WO2020181113A1

WO2020181113A1 - Lubricating compositions and base oils for use in the same

Info

Publication number: WO2020181113A1
Application number: PCT/US2020/021232
Authority: WO
Inventors: Hong Yang; Karen Kustedjo; Sooan Shin; James Garrett
Original assignee: Bp Corporation North America Inc.
Priority date: 2019-03-06
Filing date: 2020-03-05
Publication date: 2020-09-10

Abstract

Lubricating compositions and base oils are provided including compositions comprising one or more ether moieties and one or more ester/carboxylic acid moieties used in lubricating compositions that may be derived from naturally occurring vegetable oils.

Description

LUBRICATING COMPOSITIONS AND BASE OILS FOR USE IN THE SAME

FIELD OF THE INVENTION

The present invention relates to lubricating compositions and base oils for use in the same. In particular, the present invention relates to base oils for lubricating compositions comprising ether and ester moieties.

BACKGROUND OF THE INVENTION

Lubricating compositions have a variety of uses. A principal use of said compositions is in lubricating the moving parts of internal combustion engines in motor vehicles and powered equipment such as spark ignition engines and compression ignition engines. Said lubricant compositions generally comprise a variety of additives to aid the lubricating oils in performing their functions such as reduced friction and wear, improved viscosity index, detergency, and resistance to oxidation and corrosion. Said lubricant compositions generally comprise a base oil of lubricating viscosity together with the one or more additives. A lubricant base oil may comprise one or more sources of lubricating oil, referred to as base stocks. Typically, lubricants used in internal combustion engines contain about 90% by weight of base oil and around 10% by weight of additives. Lubricant base stocks may be derived from crude oil. Such base stocks are known as mineral oils. Such lubricant base stocks useful in automotive engine lubricants may be obtained as higher boiling fractions from the refining as crude oil or via synthetic routes, and are classified as Group I, II, III, IV and V base stocks according to API standard 1509,“ENGINE OIL LICENSING AND CERTIFICATION SYSTEM”, April 2007 version 16th edition Appendix E. Lubricant base stocks may also be obtained synthetically using synthetic hydrocarbons (that may themselves be derived from petroleum). Such base stocks are known as synthetic base stocks and include polyalpha-olefins (PAO), synthetic esters, polyalkylene glycols (PAG), phosphate esters, alkylated naphthalenes (AN), silicate esters, ionic fluids and multiply alkylated cyclopentanes (MAC).

Lubricant base oils may also be derived from vegetable oils. Such lubricant base oils are considered more environmentally friendly than the base oils discussed above. Lubricant base oils derived from vegetable oils are generally biodegradable. Naturally occurring vegetable oils themselves however do not always make the best lubricant base oils because they often have high viscosity, poor cold temperature properties as well as low oxidative stability. In particular, carbon-carbon double bonds in the long unbranched fatty acid chains of naturally occurring vegetable oils, and the hydrogen atom in the middle carbon atom of the glycerol unit (carbon atom in the b-position of the ester group) contribute to the low thermal oxidative stability of naturally occurring vegetable oils. Numerous methods have been applied to try and improve the properties of vegetable oils to make them more suitable for use as base oils for lubricating compositions. For example, transesterification of the vegetable oils using an alcohol in the presence of a catalyst to break the vegetable oils into alkyl esters of fatty acids has been explored. Alkyl esters of fatty acids have improved cold temperature properties over naturally occurring vegetable oils. However, the alkyl esters still have low stability to thermal oxidation because of the unsaturated fatty acid chains which comprise one or more carbon-carbon double bonds. It has been attempted to improve the thermal oxidative stability of said compounds by removing the double bonds by hydrogenation, epoxidation and carboxylation.

It has been found that the presence of ether moieties in base stocks can help improve lubricant properties of base oils. For example, ether derived base oils have been found to have various advantages over polyalphaolefms (PAO) in terms of lubricant properties.

WO 2014/207235 discloses lubricant compositions comprising base oils that comprise at least one isoprenoid compound comprising (i) one or two oxygen-containing moieties independently selected from ether and ester moieties; (ii) a first acyclic isoprenoid moiety containing 1 to 5 isoprenyl units; and (iii) optionally, a second acyclic isoprenoid moiety containing 1 to 5 isoprenyl units with the proviso that at least one isoprenoid moiety contains 3 to 5 isoprenyl units where the isoprenoid compound contains a single ether moiety.

JP 2012-56873 discloses lubricant compositions comprising base oils of the formula:

rt,

where R is a linear or branched alkyl group and A is a linear or branched alkylene moiety.

US 2009/0054284 discloses lubricant compositions including: i) base stock comprising an acid ester of a polytrimethylene ether glycol (P03G) and ii) a vegetable oil.

US 2012/0149620 discloses a base stock for a lubricating composition, said base stock comprising a glycol ether-based cyciohexanote ester.

US 3,681,440 discloses lubricating compositions for use in aircraft engines. The compositions comprise esters of tetrahydroxy dineoalkyl ethers of the following formula: US 5,290,465 discloses compounds suitable for use as refrigeration lubricants. The compounds are substituted neopolyols selected from pentaerythritol, dipentaerythritol, trimethyl ol ethane and trimethyl olpropane in which at least one of the OH groups is replaced by a moiety that comprises ether and ester groups.

Other disclosures describe processes for preparing ether-containing compounds from vegetable oils, although not for the purpose of providing a base stock for a lubricating composition.

For example, US 6,201,144 discloses processes for the production of fatty ether esters and fatty ether acids. The process comprises reacting hydroxy fatty acids with one or more of a mixture of g-, d- or E-lactones and a primary or secondary alcohol in the presence of an acid catalyst to form a fatty ether ester, before transesterifying said fatty ether ester with a second nucleophilic alcohol in the presence of an acid catalyst to produce etherified fatty acid esters. Said etherified fatty acid esters are reported to have low viscosity and low temperature melting point properties and may be used as viscosity modifiers in the creation of cosmetics and vegetable oil based biodegradable fluids such as hydraulic fluids and dielectric fluids, as opposed to lubricant base stocks.

US 5,453,534 discloses a process for the preparation of alkoxycarboxylic acid esters by the reaction of hydroxycarboxy!ic acid esters with alcohols in the presence of zeolites or hydrothermally prepared phosphates at elevated temperatures. No particular uses or advantages associated with the esters are disclosed.

There is a continued need in the art for alternative base oils for lubricating compositions. In particular, there is a continued need for lubricating composition base oils that are environmentally friendly, whilst having high lubricant performance properties. There is also a continued need for lubricant base oils with said properties that can be derived easily from natural sources in plentiful supply, for example from vegetable oils.

SUMMARY OF THE PRESENT INVENTION

The present invention is based, in part, on the surprising finding that certain compounds comprising one or more ether moieties and one or more ester/carboxylic acid moieties can be advantageously used in lubricating compositions as lubricant base stocks. Furthermore, said compounds can be derived easily from naturally occurring vegetable oils and are readily biodegradable. Said compounds have been found to exhibit significantly improved lubricant properties over naturally occurring vegetable oils from which they may deri ve. One advantage of said compounds di sclosed herein over naturally occurring vegetable oils is that they typically do not comprise any carbon-carbon double bonds, the presence of which can diminish thermal oxidative stability. A further advantage of the compounds disclosed herein for use as lubricating base oils is that they comprise one or more ether moieties. As discussed above, it has been found that ether moieties confer several advantages with regard to lubricant properties in comparison to base stocks including alkylene or alkenyl chains that do not comprise ether groups, as for instance in the case of conventional PAO base stocks. However, compounds disclosed herein have also been found to have improved lubricant properties over known ether-containing base stocks. The benefits of the invention are also enhanced when the ether moiety comprises a primary ether. Furthermore, the presence of one or more ester moieties in the compounds of the invention may also further enhance the lubri city of the base stock.

Thus, according to an aspect of the invention, there is provided a lubricating composition comprising a base oil of lubricating viscosity and one or more lubricant additives, where the base oil comprises or consists of a base stock of Formula (1) and/or Formula (2):

wherein:

R is a monovalent hydrocarbyl group;

R 2 is selected from a monovalent hydrocarbyl group or H;

Rris a monovalent hydrocarbyl group;

Li and L2 are independently selected from: i) C2 to C12 straight chain or branched a!ky!ene; ii) ; and

iii)

R.₄ is H or methyl,

m is 1, 2 or 3; and

n, o, p and q are independently 1, 2, 3 or 4.

