GB2493377A

GB2493377A - Gasoline composition comprising Mannich additive

Info

Publication number: GB2493377A
Application number: GB201113395A
Authority: GB
Inventors: Jacqueline Reid
Original assignee: Innospec Ltd
Current assignee: Innospec Ltd
Priority date: 2011-08-03
Filing date: 2011-08-03
Publication date: 2013-02-06
Also published as: GB201113395D0

Abstract

A gasoline composition comprising, as an additive, the product of a Mannich reaction between: (a) an aldehyde; (b) an amine; and (c) a substituted phenol; wherein the phenol is substituted with at least one branched hydrocarbyl group having a molecular weight of between 200 and 3000. The additive is used to reduce existing deposits or inhibit deposit formation on gasoline direct injection spark ignition engines.

Description

Fuel Compositions This invention relates to a fuel composition and additives thereto. In particular, the invention relates to additives for fuel used in spark ignition engines.

With over a hundred years of development the spark ignition (SI) engine has become a highly tuned piece of engineering. As the SI engine has become more highly tuned it has become more sensitive to variations in its construction. The construction of such engines can change with use as deposits build up on certain components and through wear of other components.

These changes in construction may not only change parameters such as power output and overall efficiency; they can also significantly alter the pollutant emissions produced. To try and minimise these time-related changes to an engine's construction fuel additives have been developed to minimise wear and deposit build-up phenomena. Examples include anti valve seat recession additives to reduce wear and detergents to reduce deposit build-up.

As engine technology has evolved so have the demands put upon fuel additive packages.

Early gasoline detergents were formulated to overcome the problem of deposit build-up on carburettors. In a carburettor a partial vacuum in part of the engine intake system is used to draw fuel into the induction system. To provide better control of the fuel air mixture carburettors were replaced with fuel injection equipment where a pressure above atmospheric pressure was used to force the fuel into the intake system and to induce better atomisation of the fuel.

As a replacement for carburettors so called throttle body injectors were used with just a single injector taking the place of the carburettor. The position of a throttle body injector was thus very similar to that of the carburettor and the temperature regime was thus similar.

To obtain greater control over the fuel delivery into the engine cylinders there was a move to using individual fuel injectors for each cylinder. These injectors were thus placed in the individual inlet ports for each cylinder; this configuration thus became known as port fuel injection or PFI. Because the fuel injector was now placed closer to the combustion chamber it tended to get hotter, also as it was closer to the engine inlet port it was more likely to be subjected to exhaust gases passing back into the inlet system during the initial part of the inlet valve opening event. This made the injector more prone to deposit build up and thus increased the demands on the fuel additive required to minimise this deposit build-up.

In the proprietor's patent EP0633920, a detergent composition is taught which addressed the issues of i) elimination of carburettor and injector fouling; ii) good detergency in the intake port and intake valve regions of the engine; Hi) elimination of valve stick, a problem often associated with the use of high molecular weight detergents; iv) corrosion protection; v) good demulsifying characteristics; and vi) little or no effect on the Octane Requirement Increase (ORI) of modern engines.

All these systems so far outlined were designed to provide an air fuel mixture that was approximately stoichiometric. The engine power was determined by the amount of stoichiometric mixture provided to the cylinder. This was controlled by restricting the flow of mixture into the cylinders, known as throttling. This inevitably incurred pumping losses thus reducing the efficiency of the overall system.

To overcome this problem engine designers have developed injection systems where the fuel is injected directly into the cylinder. Such engines are alternatively known as direct injection spark ignition (DISI), direct injection gasoline (DIG), gasoline direct injection (GDI), etc. Injecting directly into the combustion chamber allows for some degree of stratification of the charge thus allowing an overall lean mixture whilst having a local rich or stoichiometric mixture to facilitate reliable combustion. This injection strategy however means that the fuel injector is subjected to higher temperatures and pressures. This increases the likelihood of forming deposits from the high temperature degradation of the fuel, the fact that the injector is in the combustion chamber also exposes the injector to combustion gases which may contain partially oxidised fuel and or soot particles which may accumulate, increasing the level of deposits. The ability to provide good atomisation of fuel and precise control of fuel flow rates and injection duration are critical to the optimum performance of these engine designs. The radically different operating environment of the fuel injector poses a whole new set of design constraints on the development of an effective fuel additive package. Mixture stratification can also result in combustion occurring in local rich regions leading to the formation of soot particles which can increase combustion chamber deposits. Because liquid fuel is injected into the combustion chamber there is a greater risk of liquid impingement on the combustion chamber surfaces, particularly the piston crown. Liquid fuel on the combustion chamber surfaces can undergo thermal decomposition leading to gum formation and thus increase the rate of build-up of combustion chamber deposits.

An additional problem arising from injecting the fuel directly into the combustion chamber is that fuel impingement on the inlet valves is significantly reduced. The use of fuel containing detergents was relied upon to remove the deposits that build up on the inlet valve tulip as a result of lubricating oil passing down the valve stem and from combustion gases passing back into the inlet system during the initial part of the inlet valve opening event. In a direct injection engine the only possibility for fuel to impinge on the inlet valve tulip is from early injection and late inlet valve closing. This therefore makes it extremely difficult for a fuel borne detergent to have a significant effect on inlet valve deposits.

Effective control of deposits in a direct injection spark ignition gasoline engine is, therefore, a challenging task. Knowledge gained in using additives in other contexts, for example in gasoline engines using carburettors or in gasoline engines using an individual, common, fuel injector, or fuel injectors in the inlet port of each cylinder, or in diesel engines, appear to be of little assistance achieving in effective control of deposits in a direct injection spark ignition gasoline engine.

The particular difficulties in achieving effective control of deposits in a direct injection spark ignition gasoline engine are known in the art. For example they are also explained in WO 01/42399, US 7112230, US 7491248 and WO 03178553.

Even though fuel compositions and additives have been proposed for controlling deposits in each of the regimes described above, such difficulties show that there is a continuing need for fuel compositions which are effective in either or both of direct injection spark ignition gasoline engines and/or spark ignition gasoline engines without direct injection.

According to a first aspect of the present invention there is provided a gasoline composition comprising, as an additive, the product of a Mannich reaction between: (a) an aldehyde; (b) an amine; and wherein the phenol is substituted with at least one branched hydrocarbyl group having a molecular weight of between 200 and 3000.

In this specification the additive obtained from the reaction of components (a), (b) and (c) may be referred to as the Mannich additive".

Any aldehyde may be used as aldehyde component (a) of the Mannich additive. Preferably the aldehyde component (a) is an aliphatic aldehyde. Preferably the aldehyde has 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms. Most preferably the aldehyde is formaldehyde.

Amine component (b) of the Mannich additive may be at least one amino or polyamino compound having at least one NH group. Suitable amino compounds include primary or secondary monoamines having hydrocarbon substituents of 1 to 30 carbon atoms or hydroxyl-substituted hydrocarbon substituents of 1 to about 30 carbon atoms.

In preferred embodiments the amine component (b) is a polyamine.

Polyamines may be selected from any compound including two or more amine groups.

Preferably the polyamine is a (poly)alkylene polyamine (by which is meant an alkylene polyamine or a polyalkylene polyamine; including in each case a diamine, within the meaning of "polyamine"). Preferably the polyamine is a (poly)alkylene polyamine in which the alkylene component has ito 6, preferably ito 4, most preferably 2 to 3 carbon atoms. Most preferably the polyamine is a (poly) ethylene polyamine (that is, an ethylene polyamine or a polyethylene polyamine).

