Abstract: Novel t-aliphatic .alpha.-(sulfo) azo compounds: ##EQU1## and the use of compounds I as polymerization initiators for vinyl monomers and as curing agents for resins. For example, 2-t-butylazo-2-thiophenoxy-4-methylpentane, prepared by reacting a solution of thiophenol and sodium hydroxide in methanol with 2-t-butylazo-2-chloro-4-methylpentane at 10.degree. - 15.degree.C., is used to cure an unsaturated polyester-styrene resin at 115.degree.C. and to polymerize styrene at 115.degree.C.

Abstract: Novel symmetrical bis(unsymmetrical t-alkyl and t-aralkyl azo) compounds of the general formula I:r -- n = n -- r.sub.12 -- n = n -- r' (i)where R = R' = (R").sub.3 C--, e.g., 1,2-ethylene bis(4-t-butylazo-4-cyanovalerate); and the use of I for sequential generation of free radicals, e.g. styrene monomer and 1,2-ethylene bis(4-t-butylazo-4-cyanovalerate) are reacted to obtain polystyrene containing attached azo groups which in turn is reacted with methyl methacrylate monomer to obtain a block copolymer of polystyrene and poly(methyl methacrylate).

Abstract: Unsymmetrical azo compounds: ##EQU1## where (R").sub.3 C-- is tertiary-aliphatic and Z is cyano or a derivative thereof, e.g., 2-t-butylazo-2-cyanopropane; processes for preparing such azo compounds by (a) adding hydrocyanic acid to a preformed hydrazone, ##EQU2## of a ketone to form a hydrazo compound, and oxidizing the hydrazo compound; or (b) oxidizing the hydrazo compound formed by the reaction of a t-aliphatic hydrazine with hydrogen or alkali metal cyanide in water.