Preferably, Li and/or L₂ is/are selected from C₂ to C12 straight chain or branched alkylene, preferably selected from C4 to C₁₂ straight chain or branched alkylene_, more preferably selected from Ce to Cio straight chain or branched alkylene.

Preferably, Ri, R₂ and R₃ are independently selected from straight chain or branched Ci to C₁₂ alkyl and C4 to C₁₂ cycloalkyl. More preferably, R₂ and R3 are independently selected from straight or branched chain Ci to Ce alkyl, preferably straight chain Ci to C₄ alkyl, and/or wherein R is branched chain C4 to C₁₂ alkyl, preferably branched chain Ce to Cio alkyl.

Preferably, m is 1 or 2, and more preferably rn is 1.

According to yet another aspect of the invention, there is provided a base oil for a lubricating composition which base oil comprises a base stock of Formula (1) or Formula (2) as defined above and one or more additional base stocks selected from Group I, Group II, Group III, Group IV and Group V base stocks and mixtures thereof.

According to yet another aspect of the invention, there is provided a method of preparing a lubricating composition, said method comprising preparing a base stock of Formula (1) and/or Formula (2), providing a base oil comprising a base stock of Formula (1) and/or Formula (2), and preparing a lubricating composition from said base oil by blending the base oil with one or more lubricant additives.

According to yet another aspect of the invention, there is provided a method of lubricating a surface, said method comprising supplying a lubricating composition of the invention to said surface, such as wherein the lubricating composition is supplied to a surface in an internal combustion engine. According to yet another aspect of the invention, there is provided the use of a lubricating composition of the invention for lubricating a surface, such as wherein the lubricating composition is used for lubricating a surface in an internal combustion engine.

According to yet another aspect of the invention, there is provided a method of improving the oxidative stability performance, fuel economy performance, and/or piston cleanliness performance of a lubricating composition, comprising the step of providing to the lubricating composition a base stock of Formula (1) or Formula (2) as defined above and/or a base oil according to the invention.

According to yet another aspect of the invention, there is provided a method of improving the fuel economy performance and/or piston cleanliness performance of an engine and/or a vehicle, such as an automotive vehicle associated with an internal combustion engine, comprising the step of providing to the engine and/or the vehicle a base stock of Formula (1) and/or Formula (2) as defined above, a base oil according to the invention, and/or a lubricating composition according to the invention.

According to yet another aspect of the invention, there is provided the use of a base stock of Formula (1) or Formula (2) as defined above, a base oil according to the invention, and/or a lubricating composition according to the invention to improve the oxidative stability performance, fuel economy performance and/or piston cleanliness performance of a lubricating composition and/or to improve the fuel economy performance and/or piston cleanliness performance of an engine and/or a vehicle, such as an automotive vehicle associated with an internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS

The present inventions will now be described by way of example and with reference to the accompanying Figures in which:

FIGURES 1 to 5 show' various synthetic schemes for synthesizing compounds of Formula (1) from fatty acids and alkyl esters of fatty acids.

DETAILED DESCRIPTION OF THE INVENTION

Definition of terms

For the purposes of the present invention, the following terms as used herein shall, unless otherwise indicated, be understood to have the following meanings. Other terms that are not as defined below' are to be understood as their normal meaning in the art.

The term "hydrocarbyl" as used herein, refers to a monovalent or divalent group, preferably a monovalent group, comprising a major proportion of hydrogen and carbon atoms, preferably consisting exclusively of hydrogen and carbon atoms, which group may be aromatic or preferably saturated aliphatic or unsaturated aliphatic, and the hydrocarbyl group may be optionally substituted by one or more groups that are preferably selected from hydroxyl (-OH) groups, carboxylic acid groups, (>. to Ch afkoxy, C to Cs alkoxyalkoxy,€₃ to Ce cycloalkyl, -C0₂(Ci to C₆)alkyl, and -OC(0)(Ci to Cejalkyl. Additionally or

alternatively, one or more of the carbon atoms, and any substituents attached thereto, of the hydrocarbyl group may be replaced with an oxygen atom (-0-), provided that the oxygen atom is not bonded to another heteroatom. The hydrocarbyl may contain from 1 to 40 carbon atoms.

The hydrocarbyl group may be entirely aliphatic or a combination of aliphatic and aromatic portions. In some examples, the hydrocarbyl group includes a branched aliphatic chain which is substituted by one or more aromatic groups. Examples of hydrocarbyl groups therefore include acyclic groups, as well as groups that combine one or more acyclic portions and one or more cyclic portions, which may be selected from carbocyclic, aryl and heterocyclyl groups. The hydrocarbyl group includes monovalent groups and polyvalent groups as specified and may, for example, include one or more groups selected from alkyl, alkenyl, alkynyl, carbocyclyl (e.g. cycloalkyl or cycloalkenyl), aryl and heterocyclyl.

The term "alkyl" as used herein refers to a monovalent straight- or branched-chain alkyl moiety containing from 1 to 40 carbon atoms. Examples of alkyl groups include alkyl groups containing from 1 to 30 carbon atoms, e.g. from 1 to 20 carbon atoms, e.g. from 1 to 18 carbon atoms. Particular examples include alkyl groups containing 4, 6, 8, 10, 12 or 14 carbon atoms. Unless specifically indicated otherwise, the term“alkyl” does not include optional substituents.

The term "cycloalkyl" as used herein refers to a monovalent saturated aliphatic hydrocarbyl moiety containing from 3 to 40 carbon atoms and containing at least one ring, wherein said ring has at least 3 ring carbon atoms. The cycloalkyl groups mentioned herein may optionally have alkyl groups attached thereto. Examples of cycloalkyl groups include cycloalkyl groups containing from 3 to 16 carbon atoms, e.g. from 3 to 10 carbon atoms. Particular examples include cycloalkyl groups containing 3, 4, 5 or 6 ring carbon atoms. Examples of cycloalkyl groups include groups that are monocyclic, polycyclic (e.g. bicyclic) or bridged ring system. Examples of cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like.“Cycloalkenyl” groups correspond to non-aromatic cycloalkyl groups containing at least one carbon-carbon double bond.

The term "alkenyl" as used herein refers to a monovalent straight- or branched-chain alkyl group containing from 2 to 40 carbon atoms and containing, in addition, at least one carbon-carbon double bond, of either E or Z configuration unless specified. Examples of alkenyl groups include alkenyl groups containing from 2 to 28 carbon atoms, e.g. from 3 to 26 carbon atoms, e.g from 4 to 24 carbon atoms. Examples of alkenyl groups include alkenyl groups containing from 2 to 20 carbon atoms, e.g. from 2 to 12 carbon atoms, e.g. from 2 to 10 carbon atoms. Particular examples include alkenyl groups containing 2, 3, 4, 5 or 6 carbon atoms. Examples of alkenyl groups include ethenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3- butenyl, i-pentenyl, 2-pentenyl, 3-pentenyl, 1-hexenyl, 2-hexenyl, 3-hexeny! and the like.

The term“alkylene” as used herein refers to a divalent straight- or branched-chain saturated hydrocarbyl group consisting of hydrogen and carbon atoms and containing from 1 to 30 carbon atoms. Examples of alkylene groups include alkylene groups that contain from 1 to 20 carbon atoms, e.g. from 1 to 12 carbon atoms, e.g. from 1 to 10 carbon atoms. Particular examples include alkylene groups that contain 1 , 2, 3, 4, 5 or 6 carbon atoms.

The term "aryl" as used herein refers to an aromatic carbocyclic ring system containing from 6 to 14 ring carbon atoms. Examples of aryl groups include aryl groups containing from 6 to 10 ring carbon atoms, e.g. 6 ring carbon atoms. An example of an aryl group includes a group that is a monocyclic aromatic ring system or a polycyclic ring system containing two or more rings, at least one of which is aromatic. Examples of aryl groups include aryl groups that comprise from 1 to 6 exocyc!ic carbon atoms in addition to ring carbon atoms. Examples of aryl groups include aryl groups that are monovalent or polyvalent as appropriate. Examples of monovalent aryl groups include phenyl, benzyl naphthyl, fiuorenyl, azulenyl, indenyl, anthryl and the like. An example of a divalent aryl group is 1,4- phenylene.

