closing the lid. Then, the mixture was heated up in the range of 90 to 130 °C and pH about 5.0 for 6 hours and reduced to 25 °C. The obtained solution was precipitated and dried. The obtained polymuconate salt was yellow solid. The conversion of muconate salt was 77 %. The reaction selectivity of muconate salt was 96 %. The production yield was 74 %.

[0079] Preparation of the sample according to the invention 2 - 16

[0080] The samples were prepared by the same method in the preparation of the sample according to the invention 1 using the type of muconate salt, pH, concentration of muconate salt, type of initiator, concentration of initiator, water content, temperature, and time in the reaction according to table 2.

[0081] Table 2: Polymerization results of muconate salt at different conditions a Calculated by proton nuclear magnetic resonance technique b Calculated by polymer weight obtained after precipitation and drying Preparation of muconate salt by one pot synthesis

[0082] Preparation of the sample according to the invention 17

[0083] 1 M of cis,trans-muconic acid precursor was added with 10 M sodium hydroxide to obtain the solution having the concentration of sodium cis,trans-muconate salt about 4.5 M and pH about 5. Then the solution was added by sodium persulfate until the concentration of the initiator was 0.045 M. Nitrogen gas was blown before closing the lid. Then, the mixture was heated up from 90 to 130 °C for 6 hours and reduced to 25 °C. The obtained solution was filtered and dried. The obtained polymuconate salt was yellow solid. The production yield was 55 %.

[0084] Preparation of polymuconic acid and its derivatives

[0085] Preparation of polymuconic acid

[0086] Preparation of the sample according to the invention 18

[0087] 1 M of cis,trans-muconic acid precursor was added with 2 M sodium hydroxide to obtain the solution having the pH of 5. Then the solution was filtered and dried to obtain 4.0 M of sodium cis,trans-muconate salt as white solid. The obtained solution was added to sodium persulfate until the concentration of the initiator was 0.04 M. Nitrogen gas was blown before closing the lid. Then, the mixture was heated up from 90 to 130 °C and pH about 5.0 for 6 hours and reduced to 25 °C. The obtained solution was precipitated and dried. The obtained polymuconate salt was yellow solid. The 10 g / L of polymuconate salt was added with sulfuric acid until the pH of the solution was about 1. The mixture was filtered and evaporated. The obtained polymuconic acid was yellow solid. The production yield was 70 %.

[0088] Preparation of polymuconate ester

[0089] Preparation of the sample according to the invention 19 1 M of cis,trans-muconic acid precursor was added with 2 M sodium hydroxide to obtain the solution having the pH of 5. Then the solution was filtered and dried to obtain 4.0 M of sodium cis,trans-muconate salt as white solid. The obtained solution was added to sodium persulfate until the concentration of the initiator was 0.04 M. Nitrogen gas was blown before closing the lid. Then, the mixture was heated up from 90 to 130 °C and pH about 5.0 for 6 hours and reduced to 25 °C. The obtained solution was precipitated and dried. The obtained polymuconate salt was yellow solid. The 10 g / L of polymuconate salt was added with sulfuric acid until the pH of the solution was about 1. The mixture was filtered and evaporated. The obtained polymuconic acid was yellow solid. The obtained solid was dissolved in methanol until the concentration of polymuconic acid in the obtained solution was 100 g / L. Sulfuric acid was added into the solution until the concentration of sulfuric acid was 1 g / L. The solution was refluxed at the temperature in the range of 60 to 150 °C for 12 hours. When the time had reached, the temperature was reduced to 25 °C. The solution was filtered to obtain yellow solid of polymethylmuconate. The production yield was 60 %.

[0090] Preparation of polymuconate copolymer

[0091] Preparation of the sample according to the invention 20

[0092] 2 M of cis,trans-muconic acid precursor and 2 M of acrylic acid as comonomer were added with 2 M sodium hydroxide to obtain the solution having the pH of 7. Then the solution was added by sodium persulfate until the concentration of the initiator was 0.04 M. Nitrogen gas was blown before closing the lid. Then, the mixture was heated up in the range of 90 to 130 °C for 6 hours. When the time had reached, the temperature was reduced to 25 °C. The obtained solution was precipitated and dried. The obtained copolymer of muconate salt and acrylate salt was yellow solid.

[0093] The production yield was 30 %. Analysis of % production yield of muconate salt

[0094] % production yield = (weight of obtained muconate salt / theoretical weight of muconate salt) x 100 %

[0095] Analysis of % conversion of muconate salt, % reaction selective of muconate salt, and % nuclear resonance

[0096] The analysis was performed by adding heavy water as the solvent onto the sample and measured by nuclear magnetic resonance (Bruker model AVANCE III HD 500 MHz). The obtained graph was compared to the reference chemical shift (8) of the residual proton in the heavy water (D2O, 8 = 4.79 ppm).

