Patent Description:
Modifying the friction between moving parts is one of the fundamental roles of the lubricants. A high reduction of the friction is typically sought, for example, within internal combustion engines, especially since the friction directly impacts the fuel consumption. A reduction of the friction is also sought in transmissions systems without clutches of electrical vehicles. Thus, in a combustion engine or electrical vehicles, low coefficients of friction are sought, when for other applications, for example in gearboxes or other power transmission systems with clutches, higher friction coefficient are needed, that allow a better grip between the moving parts.

Another effect that may be ensured by a lubricant is an antiwear protection, that impacts the lifespan of the contacting parts. Whatever the coefficient of friction sought, it is highly preferable for a lubricant to provide an antiwear protection (for example for improving the durability of an internal combustion engines or of a gearbox).

Lubricant additives able to impart friction modification and antiwear properties to the lubricant are known, that includes compounds based of metal (based on zinc or molybdenum, typically) and/or on phosphorous and/or sulfur, such as dialkylthiophosphates for example, or molybdenum dithiocarbamate (MoDTC). These compounds have the drawback to lead to sulfur- or phosphorus- based residues and particles (referred as "SAPS" for : Sulphated Ash, Phosphorous and Sulfur) in the exhaust gas when the lubricant is used in a combustion (industrial or automotive) engine. And more generally, they constitute an issue for recycling the lubricant.

SAPS-free additives have been proposed that allow a friction modification, including for example fatty esters and amides, such as glycerol monooleate (GMO) or oleyl amides, for example, but these SAPS -free additive tend to have weaker antiwear properties than the aforementioned compounds based on metal, phosphorous and/or sulfur.

<CIT> discloses primary or secondary amino alkanediols as additives for fuels or lubricating oils to improve engine fuel economy by reducing friction and/or reducing wear.

One aim of the invention is to provide additives for lubricants, that are free from metal, sulfur and phosphorous, and that however impart a good antiwear protection at least as good as those obtained for compounds containing metal, sulfur and phosphorous such as MoDTC. The invention further aims at providing SAPS-free additives that allow to modulate the coefficient of friction.

To this end, the instant invention provides a new family of twin tailed amine derivatives, that reveal to provide especially good antiwear properties. Each of the member of the family provide a variable impact as regards the coefficient of friction, with some members of the family leading to low coefficients of friction and other to higher coefficients, which allows to modulate the coefficient of friction depending on the application by selecting a suitable member of the family, while keeping a good antiwear protection.

More precisely, according to a first aspect, one subject-matter of the instant invention is the use as an antiwear additive in a lubricant of at least one compound having the following formula (I) :
<CHM>
wherein :.

The instant invention also relates to the lubricant compositions comprising at least an oil and at least one compound having the following formula (I), typically as an antiwear additive (antiwear component) and/or as a friction modifier.

The oil contained in a lubricant composition according to the invention may typically include C20-C30 alkane chains. The oil may for example be selected from the base oils used in lubricants, typically:.

A lubricant composition according to the invention may further comprise, in addition to the base oil and the compound of formula (I), at least one additives selected from detergents, dispersants, anti-wears, extreme pressure agents, friction modifiers, antioxidants, anti-corrosion inhibitors, foam inhibitors, viscosity index improvers and pour point depressants.

The compounds of formula (I) are free from metal, sulfur and phosphorous and therefore give access to a SAPS-free technology, which is one first advantage, especially since the compounds of formula (I) do not lead to production of harmful gases when used for engine application (especially they do not induce the production of sulfated ashes produced by the burn of metals) and they are not detrimental to catalysts (as they are free from phosphorus and sulfur).

Another advantage of the compounds (I) is that they can be at least partly and preferably totally bio-based. The compounds of formula (I) may for example be prepared from a fatty internal ketone of formula (II) :.

As an example, the compounds of formula (I) may be prepared by a direct reductive amination of the fatty internal ketone of formula (II) as defined above with an amine having the following formula (III) :.

NH<NUM>-[CH<NUM>-CH<NUM>-NH-]a-A-[-CHOH-]b-CH<NUM>-OH     (III).

According to another possible route, the compounds of formula (I) may be prepared by derivatization of a primary amine (IV) :.

R-CH[NH-(CH<NUM>-CH<NUM>-NH-)aH]-R'     (IV).

wherein R, R' and a are as defined above. According to a specific embodiment, a=<NUM>; but a may be greater.

