Patent ID: 7160507

Claim:
A method of inhibiting corrosion at metal surfaces comprising the steps of: providing a corrosive system which is in contact with a metal surface; providing compounds of the formula 1 in which R 1 , R 2 , is a radical of the formula —(A—O) n —(C)—CO—O—R 5 (3) R 3 is C 1 - to C 30 -alkyl or C 2 - to C 30 -alkenyl R 4 is an organic radical having 1 to 100 carbon atoms which optionally contains heteroatoms R 5 is C 1 - to C 30 -alkyl or C 2 - to C 30 -alkenyl n is a number from 1 to 20 A is a C 2 - to C 4 -alkylene group, C is a C 1 - to C 6 -alkylene group and X is an anion; and adding said compound of formula (I) to said corrosive system as corrosion inhibitors.