Theoretical study of factors controlling rates of cyclization of radical intermediates from diallylamine and diallylammonium monomers in radical polymerizations

Tuzun N., Aviyente V., HOUK K.

JOURNAL OF ORGANIC CHEMISTRY, cilt.67, sa.15, ss.5068-5075, 2002 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 67 Sayı: 15
  • Basım Tarihi: 2002
  • Doi Numarası: 10.1021/jo0256636
  • Dergi Adı: JOURNAL OF ORGANIC CHEMISTRY
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.5068-5075
  • İstanbul Teknik Üniversitesi Adresli: Hayır

Özet

The radical cyclization reactions of models for the growing radical chains formed from N,N-diallylamine (1), N-methyl-N,N-diallylamine (2), N,N-diallylammonium (3), N-methyl-N,N-diallylammonium (4) and N,N-dimethyl-N,N-diallylammonium (5) have been investigated computationally by DFT theory, using the B3LYP functional. Models formed by hydrogen atom addition to dienes 1-5 undergo five-membered ring cyclization reactions with activation energies predicted to be 7.2, 5.0, 8.6, 6.4, and 6.2 kcal/mol, respectively. Methyl substitution on nitrogen decreases the barrier to cyclization. One methyl has a larger effect on the cyclization rate than the second methyl. This rate enhancement is attributed to a decrease in gauche interactions in the transition state as compared to the initial structure and to different destabilizing effects when an H is replaced by a methyl group. These predicted rate effects are in agreement with the experimental data on polymerization efficiencies.