WO2019129593A2

WO2019129593A2 - Methods for preparing fuel additives

Info

Publication number: WO2019129593A2
Application number: PCT/EP2018/086028
Authority: WO
Inventors: Jon Michael Stewart Deeley; Sorin Vasile Filip
Original assignee: BP Oil International Ltd
Current assignee: BP Oil International Ltd
Priority date: 2017-12-27
Filing date: 2018-12-19
Publication date: 2019-07-04
Anticipated expiration: 2020-06-27
Also published as: WO2019129593A3; GB201721969D0

Abstract

A method for preparing a substituted fuel additive d is provided. The method comprises carrying out the following reaction: ( a, b, d ) A is selected from halides and -SO₃R_13, where R₁₃ is selected from hydrogen, alkyl groups and alkali metals. L is selected from leaving groups and L' and L' is -XH or -XM, or both L and L' together form the group -O-C(O)-O-.

Description

METHODS FOR PREPARING FUEL ADDITIVES

Field of the Invention

This invention relates to methods for preparing octane-boosting additives for use in a fuel for a spark-ignition internal combustion engine. In particular, the invention relates to methods for preparing octane-boosting fuel additives that are derivatives of

benzo[l,4]oxazines and 1,5-benzoxazepine. The invention further relates to methods for preparing fuels for a spark-ignition internal combustion engine comprising the fuel additives.

Background of the Invention

Spark-ignition internal combustion engines are widely used for power, both domestically and in industry. For instance, spark-ignition internal combustion engines are commonly used to power vehicles, such as passenger cars, in the automotive industry.

Fuels for a spark-ignition internal combustion engine (generally gasoline fuels) typically contain a number of additives to improve the properties of the fuel.

One class of fuel additives is octane improving additives. These additives increase the octane number of the fuel which is desirable for combatting problems associated with pre-ignition, such as knocking. Additisation of a fuel with an octane improver may be carried out by refineries or other suppliers, e.g. fuel terminals or bulk fuel blenders, so that the fuel meets applicable fuel specifications when the base fuel octane number is otherwise too low.

Organometallic compounds, comprising e.g. iron, lead or manganese, are well- known octane improvers, with tetraethyl lead (TEL) having been extensively used as a highly effective octane improver. However, TEL and other organometallic compounds are generally now only used in fuels in small amounts, if at all, as they can be toxic, damaging to the engine and damaging to the environment.

Octane improvers which are not based on metals include oxygenates (e.g. ethers and alcohols) and aromatic amines. However, these additives also suffer from various drawbacks. For instance, N-methyl aniline (NMA), an aromatic amine, must be used at a relatively high treat rate (1.5 to 2 % weight additive / weight base fuel) to have a significant effect on the octane number of the fuel. NMA can also be toxic. Oxygenates give a reduction in energy density in the fuel and, as with NMA, have to be added at high treat rates, potentially causing compatibility problems with fuel storage, fuel lines, seals and other engine components.

Recently, a new class of octane-boosting additive has been discovered. These octane-boosting additives are derivatives of benzo[l,4]oxazines and l,5-benzoxazepines, and show great promise due to their non-metallic nature, their low oxygenate content, and their efficacy at low treat rates (see WO 2017/137518). Preferred octane-boosting additives in this class are substituted on one or more of the carbons forming part of the aromatic or heterocyclic ring.

Synthesis routes currently reported in the literature provide various descriptions of how benzoxazines could be prepared on a relatively small scale (hundreds of mg to up to 100 kg scale). For example, US 2008/064871 - which relates to compounds for the treatment or prophylaxis of diseases relating to uric acid, such as gout - discloses the preparation of benzoxazine-derived compounds.

However, such synthesis methods are not viable for preparing the new class of octane-boosting additives on an industrial scale, e.g. from 50 to up to 20,000 tonnes per year, due to the high cost of specialised raw materials, e.g. methylaminophenols, and reagents, e.g. lithium aluminium hydride and dibromoethane, which are required in stoichiometric amounts.

Accordingly, there is a need for methods for synthesising the new class of octaneboosting additives that may be implemented on a large scale and which mitigate at least some of the problems highlighted above, e.g. by avoiding the use of costly aminophenol starting materials.

Summary of the Invention

The present invention provides a method for preparing a fuel additive d having the formula:

where: R[ is hydrogen; R₂, R₃, R₄, R₅, R₁₁ and R_l2 are each independently selected from hydrogen, alkyl, alkoxy, alkoxy-alkyl, secondary amine and tertiary amine groups;

R₆, R₇, Re and R₉ are each independently selected from hydrogen, alkyl, alkoxy, alkoxy-alkyl, secondary amine and tertiary amine groups;

X is selected from -O- or -NR_l0-, where R_l0 is selected from hydrogen and alkyl groups; and

n is 0 or 1.

The method comprises carrying out the following reaction:

a b d

where: L is selected from leaving groups and L’; and

L’ is selected from -XH and -XM, where M is an alkali metal; or both L and L’ together form the group -0-C(0)-0-; and

A is selected from halides and -S0₃R_l3, where R_l3 is selected from hydrogen, alkyl groups and alkali metals.

Also provided is a fuel additive d which is obtainable by a method of the present invention.

The present invention farther provides a process for preparing a fuel for a spark- ignition internal combustion engine, said process comprising:

preparing a fuel additive d using a method of the present invention; and

blending the fuel additive with a base fuel.

A fuel for a spark-ignition internal combustion engine is also provided. The fuel comprises a fuel additive d of the present invention and a base fuel. Detailed Description of the Invention

Preparation methods

The present invention provides a method for preparing a fuel additive d. According to this method, the fuel additive d is prepared by carrying out the following reaction:

Starting material a is substituted by the group A. Group A is selected from halides (preferably from Cl and Br) and -SO₃R₁₃. In preferred embodiments, A is selected from - SO3R13.

R₁₃ is selected from hydrogen, alkyl groups (e.g. methyl, ethyl, propyl and butyl, and more preferably from methyl and ethyl) and alkali metals (e.g. sodium or potassium), preferably from hydrogen and alkali metals.

Reagent b is preferably used in an amount of from 0.8 to 6 molar equivalents, preferably from 0.9 to 4 molar equivalents, and more preferably from 1 to 2.5 molar equivalents as compared to starting material a.

The reaction may be earned out in a single step (i. e. with one set of reagents and under one set of conditions). For instance, where A represents a halogen or SO₃R₁₃, Ro being an alkali metal, and L and L’ are both -XM, then a single step reaction may be earned out.

However, in other embodiments, the reaction comprises the following steps:

d

It will be appreciated that, in some instances, step (ii) will occur spontaneously on formation of intermediate c. For the puiposes of the present invention, these instances are considered to be embodiments in which the reaction is earned out in a single step.

In step (i) of the method, an addition reaction is carried out in which an alkyl group from reagent b is added to the amine group of starting material a to form intermediate c.

In a first embodiment, reagent b is:

where L is selected from leaving groups, and is preferably -XH.

In the first embodiment, step (i) is preferably carried out in the presence of a base or an acid, and preferably a base.

The base is preferably selected from inorganic bases such as alkali metal hydroxides ( e.g . selected from sodium hydroxide and potassium hydroxide), alkali or alkaline earth metal carbonates (e.g. selected from sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate and calcium carbonate) and alkali metal fluorides (e.g. selected from sodium fluoride and potassium fluoride).

