| 摘要 |
PCT No. PCT/GB94/02769 Sec. 371 Date Aug. 28, 1996 Sec. 102(e) Date Aug. 28, 1996 PCT Filed Dec. 20, 1994 PCT Pub. No. WO95/17435 PCT Pub. Date Jun. 29, 1995A compound for effecting molecular weight control in polymerisation is a CoII chelate of formula, wherein each group R is an organic cyclic group which, independently, is a monovalent group which comprises a cyclic structure or taken together as two adjacent groups provides a divalent group, and wherein further at least one of the groups R includes at least one heteroatom selected from 0, N, S, P, halogen and Si, which heteroatom provides a substituent group or part of a substituent group on the cyclic structure, or a heteroatom of a heterocyclic ring of the cyclic structure; and wherein each group Q is independently selected from F, Cl, Br, OH, C1-12 alkoxy and C1-12 alkyl; or being a CoIII analogue of the cobalt II chelate of formula in which the Co atom is additionally covalently bonded to H, a halide or other anion, or a homolytically dissociable organic group. Free-radical polymerication of at least one ethylenically unsaturated monomer is carried out in the presence of such a compound.
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