synopsisThe polymerization of 1,3-butadiene by using organotitanium catalysts, e.g. tetramethyltitanium (classified aa a radical-type catalyst), gave rubberlike polybutadiene in low yield which was rich in the truns-l,Pstereoisomer, while the polymerization of 1 , s butadiene by use of organotitanium catalysts, e.g., tetravinyltitanium and tetraphenyltitanium (classified as a r-type catalyst) gave polybutadiene rich in the 1,2configuration in high yield. Titanocene dichloride and bisbenzenechromium iodide were each used individually to catalyze the polymerizat.ion of 1,3-butadiene with methyl Grignard reagent. In both cases polybutadienes rich in the 1,4configuration were obtained in quite low yield. These results were interpreted to be due to the lack of availability of 3d orbitals in the above-mentioned catalyst. Organic chromium, iron, cobalt, and nickel compounds were also investigated as catalysts for the polymerization of 1,Sbutadiene. Viscous, low molecular weight products were obtained in all cases. W-hen the chromium catalysts were used, a mixture of polymers, namely 1,2-and truns-l,4polybutadiene, was obtained in high yield. On the other hand, low product yields were observed with the use of the other catalysts; however, truns,truns,truns-l,5,9-cyclododecatriene was found in each case. The configuration of polybutadiene was also dependent upon the number, odd or even, of organic groups on a transition metal atom.