Hydrogen abstraction from primary amines. Substituent effects on the carbon-nitrogen bond rotation barriers in aminoalkyl radicals

Iain MacInnes*, John C. Walton, Derek C. Nonhebel

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

Hydrogen abstraction by t-butoxyl radicals from primary amines RCH 2NH2 (R = H, Me, Et, Pri, or But) gave mainly α-aminoalkyl radicals which were observed by e.s.r. spectroscopy. The barriers to rotation about the C-N bonds were determined from exchange broadening. For 2-fluoro- and 2-chloro-ethylamine the initial α-aminoalkyl radical lost hydrogen halide to give a mixture of syn- and anti-1-aza-allyl radicals. In contrast, the 1-amino-2,2,2-trifluoroethyl radical was stable under the same experimental conditions. The α-amino radicals formed on hydrogen abstraction from the methyl and t-butyl esters of glycine and the t-butyl ester of alanine were also examined. The stabilisation energy of the α-aminomethyl radical was estimated from the C-N bond rotation barriers of the aminoalkyl radicals. The pattern of stabilisation was found to be consistent with an extra stabilisation in radicals with captodative substitution.

Original languageEnglish
Pages (from-to)1789-1794
Number of pages6
JournalJournal of the Chemical Society, Perkin Transactions 2
Issue number12
Publication statusPublished - 1 Dec 1987

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