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 1 to about 22 carbon atoms, R' is hydrogen or methyl or mixtures thereof (on the individual molecule) and n is an integer of from 1 to about 12, which comprises reacting the corresponding alkoxyalkanol with a stable free radical nitroxide selected from the group consisting of 2,2,5,5-tetramethylpyrrolidin-1-oxyl, 2,2,4,4-tetramethyl-3-oxazolidin-1-oxyl, 1-aza-2,2,7,7-tetramethylcycloheptan-1-oxyl, and mixtures thereof in the presence of a NO.sub.x -generating compound selected from the group consisting of an alkali metal nitrosodisulfonate, nitric acid and mixtures thereof, at a temperature in the range of from about 0.degree. C. to about 100.degree. C. and thereafter separating out the alkoxyalkanoic acid.