Preferred basic reagents are alkali or alkaline earth metal carbonates, with potassium carbonate and calcium carbonate particularly preferred.

The acid is preferably selected from alkali metal hydro gensulfites (e.g. sodium hydrogensulfite or potassium hydro gensulfite).

The base or acid may be used in an amount of from 0.8 to 5 molar equivalents, preferably from 1 to 3 molar equivalents, and more preferably from 1.05 to 2.5 molar equivalents as compared to starting material a.

In the first embodiment, step (i) may be carried out in the presence of a solvent selected from aprotic solvents (e.g. tetrahydrofuran, acetonitrile, dimethoxy ethane, dioxane, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene carbonate, sulfolane, diphenyl ether, acetonitrile, 2-nitropropane, acetone, butan-2-one, butyl formate, ethyl acetate, isobutyronitrile, methyl acetate, methyl formate, nitromethane, oxolane and propionitrile) and water. Aprotic solvents are well- known in the art as solvents which are not capable of donating protons. Aprotic solvents do not contain hydrogen atoms bound to a nitrogen or an oxygen.

Specific combinations of reagent b, base/acid and solvent include:

2-bromoethanol, potassium carbonate and water;

2-bromoethanol, potassium fluoride and dimethylformamide;

2-chloroethanol, potassium carbonate or calcium carbonate and water;

2-chloroethanol, sodium hydrogensulfite and water.

In the first embodiment, step (i) may be earned out at a temperature of from 0 to 250 °C, preferably from 10 to 200 °C, and more preferably from 15 to 150 °C. The reaction will generally be carried out at ambient pressure, i.e. at a pressure of

approximately 1 bar.

In a second embodiment reagent b is:

In the second embodiment, step (i) may be carried out in the presence of a solvent, and preferably no further reagents beyond starting material a and reagent b.

The solvent may be selected from aprotic solvents (e.g. tetrahydrofuran, acetonitrile, dimethoxy ethane, dioxane, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene carbonate, sulfolane, diphenyl ether, acetonitrile, 2-nitropropane, acetone, butan-2-one, butyl formate, ethyl acetate, isobutyronitrile, methyl acetate, methyl formate, nitromethane, oxolane and propionitrile). Preferably the solvent is an aprotic solvent which does not contain a carbonyl group.

Alternatively, in the second embodiment, step (i) may be carried out in the absence of a solvent. The step is preferably carried out in the presence of no further reagents beyond starting material a and reagent b.

Specific combinations of reagent b and solvent include ethylene oxide and tetrahydrofuran or dimethoxyethane or dioxane.

In the second embodiment, step (i) may be carried out at a temperature of from 0 to 300 °C, preferably from 10 to 250 °C, and more preferably from 15 tol50 °C. Where step (i) is carried out in the absence of a solvent, it is preferably carried out at a temperature of greater than 100 °C. The reaction is preferably carried out under pressure, e.g. at a pressure of approximately 2 to 200 bar.

In a third embodiment, reagent b is:

where L = L’, and are preferably both -XH.

In the third embodiment, step (i) may be earned out in the presence of a catalyst. The catalyst may be selected from metal catalysts (e.g. a palladium catalyst such as Pd/C). The catalyst may be used with a metal oxide, and preferably with zinc oxide. The catalyst may be used in an amount of less than 1 molar equivalent, preferably less than 0.5 molar equivalents, and more preferably less than 0.1 molar equivalents as compared to starting material a.

In the third embodiment, step (i) may be carried out in the presence of a solvent selected from aprotic solvents (e.g. tetrahydrofuran, acetonitrile, dimethoxyethane, dioxane, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene carbonate, sulfolane, diphenyl ether, acetonitrile, 2-nitropropane, acetone, butan-2-one, butyl formate, ethyl acetate, isobutyronitrile, methyl acetate, methyl formate, nitromethane, oxolane and propionitrile) and HX-C(R₄)(R5)-[C(Rn)(R_l2)]_n- C(R4)(R5)-XH. Preferably the solvent is an aprotic solvent which does not contain a carbonyl group or HX-C(R₄)(R₅)-[C(R_ll)(R_l2)]_n-C(R4)(R5)-XH. More preferably the solvent is HX-C(R₄)(R₅)-[C(R_{l l})(Ri₂)]_n-C(R₄)(R5)-XH, i.e. the same as reagent b.

Specific combinations of reagent b , base/acid and solvent include ethylene glycol, Pd/C with zinc oxide and ethylene glycol.

In the third embodiment, step (i) may be earned out at a temperature of from 100 to 350 °C, preferably from 125 to 300 °C, and more preferably from 150 to 275 °C. The reaction will generally be carried out at ambient pressure, i. e. at a pressure of

approximately 1 bar.

In a fourth embodiment, reagent b is:

In the fourth embodiment, step (i) may be earned out in the presence of a zeolite, such as zeolite Y, sodium (faujasite). Preferably, reagent b acts as the solvent for the reaction and so no further solvent beyond reagent b is used.

The zeolite may be used in an amount of from 0.01 to 2 molar equivalents, preferably from 0.05 to 1 molar equivalents, and more preferably from 0.01 to 0.9 molar equivalents as compared to starting material a.

Alternatively, in the fourth embodiment, step (i) may be earned out in the presence of an acid catalyst, and preferably an organic acid catalyst, such as / oluene sulfonic acid. The catalyst may be used in an amount of less than 1 molar equivalent, preferably less than 0.5 molar equivalents, and more preferably less than 0.1 molar equivalents as compared to starting material a.

Where an acid catalyst is used, step (i) may be carried out in the presence of a solvent selected from aprotic solvents (e.g. tetrahydrofuran, acetonitrile, dimethoxyethane, dioxane, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene carbonate, sulfolane, diphenyl ether, acetonitrile, 2-nitropropane, acetone, butan-2-one, butyl formate, ethyl acetate, isobutyronitrile, methyl acetate, methyl formate, nitromethane, oxolane and propionitrile). Preferred solvents have a boiling point of greater than 150 °C.

Specific combinations of reagent b, zeolite or acid catalyst and solvent include: ethylene carbonate, zeolite Y, sodium (faujasite) and ethylene carbonate; and ethylene carbonate, >-toluene sulfonic acid and N-methyl-2-pyrollidone.

In the fourth embodiment, step (i) may be earned out at a temperature of from 15 to 300 °C, preferably from 100 to 275 °C, and more preferably from 150 to 250 °C. The reaction will generally be earned out at ambient pressure, i.e. at a pressure of

approximately 1 bar.

The reaction in step (i) may be conducted for a period of greater than 30 minutes, but preferably less than 6 hours, and more preferably less than 4 hours.

In step (ii), intermediate c is subjected to a ring closing reaction to form fuel additive d.

In a first embodiment, A is a halogen.

In these embodiments, step (ii) is preferably carried out in the presence of a base, and more preferably an inorganic base. The inorganic base is preferably selected from hydroxides (e.g. alkali and alkaline earth metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide), carbonates (e.g. alkali and alkaline earth metal carbonates such as sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate and caesium carbonate) and alkoxides (e.g. alkali metal /er/-butoxides such as potassium or sodium /er/-butoxide). Preferred bases are carbonates, in particular those selected from sodium carbonate and potassium carbonate.