Preferably the polyamine has 2 to 15 nitrogen atoms, preferably 2 to 10 nitrogen atoms, more preferably 2 to S nitrogen atoms.

Preferably the polyamine component (b) includes the moiety R1R2NCHR3CHR4NR5R6 wherein each of R1, R2 R3, R4, R5 and R6 is independently selected from hydrogen, and an optionally substituted alkyl, alkenyl, alkynyl, aryl, alkylaryl or arylalkyl substituent.

Thus the polyamine reactants used to make the Mannich reaction products of the present invention preferably include an optionally substituted ethylene diamine residue.

Preferably at least one of R1 and R2 is hydrogen. Preferably both of R1 and R2 are hydrogen.

Preferably at least two of R1, R2, R5 and R6 are hydrogen.

Preferably at least one of R3 and R4 is hydrogen. In some preferred embodiments each of R3 and R4 is hydrogen. In some embodiments R3 is hydrogen and R4 is alkyl, for example C to 04 alkyl, especially methyl.

Preferably at least one of R5 and R6 is an optionally substituted alkyl, alkenyl, alkynyl, aryl, alkylaryl or arylalkyl substituent.

In embodiments in which at least one of R1, R2, R3, R4, R5 and Re is not hydrogen, each is independently selected from an optionally substituted alkyl, alkenyl, alkynyl, aryl, alkylaryl or arylalkyl moiety. Preferably each is independently selected from hydrogen and an optionally In particularly preferred compounds each of R1, R2, R3, R4 and R5 is hydrogen and R6 is an optionally substituted alkyl, alkenyl, alkynyl, aryl, alkylaryl or arylalkyl substituent. Preferably R6 is an optionally substituted C(1-6) alkyl moiety.

Such an alkyl moiety may be substituted with one or more groups selected from hydroxyl, amino (especially unsubstituted amino; -NH-, -NH2), sulpho, sulphoxy, C(i-4) alkoxy, nitro, halo (especially chloro or fluoro) and mercapto.

There may be one or more heteroatoms incorporated into the alkyl chain, for example 0, N or 5, to provide an ether, amine or thioether.

Especially preferred substituents R1, R2, R3, R4, R5 or are hydroxy-C(i-4)alkyl and amino- (C(i-4)alkyl, especially HO-CH2-CH2-and H2N-CH2-CH2-.

Suitably the polyamine includes only amine functionality, or amine and alcohol functionalities.

The polyamine may, for example, be selected from ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylene-hexamine, hexaethyleneheptamine, heptaethyleneoctamine, propane-i,2-diamine, 2(2-amino-ethylamino)ethanol, and N,N-bis (2-aminoethyl) ethylenediamine (N(CH2CH2NH2)3). Most preferably the polyamine comprises tetraethylenepentamine or ethylenediamine.

Commercially available sources of polyamines typically contain mixtures of isomers and/or oligomers, and products prepared from these commercially available mixtures fall within the scope of the present invention.

The polyamines used to form the Mannich additives of the present invention may be straight chained or branched, and may include cyclic structures.

Phenol component (c) used to prepare the Mannich additives of the present invention may be substituted with ito 4 groups on the aromatic ring (in addition to the phenol OH). For example it may be a tn-or di-substituted phenol. Most preferably component (c) is a mono-substituted phenol. Substitution may be at the ortho, and/or meta, and/or para position(s).

Each phenol moiety may be ortho, meta or para substituted with the aldehyde/amine residue.

Compounds in which the aldehyde residue is ortho or para substituted are most commonly formed. Mixtures of compounds may result. In preferred embodiments the starting phenol is para substituted and thus the ortho substituted product results.

The phenol may be substituted with any common group, for example one or more of an alkyl group, an alkenyl group, an alkynl group, a nitryl group, a carboxylic acid, an ester, an ether, an alkoxy group, a halo group, a further hydroxyl group, a mercapto group, an alkyl mercapto group, an aikyl suiphoxy group, a sulphoxy group, an aryl group, an arylaikyi group, a substituted or unsubstituted amine group or a nitro group.

As mentioned above the phenol includes at least one branched hydrocarbyl substituent. The hydrocarbyl substituent may be optionally substituted with, for example, hydroxyl, halo, (especially chloro and fluoro), alkoxy, alkyl, mercapto, alkyl sulphoxy, aryl or amino residues.

Preferably the hydro carbyl group consists essentially of carbon and hydrogen atoms. The substituted phenol may include an alkenyl or alkynyl residue including one or more double and/or triple bonds.

The hydrocarbyl-based substituents are preferably predominantly saturated, that is, they contain no more than one carbon-to-carbon unsaturated bond for every ten carbon-to-carbon single bonds present. Most preferably they contain no more than one carbon-to-carbon unsaturated bond for every 50 carbon-to-carbon bonds present.

Preferably component (c) is a monoalkyl phenol, especially a para-substituted monoalkyl phenol in which the alkyl chain of the substituent is branched.

In preferred embodiments phenol component (c) used to prepare Mannich reaction product additive (ii) includes a predominantly or completely saturated branched hydrocarbyl substituent. Preferably this predominantly or completely saturated hydrocarbyl substituent is branched along the length of the chain. By branched along the length of the chain we mean that there are multiple branches from the main (or longest) chain. Preferably there is a branch at least every 10 carbon atoms along the main chain, preferably at least every 6 carbons, suitably at least every 4 carbons, for example every 3 carbon atoms or every 2 carbon atoms.

A particular carbon atom in the main hydrocarbyl chain (which is preferably an alkylene chain) may have one or two branching hydrocarbyl groups. By branching hydrocarbyl groups we mean hydrocarbyl groups not forming part of the main chain but directly attached thereto.

Thus the main hydrocarbyl chain may include the moiety -CHR1-or -CR1R2-wherein R1 and are branching hydrocarbyl groups.

Preferably each branching hydrocarbyl group is an alkyl group, preferably a C1 to C4 alkyl group, for example propyl, ethyl or most preferably methyl.

In some preferred embodiments phenol component (c) used to prepare Mannich reaction product additive (ii) includes a hydrocarbyl substituent which is substituted with methyl groups along the main chain thereof. Suitably there are a plurality of carbon atoms which each have Preferably the branching points are substantially equally spaced along the main chain of the hydrocarbyl group of phenol component (c).

Component (c) used to prepare additive (U) includes at least one branched hydrocarbyl substituent. Preferably this is an alkyl substituent. In especially preferred embodiments the hydrocarbyl substituent is derived from a polyalkene, suitably a polymer of a branched alkene, for example polyisobutene or polypropene.

In especially preferred embodiments component (c) used in the preparation of Mannich reaction product additive (ii) includes a poly(isobutene) derived substituent.

Thus the Mannich reaction product additives used in the present invention preferably include a hydrocarbyl chain having the repeating unit:

K CH3 n

Poly(isobutenes) are prepared by the addition polymerisation of isobutene, (CH3)2C=CH2.

Each molecule of the resulting polymer will include a single alkene moiety.

Conventional polyisobutenes and so-called "highly-reactive" polyisobutenes are suitable for use in preparing additive (i) of the present invention. Highly reactive polyisobutenes in this context are defined as polyisobutenes wherein at least 50%, preferably 70% or more, of the terminal olefinic double bonds are of the vinylidene type as described in EP0565285.

