E.s.r. Spectra of the Radicals Formed During the Cyclopolymerizations of Acrylic and Methacrylic Anhydrides and a Comparison with Some Related Radicals

Department of Chemistry, The Queen's University of Belfast, N. Ireland

Received 4 September 1972

The e.s.r. spectra of the radicals formed by the addition of acrylic anhydride and ntetha· crylic anhydride to a reacting mixture of t-butyl hydroperoxide and sulphur dioxide are reported. Acrylic anhydride shows two sets of lines, attributed to linear and cyclic radicals respectively related monomers (acrylic acid, ethyl acrylate, acrylonitrile) give only one set of lines, attributed to linear ntonomer radicals RM ·, with hfcc independent of the nature of R.

Methacrylic anhydride shows three sets of lint:s, attributed to cyclic radicals and two linear radicals respectively; related monomers (methacrylic acid, ethyl methacrylate, methacrylonitrile) give two sets of lines, attributed to two linear monomer radicals RM·, with hfcc dependent on the nature of R (HOSO₂ , t-BuOSO₂ ).

The problem of the assignment of the spectra to the cyclic radicals is discussed.