Methods of using ionic liquids as corrosion inhibitors

1. A method of inhibiting corrosion of a metallic surface in contact with an acidic or aqueous fluid comprising contacting the acidic or aqueous fluid with a corrosive inhibiting effective amount of an ionic liquid of the formula:

R 1 R 2 R 3 A + R 8 A + R 5 R 6 R 7 X −   (III)

wherein:

each A is nitrogen; and

X is an anion selected from the group consisting of sulfur containing anions and hydroxycarboxylates; and

wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 and R 7 are independently selected from the group consisting of benzyl; alkylbenzyl, or oxyalkyl; a straight or branched alkyl group, an alkylbenzyl group, an arylalkyl group, a straight or branched chain alkenyl group, a hydroxyalkyl group or a hydroxyalkylbenzyl group; and a polyoxyalkylene group; and R 8 is a straight or branched alkylene group, an alkylene oxyalkylene, or an alkylene polyoxyalkylene or a zwitterion.

2. The method of claim 1 , R 1 , R 2 , R 3 , R 4 , R 5 , R 6 and R 7 are independently selected from the group consisting of benzyl; oxyalkyl; a straight or branched C 1-30 alkyl group; a C 7-30 alkylbenzyl group; a C 7-30 arylalkyl group; a straight or branched C 3-30 alkenyl group; a C 1-30 hydroxyalkyl group; a C 7-30 hydroxyalkylbenzyl group; and a polyoxyalkylene group; and R 8 is a straight or branched C 1-30 alkylene, an alkylene oxyalkylene, or an alkylene polyoxyalkylene.

3. The method of claim 2 , wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 and R 7 are independently selected from a C 1-20 alkyl, —CH 2 CH 2 OH, and CH 2 CH(CH 3 )OH.

4. The method of claim 1 , wherein X is a hydroxycarboxylate.

5. The method of claim 4 , wherein X is selected from the group consisting of glycolate, lactate, citrate, glucarate, gluconate, and tartrate.

6. The method of claim 1 , wherein X is an anion of a polysulfide.

7. The method of claim 6 , wherein the anionic polysulfide is of the formula RS(S) x S) wherein R is a C 1-20 alkyl and x is 1 to 5.

8. The method of claim 1 , wherein X is an anion of a hydroxyl containing sulfur anion.

9. The method of claim 1 , wherein X is anionic 2-mercaptoethyl mercaptide.

10. The method of claim 1 , wherein X is an anionic thiol.

11. The method of claim 1 , wherein X is an anion of an alkylated thiol.

12. The method of claim 11 , wherein X is an anion of the formula HS(CH 2 ) x OH where x is from 1 to 8.

13. The method of claim 12 wherein X is the anion of HSCH 2 CH 2 OH.

14. The method of claim 1 , wherein the ionic liquid is present in a treatment composition either containing (i) a second corrosion inhibitor not an ionic liquid; or (ii) a second corrosion inhibitor of an ionic liquid wherein the anion of the ionic liquid and the anion of the second corrosion inhibitor are the same.

15. The method of claim 1 , wherein the acidic or aqueous liquid is crude oil, petroleum fuel or oil, a condensate, a distillate or cooling water.