title: Lipase-catalyzed enantioselective synthesis of (R,R)-lactide from alkyl lactate to produce PDLA (poly D-lactic acid) and stereocomplex PLA (poly lactic acid).
abstract: R-lactide, a pivotal monomer for the production of poly (D-lactic acid) (PDLA) or stereocomplex poly (lactic acid) (PLA) was synthesized from alkyl (R)-lactate through a lipase-catalyzed reaction without racemization. From among several types of lipase, only lipase B from Candida antarctica (Novozym 435; CAL-B) was effective in the reaction that synthesized (R,R)-lactide. Enantiopure (R,R)-lactide, which consisted of over 99% enantiomeric excess, was synthesized from methyl (R)-lactate through CAL-B catalysis. Removal of the methanol by-product was critical to obtain a high level of lactide conversion. The (R,R)-lactide yield was 56% in a reaction containing 100 mg of Novozym 435, 10 mM methyl (R)-lactate and 1500 mg of molecular sieve 5A in methyl tert-butyl ether (MTBE). The important monomer (R,R)-lactide that is required for the production of the widely recognized bio-plastic PDLA and the PLA stereocomplex can be obtained using this novel synthetic method.
authors.affiliation: Department of Chemical Engineering, Kwangwoon University, 447-1, Wolgye-Dong, Nowon-Gu, Seoul 139-701, Republic of Korea.
authors.forename: Byoung Wook
authors.initials: BW
authors.lastname: Jeon
authors.forename: Jumin
authors.initials: J
authors.lastname: Lee
authors.forename: Hyun Sook
authors.initials: HS
authors.lastname: Kim
authors.forename: Dae Haeng
authors.initials: DH
authors.lastname: Cho
authors.forename: Hyuk
authors.initials: H
authors.lastname: Lee
authors.forename: Rakwoo
authors.initials: R
authors.lastname: Chang
authors.forename: Yong Hwan
authors.initials: YH
authors.lastname: Kim
mesh_terms: D004146:Dioxanes / Q000737:chemistry / Q000378:metabolism*; D004800:Enzymes, Immobilized; D004951:Esterification; D005656:Fungal Proteins; D019344:Lactic Acid / Q000096:biosynthesis*; D008049:Lipase / Q000378:metabolism*; D000432:Methanol / Q000378:metabolism; D008738:Methyl Ethers / Q000737:chemistry; D062105:Molecular Docking Simulation; D056004:Molecular Dynamics Simulation; D011091:Polyesters; D011108:Polymers; D013237:Stereoisomerism
chemical_list: D004146:Dioxanes; D004800:Enzymes, Immobilized; D005656:Fungal Proteins; D008738:Methyl Ethers; D011091:Polyesters; D011108:Polymers; C043243:methyl tert-butyl ether; D019344:Lactic Acid; C033616:poly(lactide); C091880:dilactide; C093667:Novozyme 435; D008049:Lipase; D000432:Methanol
keywords: (R,R)-lactide; Alkyl (R)-lactate; Lipase; Molecular sieve; Novozym 435