Process for the preparation of concentrated solutions of fluorinated amphoteric surfactants

Claim 1

A process for the preparation of a concentrated solution of fluorinated amphoteric surfactants of the formulae ##STR11## wherein R f is straight or branched chain perfluoroalkyl of 1 to 18 carbon atoms or said perfluoroalkyl substituted by perfluoroalkoxy of 2 to 6 carbon atoms, R 1 is branched or straight chain alkylene of 1 to 12 carbon atoms, alkylenethioalkylene of 2 to 12 carbon atoms, alkyleneoxyalkylene of 2 to 12 carbon atoms or alkyleneiminoalkylene of 2 to 12 carbon atoms where the nitrogen atom contains as a third substituent hydrogen or alkyl of 1 to 6 carbon atoms, y is 1 or zero, X is oxygen or --NR, wherein R is hydrogen, lower alkyl of 1 to 6 carbon atoms, hydroxyalkyl of 1 to 6 carbon atoms, or R together with Q forms a piperazine ring, and Q is an aliphatic amino group of the formula ##STR12## wherein R 2 is a linear or branched alkylene of 2 to 12 carbon atoms, oxygen or sulfur interrupted linear or branched alkylene of up to 60 carbon atoms, or hydroxyl substituted alkylene; k is 1 or zero, with the proviso, that if X is oxygen, k is 1; R 3 and R 4 are each independently of the other an alkyl group of 1-4 carbon atoms ; said process comprising (a) reacting in a 1:1 ratio an aqueous solution of an amine with an anhydride previously dissolved in an anhydrous, non-reactive water miscible organic solvent, at a temperature of between 10° to 25° C and (b) reacting the product obtained in the first step with an R f -thiol in the presence of a non-reactive, water miscible thiol solvent, the ratio of the water miscible thiol solvent to water being such that the product is a homogeneous liquid composition.