Particularly preferred polyisobutenes are those having more than 80 mol% and up to 100% of terminal vinylidene groups such as those described in EP1344785.

Other methods of preparing polyalkylene substituted phenols, for example polyisobutene substituted phenols are known to the person skilled in the art, and include the methods described in EPB31 141.

The hydrocarbyl substituent of component (c) has an average molecular weight of 200 to 3000. Preferably it has a molecular weight of at least 225, suitably at least 250, preferably at least 275, suitably at least 300, for example at east 325 or at least 350. In some embodiments the hydrocarbyl substituent of component (c) has an average molecular weight of at least 375, preferably at least 400, suitably at least 475, for example at least 500.

In some embodiments component (c) may include a hydrocarbyl substituent having an average molecular weight of up to 2800, preferably up to 2600, for example up to 2500 or up to 2400.

In some embodiments the hydrocarbyl substituent of component (c) has an average molecular weight of from 400 to 2500, for example from 450 to 2400, preferably from 500 to 1500, suitably from 550 to 1300.

In some embodiments the hydrocarbyl substituent of component (c) has an average molecular weight of from 200 to 600.

In some embodiments the hydrocarbyl substituent of component (c) has an average molecular weight of from 500 to 1000.

In some embodiments the hydrocarbyl substituent of component (c) has an average molecular weight of from 700 to 1300.

In some embodiments the hydrocarbyl substituent of component (c) has an average molecular weight of from 1000 to 2000.

In some embodiments the hydrocarbyl substituent of component (c) has an average molecular weight of from 1700 to 2600, for example 2000 to 2500.

Unless otherwise mentioned all average molecular weights referred to herein are number average molecular weights.

Components (a), (b) and (c) used to prepare the Mannich product additives of the present invention may each comprise a mixture of compounds and/or a mixture of isomers.

B

The Mannich additive is preferably the reaction product obtained by reacting components (a), (b)and (c)ina molarratiooffrom5:1:5toO.1:1:0.1, more preferablyfrom 3:1:3toO.5:1:0.5.

To form the Mannich additive of the present invention components (a) and (b) are preferably reacted in a molar ratio of from 6:1 to 1:4 (aldehyde:amine), preferably from 4:1 to 1:2, more preferablyfrom3:1 to 1:1.

In preferred embodiments the molar ratio of component (a) to component (b) (aldehyde:amine) in the reaction mixture is preferably greater than 1:1 preferably at least 1.1:1, more preferably at least 1.3:1, suitably at least 1.5:1, for example at least 1.6:1.

Preferably, the molar ratio of component (a) to component (b) (aldehyde:amine) in the reaction mixture is less than 3:1, preferably up to 2.7:1, more preferably up to 2.3:1, for example up to 2.1:1, or up to 2:1.

Preferably, the molar ratio of component (a) to component (b) (aldehyde:amine) in the reaction mixture used to prepare the Mannich additive of the present invention is from 1.1:1 to 2.9:1, preferably from 1.3:1 to 2.7:1, preferably from 1.4:1 to 2.5:1, more preferably from 1.5:1 to 2.3:1, suitably from 1.6:1 to 2.2:1, for example from 1.7:1 to 2.1:1.

To form a preferred Mannich additive of the present invention the molar ratio of component (a) to component (c) (aldehyde:phenol) in the reaction mixture is preferably from 5:1 to 1:4, preferably from 3:1 to 1:2, for example from 2:1 to 1:1.

In preferred embodiments the molar ratio of component (a) to component (c) (aldehyde:phenol) in the reaction mixture used to prepare the Mannich additive of the present invention is greater than 1:1; preferably at least 1.1:1; preferably at least 1.2:1 and more preferably at least 1.3:1.

Preferably the molar ratio of component (a) to component (c) (aldehyde:phenol) is less than 2:1, preferably up to 1.9:1; more preferably up to 1,8:1 for example up to 1.7:1; more preferably up to 1.6:1.

Suitably the molar ratio of component (a) to component (c) (aldehyde:phenol) in the reaction mixture used to prepare the Mannich additive is from 1.05:1 to 1.95:1, preferably from 1.1:1 to 1.85:1, more preferablyfrom 1.2:1 to 1.75:1, suitablyfrom 1.25:1 to 1.65:, most preferablyfrom 1.3:1 to 1.55:1.

To form the Mannich additive of the present invention components (c) and (b) are preferably reacted in a molar ratio of from 6:1 to 1:4 (phenol amine), preferably from 4:1 to 1:2, more preferably from 3:1 to 1:2 and more preferably from 2:1 to 1:2.

Suitably the molar ratio of component (c) to component (b) (phenol:amine) in the reaction mixture is 0.7:1 to 1.9: 1, preferably 0.8:1 to 1.8:1, preferably 0.9:1 to 1.7:1, preferably 1:1 to 1.6:1 preferably 1.1:1 to 1.5:1, preferably 1.2:1 to 1.4:1.

In preferred embodiments, the molar ratio of component (c) to component (b) (phenol: amine) in the reaction mixture is greater than 0.5:1; preferably at least 0.8:1; preferably at least 0.9:1 and more preferably at least 1:1 for example at least 1.1:1.

Preferably the molar ratio of component (c) to component (b) (phenol:amine) in the reaction mixture is less than 2:1, preferably up to 1.9:1; more preferably up to 1.7:1 for example up to 1.6:1; more preferably upto 1.5:1.

In some preferred embodiments in the Mannich reaction used to form the additive the molar ratio of component (a) to component (b) is 2.2-1.01:1; the molar ratio of component (a) to component (c) is 1.99-1.01:1 and the molar ratio of component (b) to component (c) is 1:1.01-1.99.

In some preferred embodiments in the reaction used to make the Mannich additive the molar ratio of component (a) to component (b) is 2-1.6:1, the molar ratio of component (a) to component (c) is 1.6-1.2:1 and the molar ratio of component (b) to component (c) is 1:1.1-1.5.

Some preferred compounds used in the present invention are typically formed by reacting components (a), (b) and (c) in a molar ratio of 1.8 parts (a) ± 0.3 parts (a), to I pad (b), to 1.3 parts (c) ± 0.3 parts (c); preferably 1.8 parts (a) ± 0.1 parts (a), to 1 part (b) to 1.3 parts (c) ± 0.1 parts (c); preferablyapproximately 1.8:1:1.3 (a: b: c).

In some preferred embodiments the composition of the present invention may further comprise a quaternary ammonium salt additive. Suitably the quaternary ammonium salt additive is formed by the reaction a quaternising agent and a compound formed by the reaction of a hydrocarbyl-substituted acylating agent and an amine of formula (BI) or (B2): \ _ _ 4 \ _ _ N X NHR N X [O(CH2)m]nOH (Bi) (B2) wherein R2 and R3 are the same or different alkyl, alkenyl or aryl groups having from 1 to 22 carbon atoms; X is a bond or alkylene group having from 1 to 20 carbon atoms; n is from 0 to 20; m is from Ito 5; and R4 is hydrogen or aCi to C22 alkyl group.

The quaternising agent may suitably be selected from esters and non-esters.

In some preferred embodiments quaternising agents used to form the quaternary ammonium salt additives of the present invention are esters. Preferred ester quaternising agents are compounds of formula R000R1 in which R is an optionally substituted alkyl, alkenyl, aryl or alkylaryl group and R1 is a C1 to 022 alkyl, aryl or alkylaryl group.

