Amphoteric styrene derivatives useful as fluorescent brighteners

A process for the preparation of an amphoteric styrene derivative of the formula ##STR127## in which X is oxygen, sulfur, a direct bond, --SO.sub.2 N(R.sub.5 --, --CON(R.sub.5 -- or --COO--, Y.sub.1 and Y.sub.2 independently of one another are C.sub.1 -C.sub.4 -alkylene or hydroxypropylene, R.sub.1 and R.sub.2 independently of one another are C.sub.1 -C.sub.4 -alkyl or, together with the N atom, are a pyrrolidine, piperidine, hexamethyleneimine or morpholine ring, and R.sub.1, together with R.sub.5, is also a piperazine ring, R.sub.3 and R.sub.4 are hydrogen, C.sub.1-4 -alkyl, chlorine, C.sub.1-4 -alkoxy or C.sub.3-4 -alkenyl or together, in the o-position relative to one another, are a trimethylene or tetramethylene group, R.sub.5 is hydrogen, C.sub.1-4 -alkyl or cyanoethyl or, together with R.sub.1, is a piperazine ring, Q is --COO or --SO.sub.3 and n is the number 1 or 2, which comprises reacting a styrene derivative of the formula ##STR128## in which R.sub.1, R.sub.2, R.sub.3, R.sub.4, X, Y.sub.1 and n are as defined above, with a halide of the formula

• Hal--Y.sub.2 --QH
• in which Y.sub.2 and Q are as defined above and Hal is chlorine or bromine, or, if Q=--COO, with its salts, esters, amides, nitriles or lactones, or, if Q=--SO.sub.3, with its salts, aryl esters or sultones, or, if Y.sub.2 =hydroxypropylene, also with the corresponding epoxides, and saponifying the quaternary ammonium halides eventually formed.