Abstract
D,L-Lactide was effectively synthesized by a two-step reaction under microwave irradiation, namely, the polycondensation of D,L-lactic acid into oligo(D,L-lactic acid) (ODLLA) and the unzipping depolymerization of the ODLLA into D,L-lactide. The influences of microwave irradiation power, irradiation time, catalyst type, and catalyst concentration on the polycondensation and the unzipping depolymerization were investigated, respectively. The results revealed that both polycondensation and unzipping reaction were remarkably accelerated and improved by microwave energy, and the reaction time for preparation of D,L-lactide catalyzed by zinc powder was shortened by at least 50% compared with conventional heating method. The yield of D,L-lactide by microwave method was 40.3% starting from aqueous D,L-lactic acid when 1.2% (w/w) of zinc powder was applied as a catalyst and the microwave time was 3.2 hours. An alternative protocol with advantages of fast reaction and a high yield was developed for the preparation of D,L-lactide from aqueous D,L-lactic acid.
Similar content being viewed by others
References
Bendix D (1998) Polym Dregrad & Stab 59:129
Bhardwaj R, Blanchard J (1998) Int J Pharm 170:109
Kricheldorf HR (2001) Chemosphere 43:49
Södergárd A, Stolt M, Prog M (2002) Polym Sci 27:1123
Drumright RE, Patrick R, Gruber PR, Henton DE (2000) Adv Mater 12:1841
Muller M (Boehringer Ingelheim KG) (1991) US 5053522
Gruber PR, Hall ES, Kolstad JJ, Iwen ML, Benson RD, Borchardt RL (Cargill Inc.) (2001) US 6326458
Wang YL, Zhao JH (1996) J Chongqing Univ (Natural Sci Ed) 19:112
Wang YL, Gu L, Wang J, Pan J (Chongqing Univ.) (2002) CN 1394680A
Ohara H, Ito M, Sawa S (Toyota Jidosha Kabushiki Kaisha) (2003) US 6569989
Adam D (2003) Nature 421:571
Kappe CO (2004) Angew Chem Int Ed 43:6250
Liao LQ, Liu LJ, Zhang C, He F, Zhuo RX, Wan K (2002) J Polym Sci Patr A Polym Chem 40:1749
Liao LQ, Liu LJ, Zhang C, He F, Zhuo RX (2003) J Appl Polym Sci 90:2657
Yu ZJ, Liu LJ (2004) Eur Polym J 40:2213
Liao LQ, Liu LJ, Zhang C, He F, Zhuo RX (2003) Chin Chem Lett 12:761
Sándor K, Ildikó B, Jenö B, György D, Miklós D (2001) Macromol Rapid Commun 22:1063
Watanabe S, Hayama K, Imai Y (1993) Macromol Rapid Commun 14:481
Imai Y, Hisashi N, Watanabe S, Masaki K (1996) Polym J 28:256
Lu JM, Ji SJ, Chen NY, Zhang ZB, Sun ZR, Zhun XL, Shi WP (2003) J Appl Polym Sci 87:1739
Lu JM, Ji SJ, Chen NY, Zhang ZB, Sun ZR, Zhun XL, Shi WP (2003) J Appl Polym Sci 89:2611
Faghihi K, Zamani K, Mirsamie A, Sangi MR (2003) Eur Polym J 39:247
Mallakpour S, Zamanlou MR (2004) J Appl Polym Sci 91:3281
Mallakpour S, Rafiemanzelat F (2004) J Appl Polym Sci 93:1647
Mallakpour S, Kowsari E (2005) Polym Bull 53:169
Banihashemi A, Hazarkhani H, Abdolmaleki A (2004) J Polym Sci Patr A Polym Chem 42:2106
Klun U, Krzan A (2000) Polymer 41:4361
Liu LX, Zhang D, An LJ, Zhang HY, Tian YG (2005) J Appl Polym Sci 95:719
Liu LJ, Zhang C, Liao LQ, Wang XL Zhuo RX (2001) Chin Chem Lett 12:663
Zhang C, Liao LQ, Liu LJ (2004) Macromol Rapid Commun 25:1402
Liu LJ, Yang XG (2004) CN 1583740A
Yang XG, Liu LJ (2004) The fifth Chinese microwave chemistry symposium proceedings
Zhang YM, Wang P, Han N, Lei HF (2007) Macromol Rapid Commun 28:417
Kolstad J (1996) J Appl Polym Sci 62:1079
Espartero JL, Rashkov I, Li SM, Vert M (1996) Macromolecules 29:3536
Wang HL, Fang DQ, Shi TJ, Zhai LF (2005) Polym Mater Sci & Eng 21:51
Jian WF, Zhao JB, Yang WT (2003) Petrochemical Technol 32:1073
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Yang, XG., Liu, LJ. Improved preparation of D, L-lactide from D, L-lactic acid using microwave irradiation . Polym. Bull. 61, 177–188 (2008). https://doi.org/10.1007/s00289-008-0945-3
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00289-008-0945-3