Patent ID: 8716519

Claim:
A compound in acid or salt form, which contains an anion of the formula (I) and one or more cations for producing electroneutrality in which: R 1 and R 2 , independently of one another, are hydrogen, alkyl, cycloalkyl, aryl, aralkyl, —COOR 5 , —COO − Cat + , —CON(R 6 R 7 ) or —X—R 4 —CR 5 (OH)(SO 3 − ); R 4 is alkylene, polyoxyalkylene, cycloalkylene or arylene; R 5 is hydrogen, alkyl, cycloalkyl or aryl; R 3 , R 6 and R 7 , independently of one another, are hydrogen, alkyl or aryl: Cat + is a monovalent cation; X is selected from the group consisting of —O—, —CH 2 —O—, —COO— or —CONR 8 —; and R 8 is hydrogen, alkyl or aryl.