The primary amine (IV) is preferably obtained by a reductive amination of the aforementioned fatty internal ketone of formula (II) with an amine of formula H<NUM>N-(CH<NUM>-CH<NUM>-NH)a-H.

For example the compounds of formula (I) may be obtained by condensation of the primary amine (IV) with an epoxy-containing compound, such as glycidol (in this case A is -CH<NUM>- and b = <NUM>), or by reductive amination of the primary amine (IV) with an aldehyde such as glucose (in this case A is -CH<NUM>- and b = <NUM>) ; or by condensation of the primary amine (IV) with a gluconolactone (and then A is a carbonyl and b = <NUM>).

A first subclass of compounds of formula (I) useful according to the present invention are compounds wherein a≠<NUM>, namely a is equal to <NUM> or more (and typically a is equal to <NUM>). In the compounds of formula wherein a≠<NUM>, b is typically equal to <NUM> and A is preferably a methylene group (-CH<NUM>-). Thus, specific compounds of this fist subclass are especially the <NUM>-[(<NUM>-alkylaminoethyl)amino]ethanol derivatives having the following formula (I-<NUM>) :
<CHM>
wherein each of R and R', which are identical of different is as defined above, and contains between <NUM> and <NUM> carbon atoms.

These compounds of formula (I-<NUM>) may typically be obtained by a direct reductive amination of a fatty internal ketone of formula (II) with aminoethylethanolamine (AEEA) of formula HO-CH<NUM>-CH<NUM>-NH-CH<NUM>-CH<NUM>-NH<NUM>.

Another subclass of compounds of formula (I) useful according to the invention are compounds wherein b≠<NUM> (namely b is equal to <NUM>, <NUM>, <NUM> or <NUM>, and typically b=<NUM> or b=<NUM>). In these compounds, a is typically equal to <NUM>. Specific compounds of formula (I) wherein a = <NUM> include the followings:.

The compounds of formula (I-<NUM>) may be obtained by a preparation process including a step (E) of derivatizing a primary amine R-CH(NH<NUM>)-R' with gluconolactone, wherein R and R' are as defined above. The preparation process typically include, before step (E) a preparation step (E0) of the primary amine R-CH(NH<NUM>)-R', by reductive amination of a fatty internal ketone of formula (II) with ammonia.

According to another aspect, a specific subject-matter of the instant invention are the compound of formula (I-<NUM>) as defined above. Another subject matter of the invention is the preparation process of these compounds.

The compounds of formula (I), and especially the compounds of formula (I-<NUM>), (I-<NUM>), (I-<NUM>) and (I-<NUM>) exhibit good antiwear properties when introduced in a lubricant composition, when each of R and R' contains between <NUM> and <NUM> carbon atoms. Namely, the addition of the compound in the lubricant enhances the antiwear effect of the lubricant, i.e. it decreases the mechanical wear of parts in friction when the lubricant is present between the surfaces in friction. The "antiwear" properties, as referred herein, correspond to the wear protection that can be assessed for example according to the <NUM> ball wear test according to ASTM D4172 standard.

Among the family of the compounds of formula (I), the compounds of formula (I-<NUM>), (I-<NUM>), (I-<NUM>) are especially useful in lubricant composition for transmission systems such as gearboxes. In addition to the good antiwear protection discussed in the previous paragraph, the compounds of formula (I-<NUM>), (I-<NUM>), (I-<NUM>) furthermore allow to obtain relatively high friction coefficients needed in transmission systems. The friction coefficient can be measured by using a High Frequency Reciprocating Rig (HFRR) as illustrated in the appended examples. The use of at least one compound (I-<NUM>), (I-<NUM>), (I-<NUM>) as an antiwear agent and friction modifier in a lubricant used in a transmission system including clutches such as a gearbox constitutes another subject-matter of the instant invention.

When at least one compound of formula (I-<NUM>) or (I-<NUM>) or (I-<NUM>) is used in a lubricant in a transmission system including clutches, such as a gearbox, both as an antiwear agent and as a friction modifier, the total content of compounds of formula (I-<NUM>) or (I-<NUM>) or (I-<NUM>) in the lubricant is preferably between <NUM> and <NUM> % notably between <NUM> and <NUM> % by weight based on the total weight of the lubricant composition.

Besides, the compounds of formula (I-<NUM>) are especially interesting when used as additives in engine oil. In addition to the general antiwear properties of the compounds of formula (I), that increase the service life of the engine, the compounds of formula (I-<NUM>) induce very low friction coefficients, which is of particular interest in a combustion engine (industrial or automotive) or in transmissions without clutches for electrical vehicle since it allows a reduction of energy consumption. The use of at least one compound (I-<NUM>) as an antiwear and friction reducer in a lubricant for combustion engine constitute yet another subject-matter of the instant invention.

