Methods for preparing fuel additives

1. A method for preparing a fuel additive e having the formula:

where: R 1 is hydrogen;

R 2 , R 3 , R 4 , R 5 , R 11 and R 12 are each independently selected from hydrogen, alkyl, alkoxy, alkoxy-alkyl, secondary amine and tertiary amine groups;

R 6 , R 7 , R 8 and R 9 are each independently selected from hydrogen, alkyl, alkoxy, alkoxy-alkyl, secondary amine and tertiary amine groups;

X is selected from —O— or —NR 10 —, where R 10 is selected from hydrogen and alkyl groups; and

n is 0 or 1,

said method comprising carrying out the following reactions:

(i) addition of an alkylating agent b to starting material a:

to form an intermediate c; and

(ii) ring closing intermediate c to form fuel additive e,

wherein the alkylating agent b and intermediate c are selected from:

alkylating agent b

intermediate c

(1)

(2)

(3)

(4)

(5)

(6)

where: each L in alkylating agent b is independently selected from leaving groups or both L groups together form the group —O—C(O)—O—;

each R 13 is independently selected from hydrogen and alkyl groups, or both R 13 groups together with the —O—C—O— group to which they are attached form a 1,3-dioxolane or 1,3-dioxane group; and

R 14 is selected from hydrogen and alkyl groups.

2. A method according to claim 1 , wherein step (i) is carried out in the presence of a base selected from:

inorganic bases, and

organic bases.

3. A method according to claim 1 , wherein step (i) is carried out in the presence of a catalyst, wherein the catalyst is selected from acids, zeolites, metal catalysts, halogen exchange catalysts and phase transfer catalysts.

4. A method according to claim 1 , wherein step (i) is carried out in the presence of a solvent selected from tetrahydrofuran, acetonitrile, dimethoxyethane, dioxane, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene carbonate, sulfolane, diphenyl ether, acetonitrile, 2-nitropropane, acetone, butan-2-one, butylformate, ethyl acetate, isobutyronitrile, methylacetate, methyformate, nitromethane, oxolane and propionitrile, dichloromethane, dichloroethane, chloroform and water.

5. A method according to claim 1 , wherein step (i) may be carried out at a temperature of greater than 40° C.

6. A method according to claim 1 , wherein in alkylating agent b each L is independently selected from: halides, sulfonates, substituted aryloxy groups and hydroxy groups.

7. A method according to claim 1 , wherein step (ii) is carried out in the presence of a hydrogen source and a hydrogenation catalyst.

8. A method according to claim 7 , wherein the hydrogenation catalyst is selected from palladium, platinum, nickel and rhodium catalysts.

9. A method according to claim 7 , wherein the hydrogen source is hydrogen gas at a pressure of from 1 to 80 bar.

10. A method according to claim 7 , wherein step (ii) is carried out at a temperature of at least 20° C.

11. A method according to claim 7 , wherein step (ii) is carried out in the presence of an acid.

12. A method according to claim 1 , wherein the alkylating agent b and intermediate c are selected from:

alkylating agent b

intermediate c

(2)

(4)

provided that in alkylating agent b both L groups together form the group —O—C(O)—O— or at least one of the L groups is selected from —OH, and

wherein step (ii) comprises sub-steps (iia) and (iib), where the one of sub-steps (iia) and (iib) are carried out in the presence of a hydrogen source and a hydrogenation catalyst, and the other of sub-steps (iia) and (iib) comprises replacing the hydroxyl group with a halogen in a halogenation reaction.

13. A method according to claim 1 , wherein alkylating agent b and intermediate c are selected from:

alkylating agent b

intermediate c

(5)

and wherein step (ii) comprises the following sub-steps:

14. A method according to claim 13 , wherein the sub-step (iia′) is carried out in the presence of a hydrogen source and a hydrogenation catalyst.

15. A method according to claim 1 , wherein the alkylating agent b and intermediate c are selected from:

alkylating agent b

intermediate c

(1)

16. A method according to claim 1 , wherein the method is a batch process in which the fuel additive is produced in a batch quantity of greater than 100 kg.

17. A method according to claim 1 , wherein the method is a continuous process.

18. A process for preparing a fuel for a spark-ignition internal combustion engine, said process comprising:

preparing a fuel additive e having the formula:

where: R 1 is hydrogen;

R 2 , R 3 , R 4 , R 5 , R 11 and R 12 are each independently selected from hydrogen, alkyl, alkoxy, alkoxy-alkyl, secondary amine and tertiary amine groups;

R 6 , R 7 , R 8 and R 9 are each independently selected from hydrogen, alkyl, alkoxy, alkoxy-alkyl, secondary amine and tertiary amine groups;

X is selected from —O— or —NR 10 —, where R 10 is selected from hydrogen and alkyl groups; and

n is 0 or 1,

comprising carrying out the following reactions:

(i) addition of an alkylating agent b to starting material a:

to form an intermediate c; and

(ii) ring closing intermediate c to form fuel additive e,

wherein the alkylating agent b and intermediate c are selected from:

alkylating agent b

intermediate c

(1)

(2)

(3)

(4)

(5)

(6)

where: each L in alkylating agent b is independently selected from leaving groups or both L groups together form the group —O—C(O)—O—;

each R 13 is independently selected from hydrogen and alkyl groups, or both R 13 groups together with the —O—C—O— group to which they are attached form a 1,3-dioxolane or 1,3-dioxane group; and

R 14 is selected from hydrogen and alkyl groups; and

blending the fuel additive e with a base fuel.