Suitable ester quaternising agents include esters of carboxylic acids having a pKa of 3.5 or less.

The compound of formula R000R1 is preferably an ester of a carboxylic acid selected from a substituted aromatic carboxylic acid, an a-hydroxycarboxylic acid and a polycarboxylic acid.

In some preferred embodiments the compound of formula RCOOR1 is an ester of a substituted aromatic carboxylic acid and thus R is a subsituted aryl group.

Preferably R is a substituted aryl group having 6 to 10 carbon atoms, preferably a phenyl or naphthyl group, most preferably a phenyl group. R is suitably substituted with one or more groups selected from carboalkoxy, nitro, cyano, hydroxy, SR5 or NR5R6. Each of R5 and R6 may be hydrogen or optionally substituted alkyl, alkenyl, aryl or carboalkoxy groups.

Preferably each of R5 and R6 is hydrogen or an optionally substituted 01 to 022 alkyl group, preferably hydrogen or aCi to 016 alkyl group, preferably hydrogen or aCi to alkyl group, more preferably hydrogenC1 to 04 alkyl group. Preferably R5 is hydrogen and R6 is hydrogen or a C to 04 alkyl group. Most preferably R5 and R6 are both hydrogen. Preferably R is an aryl group substituted with one or more groups selected from hydroxyl, carboalkoxy, nitro, cyano and NH2. R may be a poly-substituted aryl group, for example trihydroxyphenyl.

Preferably R is a mono-substituted aryl group. Preferably R is an ortho substituted aryl group.

Suitably R is substituted with a group selected from OH, NH2, NO2 or 000Me. Preferably R is substituted with an OH or NH2 group. Suitably P is a hydroxy substituted aryl group. Most preferably R isa 2-hydroxyphenyl group.

Preferably R1 is an alkyl or alkylaryl group. P1 may be a C1 to C16 alkyl group, preferably a C1 to alkyl group, suitably a C to C alkyl group. P1 may be C to C16 alkylaryl group, preferably a C1 to C13 alkylgroup, suitably a C1 to C3 alkylaryl group. P1 may be methyl, ethyl, propyl, butyl, pentyl, benzyl or an isomer thereof. Preferably P1 is benzyl or methyl. Most preferably P1 is methyl.

An especially preferred compound of formula RCOOR1 is methyl salicylate.

In some embodiments the compound of formula RCOOR1is an ester of an a-hydroxycarboxylic acid. In such embodiments the compound has the structure:

OH

R7 C-COOR1 wherein P7 and P3 are the same or different and each is selected from hydrogen, alkyl, alkenyl, aralkyl or aryl. Compounds of this type suitable for use herein are described in EP 1254889.

Examples of compounds of formula RCOOR1 in which RCOO is the residue of an a-hydroxycarboxylic acid include methyl-, ethyl-, propyl-, butyl-, pentyl-, hexyl-, benzyl-, phenyl-, and allyl esters of 2-hydroxyisobutyric acid; methyl-, ethyl-, propyl-, butyl-, pentyl-, hexyl-, benzyl-, phenyl-, and allyl esters of 2-hydroxy-2-methylbutyric acid; methyl-, ethyl-, propyl-, butyl-, pentyl-, hexyl-, benzyl-, phenyl-, and allyl esters of 2-hydroxy-2-ethylbutyric acid; methyl-, ethyl-, propyl-, butyl-, pentyl-, hexyl-, benzyl-, phenyl-, and allyl esters of lactic acid; and methyl-, ethyl-, propyl-, butyl-, pentyl-, hexyl-, allyl-, benzyl-, and phenyl esters of glycolic acid. Of the above, a preferred compound is methyl 2-hydroxyisobutyrate.

In some embodiments the compound of formula RCOOR1 is an ester of a polycarboxylic acid.

In this definition we mean to include dicarboxylic acids and carboxylic acids having more than 2 acidic moieties. In such embodiments RCOO is preferably present in the form of an ester, that is the one or more further acid groups present in the group P are in esterified form.

Preferred esters are C1 to C4 alkyl esters.

The ester quaternising agent may be selected from the diester of oxalic acid, the diester of phthalic acid, the diester of maleic acid! the diester of malonic acid or the diester of citric acid.

One especially preferred compound of formula R000R1 is dimethyl oxalate.

In preferred embodiments the compound of formula RCOOR1 is an ester of a carboxylic acid having a pKaof less than 3.5. In such embodiments in which the compound includes more than one acid group, we mean to refer to the first dissociation constant.

The ester quaternising agent may be selected from an ester of a carboxylic acid selected from one or more of oxalic acid, phthalic acid, salicylic acid, maleic acid, malonic acid, citric acid, nitrobenzoic acid, aminobenzoic acid and 2, 4, 6-trihydroxybenzoic acid.

Preferred ester quaternising agents include dimethyl oxalate, methyl 2-nitrobenzoate and methyl salicylate.

Suitable non-ester quaternising agents include dialkyl sulfates, benzyl halides! hydrocarbyl substituted carbonates, hydrocarbyl susbstituted epoxides in combination with an acid, alkyl halides, alkyl sulfonates, sultones, hydrocarbyl substituted phosphates, hydrocarbyl substituted borates, alkyl nitrites, alkyl nitrates, hydroxides, N-oxides or mixtures thereof In some embodiments the quaternary ammonium salt may be prepared from, for example, an alkyl or benzyl halide (especially a chloride) and then subjected to an ion exchange reaction to provide a different anion as part of the quaternary ammonium salt. Such a method may be suitable to prepare quaternary ammonium hydroxides, alkoxides, nitrites or nitrates.

Preferred non-ester quaternising agents include dialkyl sulfates, benzyl halides, hydrocarbyl substituted carbonates, hydrocarbyl susbsituted epoxides in combination with an acid, alkyl halides, alkyl sulfonates, sultones, hydrocarbyl substituted phosphates, hydrocarbyl substituted borates, N-oxides or mixtures thereof.

Suitable dialkyl sulfates for use herein as quaternising agents include those including alkyl groups having 1 to 10, preferably 1 to 4 carbons atoms in the alkyl chain. A preferred compound is dimethyl sulfate.

Suitable benzyl halides include chlorides, bromides and iodides. The phenyl group may be optionally substituted, for example with one or more alkyl or alkenyl groups, especially when the chlorides are used. A preferred compound is benzyl bromide.

Suitable hydrocarbyl substituted carbonates may include two hydrocarbyl groups, which may be the same or different. Each hydrocarbyl group may contain from 1 to 50 carbon atoms, preferably from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms, suitably from 1 to 5 carbon atoms. Preferably the or each hydrocarbyl group is an alkyl group.

Preferred compounds of this type include diethyl carbonate and dimethyl carbonate.

Suitable hydrocarbyl susbsituted epoxides have the formula: wherein each of R1, R2, R3 and R4 is independently hydrogen or a hydrocarbyl group having I to SO carbon atoms. Examples of suitable epoxides include ethylene oxide, propylene oxide, butylene oxide, styrene oxide and stillbene oxide. The hydrocarbyl epoxides are used as quaternising agents in combination with an acid. In embodiments in which the hydrocarbyl substituted acylating agent is a dicarboxylic acylating agent no separate acid needs to be added. However in other embodiments an acid such as acetic acid may be used.

Especially preferred epoxide quaternising agents are propylene oxide and styrene oxide.

