Lubricating oil containing keto amide as friction reducing agent

Lubricating oil characterized by improved friction reduction contains friction reducing amounts of a keto amide prepared by the reaction of an amine and an unsaturated cyclic keto acid bearing pendant alkyl groups.

FIELD OF THE INVENTION 
This invention relates to a lubricating oil composition particularly 
characterized by decreased friction. More particularly, it relates to a 
friction modifier composition which permits attainment of lubricating oils 
characterized by decreased friction. 
BACKGROUND OF THE INVENTION 
As is well known to those skilled in the art, lubricating oil compositions 
permit operation of internal combustion engines at high efficiency. 
Lubricants of improved lubricity which permit operation with lesser 
friction make it possible to extend the efficiency and life of these 
engines, and the increased efficiency results in better fuel economy. 
It is an object of this invention to provide a composition which may be 
added to a lubricating oil as an improved friction modifier. Other objects 
will be apparent to those skilled in the art. 
STATEMENT OF THE INVENTION 
In accordance with certain of its aspects, this invention is directed to a 
process which comprises treating a (C.sub.3 -C.sub.20) alkenyl succinic 
acid anhydride at 69.degree. C.-160.degree. C. for 1-48 hours, in the 
presence of a strong Bronsted acid having a pK.sub.a of less than about 
-9, as catalyst thereby forming a cyclic keto acid; 
reacting said cyclic keto acid with an amine selected from the group 
consisting of 
(i) HO(CH.sub.2 CH.sub.2 NH).sub.x H wherein x is 1-10; 
(ii) H.sub.2 N(CH.sub.2 CH.sub.2 NH).sub.x H wherein x is 1-10; 
(iii) ((H.sub.2 CZ)(CHZ).sub.x (CH.sub.2 Z) wherein x is 1-6, Z is OH or 
NH.sub.2 and at least one Z is --NH.sub.2 ; 
(iv) (HOCH.sub.2 CH.sub.2).sub.x NH.sub.3-x wherein x is 2; 
(v) H.sub.2 NCH.sub.x (CH.sub.2 OH).sub.3-x wherein x is 0-1; 
(vi) imidazolines; and 
(vii) oxazolines 
thereby forming a keto amide; and 
recovering said keto amide. 
DESCRIPTION OF THE INVENTION 
The charge compositions which may be used to prepare the friction modifier 
of this invention may include C.sub.3 -C.sub.20 alken-2-yl-dicarboxylic 
anhydrides having the formula 
##STR1## 
wherein R is hydrogen or a C.sub.1 -C.sub.17 alkyl hydrocarbon. 
In the above formula, the R group may be hydrogen, methyl, ethyl, n-propyl, 
i-propyl, n-butyl, t-butyl, sec-butyl, amyl, hexyl, octyl, decyl, etc. It 
will be apparent that the moiety bearing the R group may be designated a 
C.sub.3 -C.sub.20 alken-2-yl group. Typical of such moieties may be 
penten-2-yl when R is the ethyl group. 
Typical of the charge compositions is the substituted succinic anhydride: 
##STR2## 
Anhydrides of substituted acids may be employed. The acid may bear inert 
substituents on any of the carbon atoms i.e. substituents which do not 
interfere with the course of the reaction. 
The preferred charge compositions may be those derived from succinic 
anhydride and preferably wherein R is hydrogen or C.sub.1 -C.sub.5 lower 
alkyl--typically methyl, ethyl, propyl, butyl, or amyl. Illustrative 
specific charge compositions may include: 
propen-2-yl-succinic anhydride 
buten-2-yl-succinic anhydride 
penten-2-yl-succinic anhydride 
hexen-2-yl-succinic anhydride 
buten-2-yl-glutaric anhydride 
penten-2-yl-adipic anhydride etc. 
The charge compositions may be available or they may be prepared as by the 
reaction of anhydrides of unsaturated dicarboxylic acids with olefins 
having a double bond in the 1-position--typified by the reaction of maleic 
acid anhydride and 1-butene. 
The charge C.sub.3 -C.sub.20 -alken-2-yl dicarboxylic acid anhydride is 
converted to a cyclic keto acid by contact, in inert solvent, with a 
strong Bronsted acid catalyst, typified by a superacid resin catalyst. The 
strong Bronsted acid catalysts which may be employed have a pK.sub.a of 
less than about -9 and typically -10 to -15. 
The inert solvents which may be employed in practice of the process of this 
invention include non-aqueous media such as those which have heretofore 
been employed in Friedel-Craft reactions. These inert diluents typically 
include hydrocarbons including benzene, toluene, xylene, etc; liquid 
halogenated hydrocarbons typified by methylene dichloride, chloroform, 
carbon tetrachloride, trichlorethane, etc; and liquid nitrohydrocarbons 
typified by nitrobenzene, nitropropane, nitrobutane; carbon disulfide; 
etc. 
Preferably the inert solvent is present in amount of 100-1000 parts, say 
400 parts per 100 parts of charge composition. 
The catalysts (including superacid resin catalysts) which may be employed 
in practice of the process of this invention may be characterized by their 
pKa of less than -9 and typically -10 to -15 as defined by N. L. Allinger 
et al in Organic Chemistry Worth Publishers Inc. (1971), p 265. 
Commercially available strong Bronsted acids, which are typical of those 
which may be employed, may include: 
TABLE 
______________________________________ 
(i) HClO.sub.4 -- perchloric acid 
(ii) CF.sub.3 SO.sub.3 H -- trifluoromethane sulfonic acid 
(iii) FSO.sub.3 H -- fluoro sulfonic acid 
(iv) Nafion H-501 resin-a perfluorosulfonic acid 
polymer superacid resin catalyst made by 
DuPont. 