The base in step (ii) is preferably used in an amount of from 0.8 to 5 molar equivalents, preferably from 1 to 3 molar equivalents, and more preferably from 1.05 to 2.5 molar equivalents as compared to intermediate c. In the first embodiment, step (ii) may be earned out in the presence of a solvent selected from aprotic solvents (e.g. tetrahydroiuran, acetonitrile, dimethoxy ethane, dioxane, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene carbonate, sulfolane, diphenyl ether, acetonitrile, 2-nitropropane, acetone, butan-2-one, butyl formate, ethyl acetate, isobutyronitrile, methyl acetate, methyl formate, nitromethane, oxolane and propionitrile).

In the first embodiment, step (ii) may be carried out at a temperature of from 15 to 300 °C, preferably from 25 to 300 °C, and more preferably from 50 to 250 °C. The reaction will generally be carried out at ambient pressure, i. e. at a pressure of

approximately 1 bar.

In a second embodiment, A is S0₃R_l3, where R_l3 is H or alkyl.

In these embodiments, step (ii) is carried out in the presence of a metal-containing reagent preferably selected from metal hydrides (preferably alkali or alkaline earth metal hydrides such as sodium hydride, potassium hydride and calcium hydride), metal alkoxides (e.g. alkali metal alkoxides, preferably alkali metal ethoxides such as sodium ethoxide or potassium ethoxide), metal carbonates (preferably alkali or alkaline earth metal carbonates such as sodium carbonate or potassium carbonate) and metals (preferably alkali or alkaline earth metals such as sodium, potassium or calcium).

The metal-containing reagent may be used in an amount of from 1 to 10 molar equivalents, preferably from 1.1 to 8 molar equivalents, and more preferably from 1.2 to 5 molar equivalents as compared to intermediate c.

In these embodiments, preferred solvents for carrying out step (ii) are selected from aprotic solvents (e.g. tetrahydrofuran, acetonitrile, dimethoxyethane, dioxane, N-methyl-2- pyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene carbonate, sulfolane, diphenyl ether, acetonitrile, 2-nitropropane, acetone, butan-2-one, butyl formate, ethyl acetate, isobutyronitrile, methyl acetate, methyl formate, nitromethane, oxolane and propionitrile), alcohols (e.g. ethanol and propanol) and water. Preferred aprotic solvents include, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, acetonitrile and dimethyl sulfoxide.

Where a metal hydride or metals are used, the solvent is preferably selected from aprotic solvents, and more preferably is tetrahydrofuran. Where a metal alkoxide is used, the solvent is preferably selected from alcohols, and more preferably is the alcohol corresponding to the alkoxide of the metal alkoxide. For instance, where a metal ethoxide is used, ethanol is preferably used as the solvent.

Specific combinations of metal containing reagent and solvent include:

metal hydride (e.g. sodium hydride or calcium hydride) and a solvent selected from tetrahydrofuran and dimethylsulfoxide;

metal alkoxide (e.g. sodium ethoxide or potassium ethoxide) and ethanol; and metal (e.g. sodium, potassium or calcium) and tetrahydrofuran.

In some instances of the second embodiment, the reaction may take place without significant heating, e.g. at room temperature, e.g. at a temperature of from 15 to 25 °C. These embodiments may be used e.g. where step (ii) is earned out using metal hydrides.

However, in other instances, to improve conversion of intermediate c to fuel additive e, the reaction mixture may be heated once the metal-containing species has been added to intermediate c.

For instance, the metal-containing species may be added to intermediate c -at a temperature of from 10 to 30 °C, preferably from 15 to 25 °C. At these temperatures, the metal-containing species is believed to convert the groups -XH, -OH and -S0₃H (where present in inteimediate c) into -XM, -OM and -S0₃M, where M is a metal ion. The metal ion is preferably an alkali or alkaline earth metal ion, and more preferably is selected from sodium, potassium and calcium ions.

To encourage ring closing, the reaction mixture may then be heated to a temperature of greater than 100 °C, preferably greater than 125 °C, and more preferably to a temperature of from 150 to 300 °C. In some instances, the solvent will evaporate and the ring-closing reaction will take place in the absence of a solvent.

In the second embodiment, step (ii) may be earned out at ambient pressure, i. e. a pressure of approximately 1 bar.

In a third embodiment, A is S0₃R_B, where R_l3 is an alkali metal, and intermediate c preferably comprises a terminal -OM group.

In these embodiments, step (ii) may be conducted in the presence of a solvent, at a temperature of greater than 125 °C, preferably greater than 150 °C, and more preferably at a temperature of from 200 to 350 °C.

A wide range of solvents may be used, provided that they have a boiling point above the temperature at which step (ii) is conducted. Suitable solvents include aprotic solvents (e.g. 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, butyl formate, ethyl acetate, isobutyronitrile, methyl acetate, methyl formate, nitromethane, oxolane, propionitrile, diphenyl ether and anisole), as well as chlorinated solvents ( e.g . dichlorobenzene) and alcohols (e.g. n-butanol). For example,

dimethylacetamide, N-methyl-2-pyrrolidone, dichlorobenzene, n-butanol, diphenyl ether or anisole may be used.

Alternatively, in the third embodiment, the step (ii) may be conducted in the absence of a solvent. Preferably, step (ii) is carried at a temperature of greater than 150 °C, more preferably greater than 200 °C, and still more preferably at a temperature of from 250 to 300 °C.

In the third embodiment, step (ii) is preferably carried out at ambient pressure, i.e. at a pressure of approximately 1 bar.

In all embodiments, steps (i) and (ii) may each be carried out for a time period of at least 30 minutes, preferably at least 2 hours, and preferably less than 24 hours.

The method of the present invention may also proceed via the following route, particularly where A is -S0₃Ri₃ and RI₃ is an alkali metal:

d

where: L is selected from leaving groups and L’; and L’ is selected from -XH and -XM.

It will be appreciated that, in some instances, step (ii’) will occur spontaneously on formation of intermediate c \ For the purposes of the presence invention, these instances are considered to be embodiments in which the reaction is carried out in a single step.

In a first embodiment, starting material a is selected from compounds in which A is a halogen, and reagent b is preferably selected from compounds in which L = L’ and are preferably both -XH.

In these embodiments, step (i¹) is preferably earned out in the presence of a base, and more preferably an inorganic base. The inorganic base is preferably selected from hydroxides (e.g. alkali and alkaline earth metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide), carbonates (e.g. alkali and alkaline earth metal carbonates such as sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate and caesium carbonate) and alkoxides (e.g. alkali metal /e/ -butoxides such as potassium /er/-butoxide and sodium /e/f-butoxide). Preferred bases are carbonates, in particular those selected from sodium carbonate and potassium carbonate.

The base in step (i') is preferably used in an amount of from 0.8 to 5 molar equivalents, preferably from 1 to 3 molar equivalents, and more preferably from 1.05 to 2.5 molar equivalents as compared to intermediate c.

