title: Dialkyl 3,3'-thiodipropionate and dialkyl 2,2'-thiodiacetate antioxidants by lipase-catalyzed esterification and transesterification.
abstract: Medium- and long-chain dialkyl 3,3'-thiodipropionate antioxidants such as dioctyl 3,3'-thiodipropionate, didodecyl 3,3'-thiodipropionate, dihexadecyl 3,3'-thiodipropionate, and di-(cis-9-octadecenyl) 3,3'-thiodipropionate were prepared in high yield by lipase-catalyzed esterification and transesterification of 3,3'-thiodipropionic acid and its dimethyl ester, respectively, with the corresponding medium- or long-chain 1-alkanols, i.e., 1-octanol, 1-dodecanol, 1-hexadecanol, and cis-9-octadecen-1-ol, in vacuo (80 kPa) at moderate temperatures (60-80 degrees C) without solvents. Immobilized lipase B from Candida antarctica (Novozym 435) was the most active biocatalyst for the preparation of medium- and long-chain dialkyl 3,3'-thiodipropionates showing enzyme activities up to 1489 units/g, whereas the immobilized lipases from Rhizomucor miehei (Lipozyme RM IM) and Thermomyces lanuginosus (Lipozyme TL IM) were by far less active ( approximately 10 enzyme units/g). Maximum conversions to dialkyl 3,3'-thiodipropionates were as high as 92-98% after 4 h of reaction time. Similarly, dihexadecyl 2,2'-thiodiacetate was prepared in high yield using 2,2'-thiodiacetic acid or diethyl 2,2'-thiodiacetate and 1-hexadecanol as the starting materials and Novozym 435 as the biocatalyst.
authors.affiliation: Institute for Lipid Research, Federal Research Centre for Nutrition and Food, 48147 Münster, Germany. niweber@uni-muenster.de
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Weber
authors.forename: Erika
authors.initials: E
authors.lastname: Klein
authors.forename: Klaus
authors.initials: K
authors.lastname: Vosmann
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D004951:Esterification; D005656:Fungal Proteins; D008049:Lipase / Q000378:metabolism*; D011422:Propionates / Q000378:metabolism*; D020103:Rhizomucor / Q000201:enzymology; D013864:Thioglycolates / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D005656:Fungal Proteins; D011422:Propionates; D013864:Thioglycolates; C013298:thiodipropionic acid; C010518:thiodiacetic acid; C093666:Lipozyme; D008049:Lipase; C431349:lipase B, Candida antarctica