Suitable alkyl halides for use herein include chlorides, bromides and iodides.

Suitable alkyl sulfonates include those having ito 20, preferably ito 10, more preferably ito 4 carbon atoms.

Suitable sultones include propane sultone and butane sultone.

Suitable hydrocarbyl substituted phosphates include dialkyl phosphates, trialkyl phosphates and 0,0-dialkyl dithiophospates. Preferred alkyl groups have ito 12 carbon atoms.

Suitable hydrocarbyl substituted borate groups include alkyl borates having 1 to 12 carbon atoms.

Preferred alkyl nitrites and alkyl nitrates have ito i2 carbon atoms.

Preferably the non-ester quaternising agent is selected from dialkyl sulfates, benzyl halides, hydrocarbyl substituted carbonates, hydrocarbyl susbsituted epoxides in combination with an acid, and mixtures thereof.

Especially preferred non-ester quaternising agents for use herein are hydrocarbyl substituted epoxides in combination with an acid. These may include embodiments in which a separate acid is provided or embodiments in which the acid is provided by the tertiary amine compound that is being quaternised. Preferably the acid is provided by the tertiary amine molecule that is being quaternised.

Preferred quaternising agents for use herein include dimethyl oxalate, methyl 2-nitrobenzoate, methyl salicylate and styrene oxide or propylene oxide optionally in combination with an additional acid.

To form the quaternary amnionium salt additives of the present invention the quaternising agent is reacted with a compound formed by the reaction of a hydrocarbyl substituted acylating agent and an amine of formula (Bi) or (B2).

When a compound of formula (Bi) is used, R4 is preferably hydrogen or a C1 to C16 alkyl group, preferably a C1 to C13 alkyl group, more preferably a C1 to C6 alkyl group. When R4 is alkyl it may be straight chained or branched. It may be substituted for example with a hydroxy or alkoxy substituent. Preferably R4 is not a substituted alkyl group. Preferably R4 is selected from hydrogen, methyl, ethyl, propyl, butyl and isomers thereof. Most preferably R4 is hydrogen.

When a compound of formula (B2) is used, m is preferably 2 or 3, most preferably 2; n is preferably from 0 to 15, preferably 0 to 10, more preferably from 0 to 5. Most preferably n isO and the compound of formula (B2) is an alcohol.

Preferably the hydrocarbyl substituted acylating agent is reacted with a diamine compound of formula (B1).

R2 and R3 are the same or different alkyl, alkenyl or aryl groups having from 1 to 22 carbon atoms. In some embodiments R2 and R3 may be joined together to form a ring structure, for example a piperidine or imidazole moiety. R2 and R3 may be branched alkyl or alkenyl groups.

Each may be substituted, for example with a hydroxy or alkoxy substituent.

Preferably R2 and R3 is each independently a C1 to C16 alkyl group, preferably a C1 to C10 alkyl group. P2 and P3 may independently be methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, or an isomer of any of these. Preferably R2 and R3 is each independently C to C4 alkyl.

Preferably P2 is methyl. Preferably P3 is methyl.

X is a bond or alkylene group having from 1 to 20 carbon atoms. In preferred embodiments when X alkylene group this group may be straight chained or branched. The alkylene group may include a cyclic structure therein. It may be optionally substituted, for example with a X is preferably an alkylene group having 1 to 16 carbon atoms, preferably 1 to 12 carbon atoms, more preferably I to B carbon atoms, for example 2 to 6 carbon atoms or 2 to 5 carbon atoms. Most preferably X is an ethylene, propylene or butylene group, especially a propylene group.

Examples of compounds of formula (BI) suitable for use herein include 1-aminopiperidine, 1- (2-aminoethyl)piperidine, 1-(3-aminopropyl)-2-pipecoline, 1-methyl-(4-methylamino)piperidine, 4-(1-pyrrolidinyl)piperidine, 1-(2-aminoethyl)pyrrolidine, 2-(2-aminoethyl)-1-methylpyrrolidine, N,N-diethylethylenediamine, N,N-dimethylethylenediamine, N,N-dibutylethylenediamine, N,N- diethyl-l,3-diaminopropane, N,N-dimethyl-1,3-diaminopropane, N,N,N- trirnethylethylenediamine, N,N-dimethyl-N'-ethylethylenediamine, N,N-diethyl-N- methylethylenediamine, N,N,N'-triethylethylenediamine, 3-dimethylaminopropylamine, 3-diethylaminopropylamine, 3-dibutylaminopropylamine, N,N,N'-trimethyl-1,3-propanediamine, N,N,2,2-tetramethyl-l,3-propanediamine, 2-amino-5-diethylaminopentane, N,N,N',N'- tetraethyldiethylenetriamine, 3,3'-diamino-N-methyldipropylamine, 3,3'-iminobis(N,N- diniethylpropylamine), 1-(3-aminopropyl)imidazole and 4-(3-aminopropymorpholine, 1 -(2-aminoethyl)piperidine, 3,3-diamino-N-methyldipropylamine, 3,3-aminobis(N,N-dimethy Ipropy lamine), or combinations thereof.

In some preferred embodiments the compound of formula (BI) is selected from from N,N-dimethyl-1,3-diaminopropane, N,N-diethyl-1 3-diaminopropane, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N,N-dibutylethylenediamine, or combinations thereof Examples of compounds of formula (B2) suitable for use herein include alkanolamines including but not limited to triethanolamine, N,N-dimethylaminopropanol, N,N- diethylaminopropanol, N,N-diethylaminobutanol, triisopropanolamine, 1-[2- hydroxyethyl]piperidine, 2-[2-(dimethylamine)ethoxy]-ethanol, N-ethyldiethanolamine, N- methyldiethanolamine, N-butyldiethanolamine, N,N-diethylaminoethanol, N,N-dimethyl amino-ethanol, 2-dimethylamino-2-methyl-I-propanol.

In some preferred embodiments the compound of formula (B2) is selected from Trhsopropanolamine, 1-[2-hydroxyethyl]piperidine, 2-[2-(dimethylamine)ethoxy]-ethanol, N- ethyldiethanolamine, N-methyldiethanolamine, N-butyldiethanolamine, N,N-diethylaminoethanol, N,N-dimethylaminoethanol, 2-diniethylamino-2-methyl-1 -propanol, or combinations thereof.

An especially preferred compound of formula (El) is dimethylaminopropylamine.

The amine of formula (Bi) or (B2) is reacted with a hydrocarbyl substituted acylating agent.

The hydrocarbyl substituted acylating agent may be based on a hydrocarbyl substituted mono-di-or polycarboxylic acid or a reactive equivalent thereof. Preferably the hydrocarbyl substituted acylating agent is a hydrocarbyl substituted succinic acid compound such as a succinic acid or succinic anhydride.

The hydrocarbyl substituent preferably comprises at least 10, more preferably at least 12, for example 30 or 50 carbon atoms. It may comprise up to about 200 carbon atoms. Preferably the hydrocarbyl substituent has a number average molecular weight (Mn) of between 170 to 2800, for example from 250 to 1500, preferably from 500 to 1500 and more preferably 500 to 1100. An Mn of 700 to 1300 is especially preferred.

