Synthesis and polymerizability of CN monomers

Abstract

The synthesis and polymerizability of imine C¼ ¼N monomers is surveyed. The investigated imines were either far more reactive than similarly substituted C¼ ¼C or C¼ ¼O monomers, or too stable to polymerize. Imines with electron-attracting substituents on N favor polymerization by anionic mechanism, but led only to low molecular weight polymers. Imines with a donor substituent on N, such as N-arylmethyleneimines, polymerized by cationic or anionic mechanism. 1-and 2-Aza-1,3-butadienes were also rather unstable and polymerized to oligomers. The symmetrically substituted 2,3-diaza-1,3-butadienes could be purified and polymerized successfully using anionic initiators, resulting in both 1,4-and 1,2-structures in the polymer backbone, depending on the substituents. KEYWORDS: anionic polymerization; azo polymers; oligomers; polyimines INTRODUCTION Polymerizations involving olefin C¼ ¼C monomers are a major sector of polymer chemistry, while polymerizations of carbonyl C¼ ¼O monomers are also well established. In contrast, polymerizations involving imine C¼ ¼N monomers have received much less attention. In this review, we shall survey existing knowledge in the area of imines and azabutadienes.

A Well-Defined Isocyano Analogue of HCo(CO)4. 1: Synthesis, Decomposition, and Catalytic 1,1-Hydrogenation of Isocyanides

“…Methylenimine 7 could be isolated from the reaction mixture, and analysis by 1 To our knowledge, 7 is the first example of a crystallographically characterized methylenimine. 120 The only previous example of an isolable methylenimine is H 2 CNDipp (Dipp = 2,6-(i-Pr 2 )C 6 H 3 ), and it has been well established that less encumbered methylenimines decompose rapidly. 121 Most importantly, CNAr Mes2 can be catalytically converted to methylenimine 7 by HCo(CNAr Mes2 ) 4 (1) under mild conditions (Scheme 8).…”

“…Consistent with this formulation, the solid-state structure (Figure ) shows a lengthened C–N bond (C–N = 1.247(5) Å) and considerable CNC bending (∠C–N–C = 120.0(3)°). To our knowledge, 7 is the first example of a crystallographically characterized methylenimine . The only previous example of an isolable methylenimine is H 2 CNDipp (Dipp = 2,6-( i -Pr 2 )­C 6 H 3 ), and it has been well established that less encumbered methylenimines decompose rapidly .…”