a hydrophilic phenol ester derivative , especially a sulphonated or carboxylated phenol ester is prepared by reacting a c 6 - c 18 substituted or unsubstituted aliphatic carboxylic acid with a c 2 - c 3 alkanoic anhydride , and reacting the resultant c 6 - c 18 acid anhydride with a substituted phenol such as an alkali metal phenol sulphonate salt or hydroxybenzene carboxylic acid to give a c 6 - c 18 acyloxy derivative of a substituted benzene . the two stage process may be carried out in the same reaction vessel without the use of solvents . the products are useful as peroxyacid bleach precursors .