Features of triamyl citrate synthesis

Objectives. To find an effective way for obtaining triamyl citrate, an environmentally friendly, biodegradable citric acid ester used as a plasticizer for PVC-based polymer compositions.

Methods. The possibilities of heterogeneous catalysis were analyzed using the case study of three commercial samples of macroporous sulfocationites (Amberlyst™ 15, Amberlyst™ 70, and TULSION® 66). Homogeneous catalysis was studied using the example of orthophosphoric acid (H₃PO₄), while self-catalysis was investigated during esterification of citric acid with amyl alcohol (ROH). The syntheses were carried out under identical conditions: T = 110 °C, the ratio of CA:ROH = 1:5 (mol) amount of catalyst 1 wt % on the reaction mass in a thermostatically controlled reactor of ideal mixing with continuous distillation of the resulting water.

Results. It was found that in all variants (even under self-catalysis conditions), the conversion of citric acid in 180 min reached 94–99%. Triamyl citrate was formed after 9 h with a yield of 90% only when using a homogeneous catalyst (H3PO4) and in the presence of a heterogeneous catalyst sample (Amberlyst ™ 15).

Conclusions. The revealed differences in the reactivity of the studied sulfocationites (Amberlyst™ 15, Amberlyst ™ 70, and TULSION® 66) confirm the well-known theoretical positions, according to which the kinetic pseudo-homogeneous model of the esterification process of hydroxy acids in excess of aliphatic alcohols is based on the law of acting masses and depends on the specific surface area of the catalyst, which for Amberlyst ™ 15 is of the greatest importance as compared to Amberlyst ™ 70 and TULSION® 66 (m²/g): 53:36:35, respectively.

1. Nikiforova T.A., Novitskaya I.B., Minina T.I. Priority directions of development of food citric acid domestic technology. Pishchevaya promyshlennost’ = Food Industry. 2010;(5):53–54 (in Russ).

2. Sushkova S.V., Levanova S.V., Glazko I.L., Alexandrov A.Yu. Esterification of citric acid with aliphatic alcohols C2–C5. Tonk. Khim. Technol. = Fine Chem. Technol. 2017;13(3):28–32. https://doi.org/10.32362/2410-65932017-12-3-28-32

3. Levanova S.V., Krasnykh E.L., Moiseeva S.V., Safronov S.P., Glazko E.L. Scientific and technological features of synthesis of new ester plasticizers based on renewable raw materials. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2021;64(6):69–75 (in Russ.). https://doi.org/10.6060/ivkkt.20216406.6369

4. Marochkin D.V., Noskov Yu.G., Kron T.E., Karchevskaya O.G., Korneeva G.A. Products of oxosynthesis in the production of complex lubricating oils. NauchnoTekhnicheskii Vestnik NK Rosneft. 2016;(4):74–80 (in Russ.).

5. Xu J., Jiang J., Zuo Z., Li J. Synthesis of tributyl citrate using acid ionic liquid as catalyst. Process Safety and Environmental Protection. 2010;88(1):28–30. https://doi.org/10.1016/j.psep.2009.11.002

6. Kolah A.K., Asthana N.S., Vu D.T., Lira C.T., Miller D.J. Triethyl citrate synthesis by reactive distillation. Ind. Eng. Chem. Res. 2008;47(4):1017–1025. https://doi.org/10.1021/ie070279t

7. Menshchikova A.A., Filatova E.V., Varlamova E.V., Amirkhanov I.R., Yazmukhamedova I.M., Suchkov Yu.G. Production plastificators based on succinic acid and alcohols 2-ethylhexanol and cyclohexanol. Uspekhi v khimii i khimicheskoi tekhnologii = Advances in Chemistry and Chemical Technology. 2017;31(12/193):66–68 (in Russ.).

8. Rahman M., Brazel C.S. The plasticizer market: an assessment of traditional plasticizers and research trends to meet new challenges. Prog. Polym. Sci. 2004;29(12):1223–1248. https://doi.org/10.1016/j.progpolymsci.2004.10.001

9. Sushkova S.V., Levanova S.V., Glazko I.L., Pavlova K.V. Kinetics of esterification of citric acid in production of trialkyl citrates. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017;60(2):74–78 (in Russ). https://doi.org/10.6060/tcct.2017602.5442

10. Osorio-Pascuas O.M., Santaella M.A., Rodriguez G., Orjuela A. Esterification kinetics of tributyl citrate production using homogeneous and heterogeneous catalysts. Ind. Eng. Chem. Res. 2015;54(50):2534–12542. https://doi.org/10.1021/acs.iecr.5b03608

11. Bohórquez W.F., Osorio-Pascuas O.M., Santaella M.A., Orjuela A. Homogeneous and heterogeneous catalytic kinetics in the production of triethyl citrate. Ind. Eng. Chem. Res. 2020;59(43):19203–19211. https://doi.org/10.1021/acs.iecr.0c03690

12. Mittal A., Nair S., Deshmukh K. The kinetic comparison study of catalytic esterification of butyric acid and ethanol over amberlyst 15 and Indion – 190 resins. Int. J. Innovative Res. Sci. Eng. Ttechnol. 2015;4(7):5860–5867.

13. Tsai Y.-T., Lin M.-mu, Lee M.-J. Kineties of heterogeneous esterification of glutaric acid with methanol over Amberlyst 35. J. of Taiwan Ins. of Chem. Eng. 2011;42(2):271–277. https://doi.org/10.1016/j.jtice.2010.07.010

14. Schastlivaya S.V., Kondratev D.N., Kozlovskii R.L., Shvets V.F. Development of a heterogeneous-catalytic method for obtaining butyl lactate. Khimicheskaya promyshlennost’ segodnya = Chemical Industry Developments. 2007;(4):20–25 (in Russ.).

15. Maslova E.V. Analysis and prospects of development of citric acid market. In: Ekonomika. Obshchestvo. Chelovek (Economy. Society. Human). Сol. of Sci. Works. V.G. Shukhov Belgorod. gos. tekhnol. univ.; 2014. V. XXII. P. 108–118 (in Russ.).

16. Alhanish A., Ghalia M.A. Developments of biobased plasticizers for compostable polymers in the green packaging applications: A review. Biotechnol. Prog. 2021;37(6):e3210. https://doi.org/10.1002/btpr.3210