No.8（2005）1.Estimation of monomer reactivities in the synthesis of poly(styrene sulfone) derivatives using computer-aided chemistry

Tsutomu SHINODA, Hiroshi UENO, Yoshio SHINDOH and Kenichi SHIMIZU

It is reported that some vinyl monomers react with sulfur dioxide to form polysulfones in liquid SO2. We found that 4-trimethylsilyloxystyrene (TMSOSt) copolymerized to give an alternating 1:1 copolymer, whereas 4-tert-butoxystyrene homopolymerized. The copolymerization was initiated by tert-butyl hydroperoxide and was considered to proceed by a free-radical mechanism. We focused our attention on the nucleophilic attack of a monomer radical on SO2. The SOMO (Singly Occupied Molecular Orbital) energies of monomer radicals and their electron densities at α-carbon atoms of vinyl moieties were calculated by the MOPAC in CAChe. They were treated at the PM5 level. The TMSOSt monomer radical, which is reactive in a polysulfone formation, had both a high SOMO energy and a high electron density. With a dihedral angle of .180° to +180° between the benzene ring and the vinyl radical moiety, the electron density varied by 51%, while the SOMO energy changed by only 4.6%.

Keywords

Sulfur dioxide, Polysulfone, 4-Trimethylsilyloxystyrene, 4-tert-butoxystyrene, Free-radical, Nucleophilic attack, SOMO energy, Electron density, MOPAC, CAChe, PM5, Dihedral angle

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