NEW MATERIAL: A precursor compound for a bleaching agent of formula I (A means alkylene, alkenylene, alkynylene, cycloalkylene, alkarylene, arylene, etc., and contains 1-12C; the hydrocarbyl moiety of X is different from the hydrocarbyl moiety of Z, and X means alkyl, alkenyl, alkynyl, etc., and contains 1-20C; Z is a leaving group and its conjugate acid has pKa of about 6-13).

EXAMPLE: Sodium-4-(4-propoxy carbonyl)benzoyloxybenzenesulfonate.

USE: A precursor of a bleaching agent. By perhydrolysis with H2O2 or peracid salt, a new peroxy acid of formula II can be obtained.

PROCESS: By use of two acids selected from the group of phthalic acid, terephthalic acid, succinic acid, glurtaric acid, azelaic acid, isophthalic acid and dodecanoic diacid, a compound of formula I can be obtained.