The hydrocarbyl based substituents may be made from homo-or interpolymers (e.g. copolymers, terpolymers) of mono-and di-olefins having 2 to 10 carbon atoms, for example ethylene, propylene, butane-I, isobutene, butadiene, isoprene, 1-hexene, 1-octene, etc. Preferably these olefins are 1-monoolefins. The hydrocarbyl substituent may also be derived from the halogenated (e.g. chlorinated or brominated) analogs of such homo-or interpolymers.

Alternatively the substituent may be made from other sources, for example monomeric high molecular weight alkenes (e.g. 1-tetra-contene) and chlorinated analogs and hydrochlorinated analogs thereof, aliphatic petroleum fractions, for example paraffin waxes and cracked and chlorinated analogs and hydrochlorinated analogs thereof, white oils, synthetic alkenes for example produced by the Ziegler-Natta process (e.g. poly(ethylene) greases) and other sources known to those skilled in the art. Any unsaturation in the substituent may if desired be reduced or eliminated by hydrogenation according to procedures known in the art.

The term "hydrocarbyl" as used herein denotes a group having a carbon atom directly attached to the remainder of the molecule and having a predominantly aliphatic hydrocarbon character.

Suitable hydrocarbyl based groups may contain non-hydrocarbon moieties. For example they may contain up to one non-hydrocarbyl group for every ten carbon atoms provided this non-hydrocarbyl group does not significantly alter the predominantly hydrocarbon character of the group. Those skilled in the art will be aware of such groups, which include for example hydroxyl, oxygen, halo (especially chloro and fluoro), alkoxyl, alkyl mercapto, alkyl sulphoxy, etc. Preferred hydrocarbyl based substituents are purely aliphatic hydrocarbon in character and do not contain such groups.

Preferred hydrocarbyl-based substituents are poly-(isobutene)s known in the art. Thus in especially preferred embodiments the hydrocarbyl substituted acylating agent is a polyisobutenyl substituted succinic anhydride.

The preparation of polyisobutenyl substituted succinic anhydrides (PIBSA) is documented in the art. Suitable processes include thermally reacting polyisobutenes with maleic anhydride (see for example US-A-3,361,673 and US-A-3,018,250), and reacting a halogenated, in particular a chlorinated, polyisobutene (PIB) with maleic anhydride (see for example US-A- 3,172,892). Alternatively, the polyisobutenyl succinicanhydride can be prepared by mixing the polyolefin with maleic anhydride and passing chlorine through the mixture (see for example GB-A-949,981).

Particularly preferred polyisobutenes are those having more than 80 mol% and up to 100% of terminal vinylidene groups such as those described in FF1344785.

Other preferred hydrocarbyl groups include those having an internal olefin for example as described in the applicants published application W02007/015080.

An internal olefin as used herein means any olefin containing predominantly a non-alpha double bond, that is a beta or higher olefin. Preferably such materials are substantially completely beta or higher olefins, for example containing less than 10% by weight alpha olefin, more preferably less than 5% by weight or less than 2% by weight. Typical internal olefins include Neodene 151810 available from Shell.

Internal olefins are sometimes known as isomerised olefins and can be prepared from alpha olefins by a process of isomerisation known in the art, or are available from other sources.

The fact that they are also known as internal olefins reflects that they do not necessarily have to be prepared by isomerisation.

Some preferred acylating agents for use in the preparation of the quaternary ammonium salt additives of the present invention are polyisobutene-substituted succinic acids or succinic anhydrides. When a compound of formula (B2) is reacted with a succinic acylating agent the resulting product is a succinic ester. When a succinic acylating agent is reacted with a compound of formula (B1) in which R4 is hydrogen the resulting product may be a succinimide or a succinamide. When a succinic acylating agent is reacted with a compound of formula (B1) in which P4 is not hydrogen the resulting product is an amide.

In preferred embodiments, the reaction product of the hydrocarbyl substituted acylating agent and the amine of formula (B1) or (B2) is an amide or an ester.

In preferred embodiments, the reaction product of the hydrocarbyl substituted acylating agent and the amine of formula (Bi) or (B2) also has at least one remaining carboxylic acid group.

This may be achieved by choosing hydrocarbyl substituted acylating agents having di or polycarboxylic acids or reactive equivalents thereof and by choosing suitable molar ratios of amines of formula (Bi) or (B2). In the case of amides prepared from amines of formula (B2) where P4 is hydrogen, it may also be necessary to control the reaction conditions to avoid forming imides. Such techniques are within the capability of someone of ordinary skill in the art.

For the avoidance of doubt, succinic esters include the monoester compounds having the general formula (01) and the diester compounds having the general formula (02); succinimides have the general formula (03); and succinamides include the monoamide compounds having the general formula (04) and the diamide compounds having have the general formula (05): In especially preferred embodiments the quaternary ammonium salt additives of the present invention are salts of tertiary amines prepared from dimethylamino propylamine and a polyisobutylene-substituted succinic anhydride. The average molecular weight of the polyisobutylene substituent is preferably from 700 to 1300, more preferably from 900 to 1100.

Particularly preferred quaternary ammonium salts of the present invention are the reaction product of a polyisobutenyl succinic acylating agent with dimethylaminopropylamine (N,N dirnethyl 1,3 propane diamine) to form either the imide and then quaternised using methyl salicylate, or to form the half amide, half acid and then quaternised using propylene oxide.

The quaternary ammonium salt additives of the present invention may be prepared by any suitable methods. Such methods will be known to the person skilled in the art and are exemplified herein. Typically the quaternary ammonium salt additives will be prepared by heating the quaternising agent and a compound prepared by the reaction of a hydrocarbyl substituted acylating agent with an amine of formula (Bi) or (B2) in an approximate 1:1 molar ratio, optionally in the presence of a solvent. The resulting crude reaction mixture may be added directly to a gasoline fuel, optionally following removal of solvent. Any by-products or residual starting materials still present in the mixture have not been found to cause any detriment to the performance of the additive. Thus the present invention may provide a gasoline composition comprising the reaction product of a quaternising agent and the reaction product of a hydrocarbyl substituted acylating agent and an amine formula (Bi) or (B2).

Suitable treat rates of the mannich additive and when present the quaternary ammonium salt additive will depend on the desired performance and on the type of engine in which they are used. For example different levels of additive may be needed to achieve different levels of pe rfo rma nce.

Suitably the Mannich additive when used is present in the gasoline composition in an amount of from I to l0000ppm, preferably from I to 1000 ppm, more preferably from 5 to 500 ppm, suitably from 5 to 250 ppm, for example from 5 to lSOppm.

Suitably the quaternary ammonium salt additive is present in the gasoline composition in an amount of from ito l0000ppm, preferably from ito 1000 ppm, more preferably from Sto 500 ppm, suitably from 5 to 250 ppm, for example from 5 to iSOppm.

The weight ratio of the quaternary ammonium salt additive to the Mannich additive is preferablyfrom 1:10 to 10:1, preferablyfrom 1:4 to4:i, forexamplefrom 1:3 to 3:1.

The composition of the present invention is a gasoline composition. By the term "gasoline", it is meant a liquid fuel for use with spark ignition engines (typically or preferably containing primarily or only C4-C12 hydrocarbons) and satisfying international gasoline specifications, such as ASTM D-439 and EN228. The term includes blends of distillate hydrocarbon fuels with oxygenated components such as alcohols or ethers for example methanol, ethanol, butanol, methyl t-butyl ether (MTBE), ethyl t-butyl ether (ETBE), as well as the distillate fuels themselves.