The term "heterocyclyl" as used herein refers to a saturated (e.g. heterocycloalkyl) or unsaturated (e.g. heteroaryl) heterocyclic ring moiety containing from 3 to 14 ring atoms, wherein said ring atoms include at least one ring carbon atom and at least one ring

heteroatom selected from nitrogen, oxygen and sulfur. Examples of heterocyclyl groups include heterocyclyl groups that contain from 3 to 10 ring atoms, e.g. from 3 to 6 ring atoms. Particular examples include heterocyclyl groups that contain 5 or 6 ring atoms, including for example, groups that are saturated, unsaturated or aromatic. Examples of heterocyclyl groups include heterocyclyl groups that, in addition to ring carbon atoms, comprise from 1 to 6 exocyclic carbon atoms. Examples of heterocyclyl groups include those that are monovalent or polyvalent as appropriate.

The term "heteroary!" as used herein refers to an aromatic heterocyclic ring system containing from 5 to 14 ring atoms, wherein said ring atoms include at least one ring carbon atom and at least one ring heteroatom selected from nitrogen, oxygen and sulfur. Examples of heteroaryl groups include heteroaryl groups that are a monocyclic ring system or a polycyclic (e.g. bicyclic) ring system, containing two or more rings, at least one of which is aromatic. Examples of heteroaryl groups include those that, in addition to ring carbon atoms, comprise from 1 to 6 exocyclic carbon atoms. Examples of heteroaryl groups include those that are monovalent or polyvalent as appropriate. Examples of heteroaryl groups include furanyl, and benzo[b]furanyl groups.

The term“base oil” as used herein refers to the continuous oil phase of the lubricating composition in which the one or more lubricant additives is dissolved or dispersed and which oil phase comprising one or more base stocks. The base oils used in the lubricating compositions of the present invention are of lubricating viscosity.

Base stocks of Formula (1) and Formula (2)

Lubricating compositions of the present invention comprise a base oil of lubricating viscosity and one or more lubricant additives, where the base oil comprises or consists of a base stock of Formula (1) and/or Formula (2):

wherein:

Ri is a monovalent hydrocarbyl group;

R₂ is selected from a monovalent hydrocarbyl group or H;

R₃ is a monovalent hydrocarbyl group

Li and L₂ are independently selected from:

i) C₂ to C₁₂ straight chain or branched alky!ene, ii) V

; and iii)

R.₄ is H or methyl,

m is 1, 2 or 3; and

n, o, p and q are independently 1, 2, 3 or 4.

In preferred embodiments, one or both of Ri and Ri is a branched monovalent hydrocarbyl group, for example a branched chain Ci to C12 alkyl. Branching in these groups helps lower the viscosity of the base oils or lubricating compositions comprising them, without leading to higher evaporation losses and undesirable NOACK volatility.

In some embodiments, Ri, R and Rs are independently selected from straight chain or branched Ci to C12 alkyl and C₄ to C₁₂ cycloalkyl. In preferred embodiments, R₂ and R₃ are independently selected from straight or branched chain Ci to Ce alkyl, more preferably straight chain Ci to€’₄ alkyl; and/or wherein Ri is straight or branched chain C₄ to C₁₂ alkyl, more preferably branched chain Cc, to C₁₀ alkyl. In particularly preferred embodiments, one or both of Ri and R₂ is branched chain, more preferably where Ri is branched and R₂ is straight chain.

In other preferred embodiments, m is 1 or 2, and more preferably 1.

In one preferred embodiment, Li and/or L2 is/are selected from C2 to C12 straight chain or branched alkylene, preferably selected from C₄ to C12 straight chain or branched alkylene_. more preferably selected from Ce to C10 straight chain or branched alkylene. For example, the base stock of Formula (1) or Formula (2) is preferably selected from a compound of Formula (3), (4), (5), (6) and (7) below:

wherein: Ri and R3 are selected from straight chain or branched Ci to C12 alkyl.

In an alternative embodiment, Li and/or Lz, preferably at least L2, is/are selected

from;

In this embodiment, n, o, p and q are preferably independently 1 or 2, and more preferably n, o, p and q are 1.

In the compounds of Formula (1) and Formula (2), Ri and R3 may be the same or different. In a preferred embodiment, Ri and R3 are the same.

In other embodiments, the moiety R2-L1 at the terminal end of Formula (1) and Formula (2) includes the same number of carbon atoms as Ri.

As the skilled person will appreciate, the base stock of Formula (1) may be derived from the reaction of one or more unsaturated fatty acids. Preferably, the one or more unsaturated fatty acids are selected from myristoleic acid, palmitoleic acid, sapienic acid, oleic acid, elaidic acid, vaccenic acid, gadoleic acid, eicosenoic acid, erucic acid, nervonic acid, imoleic acid, eicosadienoic acid, docosadienoic acid, or any combination thereof.

In an embodiment, the base stock is a base stock of Formula (1) and m ^:= 1. In this embodiment, the base stock is preferably derived from the reaction of one or more monounsaturated fatty acids (i.e fatty acids comprising one carbon-carbon double bond).

In another embodiment, the base stock is a base stock of Formula (1) and m = 2. In this embodiment, the base stock is preferably derived from the reaction of one or more di- unsaturated fatty acids (i.e. fatty acids comprising two carbon-carbon double bonds).

In another embodiment, the base stock is a base stock of Formula (1) and m = 3. In this embodiment, the base stock is preferably derived from the reaction of one or more tri- unsaturated fatty acids (i.e. fatty acids comprising three carbon-carbon double bonds).

Preferably, the reaction of one or more fatty acids to form compounds of Formula (1) comprises any one or more of hydroformylation, esterification, aceta!ization, reductive etherification, cracking, hydrogenation, and any combination thereof.

In an embodiment, the reaction of one or more fatty acids to form compounds of Formula (1) comprises hydroformylation of a carbon-carbon double bond in the fatty acid hydrocarbon chain to form an aldehyde moiety, followed by an esterifieation-acetaiization reaction in which the aldehyde moiety is converted to an acetal moiety and the terminal carboxylic acid moiety of the fatty acid is converted to an ester moiety, followed by cracking of the acetal moiety so as to form an end ether moiety, followed by hydrogenation of the en ether moiety to form an ether moiety.

In another embodiment, the compounds of Formula (1) are formed as described above, except that the starting material is a fatty acid ester instead of a fatty acid and no further esterification step is required.

In another embodiment, the reaction of one or more faty acids to form compounds of Formula (1) comprises forming an ester of the one or more fatty acids, hydroformylation of a carbon-carbon double bond in the hydrocarbon chain of the fatty acid ester to form an aldehyde moiety, followed by a reductive etherification reaction which converts the aldehyde moiety to an ether moiety.

In another embodiment, the compounds of Formula (1) are formed by

hydroformylation of a carbon-carbon double bond of an alkyl ester of a faty acid to form an aldehyde moiety, followed by hydrogenation of the aldehyde moiety to form an alcohol moiety, followed by reductive etherification of the alcohol moiety to form an ether. This method of synthesis is particularly preferred when ni =1 and the fatty acid ester comprises two or three carbon-carbon double bonds.

As the skilled person will appreciate, the base stock of Formula (2) may be derived from the reaction of one or more unsaturated fatty alcohols. In some embodiments, the base stock of Formula (2) is derived from the reaction of palmitoley! alcohol (cis-9-hexadecen-l- ol), oleyl alcohol (l-octadecenol), erucyl alcohol (cis-13-docosen-l-ol), or any combination thereof. Preferably, the reaction of one or more fatty alcohols to form compounds of Formula (2) comprises esterification, hydroformylation, acetalization, reductive etherification, cracking, hydrogenation, or any combination thereof. Preferably, one or more unsaturated fatty alcohols are converted to esters by reaction with a carboxylic acid initially before undergoing further reaction to form the base stock of Formula (2).

