Process for preparing carboxylated 2-allyl-phenols

A process for preparing a carboxylated 2-allyl-phenol of formula (I):

• ##STR8## wherein:
• n is zero or 1,
• R.sub.1 and R.sub.2, which can be the same or different, are hydrogen or C.sub.1 -C.sub.2 alkyl, comprising:
• (a) simultaneously allyl-esterifying and allyl-etherifying a hydroxy-carboxy acid of formula (II):
• ##STR9## wherein n is zero or 1, with an allyl halide of formula (III):
• X--CHR.sub.2 --CH.dbd.CHR.sub.1
• wherein R.sub.1 and R.sub.2 are as defined above and X is Cl or Br, by reacting the hydroxy-carboxy acid with an alkali metal or alkaline-earth metal carbonate in a molar ratio of carbonate/hydroxy-carboxy acid of greater than 2 while heating the reaction mixture to remove water and subsequently adding the allyl halide to the reaction mixture at 40.degree.-80.degree. C. to produce an allyl-ester allyl-ether of the hydroxy-carboxy acid and separating the allyl-ester allyl-ether from the reaction mixture;
• (b) heating the allyl-ester allyl-ether at a temperature of 200.degree. to 280.degree. C. for a period of from 2 to 6 hours in the presence of a heat stabilizer to thermally rearrange the allyl-ester allyl-ether to an allylcarboxylated 2-allyl-phenol, and recovering the allylcarboxylated 2-allyl-phenol;
• and
• (c) saponifying the allylcarboxylated 2-allyl-phenol by treatment with a strong base and subsequent acidification to produce the 2-allyl-phenol of formula (I).