QUANTUM-CHEMICAL INTERPRETATION OF THE STEREOSPECIFIC EFFECTS CHARACTERISTIC OF THE POLYMERIZATION IN ACRYLONITRILE-RLI AND METHYL ACRYLATE-RLI SYSTEMS

With the aim to find the causes of the different stereochemical behavi or characteristic of the anionic acrylonitrile (AN) and methyl acrylat e (MA) growing chains, the following model systems were investigated u sing the MNDO(a)) method: 1) compounds XCH2CH2CH(X)Li simulating racem ic (r) and meso (m) diads of AN (X = CN) and MA (X = COOCH3) at the ac tive end of the growing chain; 2) intermediate complexes of a MA r-dia d with a MA molecule in the mutual orientations which should lead to t he formation of a rr- or rm-triad; 3) compounds XCH2(CH2CH(X))2Li simu lating mm-, mr-, rm- or rr-triads of MA and their complexes with H2O a nd ethylenediamine (EDA). It was found that reaction of a MA r-diad wi th a MA molecule should preferably lead to the formation of a rm-triad in the absence of EDA and to the formation of a rr-triad in the prese nce of EDA. For AN none of the possible transformations of active diad s into triads was found to be preferred. These results are in qualitat ive agreement with the experimental data.