In an embodiment, the reaction of one or more fatty alcohols to form compounds of Formula (2) comprises reaction of the alcohol moiety of the fatty alcohol with a carboxylic acid to form an ester of the one or more fatty alcohols, hydroformylation of a carbon-carbon double bond in the fatty alcohol hydrocarbon chain to form an aldehyde moiety, followed by an acetalization reaction in which the aldehyde moiety is converted to an acetal moiety, followed by cracking of the acetal moiety so as to form an enol ether moiety, followed by hydrogenation of the enol ether moiety to form an ether moiety.

In another embodiment, the reaction of one or more fatty alcohols to form compounds of Formula (2) comprises reaction of the alcohol moiety of the fatty alcohol with a carboxylic acid to form an ester of the one or more fatty alcohols, hydroformylation of a carbon-carbon double bond in the hydrocarbon chain of the ester of the fatty alcohol to form an aldehyde moiety, followed by a reductive etherification reaction which converts the aldehyde moiety to an ether moiety.

In another embodiment, the reaction of one or more faty alcohols to form compounds of Formula (2) comprises reaction of the alcohol moiety of the fatty alcohol with a carboxylic acid to form an ester of the one or more fatty alcohols, followed by hydroformylation of a carbon-carbon double bond of the ester of the one or more fatty alcohols to form an aldehyde moiety, followed by hydrogenation of the aldehyde moiety to form an alcohol moiety, followed by reductive etherification of the alcohol moiety to form an ether.

In an embodiment, the compound of Formula (1) or Formula (2) includes a total number of carbon atoms of from 25 to 35 carbon atoms, preferably from 28 to 32 carbon atoms. Compounds of Formula (I) and Formula (2) having carbon numbers in these ranges have been found to be particularly suitable for use as base stocks in lubricating compositions according to the invention.

In an embodiment, the base stock of Formula (1) or Formula (2) has at least one or any combination of, preferably all, of:

a kinematic viscosity at 40 °C of less than 25 cSt, such as less than 20 cSt, or less than 17 cSt;

a kinematic viscosity at 100 °C of less than 7 cSt, such as less than 5 cSt, or less than 4 cSt;

a vi scosity index of greater than 100, such as greater than 110, or greater than 120;

a DSC (Differential Scanning Calorimeter) oxidation onset temperature >190 °C, preferably >200 "C;

a viscosity at 150 °C and a shear rate of 10⁶ s ¹ of no greater than 1.7 cP, such as no greater than 1.5 cP;

a Noack volatility of less than 26 %, such as less than 20%, less than 16 %, or less than 12 % by weight, and

a pour point of less than -10 °C, such as less than -25 °C, or less than -35 °C, or less than - 50 "C.

a kinematic viscosity at 40 °C of less than 60 cSt, such as less than 55 cSt, or less than 50 cSt,

a kinematic viscosity at 100 °C of less than 12 cSt, such as less than 10 cSt, or less than 9 5 cSt;

a viscosity index of greater than 100, such as greater than 110, or greater than 120;

a Noack volatility of less than 25 %, such as no more than 20%, less than 15 %, or less than 10 % by weight.

In an embodiment, the lubricating composition has at least one or any combination of, preferably all, of:

an oxidative stability performance on a CEC -L -088-02 and/or CEC-L-111-16 test indicated by an absolute viscosity increase at 40 °C of no more than 45 cSt, such as no more than 35 cSt or no more than 25 cSt;

a fuel economy performance on a CEC-L-054-96 test of at least 2.5 %, such as at least 3 %; and a piston cleanliness performance on a CEC-L-088-02 and/or CEC-L-111-16 test indicated by an overall piston merit of at least 8.5, such as 9.

Compounds of Formula (1) and Formula (2) may comprise primary ether moieties, secondary' ether moieties, or both primary and secondary ether moieties. In preferred embodiments, the compounds of Formula (1) and/or Formula (2) comprise primary ether moieties. More preferably, the R1-O-CH2- moiety of the base stock comprises a primary ether (i.e. where the carbon ato of Ri which is bonded to the oxygen atom of the above moiety is itself only bonded to one carbon atom). Still more preferably, the compounds of Formula (1) and/or Formula (2) do not comprise secondary ether moieties. For example, in one preferred embodiment, m = 1 and the compounds of Formula (1) and Formula (2) comprise primary ether moieties and do not comprise secondary ether moieties.

As will be appreciated by the skilled person, the term“primary ether” as used herein refers to the scenario where both carbon atoms adjacent to the oxygen atom of the ether moiety are only bonded to one other carbon atom. In contrast, the term secondary ether moiety as used herein refers to the scenario where either one of, or both, of the carbon atoms adjacent to the oxygen atom of the ether moiety are bonded to two carbon atoms.

Advantageously, it has been found by the inventors that compounds of Formula (1) and Formula (2) comprising primary ether moieties and preferably no secondary ether moieties have particularly advantageous properties that lead to improved performance as base stocks in lubricating compositions over compounds that lack a primary ether moiety. For example, such compounds of Formula (1) and Formula (2) have been found to have a lower kinematic viscosity, a higher viscosity index, and/or a greater resistance to oxidation in lubricating compositions.

Base stocks of Formula (1) and Formula (2) may be synthesized by any suitable technique.

In one embodiment, compounds of Formula (1) may be synthesized by a process that involves subjecting an unsaturated carboxylic acid starting material to hydroformyl ation- esterification-acetaiization reactions, followed by cracking of the acetal to an en ether, followed by hydrogenating the end ether so as to form the compound of Formula (1). In an embodiment, the carboxylic acid is a fatty acid. Preferably, the fatty acid is oleic acid.

The hydroformylation-esterification-acetalization reactions are typically conducted by reacting a carboxylic acid starting material with a mixture of carbon monoxide and hydrogen in a solvent in the presence of a hydroformylation catalyst (such as a suitable rhodium or cobalt catalyst, for example cobalt carbonyl (HCo(CO)4), or a phosphine-modified derivative thereof (HCoiCO^iPRs), and rhodium phosphine (HRh(CO)(PPh3)3) at elevated temperature, preferably from 100°C to 150°C, and at elevated pressure, preferably up to around 2000 psi (13.8 MPa). Hydroformyiation occurs at the carbon-carbon double bond before esterification- acetalization of the hydroformulated carboxylic acid takes place.

The hydroformylation-esterification-acetalization reactions are typically conducted in one or two process steps. In the one process step approach, the reaction is performed in the presence of an alcohol solvent, preferably a low molecular weight alcohol such as C₁-C₄ alcohol. The presence of the alcohol solvent leads to in situ esterification-acetalization of the hydroformylated carboxylic acid, as it is formed. In the two process step approach, the carboxylic acid starting material undergoes hydroformyiation (for example, in the absence of a labile alcohol solvent) so as to first form the hydroformylated product followed by a separate esterification-acetalization reaction.

The subsequent step of converting the acetal product of the hydroformyl ation- esterification-acetalization reactions to an enol ether typically involves a thermal cracking reaction at a temperature of preferably from !5Q°C to 18Q°C and preferably under vacuum distillation conditions.

The reaction of oleic acid under the conditions described above so as to form a base stock of Formula (1) is shown in Figure 1, where: a = hydroformylation-esterification- aeeta!ization, b = hydroformyiation, c = esterification-acetalization, d = cracking, e = hydrogenation. Synthetic route a-d-e involves the one step hydroformylation-esterification- acetalization reaction, whilst synthetic route b-c-d-e involves the two step hydroformylation- esterification-acetalization reaction, as discussed above.

