Cationic Polymerization of 5-Methyl-2, 3-dihydrofuran

5-Methyl-2, 3-dihydrofuran(MDHF) was polymerized in toluene at low temperature by organometallic compounds(e.g. Al(C2Hs)2Ci), and the microstructure of high polymer obtained was studied by NMR. The methyl ethyl ketone-insoluble part in the polymer has not been obtained in the crystalline state till now, .but was found to be stereospecific. A triplet due to a-methyl protons with different chemical configurations may be assigned to di-isotactic, heterotactic, and di-syndiotactic with increasing magnetic field. A neariy linear relationship between the Qptical density ratio D1372/D1360 in polymer and the di-syndiotacticity was observed, The conditiQns for obtaining poly-MDHF with high stereospeificity using Ziegler cataiysr are discussed. The poiymerizatipn in the presence of asymmetric cationic catalysts ffom Al(C2Hs)2Cl apd P-phenyialanine led to polymerS having optical activity. The optidalactivity shown by the polymer indicates the presence of chains an erythro-di-isotactic structure.