Abstract: A process for the preparation of a diazocyano acid, which comprises reacting a keto-acid or its sodium salt with a cyanogen compound such as sodium cyanide or hydrogen cyanide and a hydrazine in water to form a concentrated aqueous solution of a hydrazo compound, adding acetone and/water to the concentrated aqueous solution to form a solution of the hydrazo compounds, adding chlorine gas to the solution to oxidize the hydrazo compound and form a diazocyano acid, adding acetone to the obtained reaction mixture during or after the oxidation if necessary, and separating and recovering the supernatant layer of the acetone-water solution containing the diazocyano acid from the mixture.

Abstract: A process for the preparation of a diazocyano acid, which comprises reacting a keto-acid or its sodium salt with a cyanogen compound such as sodium cyanide or hydrogen cyanide and a hydrazine in water to form a concentrated aqueous solution of a hydrazo compound, adding acetone or acetone and water to the concentrated aqueous solution to form an acetone-water solution of the hydrazo compound, adding an oxidant such as chlorine gas to the solution to oxidize the hydrazo compound and form a diazocyano acid, forming at least two transparent liquid layers by adding acetone and/or water to the obtained reaction mixture during or after oxidation if necessary, and further adding sodium chloride to the reaction mixture if necessary, and separating and recovering the upper layer of the acetone-water solution containing the diazocyano acid from the mixture.

Abstract: A process for polymerizing 1,3-butadiene, comprising bring into contact a 1,2-polymerization catalyst consisting essentially of a soluble cobalt compound, an organic aluminum halide, an organic lithium compound, and carbon disulfide or phenyl isothiocyanate with 1,3-butadiene in a polymerization medium. The process can be applied particularly advantageously in the preparation of 1,2-polybutadiene, and the resultant 1,2-polybutadiene has a content of syndiotactic 1,2-structural units of not less than 90%, a melting point of 200.degree. C. to 220.degree. C., and an intrinsic viscosity [.eta.] of 1.2 to 7.

Abstract: A polybutadiene rubber having an enhanced mechanical strength is produced by a process comprising two successive steps of:(A) cis-1,4-polymerizing 1,3-butadiene in a polymerization medium in the presence of a catalyst comprising a cobalt compound and a dialkyl aluminium halide of the formula (I): AlR.sub.2 X, wherein R=C.sub.2 -8 alkyl and X=halogen, and;(B) subjecting a mixture of the resultant cis-1,4-polybutadiene and the non-reacted 1,3-butadiene in the polymerization medium to a 1,2-polymerization in the presence of a catalyst comprising a cobalt compound, a dialkyl aluminium halide of the formula (I), carbon disulfide and an electron donative organic compound.