In the first embodiment, step (i¹) may be carried out in the presence of a solvent selected from aprotic solvents (e.g. tetrahydrofuran, acetonitrile, dimethoxyethane, dioxane, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene carbonate, sulfolane, diphenyl ether, acetonitrile, 2-nitropropane, acetone, butan-2-one, butyl formate, ethyl acetate, isobutyronitrile, methyl acetate, methyl formate, nitromethane, oxolane and propionitrile).

In the first embodiment, step (i’) may be earned out at a temperature of from 15 to 300 °C, preferably from 25 to 300 °C, and more preferably from 50 to 250 °C. The reaction will generally be carried out at ambient pressure, i. e. at a pressure of

approximately 1 bar.

In a second embodiment, starting material a is selected from compounds in which A is S0₃R_l3, where R_l3 is an alkali metal, and reagent b is selected from compounds in which L’ is -XM, and L is preferably also -XM. In these embodiments, step (i') may be conducted in the presence of a solvent at a temperature of greater than 125 °C, preferably greater than 150 °C, and more preferably at a temperature of from 200 to 350 °C.

A wide range of solvents may be used, provided that they have a boiling point above the temperature at which step (i') is conducted. Suitable solvents include aprotic solvents (e.g. 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, butyl formate, ethyl acetate, isobutyronitrile, methyl acetate, methyl formate, nitromethane, oxolane, propionitrile, diphenyl ether and anisole), as well as chlorinated solvents (e.g. dichlorobenzene) and alcohols (e.g. n-butanol). For example,

Alternatively, in the second embodiment, step (i') may be conducted in the absence of a solvent. In these instances, step (i') is carried at a temperature of greater than 150 °C, more preferably greater than 200 °C, and still more preferably at a temperature of from 250 to 300 °C.

In the second embodiment, step (i') is preferably carried out at ambient pressure, i.e. at a pressure of approximately 1 bar.

In a third embodiment, starting material a is selected from compounds in which A is S0₃R_l3, where RI₃ is an alkali metal, and reagent b is selected from compounds in which L’ is -XH, and L is preferably also -XH,

In these embodiments, step (i') may comprise converting the -XH group(s) in reagent b into -XM groups, and reacting the converted reagent b with starting material a. Typically, reagent b will be converted into its metallated form before it is added to starting material a , though the conversion of reagent b may also take place in the presence of starting material a.

The -XH group(s) may be converted into -XM groups in the presence of a metal- containing reagent selected from metal hydrides (preferably alkali or alkaline earth metal hydrides such as sodium hydride, potassium hydride and calcium hydride), metal alkoxides (e.g. alkali metal alkoxides, preferably alkali metal ethoxides such as sodium ethoxide or potassium ethoxide, or alkali metal /e/V-butoxides such as potassium te/7-butoxides), metal carbonates (preferably alkali or alkaline earth metal carbonates such as sodium carbonate or potassium carbonate), metal hydroxides (preferably alkali or alkaline earth metal hydroxides such as sodium hydroxide, potassium hydroxide or calcium hydroxide) and metals (preferably alkali or alkaline earth metals such as sodium, potassium or calcium).

In these embodiments, preferred solvents for carrying out the conversion of the - XH group(s) to -XM are selected from aprotic solvents (e.g. tetrahydrofuran, acetonitrile, dimethoxyethane, dioxane, N-methyl-2-pyrrolidone, dimethylformamide,

dimethylacetamide, dimethyl sulfoxide, ethylene carbonate, sulfolane, diphenyl ether, acetonitrile, 2-nitropropane, acetone, butan-2-one, butyl formate, ethyl acetate, isobutyronitrile, methyl acetate, methyl formate, nitromethane, oxolane and propionitrile), alcohols (e.g. ethanol and propanol) and water.

Specific combinations of metal containing reagent and solvent include:

metal base (e.g. sodium hydroxide, potassium hydroxide, calcium hydroxide or potassium terf-butoxide) with water;

metal hydride (e.g. sodium hydride or calcium hydride) with tetrahydrofuran; metal alkoxide (e.g. sodium ethoxide or potassium ethoxide) with ethanol; and metal (e.g. sodium, potassium or calcium) with tetrahydrofuran.

The conversion of -XH to -XM may take place at a temperature of from 10 to 30 °C, and preferably from 15 to 25 °C. Higher temperatures may also be used, e.g. up to 300 °C, if conversion does not readily occur at the lower temperatures.

Once the -XH group(s) of reagent b have been converted to -XM, then the reaction between the metallated reagent b and starting material a may be carried out using the conditions detailed in the second embodiment of step (ί').

In the third embodiment, step (i') is preferably carried out at ambient pressure, i. e. at a pressure of approximately 1 bar. In a fourth embodiment, starting material a is selected from compounds in which A is SO₃R₁₃, where R_l3 is H or alkyl, and reagent b is selected from compounds in which L’ is -XM and L is preferably also -XM,

In these embodiments, step (i') may comprise converting the -SO₃R₀ group in starting material a into an -SO₃M group, and reacting the converted starting material a with reagent b. Typically, starting material a will be converted into its metallated form before it is added to reagent b, though the conversion of starting material a may also take place in the presence of reagent b.

The -S0₃R_I3 group may be converted into an - SO₃M group in the presence of a metal-containing reagent selected from metal hydrides (preferably alkali or alkaline earth metal hydrides such as sodium hydride, potassium hydride and calcium hydride), metal alkoxides (e.g. alkali metal alkoxides, preferably alkali metal ethoxides such as sodium ethoxide or potassium ethoxide, or alkali metal /e/Y-butoxides such as potassium tert- butoxides), metal carbonates (preferably alkali or alkaline earth metal carbonates such as sodium carbonate or potassium carbonate), metal hydroxides (preferably alkali or alkaline earth metal hydroxides such as sodium hydroxide, potassium hydroxide or calcium hydroxide) and metals (preferably alkali or alkaline earth metals such as sodium, potassium or calcium).

In these embodiments, preferred solvents for carrying out the conversion of the - S0₃H group to - SO₃M are selected from aprotic solvents (e.g. tetrahydrofuran, acetonitrile, dimethoxyethane, dioxane, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene carbonate, sulfolane, diphenyl ether, acetonitrile, 2-nitropropane, acetone, butan-2-one, butyl formate, ethyl acetate,

isobutyronitrile, methyl acetate, methyl formate, nitromethane, oxolane and propionitrile), alcohols (e.g. ethanol and propanol) and water.

Where a metal hydride or metals are used, the solvent is preferably selected from aprotic solvents, and more preferably is tetrahydrofuran. Where a metal alkoxide is used, the solvent is preferably selected from alcohols, and more preferably is the alcohol corresponding to the alkoxide of the metal alkoxide. For instance, where a metal ethoxide is used, ethanol is preferably used as the solvent. Specific combinations of metal containing reagent and solvent include:

metal base ( e.g . sodium hydroxide, potassium hydroxide, calcium hydroxide or potassium /e/ -butoxide) with water;

metal hydride {e.g. sodium hydride or calcium hydride) with tetrahydrofuran; metal alkoxide {e.g. sodium ethoxide or potassium ethoxide) with ethanol; and metal {e.g. sodium, potassium or calcium) with tetrahydrofuran.

The conversion of the - S0₃H group to - S0₃M may take place at a temperature of from 10 to 30 °C, and preferably from 15 to 25 °C. Higher temperatures may also be used, e.g. up to 300 °C, if conversion does not readily occur at the lower temperatures.