The gasoline compositions of the present invention may suitably comprise one or more additional components selected from carrier oils; acylated nitrogen compounds which are the reaction product of a carboxylic acid-derived acylating agent and an amine; hydrocarbyl-substituted amines wherein the hydrocarbyl substituent is substantially aliphatic and contains at least 8 carbon atoms; and aromatic esters of a polyalkylphenoxyalkanol. Compounds of these general types will be known to the person skilled in the art.

The gasoline composition of the present invention may include one or more further additives such as those which are commonly found in gasoline fuels. These include, for example, other detergents, dispersants, anti-oxidants, anti-icing agents, metal deactivators, lubricity additives, friction modifiers, dehazers, corrosion inhibitors, dyes, markers, octane improvers, anti-valve-seat recession additives, stabilisers, demulsifiers, antifoams, odour masks, conductivity improvers and combustion improvers. Examples of suitable amounts of each of these types of additives will be known to the person skilled in the ad.

According to a second aspect of the present invention there is provided an additive package which upon addition to a gasoline fuel provides a composition of the first aspect.

The additive package may comprise a mixture of the Mannich additive, optionally the quaternary ammonium salt additive and optionally further additives, for example those described above. Alternatively the additive package may comprise a solution of additives, suitably in a mixture of carrier oils and/or solvents.

Preferred features of the second aspect are as defined in relation to the first aspect.

According to a third aspect of the present invention there is provided a method of operating a spark ignition gasoline engine, the method comprising combusting in the engine a composition of the first aspect.

The present invention may provide a method of controlling deposits in a spark ignition gasoline engine.

Controlling deposits in this specification is intended to cover one or more of: reducing existing deposits ("clean-up"); reducing deposit formation ("keep-clean"); modifying deposits so as to reduce their negative effects.

It has surprisingly been found that the gasoline compositions of the present invention achieve good control of deposits in spark ignition gasoline engines.

It has surprisingly been found that the gasoline compositions used in this invention achieve good control of deposits even in the demanding context of the direct injection spark ignition gasoline engine.

This control of deposits may lead to a significant reduction in maintenance costs and/or an increase in power and/or an improvement in fuel economy.

The present invention may suitably provide a method of controlling deposits in a direct injection spark ignition gasoline engine, the method comprising adding into the gasoline to be combusted a Mannich additive as defined in relation to the first aspect and optionally a quaternary ammonium salt additive as defined herein.

The present invention may suitably provide a method of improving the efficiency of a direct injection spark ignition gasoline engine, the method comprising adding into the gasoline to be combusted a Mannich additive as defined in relation to the first aspect and optionally a quaternary ammonium salt additive as defined herein.

The present invention may suitably provide a method of operating a direct injection spark ignition gasoline engine, the method comprising adding into the gasoline to be combusted a Mannich additive as defined in relation to the first aspect and optionally a quaternary ammonium salt additive as defined herein; wherein the method provides one or more of:- * improved fuel economy * reduced maintenance * less frequent overhaul or replacement of injectors * improved driveability * improved power * improved acceleration.

Preferred features of the methods of the present invention are as defined in relation to the first aspect.

According to a further aspect of the present invention there is provided the use of a Mannich reaction product additive as defined in relation to the first aspect in a gasoline composition to improve the engine performance of a gasoline engine when using said gasoline composition.

The present invention may suitably provide the use of a Mannich additive as defined in relation to the first aspect and optionally a quaternary ammonium salt additive as defined herein added into gasoline to control deposits in a direct injection spark ignition gasoline engine.

The present invention may suitably provide the use of a Mannich additive as defined in relation to the first aspect and optionally a quaternary ammonium salt additive as defined herein added into gasoline to improve efficiency in a direct injection spark ignition gasoline engine.

The present invention may suitably provide the use of a gasoline comprising a Mannich additive as defined in relation to the first aspect and optionally a quaternary amrnonium salt additive as defined herein in a direct injection spark ignition gasoline engine to provide one or more of:- * improved fuel economy * reduced maintenance * less frequent overhaul or replacement of injectors * improved driveability * improved power * improved acceleration Preferred features of the uses of the present invention are as defined in reiation to the first aspect.

The invention will now be further described with reference to the following non-limiting

examples:

Example I

Additive A, a Mannich additive of the present invention was prepared as follows: Phenol alkylated with 1000 MW PIB (356.3g, 0.32Gmoles) and Caromax 20 (185.7g) were charged to a reactor and mixed with constant stirring at ambient temperature below 3OdegC under a nitrogen purge. Ethylenediamine (19.6g, 0.326 moles) was then charged to the reactor. The mixture was heated to a temperature of S5degC. Formalin (26.7g, 0.326moles, 36.6wt% formaldehyde in water and methanol) was charged to the reactor over lhr at 95-lOOdegC. A mild exotherm was noted. Following the addition the mixture was held at 95degC for lhr. The reaction mixture was heated to reflux. The azeotropic blend of water and solvent was removed continuously over a period lasting 2 hours. The temperature was increased as required to sustain removal of water, then the reaction mixture heated gradually to lSOdegC.

The product dissolved in Caromax 20 was obtained as a clear amber solution (561.9g).

Additive A was found to contain 65% non-volatiles and 35% solvent.

Example 2

Additive B, the reaction product of a hydrocarbyl substituted acylating agent and a compound of formula (Bi) was prepared as follows: 523.BBg (0.425 moles) PIBSA (made from 1000 MW P18 and maleic anhydride) and 373.02g Caromax 20 were charged to 1 litre vessel. The mixture was stirred and heated, under nitrogen to 50°C. 43.69g (0.425 moles), DMAPA was added and the mixture heated to 160°C for 5 hours, with concurrent removal of water using a Dean-Stark apparatus. Additive B was believed to be approximately 60% active material and 40% solvent.

[Note: FIB herein means polyisobutene; PIBSA means polyisobutenyl-substituted succinic anhydride; DMAPA means dirnethylaminopropylamine]

Example 3

Additive C, an additive comprising a quaternary ammonium salt(s) additive of the present invention was prepared as follows: 588.24g (0.266 moles) of Additive B mixed with 40.66g (0.266 moles) methyl salicylate under nitrogen. The mixture was stirred and heated to 160°C for 16 hours.

The product mixture of this reaction was used without further processing as additive C and contained the quaternary amrnonium salt(s) additive of the present invention, together with any unreacted raw materials, other reaction products and solvent. The solvent content of Additive C was approximately 35%.

Example 4

A second sample of quaternary ammonium salt additive of the present invention was prepared, Additive D. Additive D was prepared in a similar way to the additives described above, using the following raw materials: 1000 MW FIB, (45.4 parts weight), maleic anhydride (4.2 parts weight), DMAPA (4.2 parts weight), solvent (39.9 parts weight), methyl salicylate (6.3 parts weight). The finished product contained approximately 40% solvent.

Example 5

A gasoline composition X was prepared by adding 75 ppm additive A, 75 ppm additive 0 and ppm additive E to a batch of DFI2 reference fuel.

Additive E is a carrier oil compound, namely a linear 010 alcohol polyether with 24 P0 units.

Additive E did not contain any solvents.

Table I below shows the specification for the 0FI2 reference fuel.

