NEW MATERIAL:Compounds of the formula (X is -H, -Cl, -O-CH3, etc., when n=1 and Cl at 2 and 4 position when n=2; m is 2-15).

USE: Radical polymerization initiators for ethylenic unsaturated monomers. having stability on standing.

PREPARATION: A mixture of 7,12-dimethyloctadecane-1,18-dicarboxylic acid chloride and a monobasic acid chloride corresponding to end groups of a compound of the formula is gradually added to an aqueous solution of a peroxidation agent such as a sodium peroxide or potassium peroxide with stirring and reacted to obtain the compound of the formula. The mole ratio on the monobasic acid based on the compound of the formula is 1:(0.07-1). The amount of the peroxide used is about 0.5-1.5 equivalent based on that of chloride of the raw oxide mixture. Compounds of the formula have high initiator efficiency and enable cycle-up in polymerization. The compounds can remarkably improve workability and have an effect such as high handling stability.