[0097] The % conversion and % reaction selective can be calculated from the following equations:

[0098] % conversion = —lp<Mu>'+lLev—x100%; lMu + Ip(Mu) +lLev

[0099] % reaction selective

[0100] % yield = (% conversion X % reaction selective) / ! 00; wherein, (integral of polymuconate salt between 5 = 5.3 - 5.7 ppm) X

[0101] I Lev is(integral of levulinate salt at 5 = 2.78 ppm) X

[0102] IMuis the total integral of muconate salt isomers comprising (integral of cis,trans-muconate salt at 5 = 7.61 ppm) + (integral of cis, cis- muconate salt at chemical shift 5 = 6.97ppm) (integral of trans, trans- muconate salt at chemical shift 5 = 7.04 ppm) X |; and

[0103] % yield = (% conversion X % reaction selective) / ! 00. Analysis of % production yield of polymuconic acid and its derivatives

[0104] % production yield = (weight of obtained polymer / theoretical weight of polymer) x 100 %

[0105] Test results

[0106] Test result of preparation of polymuconate salt using muconate salt as monomer

[0107] From the polymerization testing using sodium cis,trans-muconate salt at pH of 5 at different conditions as shown in table 2, it was found that the sodium cis,trans-muconate salt could be converted to polymuconate salt. Moreover, levulinate salt was obtained as the by product. The % conversion rate was from 45 to 77 %. The % reaction selectivity of polymuconate salt was from 83 to 99%. When comparing the analytical results to the comparative sample 1 that used cis,trans- muconic acid as the monomer, it was found that the polymerization of cis,trans-muconic acid provided only 8.6 % yield. Therefore, it can be concluded that the polymerization using muconate salt as the monomer in the sample according to the invention can provide better polymerization than the use of muconic acid as the precursor.

[0108] Test result of the effect of different factors to polymerization

[0109] From the testing, it was found that when the concentration of the solution was reduced, the % conversion also decreased. When the concentration of the solution was high, the viscosity of the solution was higher and became solid during the reaction. This caused difficulty for the reaction. Moreover, it was found that at pH more than 5, there was no significant effect to the % conversion, but the % reaction selectivity was higher, which was affected from the lower generation of the levulinate salt by product.

[0110] Test result of the effect of the content and amount of initiator to polymerization

[0111] From the sample according to the invention, it shows that the content and type of initiator affected the polymerization of muconate salt. When reducing the amount of the initiator, the % conversion and % reaction selectivity was decreased. This might cause by the lower amount of the free radical in the system that reduced the rate of polymerization. When used different type of the initiator, it could perform the polymerization to generate polymuconate salt.

[0112] Test result of the effect of the type of muconate salt to polymerization

[0113] The use of sodium cis,cis-muconate salt and sodium trans, trans-muconate salt as the monomer could provide polymerization as same as the use of sodium cis, trans-muconate salt. But because sodium cis,cis-muconate salt and sodium trans, trans-muconate salt had lower solubility than sodium cis, trans-muconate salt, the polymerization needed to be operated at lower concentration and higher temperature.

[0114] Preparation of polymuconate salt in one pot synthesis

[0115] From the testing of the preparation of polymuconate salt in one pot synthesis, it was found that this method could synthesis the polymuconate salt as well. The % conversion was 60 % and the % reaction selectivity was 93 %.

[0116] Preparation of polymuconic acid and its derivatives

[0117] The polymuconate salt obtained after the end of the polymerization can be converted into polymuconic acid by exposing to acid. The obtained polymuconic acid can be converted to polymuconate ester by esterification with alcohol derivatives. Apart from polymuconic acid and polymuconate ester, the copolymer of polymuconate can be prepared by the reaction with comonomer from acrylic derivatives, methacrylic derivatives, styrene derivatives as disclosed in the examples of the invention.

[0118] Best Mode of the Invention

[0119] Best mode of embodiment of the invention is as provided in the description of the invention.

Claims

Claims1. A process for preparing polymuconate salts, wherein said process comprises the following steps:(a) reacting muconic acid precursor with a base in aqueous solution to obtain muconate salt; and(b) adding an initiator to the muconate salt solution obtained from step (a) and operating at the determined temperature to obtain polymuconate salts.

2. The process according to claim 1 , wherein the muconic acid precursor comprises cis,cis- muconic acid, cis,trans-muconic acid, trans, trans-muconic acid, or a mixture thereof.