Once the - S0₃H group(s) of starting material a has been converted to - S0₃M, then the reaction between the metallated starting material a and reagent b may be carried out using the conditions detailed in the second embodiment of step (ί').

In the fourth embodiment, step (i') is preferably earned out at ambient pressure, i.e. at a pressure of approximately 1 bar.

In a fifth embodiment, starting material a is selected from compounds in which A is S0₃R_l3, where ¾₃ is H or alkyl, and reagent b is selected from compounds in which L’ is - XH and L is preferably also -XH.

In these embodiments, step (i') may comprise converting the -S0₃R_l3 group in starting material a into an -S0₃M group, and converting the -XH group(s) in reagent b into -XM groups, and reacting the converted starting material a with converted reagent b.

In some embodiments, starting material a and reagent b may be converted separately {e.g. using the conditions described in the fourth and third embodiments of step (i'), respectively) before being combined for conversion into intermediate c’ {e.g. using the conditions described in the second embodiment of step (i')).

However, in the fifth embodiment, it is generally preferred for conversion and reaction of starting material a and reagent b to take place together.

In these embodiments, step (i') may be conducted in the presence of a metal- containing reagent selected from metal hydrides (preferably alkali or alkaline earth metal hydrides such as sodium hydride, potassium hydride and calcium hydride), metal alkoxides {e.g. alkali metal alkoxides, preferably alkali metal ethoxides such as sodium ethoxide or potassium ethoxide, or alkali metal /e/7-butoxides such as potassium /e/ -butoxidcs), metal carbonates (preferably alkali or alkaline earth metal carbonates such as sodium carbonate or potassium carbonate), metal hydroxides (preferably alkali or alkaline earth metal hydroxides such as sodium hydroxide, potassium hydroxide or calcium hydroxide) and metals (preferably alkali or alkaline earth metals such as sodium, potassium or calcium).

In these embodiments, preferred solvents for carrying out step (i') are selected from aprotic solvents (e.g. tetrahydrofuran, acetonitrile, dimethoxyethane, dioxane, N-methyl-2- pyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene carbonate, sulfolane, diphenyl ether, acetonitrile, 2-nitropropane, acetone, butan-2-one, butyl formate, ethyl acetate, isobutyronitrile, methyl acetate, methyl formate, nitromethane, oxolane and propionitrile), alcohols (e.g. ethanol and propanol) and water.

Specific combinations of metal containing reagent and solvent include:

metal base (e.g. sodium hydroxide, potassium hydroxide, calcium hydroxide or potassium te/Y-butoxide) with water;

metal hydride (e.g. sodium hydride or calcium hydride) with tetrahydrofuran;

metal alkoxide (e.g. sodium ethoxide or potassium ethoxide) with ethanol; and metal (e.g. sodium, potassium or calcium) with tetrahydrofuran.

In these embodiments, step (i¹) may take place at a temperature of from 100 to 350 °C, preferably from 125 to 325 °C, and more preferably from 150 to 300 °C.

In these embodiments, step (i') is preferably carried out at ambient pressure, i. e. at a pressure of approximately 1 bar.

In a sixth embodiment, starting material a is selected from compounds in which A is -S0₃Ri₃, where R_l3 is an alkali metal, and reagent b is selected from compounds in which L’ is -XH and L is a leaving group (e.g. a halogen or sulfonate), and where R₂ = R₄ and R₃ = R₅. Without wishing to be bound by theory, in these embodiments it is believed that step (i') proceeds via the following route:

In the sixth embodiment, steps (i) may be conducted in the presence of a solvent selected from aprotic solvents (e.g. tetrahydrofuran, acetonitrile, dimethoxy ethane, dioxane, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene carbonate, sulfolane, diphenyl ether, acetonitrile, 2-nitropropane, acetone, butan-2-one, butyl formate, ethyl acetate, isobutyronitrile, methyl acetate, methyl formate, nitromethane, oxolane and propionitrile).

Step (i) may take place at a temperature of from 15 to 300 °C. However, loss of S0₂ and, thus, formation of intermediate c’ may be encourage by heating. In some embodiments, the reaction mixture in step (i) is heated to a temperature of from 100 to 350 °C. Though the reaction will generally stop at intermediate c ', some conversion into fuel additive d may be observed.

In the sixth embodiment, step (i') is preferably carried out at ambient pressure, i.e. at a pressure of approximately 1 bar.

In step (ii’), intermediate c’ is subjected to a ring closing reaction to form fuel additive d.

Step (ii’) of the method may be conducted in the presence of a hydrogen halide, preferably hydrogen bromide or hydrogen chloride. This is particularly preferred where a hydroxy group is present in intermediate c \ The hydrogen halide is preferably in the form of an aqueous solution, e.g. containing greater than 20 %, preferably greater than 40 % and preferably greater than 50 % by weight of the hydrogen halide.

A molar excess of hydrogen halide is preferably used, for instance by using hydrogen halide in an amount of at least 5 molar equivalents, preferably at least 10 molar equivalents, and more preferably at least 15 molar equivalents as compared to intermediate c’.

In these embodiments, step (ii’) may be conducted at a temperature of greater than 60 °C, preferably greater than 70 °C, and more preferably greater than 80 °C.

In these embodiments, step (ii’) may be conducted at ambient pressure, i. e.

approximately 1 bar.

The reaction with the hydrogen halide in step (ii’) is preferably quenched using a base, for instance using an inorganic base such as an alkali metal hydroxide (e.g. sodium hydroxide or potassium hydroxide) or aqueous ammonia.

Alternatively, step (ii’) may be conducted in the presence of a thionyl halide, a phosphorus tetrahalide, a phosphorus pentahalide, a phosphoryl halide, or halogen gas ( i.e . Br₂, Cl₂, etc.) or a carbon tetrahalide in combination with a trialkylphosphine (e.g.

trimethyl phosphine) or a triaryl phosphine (e.g. triphenyl phosphine). In these

embodiments, the halogenation reaction is preferably conducted in the presence of an aprotic solvent (e.g. 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 or propionitrile, and preferably a non-ether aprotic solvent, such as dimethyl formamide, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, acetone, dioxane, ethylene carbonate and acetonitrile) or a chlorinated solvent (e.g. dichloromethane, dichloroethylene or trichloromethane).

For instance, the reaction may be carried out using: a thionyl halide, in the presence of a chlorinated solvent (e.g. dichloromethane, dichloroethylene or trichloromethane); a halogen gas or carbon tetrahalide in the presence of a triaryl phosphine (e.g. triphenyl phosphine) or trialkyl phosphine and preferarbly an aprotic solvent (e.g. acetonitrile) or a chlorinated solvent (e.g. dichloromethane); a phosphorus trihalide, a phosphorus pentahalide or a phosphoryl halide, preferably in the presence of an ammonium salt (e.g. tetraalkylammonium halides such as tetrabutylammonium bromide); or an alkyl- or aryl- sulfonyl chloride (e.g. toluenesulfonyl chloride or methanesulfonyl chloride), preferably in the presence of a trialkylamine (e.g. trimethyl amine), and preferably in the presence of a chlorinated solvent (e.g. dichloromethane).

