- Dialkyl 3,3′-thiodipropionate and dialkyl 2,2′-thiodiacetate antioxidants by lipase-catalyzed esterification and transesterification
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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°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 (～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.
- Weber, Nikolaus,Klein, Erika,Vosmann, Klaus
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p. 2957 - 2963
(2007/10/03)
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- Esters of Thiodiglycollic and Thiodipropionic Acids and 2,5-Dicarboxy-3,4-dihydroxythiophene as Potential Slow Acting Anticancer Agents
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A series of esters of thiodiglycollic and thiodipropionic acids and 2,5-dicarboxy-3,4-dihydroxythiophene have been synthesised with a view to testing their anticancer properties.The esters, as against parent acids are expected to have a prolonged effect.
- Kumar, Anil,Tilak, B. D.
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p. 880 - 882
(2007/10/02)
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- Stabilizer for synthetic resins
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Synthetic resins, particularly polyolefins, are markedly improved in their resistances to heat and oxidation by the incorporation of a 2-methyl-4-t-butyl-5-hydroxyphenylalkanoic acid ester alone or in combination with a thioether-type antioxidant represented by the general formula STR1 wherein R represents an alkyl group of 12 to 20 carbon atoms, or by the general formula STR2 wherein R represents an alkyl group of 4 to 20 carbon atoms.
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