When at least one compound of formula (I-<NUM>) is used in a lubricant in a combustion engine, both as an antiwear agent and as a friction reducer, the total content of compounds of formula (I-<NUM>) in the lubricant is between <NUM> and <NUM> % notably between <NUM> and <NUM> % by weight based on the total weight of the lubricant composition.

Various specific advantages and possible embodiments of the invention will now be described in more details.

The compounds of formula (I) constitute a generic family of compounds with a so-called "twin-tailed" structure, wherein the groups R and R' correspond to the two "tails" of the structure. The two tails R and R' may be identical. Alternatively, R and R' may be distinct.

Each of the groups R and R' is a C<NUM>-C<NUM> aliphatic group. Each of R and R' is linear or branched, typically linear. Besides, each of R and R' may comprise cycloaliphatic groups. The number of carbon atom in each of R and R' is preferably from <NUM> to <NUM>, notably from <NUM> to <NUM>, for example from <NUM> to <NUM>. The number of carbon atoms of R and R' can be even or odd numbers. For example R and R' may be a, linear or branched, not cyclized or partially cyclized, aliphatic C<NUM>-C<NUM> aliphatic group, notably a linear and not cyclized aliphatic C<NUM>-C<NUM> group.

Groups R and R' having a number of carbon atoms or <NUM> or more, for example of <NUM> or more, notably of <NUM> or more and for example of <NUM> or more are especially interesting in terms of solubility -or at least of dispersibility- of the compounds of formula (I) in the lubricant wherein they are used as additives. On the contrary, the compounds of formula (I) carrying R and R' groups with a lower number of carbon atoms (for example when R and R' are methyl, ethyl or propyl groups or, more generally, when the total number of carbon atoms in R plus in R' is below <NUM>) exhibit a well lower solubility.

Especially, the higher the number of carbon atoms in R and R' and the better the solubility in group <NUM> oils used in oils for combustion engines, with a good solubility when R and R' contain at least <NUM>, more preferably at least <NUM> and even more preferably more than <NUM> carbon atoms, for example <NUM> carbon atoms or more.

This is a great advantage of the invention when Groups R and R' have a high number of carbon, preferably in the above recited ranges, since the invention allows then to make use of compounds (I) in a lubricant without the need of any co-additives such as surfactants. In addition to a direct impact on the costs and complexity of the obtained compositions, this possibility of precluding co-additives avoids any potential negative interactions with the composition and related toxicity issues.

Each of the groups R and R' is a C<NUM>-C<NUM> aliphatic group and the compound (I) is specifically used without any surfactant and, preferably, without any additive for improving the dispersibility or the solubility of said compounds (I) in the lubricant.

Besides the groups R and R' have a number of carbon atoms preferably of <NUM> or less, for example of <NUM> or less, notably of <NUM> or less. In the scope of the instant invention, the inventors have found that it notably leads to a proper adhesion to the surfaces to be protected by the lubricant.

The R and R' groups are preferably free from -C=C- double bond and -C≡C- triple bond -, but according to specific embodiments, R and R' may comprise at least one -C=C-double bond.

Advantageously, each of the R and R' groups is selected from alkyl groups, alkenyl groups, alkanedienyl groups, alkanetrienyl groups and alkylnyl groups. Preferably, R and R' are independently chosen from alkyl and alkenyl groups, preferably linear and not cyclized. R and R' may for example be independently selected from linear and not cyclized C<NUM>-C<NUM> alkyl and linear and not cyclized C<NUM>-C<NUM> alkenyl groups, for example from linear and not cyclized C<NUM>-C<NUM> alkyl groups.

The R and R' groups present in the compounds of formula (I) are typically the R and R' group of a fatty internal ketone of formula (II) as defined above, which is itself advantageously obtained from a decarboxylative ketonization reaction of corresponding fatty acids RCOOH and R'COOH. These fatty acids RCOOH and R'COOH may typically be selected from caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, isostearic acids, oleic acid, linoleic acid, linolenic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid or mixtures thereof. The internal ketone of formula (II) may be a symmetric internal ketone obtained from only one fatty acid (in that case, R and R' are identical and RCOOH=R'COOH). Alternatively, the internal ketone of formula (II) is asymmetric (R≠R') if obtained from two distinct fatty acids. Preferably the starting fatty acids RCOOH and R'COOH are used in the form of a mixture is, typically in the form of the so-called cuts which are obtained from vegetable or animal oils through saponification or alcoholysis. For example, the fatty acids cut is derived from coconut oil or palm kernel oil and contains a mixture of fatty acids which can comprise fatty acids having <NUM> carbon atoms up to <NUM> carbon atoms. In the case the internal ketone (II) is obtained from a cut of fatty acids R-CO<NUM>H, all the possible ketones R-(C=O)-R obtained by combination of the R groups of the starting fatty acids are formed.

