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Transfer agent
About: Transfer agent is a research topic. Over the lifetime, 894 publications have been published within this topic receiving 9799 citations.
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TL;DR: Cobaloxime, synthesized from CoII acetate and dimethylglyoxime was used as a chain transfer agent in the free radical polymerization of methyl methacrylate as discussed by the authors.
Abstract: Cobaloxime, synthesized from CoII acetate and dimethylglyoxime, was used as a chain transfer agent in the free radical polymerization of methyl methacrylate. It proved to be a catalytic chain transfer agent analogous to work recently reported on cobalt porphyrins. Chain transfer constants ranged from 103–104 and were chain length dependent. Catalytic behavior was demonstrated by calculating turnover numbers which showed that each cobaloxime molecule participated in many hundreds of chain transfer reactions.
99 citations
TL;DR: In particular, the linear increase in number-average molar mass (Mn) with monomer conversion, from very low conversion values, indicated a large apparent chain transfer constant to tert-butyl dithiobenzoate (t-BDB) as mentioned in this paper.
Abstract: The RAFT polymerization of n-butyl acrylate was studied in the presence of various concentrations of tert-butyl dithiobenzoate (t-BDB) as a chain transfer agent, and various concentrations of AIBN as an initiator at 60 and 90 °C. The polymerizations exhibited the expected features of controlled systems. In particular, the linear increase in number-average molar mass (Mn) with monomer conversion, from very low conversion values, indicated a large apparent chain transfer constant to t-BDB. The kinetic study showed two typical characteristics already observed in RAFT polymerizations of various acrylates: the existence of an induction period and a strong rate retardation, both enhanced by the increase in t-BDB initial concentration. ESR spectroscopy was applied at 90 °C and revealed the existence of an unexpectedly large concentration of intermediate radicals. The system was examined and discussed considering either the possibility of cross-termination between a propagating macroradical and an intermediate o...
90 citations
TL;DR: Reversible addition–fragmentation chain transfer of N-isopropylacrylamide with a chain transfer agent containing an activated-ester moiety was employed to prepare well-defined temperature-responsive polymers for conjugation to amine-containing proteins.
87 citations
86 citations
TL;DR: In this paper, a parallel with triethylborane-mediated reactions is established, where diethylzinc can be used to promote radical additions to CN bond containing radical acceptors and to enones.
Abstract: In the presence of oxygen, diethylzinc can be used to promote radical additions to CN bond containing radical acceptors and to enones. In these reactions, it plays at the same time the role of the initiator and the role of the chain-transfer reagent. A parallel with triethylborane-mediated reactions is established. The methodology is restricted to secondary and tertiaryalkyl radicals generated from the corresponding alkyl iodides. It could not be extended either to CC bond containing radical acceptors such as methyl methacrylate and nitrocyclohexene or to diethylazodicarboxylate.
83 citations