Composition, method and use

1. A gasoline fuel or lubricating composition comprising a quaternary ammonium salt of formula (I):

wherein X is a linking group; Y is 0, NH or NR 1 wherein R 1 is H or an optionally substituted hydrocarbyl group; Q + is a moiety that includes a quaternary ammonium cation; A − is an anion; R 2 is an optionally substituted alkylene group; R 3 is hydrogen or an optionally substituted hydrocarbyl group; and n is 0 or a positive integer; provided that n is not 0 when R 3 is hydrogen.

2. A method of improving the performance of an engine, the method comprising combusting in the engine a gasoline fuel composition comprising as an additive a quaternary ammonium salt of formula (I):

wherein X is a linking group; Y is O, NH or NR 1 wherein R 1 is H or an optionally substituted hydrocarbyl group; Q + is a moiety that includes a quaternary ammonium cation; A − is an anion; R 2 is an optionally substituted alkylene group; R 3 is hydrogen or an optionally substituted hydrocarbyl group; and n is 0 or a positive integer; provided n is not 0 when R 3 is hydrogen.

3. The composition according to claim 1 wherein the quaternary ammonium salt additive is prepared by reacting:

(a) a hydrocarbyl substituted dicarboxylic acid or anhydride thereof; with

(b) an alcohol of formula R 3 (OR 2 ) n OH;

(c) a reactive alcohol or amine including a tertiary amino group; and

(d) a quaternising agent.

4. The composition according to claim 1 wherein X is an optionally substituted alkylene or arylene group and R 4 is an optionally substituted hydrocarbyl group.

5. The composition according to claim 1 wherein n is 0 and R 3 is an optionally substituted alkyl or alkenyl group having 4 to 40 carbon atoms.

6. The composition according to claim 1 wherein each R 2 is ethylene or propylene.

7. The composition according to claim 6 wherein R 3 is hydrogen and n is at least 1.

8. The composition according to claim 6 wherein R 3 is an optionally substituted alkyl group having 4 to 40 carbon atoms and n is from 1 to 40.

9. The composition according to claim 1 wherein Q + is a group having the formula:

wherein R 5 is an optionally substituted alkylene, arylene or alkenylene group and each of R 6 , R 7 and R 8 is independently an optionally substituted hydrocarbyl group.

10. The composition according to claim 9 wherein R 5 is an optionally substituted alkylene group having 1 to 6 carbon atoms, R 6 is C 1 to C 6 alkyl, R 7 is C 1 to C 6 alkyl and R 8 is an unsubstituted C 1 to C 6 alkyl group or a hydroxy substituted C 1 to C 40 alkyl group.

11. The composition according to claim 1 wherein A − is a carboxylate anion.

12. The composition according to claim 1 wherein the quaternary ammonium salt additive is prepared by reacting:

(a) an optionally substituted succinic acid or anhydride thereof;

(b) an alcohol of formula H(OR 2 ) n OH or R 3 OH;

(c) a reactive alcohol including a tertiary amino group; and

(d) a quaternising agent.

13. The composition according to claim 1 wherein the quaternary ammonium salt additive is prepared by reacting:

(a) a succinic acid or anhydride thereof substituted with a C 20 to C 24 alkyl or alkenyl group;

(b) a polypropylene glycol or butanol;

(c) dimethylaminopropanol; and

a quaternising agent selected from the group consisting of: methyl salicylate, dimethyl oxalate and a hydrocarbyl epoxide in combination with an acid.

14. The composition according to claim 1 wherein the composition is a lubricating composition.

15. The composition according to claim 1 wherein the composition is a gasoline fuel composition.

16. The composition according to claim 15 wherein the gasoline fuel composition comprises one or more further detergents selected from the group consisting of:

a) carrier oils

b) acylated nitrogen compounds which are the reaction product of a carboxylic acid-derived acylating agent and an amine

c) hydrocarbyl-substituted amines wherein the hydrocarbyl substituent is substantially aliphatic and contains at least 8 carbon atoms

d) mannich base additives comprising nitrogen-containing condensates of a phenol, aldehyde and primary or secondary amine

e) aromatic esters of a polyalkylphenoxyalkanol; and

f) quaternary ammonium salts.

17. The composition according to claim 15 wherein the gasoline fuel composition comprises a mixture of two or more quarternary ammonium salt additives.

18. The method according to claim 2 wherein the engine is a direct injection spark ignition engine.

19. The method according to claim 2 which achieves “keep clean” performance.

20. The method according to claim 2 which achieves “clean up” performance.

21. The method according to claim 2 which combats injector deposits.

22. The method according to claim 21 wherein the deposits are internal injector deposits.

23. The method according to claim 2 which achieves an improvement in performance of one or more of:

improved fuel economy

reduced maintenance

less frequent overhaul or replacement of injectors

improved driveability

improved power; or

improved acceleration.