Alternatively, the compounds of formula (I) may be obtained from an internal ketone (II) derived from so called naphthenic acids. The term "naphthenic acid" generally denotes a mixture of cyclopentyl and cyclohexyl carboxylic acids with a carbon backbone of usually <NUM> to <NUM> carbon atoms. Naphthenic acids are obtained by oxidation of the naphtha fraction of crude oil and their composition varies with the crude oil composition and the conditions during refining and oxidation.

The compounds of formula (I) are typically obtained from a fatty internal ketone of formula (II) as defined above.

The following examples illustrate the invention.

A compound C1 having the following formula was synthetized according to the protocol described below, from <NUM>-tricosanone which is an internal ketone of formula (II) wherein R=R'=-(CH<NUM>)<NUM>-CH<NUM>
<CHM>.

In a <NUM> double-jacketed reactor equipped with a mechanical stirrer (propeller with four inclined plows), a condenser and a temperature probe were added:.

The mixture was allowed to stir at room temperature (<NUM>) and <NUM> of titanium tetraisopropoxide (<NUM> mole, <NUM> eq. ) was added.

The mixture was then allowed to stir at room temperature overnight and then <NUM> of methanol was added followed by the progressive and careful addition of <NUM> of NaBH<NUM> (<NUM> mole, <NUM> eq.

The mixture is then stirred at room temperature for <NUM> hours. <NUM> of water is then added (precipitation of TiO<NUM> observed) followed by the addition of <NUM> of diethyl ether.

The suspension was then filtered to remove solid TiO<NUM> and the organic phase was separated from the filtrate.

The organic phase was washed <NUM> times with <NUM> of an aqueous NaOH solution (<NUM>), <NUM> time with <NUM> of water, dried over MgSO<NUM>, filtered and evaporated to afford a pale yellow oil.

<NUM> of methanol was then added to the crude oil in order to precipitate the insoluble alcohol by-product which is filtered out.

After methanol evaporation <NUM> of product is obtained as a pale yellow oil.

A compound C2 having the following formula was synthetized according to the protocol described below, from <NUM>-tricosanone which is an internal ketone of formula (II) wherein R=R'=-(CH<NUM>)<NUM>-CH<NUM>
<CHM>.

The reaction was conducted in carefully dried vessels and under an inert argon atmosphere.

Fresh commercial anhydrous THF and MeOH were used as such.

The milky heterogeneous mixture was stirred at <NUM> at which temperature and turned homogeneous transparent orange. It was allowed to stir at this temperature overnight. The obtained mixture was then cooled down to <NUM> and anhydrous methanol (<NUM>) is added into the reactor followed by careful addition of <NUM> of NaBH<NUM> (<NUM> mmol, 2eq) portion wise while monitoring foaming during the addition. The mixture was then stirred at <NUM> for <NUM> hours.

After <NUM>, <NUM>H NMR analysis in MeOD (sampling <NUM>-<NUM> drops from the mixture, addition of water and diethyl ether, filtration of formed TiO<NUM> on celite, solvent evaporation and MeOD addition) showed the formation of the expected product.

The reaction mixture was allowed to cool down to room temperature and water (<NUM>) was added slowly to quench NaBH<NUM> excess followed by <NUM> of diethyl ether.

The mixture was filtered on celite to remove the large amount of TiO<NUM> and the solid was washed several times with diethyl ether. The filtrate was decanted and the organic phase was washed <NUM> times with water and <NUM> time with brine. The organic phase was dried over MgSO<NUM>, filtered and evaporated to afford crude product as a yellow oil which crystallizes at room temperature.

The product was then purified thanks to flash chromatography on silica gel using CHCl<NUM>:iPrOH eluent with a gradient going from <NUM>% chloroform to <NUM>/<NUM> CHCl<NUM>:iPrOH (<NUM>/min) followed by elution with isopropanol (<NUM>/min).

After solvent evaporation <NUM> of product analytically pure was obtained in the form of a clear oil which crystallizes as a white solid at room temperature.