Table I

Parameter Units Result Mm. Max. Method RON -96.6 95.0 -EN ISO 5164 MON -86.9 85.0 -EN ISO 5163 Density at 15°C kgIm 733.6 720.0 775.0 EN ISO 12185 DVPE kPa 86.3 60.0 90.0 EN 13016-1 Distillation IBP DC 28.4 --EN ISO 3405 Dist. 70°C %vol 33.2 22.0 50.0 EN ISO 3405 Dist. 100°C %vol 52.6 46.0 71.0 EN ISO 3405 Dist. 150°C %vol 93.5 75.0 -EN ISO 3405 Distillation FBP DC 182.4 -210.0 EN ISO 3405 Dist. Residue %vol 1.0 -2.0 EN ISO 3405 Olefins %vol 7.5 -18.0 EN ISO 22854 Aromatics %vol 32.1 -42.0 EN ISO 22854 Saturates %vol 59.5 --EN ISO 22854 Benzene %vol 0.75 -5.00 EN ISO 22854 Methanol %vol <0.1 -3.00 EN ISO 22854 Ethanol %vol 0.90 -1.00 EN ISO 22854 Iso-Propanol %vol <0.1 -10.00 EN ISO 22854 Iso-Butanol %vol <0.1 -7.00 EN ISO 22854 TBA %vol <0.1 -7.00 EN ISO 22854 MTBE %vol <0.1 -15.00 EN ISO 22854 Oxygenates %vol 0.9 --EN ISO 22854 Oxygen content %wt 0.3 -2.7 EN ISO 22854 Sulphur mg/kg 5.8 --EN ISO 20846 Lead mg/I <2.5 -5.0 EN 237 Oxidation stability mm >1200 360 -EN ISO 7536 Unwashed Gum mgflOOml 5 --EN ISO 6246 Solvent washed gum mg/lOOmI 3 -5 EN ISO 6246 Hydrogen %wt 13.3 --ASTM D 3343 Carbon %wt 86.35 --ASTM D 3343 Carbon! Hydrogen ratio -6.49 --ASTM 0 3343 Hydrogen/Carbon ratio -0.154 --ASTM D3343 Net heating value MJ/kg 42,678 --ASTM D 3338 Net heating value Btu!lb 18347 --ASTM D 3338 Composition X was tested according to the CEC F-05-93 Intake Valve Deposit Test Method.

This test method is designed to evaluate the propensity of gasoline or gasoline additive formulations to prevent intake valve deposits in fuel injected engines.

The engine is an in-line, four cylinder, four stroke 2.3 litre overhead camshaft mechanical/electronic fuel injection engine. After running-in (new engine only) and checking, the engine is operated for a period of 60 hours under cyclic conditions, simulating stop-go operation, with the inlet valves pegged to prevent rotation. The ability of a gasoline or gasoline formulation to influence deposit formation on the inlet valves is determined The results are expressed by the weight of the deposits accumulated during the test on the intake valves and in terms of deposit merit ratings based on a scale from 4.6 (extremely heavy inlet valve deposits) to (clean inlet valve).

The results are presented as the average, over 4 valves.

Full details of the CEC F-06-93 test method can be obtained from the CEC (The Coordinating European Council for the Development of Performance Tests for Fuels, Lubricants and Other Fluids, having its registered office in Brussels, Belgium).

The results for composition X and the base fuel are: Cornposit'n Additive Additive Additive Valve Valve A D E Weight Rating (nigllitre) (mg/litre) (mg/litre) (mg/valve) DF12 fuel ---714.8 7.0 X 75 75 150 22.1 9.8

Claims

<claim-text>Claims 1. A gasoline composition comprising, as an additive, the product of a Mannich reaction between: (a) an aldehyde; (b) an amine; and wherein the phenol is substituted with at least one branched hydrocarbyl group having a molecular weight of between 200 and 3000.</claim-text> <claim-text>2. A gasoline composition according to claim 1 wherein phenol component (c) used to prepare the Mannich additive includes a poly(isobutene) derived substituent.</claim-text> <claim-text>3. A gasoline composition according to claim 1 or claim 2 wherein in the reaction used to make the Mannich additive the molar ratio of component (a) to component (b) is 2-1.6:1, the molar ratio of component (a) to component (c) is 1.6-1.2:1 and the molar ratio of component (b) to component(c) is 1:1.1-1.5.</claim-text> <claim-text>4. A gasoline composition according to any preceding claim wherein component (a) used to prepare the Mannich additive is formaldehyde.</claim-text> <claim-text>5. A gasoline composition according to any preceding claim wherein component (b) used to prepare the Mannich additive is a (poly)ethylene polyamine.</claim-text> <claim-text>6. A gasoline composition according to any preceding claim which further comprises a quaternary ammonium salt additive formed by the reaction a quaternising agent and a compound formed by the reaction of a hydrocarbyl-substituted acylating agent and an amine of formula (B1) or (B2): R2 R2 \ _ _ 4 \ _ _ N X NHR N X [O(CH2)]OH (Bi) (B2) wherein R2 and R3 are the same or different alkyl, alkenyl or aryl groups having from 1 to 22 carbon atoms; X isa bond or alkylene group having from 1 to 20 carbon atoms; n is from 0 to 20; m is from ito 5; and R4 is hydrogen or a C to 022 alkyl group.</claim-text> <claim-text>7. A gasoline composition according to claim 6 wherein the quaternising agent is selected from esters, dialkyl sulfates, benzyl halides, hydrocarbyl substituted carbonates, hydrocarbyl susbsituted epoxides in combination with an acid, alkyl halides, alkyl suifonates, sultones, hydrocarbyl substituted phosphates, hydrocarbyl substituted borates, alkyl nitrites, alkyl nitrates, N-oxides or mixtures thereof.</claim-text> <claim-text>8. A gasoline composition according to claim 7 wherein the quaternising agent is an ester of formula RCQOR1 in which R is an optionally substituted alkyl, alkenyl, aryl or alkylaryl group and R1 is a C to 022 alkyl, aryl or alkylaryl group.</claim-text> <claim-text>9. A gasoline composition according to claim 7 wherein the quaternising agent is selected from dialkyl sulfates, benzyl halides, hydrocarbyl substituted carbonates, hydrocarbyl susbsituted epoxides in combination with an acid, alkyl halides, alkyl sulfonates, sultones, hydrocarbyl substituted phosphates, hydrocarbyl substituted borates, alkyl nitrites, alkyl nitrates, hydroxides, N-oxides or mixtures thereof.</claim-text> <claim-text>10. A gasoline composition according to claim 7 wherein the quaternising agent is selected from dimethyl oxalate, methyl 2-nitrobenzoate, methyl salicylate, styrene oxide or propylene oxide optionally in combination with an additional acid, and mixtures thereof ii. An additive package optionally comprising a carrier fluid which upon addition to a gasoline fuel provides a composition as claimed in any preceding claim.12. A method of operating a spark ignition gasoline engine, the method comprising combusting in the engine a composition as claimed in any preceding claim.13. The use of a Mannich reaction product additive as defined in any of claims ito 10 in a gasoline composition to improve the engine performance of a gasoline engine when using said gasoline composition.14. The use of a Mannich reaction product additive as defined in any of claims 1 to 10 in combination with a quaternary ammonium salt additive as defined in any of claims 6 to 10 to improve the engine performance of a gasoline engine when using said gasoline composition.15. Use according to claim 13 or 14, to reduce existing deposits ("clean-up") or to reduce deposit formation (keep clean").16. Use according to one or more of claims 13, 14 and 15, where the gasoline engine is a direct injection spark ignition gasoline engine.</claim-text>