Process for the preparation of alkoxyalkanoic acids

A process for the preparation of an alkoxyalkanoic acid of the formula RO(CH.sub.2 CHR'O).sub.n CH.sub.2 CO.sub.2 H wherein R is an alkyl group of from about 1 to about 22 carbon atoms, R' is hydrogen or alkyl or mixtures thereof (on the individual molecule) and n is an integer of from about 1 to about 500, which comprises reacting the corresponding alkoxyalkanol with a stable free radical nitroxide having the formula:

• ##STR14## wherein (1) (a) each of R.sub.1, R.sub.2, R.sub.3 and R.sub.4 is an alkyl, aryl or heteroatom substituted alkyl group having 1 to about 15 carbon atoms, and (b) R.sub.5 and R.sub.6 (i) each is an alkyl group having 1 to about 15 carbon atoms provided that R.sub.1 -R.sub.6 are not all alkyl groups, or a substituted alkyl group having 1 to about 15 carbon atoms wherein the substituent is hydrogen, cyano, --CONH.sub.2, --OCOCH, OCOC.sub.2 H.sub.5, carbonyl, alkenyl wherein the double bond is not conjugated with the nitroxide moiety, or --COOR wherein R of the --COOR group is alkyl or aryl, or (ii) together form part of a ring that contains at least 3 carbon atoms and up to two heteroatoms of O or N, (2) the ##STR15## moiety and the ##STR16## moiety individually are aryl, or (3) the ##STR17## moiety and the ##STR18## moiety together form a bicyclic ring with the proviso that the group directly adjacent to the N-O moiety is a bridgehead C--H, or a fully alkylated carbon, in the presence of a cerium salt which is at least partially soluble, a nitrite compound, a highly polar solvent, an oxidant and water, at a temperature in the range of from about 0.degree. C. to about 100.degree. C. and thereafter separating out the alkoxyalkanoic acid.