<NUM>H NMR (MeOD, <NUM>) δ (ppm): <NUM>-<NUM> (m, <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM> (dd, J = <NUM>, J = <NUM>, <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM> (t, J = <NUM>, <NUM>).

<NUM>C NMR (MeOD, <NUM>) δ (ppm): <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> (terminal CH<NUM>).

A compound C3 having the following formula was synthetized according to the protocol described below, from <NUM>-hentriacontanone which is an internal ketone of formula (II) wherein R=R'=-(CH<NUM>)<NUM>-CH<NUM>
<CHM>.

The reaction was conducted under an inert argon atmosphere.

The mixture was then stirred at room temperature and <NUM> of Ti(OEt)<NUM> (<NUM>, <NUM> mmoles, <NUM> eq. ) was added into the reactor.

The mixture is then stirred at <NUM> overnight and it was observed that during the course of the reaction the mixture becomes homogeneous.

At the end of the reaction, the temperature was cooled down at <NUM> and <NUM> of anhydrous methanol was added into the reactor followed by the careful and slow addition of <NUM> of NaBH<NUM> (<NUM> moles, <NUM> eq. Care should be taken as foaming can occur during NaBH<NUM> addition.

The reaction medium was then stirred at <NUM> for 3h00.

Then the mixture was cooled down at room temperature and <NUM> of water was added followed by <NUM> of diethyl ether. During water addition precipitation of TiO<NUM> occured. The suspension was filtered, the solid was washed several times with diethyl ether and the biphasic filtrate was separated. The organic phase was again filtered over celite and was washed with water and brine. The organic phase was then dried over MgSO<NUM>, filtered and evaporated to afford the crude material as a yellow paste (<NUM>).

The crude was then purified through flash chromatography over silica gel using CHCl<NUM>:isopropanol mixture as the eluent with a gradient going from <NUM>:<NUM> to <NUM>:<NUM>.

After solvent evaporation <NUM> of pure product is obtained (<NUM> mmoles).

A compound C4 having the following formula was synthetized according to the protocol described below, from <NUM>-pentatriacontanone which is an internal ketone of formula (II) wherein R=R'=-(CH<NUM>)<NUM>-CH<NUM>
<CHM>.

A solution of pentatriacontan-<NUM>-one (<NUM>, <NUM> mole, <NUM> eq. ) in <NUM>-Methyl THF (<NUM>) was prepared in a <NUM> double-jacketed reactor equipped with a mechanical stirrer (propeller with four inclined plows) a condenser and a temperature probe.

To this solution were added under stirring:.

The solution was refluxed at <NUM> for <NUM> and kept at <NUM> overnight under stirring. The reaction mixture was then diluted with MeOH (<NUM>), followed by addition of NaBH4 portion wise (<NUM>, <NUM> mole, <NUM> eq. ) and stirred at <NUM> for <NUM>.

The reaction mixture was further stirred at room temperature over the weekend. The reaction mixture was then quenched with <NUM> of water and the resulting mixture was concentrated under reduced pressure to remove <NUM>-Me THF and methanol. To the residue was added toluene (<NUM>) and the mixture was concentrated under vacuum to remove toluene-water azeotrope.

The resulting white TiO2 solid was filtered over celite and washed with large amounts of chloroform. The filtrate was washed with DI water and brine solution.

The combined organic phase was concentrated under reduced pressure and dried. The crude was then purified by flash chromatography over silica gel to yield <NUM> of pure product (<NUM> mole).

A compound C5 having the following formula was synthetized according to the protocol described below,from <NUM>-tricosanone which is an internal ketone of formula (II) wherein R=R'=-(CH<NUM>)<NUM>-CH<NUM>
<CHM>.

All the reactions were conducted under an inert argon atmosphere.

In a <NUM> three necked round bottom flask equipped with a magnetic stirrer, a condenser, a temperature probe and a heater was prepared a solution of tricosan-<NUM>-one (<NUM>, <NUM> mol, <NUM> eq. ) in <NUM> of methanol.

Then NH<NUM>OAc (<NUM>, <NUM>. 95mol, <NUM> eq. ) followed by NaCNBH<NUM> (<NUM>, <NUM> mol, <NUM> eq. ) are added into the mixture in small portions. The reaction media was stirred at room temperature for <NUM> hour. Finally, the mixture was heated under reflux for <NUM> hours. Then the reaction media was cooled down to room temperature and concentrated under vacuum. Finally, <NUM> of a saturated NaHCO<NUM> aqueous solution and <NUM> of methyl-tertbutyl ether MTBE were added to the residue and the mixture was stirred at room temperature for <NUM> hour. Concentrated aqueous NaOH solution was added in order to adjust the pH around <NUM>.