As a further alternative, step (ii’) may be carried out in the presence of HalOS0₂A or AS0₂-0-S0₂A, where Hal is a halogen (preferably selected from Cl and Br) and A is selected from tolyl, methyl, -CF₃, -CH₂Cl, phenyl and p-nitrophenyl. The reaction may be conducted in the presence of an aprotic solvent (e.g. 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 or propionitrile, and preferably a non-ether aprotic solvent, such as dimethyl formamide, N-methyl-2- pyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, acetone, dioxane, ethylene carbonate or acetonitrile, and preferably dimethyl formamide, N-methyl- 2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, acetone, dioxane, ethylene carbonate or acetonitrile) or a chlorinated solvent (e.g. dichloromethane, dichloroethylene or trichloromethane).

In all embodiments, steps (G) and (ii’) may each be carried out for a time period of at least 30 minutes, preferably at least 2 hours, and preferably less than 24 hours.

Reagent b is selected from:

L is selected from leaving groups and L’, and L’ is selected from -XH and -XM, where M is an alkali metal; or both L and L’ together form the group -0-C(0)-0-, a group which effectively provides two leaving groups.

Suitable leaving groups L include: halides (e.g. Cl, Br, I), substituted aryloxy groups (e.g. -O-Ar, where Ar is selected from nitro-substituted aryl groups such as p- nitrophenyl) and sulfonates (e.g. -0S0₂A, where A is selected from tolyl, methyl, -CF₃, - CH₂Cl, phenyl and p-nitrophenyl). L is preferably selected from Cl, Br, -L’, and more preferably is L’.

Suitable M groups include: sodium, potassium and lithium, with sodium and potassium preferred.

The methods of the present invention are preferably carried out on an industrial scale. For instance, where the method of preparing fuel additive d is a batch process, the fuel additive is preferably produced in a batch quantity of greater than 100 kg, preferably greater than 150 kg, and more preferably greater than 200 kg. The method of the present invention may also be earned out as a continuous process.

In order to produce the fuel additive d on an industrial scale, the reaction is preferably carried out in a reactor or, where the reaction comprises sub-steps (i) and (ii) or (G) and (ii’), reactors having a capacity of at least 500 L, preferably at least 750 L, and more preferably at least 1000 L. It will be appreciated that, where the reaction comprises sub-steps, more than one (e.g. each) sub-step may be carried out in the same reactor. Octane-boosting fuel additive

Fuel additives d that are prepared using the methods of the present invention have the following formula:

where: Ri is hydrogen;

R₂, R₃, ), R₅, Rn and RJ₂ are each independently selected from hydrogen, alkyl, alkoxy, alkoxy-alkyl, secondary amine and tertiary amine groups;

n is 0 or 1,

provided that at least one of R₂, R₃, R₄, R₅, R R₇, R₈, R₉, Rn and RJ₂ is selected from a group other than hydrogen. Preferred substituents for the fuel additives are described below. It will be appreciated that the preferred substitution patterns also apply to the starting material a, reagent b, and intermediates c and c’ from which the fuel additive d is prepared.

In some embodiments, R₂, R₃, R₄, R₅, Rn and R_l2 are each independently selected from hydrogen and alkyl groups, and preferably from hydrogen, methyl, ethyl, propyl and butyl groups. More preferably, R₂, R₃, R₄, R₅, Rn and RJ₂ are each independently selected from hydrogen, methyl and ethyl, and even more preferably from hydrogen and methyl.

In some embodiments, R₆, R₇, R₈ and R₉ are each independently selected from hydrogen, alkyl and alkoxy groups, and preferably from hydrogen, methyl, ethyl, propyl, butyl, methoxy, ethoxy and propoxy groups. More preferably, R₆, R₇, R₈ and R₉ are each independently selected from hydrogen, methyl, ethyl and methoxy, and even more preferably from hydrogen, methyl and methoxy.

At least one of R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, Rn and RI₂, and preferably at least one of R₆, R₇, R₈ and R₉, is selected from a group other than hydrogen. More preferably, at least one of R₇ and R₈ is selected from a group other than hydrogen. Alternatively stated, the octane-boosting additive is substituted in at least one of the positions represented by R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, Rn and RI₂, preferably in at least one of the positions represented by R₆, R₇, Rs and R₉, and more preferably in at least one of the positions represented by R₇ and R₈. It is believed that the presence of at least one group other than hydrogen may improve the solubility of the octane-boosting additives in a fuel.

Also advantageously, no more than five, preferably no more than three, and more preferably no more than two, of R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, Rn and R_J2 are selected from a group other than hydrogen. Preferably, one or two of R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, Rn and R_l2 are selected from a group other than hydrogen. In some embodiments, only one of R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, Rn and R_l2 is selected from a group other than hydrogen.

It is also preferred that at least one of R₂ and R₃ is hydrogen, and more preferred that both of R₂ and R₃ are hydrogen.

ln preferred embodiments, at least one of R₄, R₅, R₇ and R₈ is selected from methyl, ethyl, propyl and butyl groups and the remainder of R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, Rn and RI₂ are hydrogen. More preferably, at least one of R₇ and R₈ are selected from methyl, ethyl, propyl and butyl groups and the remainder of R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, Rn and Rn are hydrogen. In further preferred embodiments, at least one of R₄, R₅, R and R₈ is a methyl group and the remainder of R₂, R₃, R₄, R₅, R₆, R₇, R₈, R_¾ R₁₁ and R₁₂ are hydrogen. More preferably, at least one of R₇ and R₈ is a methyl group and the remainder of R₂, R₃, R₄, R₅, Re, R₇, R₈, R₉, Rn and RJ₂ are hydrogen.

Preferably, X is -O- or -NR₁₀-, where R_l0 is selected from hydrogen, methyl, ethyl, propyl and butyl groups, and preferably from hydrogen, methyl and ethyl groups. More preferably, R] ₀ is hydrogen. In preferred embodiments, X is -0-.

n may be 0 or 1, though it is preferred that n is 0.

Octane-boosting fuel additives that may be used in the present invention include:

Preferred octane-boosting fuel additives include:

Particularly preferred is the octane-boosting additive:

A mixture of fuel additives d may be used in the fuel composition. For instance, the fuel composition may comprise a mixture of:

It will be appreciated that references to alkyl groups include different isomers of the alkyl group. For instance, references to propyl groups embrace n-propyl and i-propyl groups, and references to butyl embrace n-butyl, isobutyl, sec-butyl and tert-butyl groups. Additive and fuel compositions

The present invention provides fuel additives d which are obtainable by a method of the present invention. Preferably, the fuel additives are obtained by a method of the present invention.

The present invention also provides a process for preparing a fuel for a spark- ignition internal combustion engine, said process comprising: preparing a fuel additive d using a method of the present invention; and blending the fuel additive with a base fuel.

A fuel for a spark-ignition internal combustion engine is also provided. The fuel comprises a fuel additive d, obtainable and preferably obtained by a method of the present invention, and a base fuel.

Gasoline fuels (including those containing oxygenates) are typically used in spark- ignition internal combustion engines. Commensurately, the fuel composition that may be prepared according to the process of the present invention may be a gasoline fuel composition.