In another embodiment, base stocks of Formula (1) or (2) are prepared in the same manner as described above, with the exception that the starting material is an unsaturated ester of a carboxylic acid. In an embodiment, the starting material which is used for preparing a compound of Formula (1) is an unsaturated ester of a fatty acid, preferably an unsaturated ester of oleic acid. In an embodiment, the starting material which is used for preparing a compound of Formula (2) is an unsaturated ester of a fatty alcohol. As will be appreciated, when the starting material is an unsaturated ester of a carboxylic acid, the first step of the reaction only involves hydroformyiation followed by acetalization. There is no requirement for an esterification step because the carboxylic acid moiety in the starting material molecule has already been esterified. The reaction of an oleic acid ester under the conditions discussed above to form a base stock of Formula (1) is shown in Figure 2, where: a = hydroformylation-acetalization, b = hydroformylation, c = acetalization, d ^:= cracking, e = hydrogenation. Synthetic route a-d-e involves the one step hydroformylation-esterification- acetalization reaction whilst synthetic route b-c-d-e involves the two step hydroformy!ati on-esterification- acetalization reaction

The synthesis of the enol ether of fatty acids via an acetal ester as described above is disclosed in: Frankel, E.N ei ai, Journal of the American Oil Chemist’s Society (JAOCS), Volume 49, pages 222 to 228, 1972; Journal of the American Oil Chemist’s Society (JAOCS), Volume 53, Pages 190 to 195, 1976; Journal of the American Oil Chemist’s Society (JAOCS), Volume 53, Number 5, pages 198 to 203, 1976; Journal of the American Oil Chemist’s Society (JAOCS), Volume 61, pages 419 to 425, 1984 Hydroformylation of mono-un saturated and polyunsaturated fatty acids or fatty acid alkyl esters is described in Journal of the American Oil Chemist’s Society (JAOCS), Volume 61, pages 419 to 425, 1984 and US 3,787,459

In some embodiments, base stocks of Formula (1) or (2) may be synthesized by subjecting an unsaturated alkyl ester starting material to a hydroformylation step, followed by a reductive etherification step with alcohol. In one embodiment, the unsaturated alkyl ester starting material which is used for preparing a compound of Formula (1) is an alkyl ester of a fatty acid. Preferably, the unsaturated alkyl ester starting material is an alkyl ester of oleic acid. In an embodiment, the starting material which is used for preparing a compound of Formula (2) is an unsaturated ester of a fatty alcohol.

The hydroformylation step typically comprises reacting the starting material with a mixture of carbon monoxide and hydrogen in a suitable solvent such as toluene in the presence of a suitable hydroformylation catalyst (such as a suitable rhodium or cobalt catalyst, for example cobalt carbonyl (HCo(CO)4), or a phosphine-modified derivative thereof (HCo(CO)3(PR.3), and rhodium phosphine (HRh(CO)(PPh3)3) such as rhodium at elevated temperature, preferably from 10Q°C to 150°C, and at elevated pressure, preferably up to 2000 psi (13.8 MPa). The hydroformylated reaction product of this step may then be further converted into an ether by reductive etherification with an alcohol using a suitable catalyst, including acid catalysts (e.g. acid resins and zeolites) or hydrogenation catalysts (e.g. such as Pd, Pt and Ni based catalysts) . Alternatively, the desired product may be formed through an acetalization step in the presence of an alcohol and an acid catalyst, such as those exemplified above, before one of the alcohol groups is removed from the acetal by hydrogenation using a hydrogenation catalyst. The formation of a compound of Formula (1) by such a process, starting form an alkyl ester of oleic acid is shown in Figure 3, where; a ^::: hydroformylation, b= reductive etherification, c = acetalization, and d = hydrogenation. Synthetic route a-b corresponds to the route of hydroformylation and reductive etherification, whilst synthetic route a-c-d gives the route for hydroformylation, acetalization and hydrogenation.

Base stocks of Formula (1) may also be synthesized starting from carboxylic acid or ester starting materials that comprise more than one carbon-carbon double bond. For example, base stocks of Formula (1) may be synthesized starting from fatty acids or alkyl esters of fatty acids that comprise more than one carbon-carbon double bond. Examples of such fatty acids include di-unsaturated fatty acids (two carbon-carbon double bonds) and tri- unsaturated fatty acids (three carbon-carbon double bonds). In an embodiment, the starting materials for producing base stocks of Formula (1) comprise linoleic acid, Iinolenic acid, or esters of said acids. Either of the synthetic methods discussed above in the context of monounsaturated starting materials may also be applied to starting materials comprising two or three carbon-carbon double bonds.

Base stocks of Formula (1) produced from such starting materials will compri se more than one ether moiety because the reaction conditions introduce an ether moiety at each double bond in the starting material molecule.

In another embodiment, compounds of Formula (1) comprising more than one ether moiety may be produced from a starting material that is an alkyl ester of a fatty acid where the starting material comprises two or three carbon-carbon-double bonds. Accordingly, starting materials may include alkyl esters of linoleic acid or Iinolenic acid. The method typically comprises a step of hydroformylation of the starting material, before hydrogenation of the reaction product of the hydroformylation step to form an alcohol; before reductive etherification of the alcohol with an aldehyde to form ether moieties, substantially as described hereinbefore.

The step of hydroformylation is substantially as described hereinabove. After this step, hydrogenation to reduce the aldehyde functions to hydroxyl groups may take place. After this step, the product of the hydrogenation step is typically reacted with an aldehyde in the presence of a suitable catalyst including acid catalysts (e.g. acid resins and zeolites) or hydrogenation catalysts (e.g. such as Pd, Pt and Ni based catalysts) so as to form ether moieties by reductive etherification. Alternatively, reductive etherification of the hydroformylated product may be undertaken using an alcohol. Preparation of compounds of Formula (1) comprising multiple ether groups are in Figure 4 (starting from an alkyl ester of linoleic acid) and Figure 5 (starting from an alky] ester of linolenic acid), where: a = hydroformylation, b = reductive etherification with an alcohol (RiOH), c = hydrogenation and b ^:= reductive etherification with an aldehyde (RiCHO). In both Figure 4 and Figure 5, synthetic route a-b is the path of hydroformylation followed by reductive etherification with an alcohol, whilst synthetic route a-c-d is the path of hydroformylation followed by hydrogenation of the formed aldehyde to alcohol, then reductive etherification of the product with an aldehyde

Base stocks of Formula (2) may be synthesized in similar ways to those described above. In particular, unsaturated carbon-carbon double bonds in appropriate starting materials, such as unsaturated fatty alcohols, may be converted to ether moieties using the methods discussed above.

Lubricating compositions and base oils

The lubricating compositions of the invention are preferably for use in engines. The term lubricating composition or lubricant composition as used herein in the context of a lubricating composition for use in an engine is intended to refer to compositions suitable for lubricating the working parts of an engine. Preferably, the engine is an internal combustion engine. Suitable internal combustion engines include, for example, engines used in automotive applications, engines used in marine applications and engines used in land- based power generation plants and engines in wind turbine. The lubricating compositions are particularly suited to use in an automotive internal combustion engine.

As will be appreciated, a base oil of a particular viscosity may be suitable for one specific lubricating function within an engine, whereas a different base oil with different viscosity may be suitable for a different lubricating function within said engine. The suitability of a particular base oil with a particular viscosity for a particular lubricating function in an engine would be familiar to those of skill in the art.

The lubricating compositions of the present disclosure comprise a base oil formed of one or more base stocks. The base oil of the lubricating composition of the invention may consist of only a base stock according to Formula (1) or Formula (2). Alternatively, the base oil of the invention may comprise a base stock according to Formula (1) or Formula (2) and an additional base stock. For example, the base oil may comprise a base stock compound of Formula (1) or Formula (2) and one or more additional base stocks selected from Group I, Group II, Group III, Group IV and Group V base stocks and mixtures thereof. The one or more additional base stocks may be selected from naphthenic, aromatic, and paraffinic mineral oils. Suitable synthetic oils may also be selected from, among others, ester-type oils (such as silicate esters, pentaerythritol esters and carboxylic acid esters), esters, diesters, polyol esters, polyalphaolefms (also known as PAOS or poly-alpha-olefms), hydrogenated mineral oils, silicones, silanes, polysiloxanes, alkylene polymers, polyglycol ethers, polyols, bio-based lubricants and/or mixtures thereof.

The base oil may thus comprise 100% of a base stock compound of Formula (1) and/or Formula 2. Alternatively, the base oil comprises greater than 10 %, such as greater than 25 %, or greater than 40 % by weight of the base stock of Formula (1) and/or Formula (2). Thus, in some embodiments, the base oil of the lubricating composition of the invention comprises one or more additional base stocks selected from Group I, Group II, Group III, Group IV and Group V base stocks, and mixtures thereof.