The obtained product (tricosan-<NUM>-amine) was extracted with MTBE and the organic phase was washed several times with water and brine. The organic phase is dried with K<NUM>CO<NUM>, filtered and concentrated in vacuum to afford <NUM> of crude yellow oil.

The crude was then purified through flash chromatography column over silica gel using dichloromethane : methanol mixture as the eluent with a gradient going from DCM :
MeOH =<NUM>:<NUM> to DCM : MeOH= <NUM> : <NUM> + <NUM>% Et<NUM>N. After solvent evaporation <NUM> (<NUM> mol) of pure light yellow oil was obtained.

The reaction is conducted under an inert argon atmosphere.

In a <NUM> round bottom flask equipped with a condenser, a magnetic stirrer, a heater and a temperature probe were added:.

The mixture was stirred at <NUM> for <NUM> hours and then is allowed to cool down to room temperature.

<NUM> of water was then added into the reaction mixture and the product is extracted with 3x500 mL of chloroform.

The organic phases were gathered, washed again with <NUM> of water, dried over MgSO<NUM>, filtered and the solvent is evaporated to afford <NUM> of a pale yellow paste.

At this stage the crude product still contained residual amounts of the starting amine, therefor the solid was washed with 3x100 mL of ethyl acetate.

The solid is then dried to remove traces of solvent and <NUM> of analytically pure product (<NUM> mmoles) is obtained as a white solid.

A compound C6 having the following formula was synthetized according to the protocol described below,from <NUM>-hentriacontanone which is an internal ketone of formula (II) wherein R=R'=-(CH<NUM>)<NUM>-CH<NUM>
<CHM>.

Same protocol as described in step <NUM> of example <NUM> has been followed, but starting from hentriacontan-<NUM>-amine instead of tricosan-<NUM>-amine.

In a <NUM> round bottom flask equipped with a condenser, a magnetic stirrer, a heater and a temperature probe wereadded:.

The mixture was stirred at <NUM> for <NUM> days and then was allowed to cool down to room temperature.

<NUM> of water was then added into the reaction mixture followed by <NUM> of chloroform. The obtained precipitate is filtered out and the solid was washed with <NUM>*<NUM> of ethyl acetate.

The solid was then dried to remove traces of solvent and <NUM> of analytically pure product (<NUM> mmoles) is obtained as a white solid.

The synthetized compounds C1-C6 have been tested according to the following protocols ("<NUM> ball wear test" and "Friction test" defined hereinafter).

A further compound, herein referred as "compound C7", has been tested according to the same protocol for the friction test as comparison.

This compound C7, purchased from Asta Tech Inc, is <NUM>-(isopropylamino)propane-<NUM>,<NUM>-diol (<NPL>) of formula:
<CHM>.

For the sake of comparison, the following additives have been tested in the same conditions:.

All the tests run for <NUM> at <NUM> under a <NUM> load, at a <NUM> rpm speed.

Each candidate is added at 1wt% in a Group II mixture base oil of 45wt% of a base oil at <NUM>. 5cSt at 100C and <NUM>% of a base oil at 12cSt at <NUM> to meet an overall kinematic viscosity at <NUM> cSt at <NUM>.

Friction has been evaluated using a HFRR (High Frequency Reciprocating Rig) under the following conditions:
slide ball on disc: metal/metal under a <NUM> load at a <NUM> microns stroke, at <NUM> for <NUM> and then ramped to <NUM> @ <NUM>/min for <NUM>.

Each candidate was added at 1wt% in a Group III base oil with a kinematic viscosity at 8cSt at <NUM> to mimic a typical engine oil (SAE <NUM>).

The obtained results are reported in the following Table <NUM> :.

Claim 1:
Use as an antiwear additive in a lubricant of at least one compound having the following formula (I) :
<CHM>
wherein :
each of R and R', which are identical or different, is a aliphatic group containing between <NUM> and <NUM> carbon atoms ; and
a is an integer selected from <NUM>, <NUM>, <NUM>, <NUM> and <NUM> and preferably a=<NUM> or a=<NUM>; and
b is an integer selected from <NUM>, <NUM>, <NUM>, <NUM> and <NUM>; and
; and
A is a methylene group -CH<NUM>- ; or a carbonyl group -C(=O)-