Process for selective production of trans-1,4-polybutadiene

A process for selective production of trans-1,4-polybutadiene which comprises using a catalyst system consisting essentially of:

• as the catalyst component (A), a titanium compound represented by the general formula Ti(R).sub.l (OR').sub.m X.sub.4-(l+m), wherein R and R' independently denote a hydrocarbon group of 1-20 carbon atoms, X denotes a halogen atom, and l and m denote numerals satisfying the inequalities l.gtoreq.0, m.gtoreq.0 and l+m .ltoreq.4,
• as the catalyst component (B), an organoaluminum compound represented by the general formula AlR.sup.1.sub.a Z.sub.3-a, wherein R.sup.1 denotes a hydrocarbon group of 1-20 carbon atoms, Z denotes a halogen atom, and a denotes a numeral satisfying the inequality l.ltoreq.a .ltoreq.3, wherein catalyst component (B) is used relative to the catalyst component (A) in the range of 1 to 100,000 in terms of the ratio of aluminum to titanium atom, and
• as the catalyst component (C), all organic compound having at least two hydroxyl groups represented by the general formula V or VI ##STR7## wherein Y denotes ##STR8## R.sup.6 being hydrogen or a hydrocarbon group of 1-6 carbon atoms;
• R.sup.2, R.sup.3, R.sup.4 and R.sup.5 must be the same or different from one another and independently denote a hydrocarbon group of 1-20 carbon atoms, hydroxyl group, nitro group, nitrile group, hydrocarbyloxy group or halogen atom;
• n' denotes 0 or an integer of 1 or more and represents the number of times of repetition of the unit Y;
• y, y', y", z, z' and z" independently denote the number of substituents bonded to the aromatic ring, y, y', z and z' being independently 0 or an integer of from 1 to 2, y" and z" being independently 0 or an integer of from 1 to 3;
• for polymerization including reacting catalyst component (C) with catalyst component (A) prior to using said system for polymerization.