RELATIVE IMPORTANCE OF SIDE REACTIONS IN THE RLI-ACRYLONITRILE - DIMETHYLFORMAMIDE SYSTEM

The probability of interaction of anionically growing poly(acrylonitri le) chains with dimethylformamide (DMF) in the acrylonitrile (AN)-RLi- DMF system was investigated by means of NMR and semiempirical, quantum chemical calculations (MNDO). According to the NMR data, poly(acrylon itrile) synthetized with various ROLi initiators does not contain trac es of DMF fragments. Quantum chemical calculations were carried out ta king CH3-CH2CH(CN)-Li as a model compound and simulating the anionic a ctive site of AN. The results obtained show that the interaction of th is compound with AN is highly preferred (by 100 kJ/mol) to that with D ME Qualitatively similar results are related to the butyllithium(BuLi) -AN and BuLi-DMF systems. However, the reaction between BuLi and DMF i s exothermic (in contrast to that between the active site of the model compound with DMF). This fact is in agreement with the effective addi tion of BuLi to DMF in the absence of any competing compound.