TRIVALENT TITANIUM CATALYST FOR PRODUCTION OF HIGHLY SYNDIOTACTIC POLYSTYRENE, ITS PRODUCTION, CATALYST COMPOSITION AND PRODUCTION OF POLYSTYRENE BY USING THE COMPOSITION

PROBLEM TO BE SOLVED: To obtain a highly active catalyst by combining a trivalent titanium catalyst obtained by reacting a product of reaction of TiCl3 with a diketone in the presence of tetrahydrofuran with silanolamine or the like with an activated transition metal cocatalyst. SOLUTION: Tetrahydrofuran is added to TiCl3 .3 tetrahydrofuran under agitation, and a diketone represented by formula I (R and R are each a 1-12C alkyl, an aryl or the like) is added and reacted at room temperature to obtain a compound (A) represented by formula II (T is tetrahydrofuran). Next, compound A is mixed with a compound being silanolamine or a salt (B) thereof (e.g. HN[Si(CH3 )2 ]2 ) in an A/B molar ratio of 1/2.5 or above and reacted at room temperature to obtain a trivalent titanium catalyst represented by formula III (X and X are each a 1-12C alkoxyl, a halogen or the like). Styrene is polymerized in the presence of a catalyst composition prepared by combining the trivalent titanium catalyst with an activated transition metal cocatalyst (e.g. methylaluminoxane) to obtain a highly syndiotactic polystyrene.