In another aspect, the present invention provides a base oil for use in the lubricating composition described herein, wherein the base oil comprises a base stock Formula (1) or Formula (2) and further comprises one or more additional base stocks selected from Group I, Group II, Group III, Group IV and Group V base stocks, and mixtures thereof. Preferably, the base oil comprises greater than 10 %, such as greater than 25 %, or greater than 40 % by weight of the base stock of Formula (1) and/or Formula (2).

The lubricating composition of the invention may comprise any suitable amount of base oil and one or more lubricant additives. Typically, the one or more additives are present in the composition in an amount of from 0.1 wt. % to 40 wt. %, for example, 5 wt. % to 40 wt. %, such as 10 wt. % to 30 wt. %, although it is possible for the one or more additives to be present in amounts outside of this range. Accordingly, the lubricating composition may comprise greater than 50 %, such as greater than 65 %, or greater than 80 % by weight of base oil, and preferably from 85% to 95% by weight of base oil.

Suitable lubricant additives include detergents (including metallic and non- metallic detergents), friction modifiers, dispersants (including metallic and non-metallic dispersants), viscosity modifiers, dispersant viscosity modifiers, viscosity index improvers, pour point depressants, anti-wear additives, rust inhibitors, corrosion inhibitors, antioxidants (sometimes also called oxidation inhibitors), anti-foams (sometimes also called anti-foaming agents), seal swell agents (sometimes also called seal compatibility agents), extreme pressure additives (including metallic, non-metallic, phosphorus containing, non-phosphorus containing, additional sulfur containing and non-sulfur containing extreme pressure additives), surfactants, demulsifiers, anti-seizure agents, wax modifiers, lubricity agents, anti-staining agents, chromophoric agents, metal deactivators, and mixtures of two or more thereof. In some embodiments, the lubricating composition comprises a detergent. Examples of detergents include ashless detergents (that is, non-metal containing detergents) and metal- containing detergents. Suitable non-metallic detergents are described for example in US 7,622,431. Metal-containing detergents comprise at least one metal salt of at least one organic acid, which is called soap or surfactant. Suitable organic acids include for example, sulphonic acids, phenols (suitably suifurised and including for example, phenols with more than one hydroxyl group, phenols with fused aromatic rings, phenols which have been modified for example, alkylene bridged phenols, and Mannich base-condensed phenols and saligenin-type phenols, produced for example by reaction of phenol and an aldehyde under basic conditions) and suifurised derivatives thereof, and carboxylic acids including for example, aromatic carboxylic acids (for example hydrocarbyl-substituted salicylic acids and derivatives thereof, for example hydrocarbyl substituted salicylic acids and suifurised derivatives thereof).

In some embodiments, the lubricating composition comprises a friction modifier. Suitable friction modifiers include for example, ash-producing additives and ashless additives. Examples of suitable friction modifiers include fatty acid derivatives including for example, fatty acid esters, amides, amines, and ethoxylated amines. Examples of suitable ester friction modifiers include esters of glycerol for example, mono-, di-, and tri-oleates, mono-palmitates and mono-myri states. A particularly suitable fatty acid ester friction modifier is glycerol monooleate. Examples of suitable friction modifiers also include molybdenum compounds for example, organo molybdenum compounds, molybdenu dialkyldithi ocarbamat.es, molybdenum dialkylthiophosphates, molybdenum disulfide, tri molybdenum cluster dialkyldithiocarbamates, non-sulfur molybdenum compounds and the like. Suitable molybdenum-containing compounds are described for example, in EP 1533362 A1 for example in paragraphs [0101] to [0117].

In some embodiments, the lubricating composition comprises a dispersant. Examples of suitable ashless dispersants include oil soluble salts, esters, amino-esters, amides, imides and oxazolines of long chain hydrocarbon-substituted mono- and polycarboxylic acids or anhydrides thereof; thiocarhoxylate derivatives of long chain hydrocarbons; long chain aliphatic hydrocarbons containing polyamine moieties attached directly thereto; Mannich condensation products formed by condensing a long chain substituted phenol with formaldehyde and polyalkylene polyamine; Koch reaction products and the like.

In some embodiments, the lubricating composition comprises a dispersant viscosity modifier. Examples of suitable dispersant viscosity modifiers and methods of making them are described in WO 99/21902, WO 2003/099890 and WO 2006/099250 In some embodiments, the lubricating composition comprises a viscosity index improver. Examples of suitable viscosity modifiers include high molecular weight hydrocarbon polymers (for example polyisobutylene, copolymers of ethylene and propylene and higher alpha-olefins); polyesters (for example polymethacrylates); hydrogenated po!y(styrene~co~butadiene or isoprene) polymers and modifications (for example star polymers); and esterified poly(styrene-co-maleic anhydride) polymers. Oil- soluble viscosity modifying polymers generally exhibit number average molecular weights of at least about 15000 to about 1000000, such as about 20000 to about 600000 as determined by gel permeation chromatography or light scattering methods.

In some embodiments, the lubricating composition comprises a pour point depressant. Examples of suitable pour point depressants include Cg to Cig dialkyl fumarate/vinyl acetate copolymers, methacrylates, polyacrylates, polyarylamides, polymethacrylates, polyalkyl methacrylates, vinyl fumarates, styrene esters, condensation products of haloparaffm waxes and aromatic compounds, vinyl carboxylate polymers, terpolymers of dialkyfumarates, vinyl esters of fatty acids and allyJ vinyl ethers, wax naphthalene and the like. In at least some examples, the at least one lubricant additive includes at least one anti-wear additive. Examples of suitable anti -wear additives include non-phosphorus containing additives for example, su!furised olefins. Examples of suitable anti-wear additives also include phosphorus-containing anti-wear additives. Examples of suitable ashless phosphorus- containing anti-wear additives include trilauryl phosphite and tri phenyl phosphorothionate and those disclosed in paragraph [0036] of US 2005/0198894 Examples of suitable ash-forming, phosphorus-containing anti-wear additives include dihydrocarbyl dithiophosphate metal salts. Examples of suitable metals of the dihydrocarbyl dithiophosphate metal salts include alkali and alkaline earth metals, aluminium, lead, tin, molybdenum, manganese, nickel, copper and zinc. Particularly suitable dihydrocarbyl dithiophosphate metal salts are zinc dihydrocarbyl dithiophosphates (ZDDP).

In some embodiments, the lubricating composition comprises a rust inhibitor. Examples of suitable rust inhibitors include non-ionic polyoxyalkylene polyols and esters thereof) polyoxyalkylene phenols, polyoxyalkylene polyols, anionic alky sulphonic acids, zinc dithiophosphates, metal phenolates, basic metal sulphonates, fatty acids and amines.

In some embodiments, the lubricating composition comprises a corrosion inhibitor. Examples of suitable corrosion inhibitors include phosphosulfurised hydrocarbons and the products obtained by the reaction of phosphosulfurised hydrocarbon with an alkaline earth metal oxide or hydroxide, non-ionic polyoxyalkylene polyols and esters thereof, polyoxyalkylene phenols, thiadiazoles, triazoles and anionic alkyl sulphonic acids. Examples of suitable epoxidised ester corrosion inhibitors are described in US 2006/0090393.

In some embodiments, the lubricating composition comprises an antioxidant. Examples of suitable antioxidants include alkylated diphenylamines, N-alkylated phenyl enedi amines, phenyl -a-naphthylamine, alkylated phenyl-a- naphthylamines, dimethylquinolines, trimethyldi hydroquinolines and oligomeric compositions derived therefrom, hindered pheno!ies (including ashless (metal-free) phenolic compounds and neutral and basic metal salts of certain phenolic compounds), aromatic amines (including alkylated and non-a!ky!ated aromatic amines), sulfurised alkyl phenols and alkali and alkaline earth metal salts thereof, alkylated hydroqui nones, hydroxylated thiodiphenyl ethers, alkylidenebisphenois, thiopropionates, metallic dithiocarbamates, 1,3,4- dimercaptothiadi azole and derivatives, oil soluble copper compounds (for example, copper dihydrocarbyl thio- or thio-phosphate, copper salts of a synthetic or natural carboxylic acids, for example a Cg to O.g fatty acid, an un saturated acid or a branched carboxylic acid, for example basic, neutral or acidic Cu(I) and/or Cu(II) salts derived from alkenyl succinic acids or anhydrides), alkaline earth metal salts of alkylphenolthioesters, suitably containing Cs to Co alkyl side chains, calcium nonylphenol sulfide, barium t-oetylphenyl sulfide, dioctylphenylamine, phosphosulfurised or sulfurised hydrocarbons, oil soluble phenates, oil soluble sulfurised phenates, calcium dodecylphenol sulide, phosphosulfurised hydrocarbons, sulfurised hydrocarbons, phosphorus esters, low sulfur peroxide decomposers and the like.

