| 摘要 |
1,182,376. Polymerizing beta-propiolactones. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. 1 July, 1968, No. 31239/68. Heading C3R. In the manufacture of polyesters by polymerizing a beta-propiolactone in the presence of an anionic initiator and a chain-transfer agent, there is used as the latter (a) an aldehyde or ketone substituted on the alpha-position relative to the carbonyl group with one or more halogen atoms or (b) a tautomeric form of such a compound. Specified compounds are trichloroacetaldehyde, a:a-dichloroacetophenone, ethyl alpha-chloro-beta-oxobutyrate, alphabromocyclohexanone, 1:1:1-trichloro- 2 -propanone and 3-chloro-2-butanone. The catalyst may be a tertiary amine, an organo-phosphorus compound, a betaine or a " living " prepolymer as disclosed in Specifications 1,133,293 and 1,133,294. The lactone may be beta-propiolactone or the latter substituted in the alphaposition with one or two alkyl or chloromethyl groups. Polymerization may be effected by a bulk process or by a solution or slurry process. Examples describe the polymerization of pivalolactone. . |