3. The process according to claim 1 or 2, wherein the muconic acid precursor is cis, trans- muconic acid.

4. The process according to claim 1 , wherein the base in step (a) is selected from inorganic base of hydroxide of alkali metals or alkaline earth metals, or organic base of amine.

5. The process according to claim 1 or 4, wherein the base is sodium hydroxide, potassium hydroxide, or a mixture thereof.

6. The process according to claim 1, wherein the initiator in step (b) is selected from inorganic initiator, or organic initiator of peroxide or persulfate.

7. The process according to claim 1 or 6, wherein the initiator is sodium persulfate, potassium persulfate, ammonium persulfate, or a mixture thereof.

8. The process according to claim 1, wherein the concentration of the initiator is in the range of 0.001 - 0.25 M.

9. The process according to claim 1, wherein the concentration of muconate salt solution in step (b) is in the range 1.0 - 6.0 M.

10. The process according to claim 1, wherein the reaction in step (b) is operated at the temperature from 90 to 130 °C and pH from 5.0 to 14.0.

11. A process for preparing polymuconic acid and its derivatives, wherein said process comprises the following step:(a) reacting muconic acid precursor with a base in aqueous solution to obtain muconate salt;(b) adding an initiator to the muconate salt solution obtained from step (a) and operating at the determined temperature to obtain polymuconate salts;(c) adding the acid to the polymuconate salts obtained from step (b) to obtain polymuconic acid; and(d) optionally, adding the esterification catalyst and esterification agent selected from alcohol having 1 to 10 carbon atoms to polymuconic acid in step (c) and operating at the temperature in the range of 60 to 150 °C.

12. The process according to claim 11, wherein the muconic acid precursor comprises cis, cis- muconic acid, cis,trans-muconic acid, trans, trans-muconic acid, or a mixture thereof.

13. The process according to claim 11, wherein the base in step (a) is selected from inorganic base of hydroxide of alkali metals or alkaline earth metals, or organic base of amine.

14. The process according to claim 11 or 13, wherein the base is sodium hydroxide, potassium hydroxide, or a mixture thereof.

15. The process according to claim 11, wherein the initiator in step (b) is selected from inorganic initiator, or organic initiator of peroxide or persulfate.

16. The process according to claim 11 or 15, wherein the initiator is sodium persulfate, potassium persulfate, ammonium persulfate, or a mixture thereof.

17. The process according to claim 11, wherein the concentration of the initiator is in the range of 0.001 - 0.25 M.

18. The process according to claim 11, wherein the concentration of muconate salt solution in step (b) is in the range of 1.0 - 6.0 M.

19. The process according to claim 11, wherein the reaction in step (b) is operated at the temperature in the range of 90 to 130 °C and pH in the range of 5.0 to 14.0.

20. The process according to claim 11 , wherein the acid in step (c) is selected from sulfuric acid, hydrochloric acid, or acetic acid.

21. The process according to claim 11, wherein the esterification catalyst in step (d) is selected from acid or alkoxide metal.

22. The process according to claim 11 or 20, wherein the esterification catalyst is sulfuric acid and p-toluenesulfonic acid.

23. The process according to claim 11, wherein the esterification agent in step (d) is methanol, propanol, or butanol.

24. A process for preparing polymuconate copolymer, wherein said process comprises the following steps:(a) reacting the muconic acid precursor and comonomer selected from acrylic derivatives, methacrylic derivatives, and styrene derivatives with base in an aqueous solution to obtain the mixture of muconate salt and comonomer; and(b) adding the initiator to the solution comprising the mixture of muconate salt and comonomer from step (a) to obtain the polymuconate copolymer.

25. The process according to claim 24, wherein the comonomer is sodium acrylate salt, sodium methacrylate salt, or a mixture thereof.

26. The process according to claim 24, wherein the base in step (a) is selected from inorganic base of hydroxide of alkali metals or alkaline earth metals, or organic base of amine 27. The process according to claim 24 or 25, wherein the base is sodium hydroxide, potassium hydroxide, or a mixture thereof.

28. The process according to claim 24, wherein the initiator in step (b) is selected from inorganic initiator, or organic initiator of peroxide or persulfate.

29. The process according to claim 24 or 27, wherein the initiator is sodium persulfate, potassium persulfate, ammonium persulfate, or a mixture thereof.

30. The process according to claim 24, wherein the concentration of the initiator is in the range of 0.001 - 0.25 M.

31. The process according to claim 24, wherein the concentration of muconate salt solution in step (b) is in the range of 1.0 - 6.0 M and the concentration of comonomer is in the range of 1.0 - 6.0 M.

32. The process according to claim 24, wherein the reaction in step (b) is operated at the temperature in the range of 90 to 130 °C and pH in the range of 5.0 to 14.0.

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