In some embodiments, the lubricating composition comprises an antifoam agent. Examples of suitable anti-foam agents include silicones, organic polymers, siloxanes (including poly siloxanes and (poly) dimethyl siloxanes, phenyl methyl siloxanes), acrylates and the like.

In some embodiments, the lubricating composition comprises a seal swell agent. Examples of suitable seal swell agents include long chain organic acids, organic phosphates, aromatic esters, aromatic hydrocarbons, esters (for example butylbenzyl phtha!ate) and polybutenyl succinic anhydride.

The lubricating composition may comprise lubricant additives in the amounts shown in Table 1. Table 1

The lubricating compositions may have a kinematic viscosity at 40 °C of less than about 60 cSt, such as less than about 55 cSt, or less than about 50 cSt. The lubricating compositions may have a kinematic viscosity at 100 ^C'C of less than about 12 cSt, such as less than about 10 cSt, or less than about 9.5 cSt The lubricating compositions may have a viscosity index of greater than about 100, such as greater than about 110, or greater than about 120. The kinematic viscosity at 40 °C and the kinematic viscosity at 100 °C may be measured according to ASTM D445. The viscosity index may be calculated according to ASTM D2270.

The lubricating compositions may have a Noack volatility of less than about 25 %, such as less than about 20 %, less than about 15 %, or less than about 10 % by weight. Noack volatility may be measured according to CEC-L-40-A-93.

The lubricating compositions may have a viscosity at 150 °C and a shear rate of 10° s 1 of no greater than 3 cP, such as no greater than 2.8 cP. This high temperature high shear viscosity may be measured according to CEC-L-36-A-90.

The lubricating composition may have at least one of;

an oxidative stability performance on a CEC-L-088-02 and/or CEC-L-111-16 test indicated by an absolute viscosity increase at 40 °C of no more than 45 cSt, such as no more than 35 cSt or no more than 25 cSt; a fuel economy performance on a CEC-L-054-96 test of at least 2.5 ¾, such as at least 3 %; and a piston cleanliness performance on a CEC-L-088-02 and/or CEC-L-111-16 test indicated by an overall piston merit of at least 8.5, such as 9.

The lubricating compositions may have a cold-crankcase simulator performance at -30 °C of less than about 3000, such as less than about 2800, or less than about 2750, for example as measured according to ASTM D5293.

Preferred lubricating compositions meet the requirements set out in SAE J30Q.

Preferably, the lubricating composition has at least one of:

a kinematic viscosity at 40 °C of less than 60 cSt, such as less than 55 cSt, or less than 50 cSt;

a kinematic viscosity at 100 °C of less than 12 cSt, such as less than 10 cSt, or less than 9.5 cSt;

a viscosity at 150 °C and a shear rate of 10° s ¹ of no greater than 3 cP, such as no greater than 2.8 cP; and

In yet another aspect, the present invention provides a method for preparing the lubricating composition of the invention, said method comprising preparing a base stock of Formula (1) and/or Formula (2) by any method described hereinbefore, providing a base oil comprising the base stock of Formula (1) and/or Formula (2), and preparing a lubricating composition front said base oil by blending the base oil with one or more lubricant additives. For example, preparation of the base stock of Formula (1) or Formula (2) may comprise: i) hydrofonnylation, acetalization, cracking and hydrogenation steps or ii) hydrofonnylation and reductive etherification steps. As will be appreciated, an esterification step may also be included in the preparation of the base stock of Formula (1) or Formula (2) as discussed hereinbefore, depending on whether for instance a fatty acid or fatty alcohol starting material is used, as opposed to an ester of those compounds.

Methods and uses

The present invention also provides methods of lubricating a surface, said method comprising supplying a lubricant composition as described above to said surface. The invention also provides the use of lubricant compositions of the present invention for lubricating a surface. The surface can be a surface in an engine in the case where the lubricant composition is being used as an engine lubricant. The invention also provides methods of improving the fuel economy performance and/or piston cleanliness performance of an engine and/or a vehicle, such as an automotive vehicle associated with an internal combustion engine, comprising the step of providing to the engine and/or the vehicle a lubricating composition according to the invention. The invention also provides the use of a lubricating composition of the inventi on to improve the fuel economy performance and/or piston cleanliness performance of an engine and/or a vehicle, such as an automotive vehicle associated with an internal combustion engine. In said applications, the lubricant composition is for use in lubricating an engine.

The invention also provides methods of improving the oxidative stability performance, fuel economy performance, and/or piston cleanliness performance of a lubricating composition, comprising the step of providing to the lubricating composition a base stock of Formula (1) or Formula (2) as described above. The invention also provides the use of a base stock of Formula (1) or Formula (2) as described above, a base oil of the invention, and/or a lubricating composition of the invention to improve the oxidative stability performance, fuel economy performance and/or piston cleanliness performance of a lubricating composition and/or to improve the fuel economy performance and/or piston cleanliness performance of an engine and/or a vehicle, such as an automotive vehicle associated with an internal combustion engine.

Methods of operating said engines using lubricants of the invention including the application of said lubricants to the engines are known to the skilled person. The skilled person would also be aware of the necessary amounts of lubricating oil compositions of the invention to use in the methods and uses discussed above.

The invention will now be described with reference to the accompanying examples, which are not limiting in nature.

EXAMPLES

The following compounds according to Formula (1) or Formula (2) were synthesised from unsaturated fatty acids (Examples 1 and 2) and unsaturated fatty alcohols (Examples 3 and 4), preparable by methods involving hydroformyiation and reductive etherification steps, as described herein. Example 1

Ethyl 10-(((2-ethylhexyl)oxy)methyl)octadecanoate was synthesized from ethyl oleate and 2-ethyl hexanoi.

Example 2

Isobutyl 10-(((2-ethylhexyl)oxy)methyl)hexadecanoate.

Example 3

10-(((2-ethylhexyl)oxymethyl)hexadecyl isobutyrate.

10-(((2-ethyl)oxy)methyl)octadecyl acetate

The properties of the compounds of Examples 1 to 4 were analysed and Table 2 below compares the assessed properties with commercially available base oil (PAO 4). Table 2

As is clear from the result of Table 2, the compounds used in the compositions of the invention have a lower kinematic viscosity than PAO 4 and a higher viscosity index. A higher viscosity index and lower kinematic viscosity are particularly preferable properties for a base stock for use in a base oil of a lubricating composition. It can also be seen that the compounds of the invention have similar pour points to PAO 4, and also do not degrade via oxidation until at least 200°C, demonstrating that said compounds may be useful as lubricating compositions in vehicle engines.

As may also be seen from the results of Table 2, the compounds of Examples 1 to 4 all advantageously have lower viscosity than PA04, whilst having greater viscosity index. The presence of the ester group in the compounds of Examples 1 to 4 also enhances lubricity. The compound of Example 1, for instance, may also be prepared partially or even entirely from renewable sources.

Example 5

To study the different properties of primary and secondary ethers, Compounds A to F below were synthesized. Compounds A to E are not of the present invention, whereas Compound F (which is the same as the compound of Example 1) corresponds to a compound of Formula (1) / (3).

Compound A Compound B

Compound C Compound D

Various properties determined for Compounds A to F are shown in Table 3 below.

Table 3

A comparison of the results in Table 3 above show that

comprising primary ether moieties (Compounds D to F) oxidize at higher temperatures than compounds comprising secondary ether moieties (Compounds A to C). This is the case for both compounds comprising ether moieties with no ester moieties (demonstrated by comparing the oxidation temperature of Compounds A and B with that of Compounds D and E), and also for compounds comprising both ester and ether moieties (demonstrated by comparing the oxidation temperature of Compounds C and F). The fact that the primary ether compounds oxidize at higher temperatures than the secondary ethers means that the primary ether compounds are expected to find greater utility as base stocks for use in lubricating compositions because they would be expected to oxidize less when used in engines due to the high temperatures encountered therein. Compound F (a compound according to Formula (1)) also can be seen to have viscosities and viscosity indexes suitable for use in lubricating compositions for use in engines.