The fuel composition may comprise a major amount (i.e. greater than 50 % by weight) of liquid fuel (“base fuel”) and a minor amount (i.e. less than 50 % by weight) of additive composition of the present invention. Examples of suitable liquid fuels include hydrocarbon fuels, oxygenate fuels and combinations thereof.

The fuel composition may contain the octane-boosting fuel additive d in an amount of up to 20 %, preferably from 0.1 % to 10 %, and more preferably from 0.2 % to 5 % weight additive / weight base fuel. Even more preferably, the fuel composition contains the fuel additive in an amount of from 0.25 % to 2 %, and even more preferably still from 0.3 % to 1 % weight additive / weight base fuel. It will be appreciated that, when more than one octane-boosting fuel additive d is used, these values refer to the total amount of fuel additive d in the fuel.

The fuel compositions may comprise at least one other further fuel additive.

Examples of such other additives that may be present in the fuel compositions include detergents, friction modifiers/anti-wear additives, corrosion inhibitors, combustion modifiers, anti-oxidants, valve seat recession additives, dehazers/demulsifiers, dyes, markers, odorants, anti-static agents, anti-microbial agents, and lubricity improvers.

Further octane improvers may also be used in the fuel composition, i.e. octane improvers which do not have the structure of octane-boosting fuel additive d.

The fuel compositions are used in a spark-ignition internal combustion engine. Examples of spark-ignition internal combustion engines include direct injection spark- ignition engines and port fuel injection spark-ignition engines. The spark-ignition internal combustion engine may be used in automotive applications, e.g. in a vehicle such as a passenger car. The invention will now be described with reference to the following non-limiting examples.

Examples

Example 1 : Preparation of fuel additive d via steps (T) and (if)

Fuel additive d was prepared according to the following scheme:

A mixture of 5-methyl-2-aminosulfonic acid 1 (12.5 g, 6.67 mmol), 2- chloroethanol (3 eq) and K₂C0₃ (3 eq) in 8 volumes of water was heated at reflux for 16 hours and cooled to ambient temperature. The resulting solid was filtered and dried to afford 8.84 g (57 %) of intermediate 2 as an off- white solid.

Intermediate 2 was converted to fuel additive 3 following a typical procedure in which compound 2 is suspended or dissolved in a solvent, the mixture is cooled at a temperature varying from -10 to 10 °C or left at ambient, and the metal source, e.g.

metallic sodium, sodium hydride or sodium ethoxide, is added portionwise under stirring. The resulting suspension is filtered and dried to afford a solid or a waxy-solid. The solid is heated at 150 to 300 °C, at ambient pressure or in vacuo (10 to 10 mbar), while the resulting product 4 is distilled of as it forms to afford an oil.

Example 2: Preparation of fuel additive d via steps and (ii’)

Fuel additive d was prepared according to the following scheme:

Intermediate 2 was prepared following a typical procedure in which a diol reagent is cooled at a temperature varying from -10 to 10 °C or left at ambient, and the metal source, e.g. sodium hydroxide, metallic sodium, sodium hydride or sodium ethoxide, is added portionwise under stirring. The resulting solution or suspension is filtered or the solvent is evaporated, and the residue is dried to afford NaO-CH₂-CH₂-ONa as a solid or a waxy-solid. Compound 1 is heated at 150 to 300 °C in the presence of NaO-CH₂-CH₂- ONa (1-4 eq), at ambient pressure. Upon completion, the reaction mixture is neutralised to pH 7 with aqueous HC1, the product is partitioned between ethyl acetate and water, the organic phase is separated and dried over sodium sulphate. The solvent is evaporated in vacuo and the residue recrystallized from iso-propanol to afford intermediate 2 as a solid.

Product 3 was prepared by stirring intermediate 2 (0.5 g, 3 mmol) with 48 % HBr (5 ml) at 120 °C for 16 hours. The reaction mixture was added to water and basified with NaHC0₃ and solid filtered off and dried (660 mg). NMR and LCMS confirm the conversion of OH in 2 to Br. The intermediate was refluxed in ethyl acetate (25 ml) and triethylamine (2 ml) for 16 hours. TLC shows spot to spot conversion so the reaction mixture was washed with water, dried and evaporated to give product 3 in an 84 % yield.

The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as "40 mm" is intended to mean "about 40 mm.”

Every document cited herein, including any cross referenced or related patent or application, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope and spirit of this invention.

Claims

Claims:

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

where: R is hydrogen;

R₂, R₃, R₄, R₅, R_{I 1} and R_J2 are each independently selected from hydrogen, alkyl, alkoxy, alkoxy-alkyl, secondary amine and tertiary amine groups;

R₅, R₇, R_S and Rg are each independently selected from hydrogen, alkyl, alkoxy, alkoxy-alkyl, secondary amine and tertiary amine groups;

n is 0 or 1 ,

said method comprising carrying out the following reaction:

a b d

where: L is selected from leaving groups and L’; and

L’ is -XH or -XM, where M is an alkali metal; or

both L and L’ together form the group -0-C(0)-0-; and A is selected from halides and -S0₃Ri₃, where RI₃ is selected from hydrogen, alkyl groups and alkali metals.

2. A method according to claim 1, wherein reagent b is preferably used in an amount of from 0.8 to 6 molar equivalents, preferably from 0.9 to 4 molar equivalents, and more preferably from 1 to 2.5 molar equivalents as compared to starting material a.

3. A method according to claim 1 or claim 2, wherein the method comprises the following steps:

d

4. A method according to claim 3, wherein reagent b is:

where L is selected from leaving groups, and L’ is preferably -XH, wherein step (i) is carried out in the presence of a base selected from inorganic bases such as alkali metal hydroxides (e.g. selected from sodium hydroxide and potassium hydroxide), alkali or alkaline earth metal carbonates (e.g. selected from sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate and calcium carbonate) and alkali metal fluorides (e.g. selected from sodium fluoride and potassium fluoride).

5. A method according to claim 3, wherein reagent b is:

wherein step (i) is carried out:

in the presence of a solvent, e.g. selected from aprotic solvents, and preferably no further reagents beyond starting material a and reagent b; or

In the absence of a solvent, and preferably no further reagents beyond starting material a and reagent b.

6. A method according to claim 3, wherein reagent b is:

where L = L’, and are preferably both -XH,

wherein step (i) is be carried out in the presence of a catalyst, preferably selected from metal catalysts (e.g. a palladium catalyst such as Pd/C).

7. A method according to claim 3, wherein reagent b is:

wherein step (i) is carried out in the presence of a zeolite such as zeolite Y, sodium (faujasite), or an acid catalyst, and preferably an organic acid catalyst such as p- toluene sulfonic acid.

8. A method according to any of claims 3 to 7, wherein A is a halogen, and wherein step (ii) is carried out in the presence of a base, and more preferably an inorganic base, such as an inorganic base selected from hydroxides (e.g. alkali and alkaline earth metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide) and carbonates (e.g. alkali and alkaline earth metal carbonates such as sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate and caesium carbonate) and alkoxides (e.g. alkali metal ferf-butoxides such as potassium or sodium tert- butoxide).