Claims

1 A lubricating composition comprising a base oil of lubricating viscosity and one or more lubricant additives, where the base oil comprises or consists of a base stock of Formula (1) and/or Formula (2):

wherein:

Ri is a monovalent hydrocarbyl group;

R2 is a monovalent hydrocarbyl group or H;

R3 is a monovalent hydrocarbyl group;

Li and L2 are independently selected from:

R.₄ is H or methyl,

m is 1, 2 or 3; and

n, o, p and q are independently 1, 2, 3 or 4.

2. A lubricating composition according to Claim 1, wherein R , 1¾ and R3 are independently selected from straight chain or branched Ci to C12 alkyl and C4 to C12 cycloalkyl.

3. A lubricating composition according to Claim 1 or Claim 2, wherein R2 and R3 are independently selected from straight or branched chain Ci to Ce alkyl, preferably straight chain Ci to (A alkyl, and/or wherein Ri is straight or branched chain CA to (>.2 alkyl, preferably branched chain Ce to C10 alkyl.

4. A lubricating composition according to any one of Claims 1 to 3, wherein L· and/or L2 is/are selected from C2 to C12 straight chain or branched alkyl ene, preferably selected from C4 to C12 straight chain or branched alkylene_, more preferably selected from Ce to C10 straight chain or branched alkylene.

5. A lubricating composition according to any one of Claims 1 to 3, wherein L- and/or

6. A lubricating composition to any one of Claims 1 to 3 and 5, wherein n, o, p and q are independently 1 or 2, preferably wherein n, o, p and q are 1.

7. A lubricating composition according to any one of the preceding claims, wherein m is 1 or 2, preferably where m is 1.

8. A lubricating composition according to any one of the preceding claims, wherein the moiety R1-O-CH2-, is a primary ether.

9. A lubricating composition according to any one of the preceding claims, wherein the compounds of Formula (1) and Formula (2) do not comprise a secondary or tertiary ether.

I 0. A lubricating composition according to any one of the preceding claims, wherein R· and R3 are the same.

I I . A lubricating composition according to any one of the preceding claims, wherein the moiety R2-L1 at the terminal end includes the same number of carbon atoms as Ri.

12. A lubricating composition according to any one of Claims 1 to 4, and any preceding claims dependent thereon, wherein the base stock of Formula (1) is derived from the reaction of one or more unsaturated fatty acids.

13. A lubricating composition according to Claim 12, wherein the fatty acid is selected from myristoleic acid, palmitoleic acid, sapienic acid, oleic acid, elaidic acid, vaccenic acid, gadoieic acid, eicosenoic acid, erucic acid, nervonie acid, linoleic acid, eicosadienoic acid, docosadienoic acid, or any combination thereof.

14. A lubricating composition according to Claims 12 and 13, wherein the reaction comprises: i) hydroformylation, esterification, acetalization, cracking and

hydrogenation steps; or ii) hydroformylation, esterification and reductive

etherification steps.

15. A lubricating composition according to any one of Claims 1 to 4, and any preceding claims dependent thereon, wherein the base stock of Formula (1) or Formula (2) is selected from a compound of Formula (3), (4), (5), (6) and (7) below:

wherein: Ri and R3 are selected from straight chain or branched C to C12 alkyl.

16. A lubricating composition according to any one of the preceding claims, wherein the base stock of Formula (1) or Formula (2) includes a total number of carbon atoms of from 25 to 35 carbon atoms, preferably from 28 to 32 carbon atoms.

17. A lubricating composition according to any one of the preceding claims, wherein the base stock of Formula (!) or Formula (2) has at least one, preferably all, of:

a kinematic viscosity at 40 °C of less than 25 cSt, such as less than 20 eSt, or less than 17 cSt;

a viscosity index of greater than 100, such as greater than 110, or greater than

120,

a DSC (Differential Scanning Calorimeter) oxidation onset temperature >190 °C, preferable >200 °C

a viscosity at 150 °C and a shear rate of iO⁶ s ¹ of no greater than 1.7 cP, such as no greater than 1.5 cP;

a Noack volatility of less than 26 %, such as less than 20%, less than 16 %, or less than 12 % by weight; and

a pour point of less than -10 °C, such as less than -25 °C, or less than -35 °C, or less than - 50 °C.

18. A lubricating composition of any one of the preceding claims, wherein the lubricating composition has at least one, preferably all, of

a viscosity index of greater than 100, such as greater than 1 10, or greater than

120;

19. A lubricating composition of any one of the preceding claims, wherein the lubricating composition has at least one, preferably all, of: an oxidative stability performance on a CEC-L-088-02 and/or CEC-L-11 1-16 test indicated by an absolute viscosity increase at 40 °C of no more than 45 cSt, such as no more than 35 cSt or no more than 25 cSt;

a fuel economy performance on a CEC-L-054-96 test of at least 2.5 %, such as at least 3 %; and

a piston cleanliness performance on a CEC-L-088-02 and/or CEC-L-111-16 test indicated by an overall piston merit of at least 8.5, such as 9.

20. A lubricating composition according to any one of the preceding claims, wherein the base oil of the lubricating composition further comprises one or more additional base stocks selected from Group I, Group II, Group III, Group IV and Group V base stocks, and mixtures thereof.

21. A lubricating composition according to any one of the preceding claims, wherein the lubricating composition comprises greater than 50 %, such as greater than 65 %, or greater than 80 % by weight of base oil.

22. A base oil for a lubricating composition which base oil comprises a base stock of Formula (1) or Formula (2) according to any one of Claims 1 to 16 and one or more additional base stocks selected from Group I, Group II, Group III, Group IV and Group V base stocks and mixtures thereof.

23. The base oil of Claim 22, wherein the base oil comprises greater than 10 %, such as greater than 25 %, or greater than 40 % by weight of the base stock of Formula (1) or Formula (2) as defined in any of Claims 1 to 16

24. A method of preparing a lubricating composition, said method comprising preparing a base stock of Formula (1) or Formula (2), providing a base oil comprising the base stock of Formula (1) and/or Formula (2) and optionally one or more additional base stocks selected from Group I, Group II, Group III, Group IV and Group V base stocks and mixtures thereof, and preparing a lubricating composition from said base oil by blending the base oil with one or more lubricant additives.

25. The method of Claim 24, wherein preparing the base stock of Formula (1) or Formula (2) comprises: i) hydroformylation, acetalization, cracking and hydrogenation steps; or ii) hydroformylation and reductive etherification steps.

26. A method of lubricating a surface, said method comprising supplying a lubricating composition according to any of Claims 1 to 21 to said surface, such as wherein the lubricating composition is supplied to a surface in an internal combustion engine.

27. Use of a lubricating composition according to any of Claims 1 to 21 for lubricating a surface, such as wherein the lubricating composition is used for lubricating a surface in an internal combustion engine

28. A method of improving the oxidative stability performance, fuel economy performance, and/or piston cleanliness performance of a lubricating composition, comprising the step of providing to the lubricating composition a base stock of Formula (1) or Formula (2) as defined in any one of Claims 1 to 16 and/or a base oil according to Claims 22 or 23.

29. A method of improving the fuel economy performance and/or piston cleanliness performance of an engine and/or a vehicle, such as an automotive vehicle associated with an internal combustion engine, comprising the step of providing to the engine and/or the vehicle a base stock as defined in any one of Claims 1 to 16, a base oil according to Claims 22 or 23, and/or a lubricating composition according to any one of Claims 1 to 21

30. Use of a base stock of Formula (!) or Formula (2) as defined in any one of Claims 1 to

16, a base oil according to any of Claims 22 or 23, and/or a lubricating composition according to any one of Claims 1 to 21 to improve the oxidative stability performance, fuel economy performance and/or piston cleanliness performance of a lubricating composition and/or to improve the fuel economy performance and/or piston cleanliness performance of an engine and/or a vehicle, such as an automotive vehicle associated with an internal combustion engine.