9. A method according to any of claims 3 to 7, wherein A is S0₃R_l3, where RJ₃ is H or alkyl, and wherein step (ii) is carried out in the presence of a metal-containing reagent preferably selected from metal hydrides (preferably alkali or alkaline earth metal hydrides such as sodium hydride, potassium hydride and calcium hydride), metal alkoxides (e.g. alkali metal alkoxides, preferably alkali metal ethoxides such as sodium ethoxide or potassium ethoxide), metal carbonates (preferably alkali or alkaline earth metal carbonates such as sodium carbonate or potassium carbonate) and metals (preferably alkali or alkaline earth metals such as sodium, potassium or calcium).

10. A method according to any of claims 3 to 7, wherein A is S0₃RJ₃, where RI₃ is an alkali metal, and intermediate c preferably comprises a terminal -OM group, and wherein step (ii) is:

conducted in the presence of a solvent at a temperature of greater than 125 °C, preferably greater than 150 °C, and more preferably at a temperature of from 200 to 350 °C, or in the absence of a solvent, at a temperature of greater than 150 °C, more preferably greater than 200 °C, and still more preferably at a temperature of from 250 to 300 °C.

11. A method according to claim 1 or 2, wherein the method comprises the following steps:

where: L is selected from leaving groups and L’; and

L’ is selected from -XH and -XM.

12. A method according to claim 11, wherein starting material a is selected from compounds in which A is a halogen, and reagent b is preferably selected from compounds in which L = L’ and preferably -XH, wherein step (i') is earned out in the presence of a base, and more preferably an inorganic base, preferably selected from hydroxides (e.g. alkali and alkaline earth metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide), carbonates (e.g. alkali and alkaline earth metal carbonates such as sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate and caesium carbonate), and alkoxides (e.g. alkali metal /er/-butoxides such as potassium /e/7-butoxidc and sodium /e -butoxide.

13. A method according to claim 11, wherein starting material a is selected from compounds in which A is S0₃R_l3, where R_l3 is an alkali metal, and reagent b is selected from compounds in which L’ is -XM, and L is preferably also -XM, wherein step (i¹) may be conducted:

in the presence of a solvent, at a temperature of greater than 125 °C, preferably greater than 150 °C, and more preferably at a temperature of from 200 to 350 °C; or

in the absence of a solvent at a temperature of greater than 150 °C, more preferably greater than 200 °C, and still more preferably at a temperature of from 250 to 300 °C.

14. A method according to claim 11, wherein starting material a is selected from compounds in which A is S0₃R_l3, where R_l3 is an alkali metal, and reagent b is selected from compounds in which L’ is -XH, and L is preferably also -XM, wherein step (i') comprises:

converting the -XH group(s) in reagent b into -XM groups, e.g. in the presence of a metal-containing reagent selected from metal hydrides (preferably alkali or alkaline earth metal hydrides such as sodium hydride, potassium hydride and calcium hydride), metal alkoxides (e.g. alkali metal alkoxides, preferably alkali metal ethoxides such as sodium ethoxide or potassium ethoxide, or alkali metal /erZ-butoxides such as potassium tert- butoxides), metal carbonates (preferably alkali or alkaline earth metal carbonates such as sodium carbonate or potassium carbonate), metal hydroxides (preferably alkali or alkaline earth metal hydroxides such as sodium hydroxide, potassium hydroxide or calcium hydroxide) and metals (preferably alkali or alkaline earth metals such as sodium, potassium or calcium), and

reacting the converted reagent b with starting material a.

15. A method according to claim 11, wherein starting material a is selected from compounds in which A is S0₃Ri₃, where R_l3 is H or alkyl, and reagent b is selected from compounds in which L’ is -XM and L is preferably also -XM, wherein step (i') comprises: converting the -S0₃Ri₃ group in starting material a into an -S0₃M group, e.g. in the presence of a metal-containing reagent selected from metal hydrides (preferably alkali or alkaline earth metal hydrides such as sodium hydride, potassium hydride and calcium hydride), metal alkoxides (e.g. alkali metal alkoxides, preferably alkali metal ethoxides such as sodium ethoxide or potassium ethoxide, or alkali metal /erZ-butoxides such as potassium ZerZ-butoxides), metal carbonates (preferably alkali or alkaline earth metal carbonates such as sodium carbonate or potassium carbonate), metal hydroxides (preferably alkali or alkaline earth metal hydroxides such as sodium hydroxide, potassium hydroxide or calcium hydroxide) and metals (preferably alkali or alkaline earth metals such as sodium, potassium or calcium); and

reacting the converted starting material a with reagent b.

16. A method according to claim 11, wherein starting material a is selected from compounds in which A is S0₃Ri₃, where R_l3 is H or alkyl, and reagent b is selected from compounds in which L’ is -XH and L is preferably also -XH, wherein step (ί') is conducted in the presence of a metal-containing reagent selected from metal hydrides (preferably alkali or alkaline earth metal hydrides such as sodium hydride, potassium hydride and calcium hydride), metal alkoxides (e.g. alkali metal alkoxides, preferably alkali metal ethoxides such as sodium ethoxide or potassium ethoxide, or alkali metal /e -butoxides such as potassium te/7-butoxides), metal carbonates (preferably alkali or alkaline earth metal carbonates such as sodium carbonate or potassium carbonate), metal hydroxides (preferably alkali or alkaline earth metal hydroxides such as sodium hydroxide, potassium hydroxide or calcium hydroxide) and metals (preferably alkali or alkaline earth metals such as sodium, potassium or calcium)..

17. A method according to any of claims 11 to 16, wherein step (ii’) is carried out in the presence of a hydrogen halide, preferably hydrogen bromide or hydrogen chloride.

18. A method according to any of claims 1 to 17, wherein L is selected from: halides (e.g. Cl, Br, I), substituted aryloxy groups (e.g. -O-Ar, where Ar is selected from nitro- substituted aryl groups such as p-nitrophenyl), sulfonates (e.g. -0S0₂A, where A is selected from tolyl, methyl, -CF₃, -CH₂C1, phenyl and p-nitrophenyl) and L’, and preferably from Cl, Br and L’, and more preferably is L’.

19. A method according to any of claims 1 to 18, wherein the method is a batch process in which the fuel additive is produced in a batch quantity of greater than 100 kg, preferably greater than 150 kg, and more preferably greater than 200 kg.

20. A method according to any of claims 1 to 18, wherein the method is a continuous process.

21. A method according to any of claims 1 to 20, wherein the reaction is carried out in a reactor or, where the reaction comprises sub-steps (i) and (ii) or (i') and (ii’), reactors having a capacity of at least 500 L, preferably at least 750 L, and more preferably at least 1000 L.

22. A fuel additive having the formula:

where: R[ is hydrogen;

R₂, R₃, R₄, R₅, R₁₁ and R_l2 are each independently selected from hydrogen, alkyl, alkoxy, alkoxy-alkyl, secondary amine and tertiary amine groups;

Re, R₇, R_S and R₉ are each independently selected from hydrogen, alkyl, alkoxy, alkoxy-alkyl, secondary amine and tertiary amine groups;

n is 0 or 1,

wherein the fuel additive is obtainable by a method according to any of claims 1 to 21.

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

preparing a fuel additive using a method according to any of claims 1 to 21; and blending the fuel additive with a base fuel.

24. A fuel for a spark-ignition internal combustion engine, said fuel comprising a fuel additive according to claim 22 and a base fuel.