______________________________________ 
Catalyst may be present in catalytic amount of 1-10 parts, say 5 parts per 
100 parts of charge composition. This catalytic amount of catalyst is 
found to permit reaction to be readily carried out. 
The preferred strong Bronsted acid may be one contained in an organic resin 
or inorganic support. This allows for easy removal from the reaction 
mixture as by filtration and easy recycle or regeneration. One such 
preferred superacid resin catalyst is the Nafion H-501 catalyst, an 
anhydrous acidic resin stable at temperatures above 100.degree. C. Other 
suitable catalysts include the well-known cross-linked 
styrene/divinylbenzene copolymers containing sulfonic acid groups which 
are preferably prepared so as to be highly porous. Such macroporous resins 
are well-known and may be produced, for example, according to the 
procedures of U.S. Pat. Nos. 3,418,262; 3,509,078; 3,551,358; 3,637,535 or 
3,586,646. A preferred catalyst may be a perfluorosulfonic acid polymer in 
the acid form. An example of such a resin is Nafion 511, a granulated 
perfluorosulfonic acid polymer of 1.0 mm diameter nominal size. The resin 
is formed by copolymerization of tetrafluoroethylene and various monomers 
such as perfluoro-3.6-dioxa-4-methyl-7-octene sulfonyl fluoride. The resin 
is available commercially from E. I. duPont de Nemours and Company. 
Prior to use the resin is treated with a strong acid so as to convert the 
resin into the acid form. 
Catalyst may be present in catalytic amount of 1-10 parts, say 5 parts per 
100 parts of charge composition. This catalytic amount of catalyst is 
found to permit reaction to be readily carried out. 
Reaction may be carried out by contacting the charge anhydride in inert 
solvent in the presence of the catalytic amount of catalyst. Typically 
temperature is 25.degree. C.-180.degree. C., preferably 69.degree. 
C.-145.degree. C., say 98.degree. C.; and pressure may be atmospheric 
pressure. Reaction normally may proceed with agitation over 1-48 hours, 
say 24 hours at the reflux temperature of the solvent, commonly heptane. 
Work-up of the reaction mixture may include filtration to remove the 
preferred strong Bronsted acid resin catalyst (which may be readily reused 
repeatedly without any regeneration treatment). The solvent may then be 
stripped off if desired--although the reaction mixture may if desired be 
used as is i.e. product plus solvent. The product, usually crystalline, 
may be recrystallized from the same or different solvent. 
The product keto acid reaction mix may prinicpally contain two keto acids. 
Reaction may be considered to include the following: 
##STR3## 
Although it may be possible to effect separation of the two product cyclic 
keto acids by chromatographic methods (gas or column chromatography) it is 
found that for many uses this is not necessary. If the product is to be 
converted to keto amides, satisfactory results may be attained with no 
further work-up or pretreating after preferred removal of the solvent. 
Typical of the products is that containing 
2-alkyl-cyclohexene-3-one-5-carboxylic acid (IV) and the corresponding 
five-member ring (V). 
##STR4## 
In practice of the process of this invention, the cyclized keto acid 
typically prepared as noted and without separation of the several cyclic 
products from each other may be amidated by reacting with an amine 
selected from the group consisting of 
(i) HO(CH.sub.2 CH.sub.2 NH).sub.x H wherein x is 1-10; 
(ii) H.sub.2 N(CH.sub.2 CH.sub.2 NH).sub.x H wherein x is 1-10; 
(iii) (H.sub.2 CZ) (CHZ).sub.x (CH.sub.2 Z) wherein x is 1-6 and Z is --OH 
or NH.sub.2 and at least one Z is --NH.sub.2 ; 
(iv) (HOCH.sub.2 CH.sub.2)x NH.sub.3-x wherein x is 2; 
(v) H.sub.2 NCH.sub.x (CH.sub.2 OH).sub.3-x wherein x is 0-1; 
(vi) imidazolines; and 
(vii) oxazolines 
thereby forming a keto amide; and 
recovering said keto amide. 
When the amine has the formula HO(CH.sub.2 CH.sub.2 NH).sub.x H wherein x 
is 1-10, the amine may typically be one of the following: 
TABLE 
______________________________________ 
HOCH.sub.2 CH.sub.2 NH.sub.2 
HOCH.sub.2 CH.sub.2 NHCH.sub.2 CH.sub.2 NH.sub.2 
HOCH.sub.2 CH.sub.2 NHCH.sub.2 CH.sub.2 NHCH.sub.2 CH.sub.2 CH.sub.2 
NH.sub.2 
______________________________________ 
When the amine has the formula H.sub.2 N(CH.sub.2 CH.sub.2 NH).sub.x H 
wherein x is 1-10, the amine may typically be one of the following: 
TABLE 
______________________________________ 
H.sub.2 NCH.sub.2 CH.sub.2 NH.sub.2 
H.sub.2 NCH.sub.2 CH.sub.2 NHCH.sub.2 CH.sub.2 NH.sub.2 
H.sub.2 NCH.sub.2 CH.sub.2 NHCH.sub.2 CH.sub.2 NHCH.sub.2 CH.sub.2 
NH.sub.2 
______________________________________ 
When the amine has the formula (H.sub.2 CZ) (CHZ).sub.x (CH.sub.2 Z) 
wherein x is 1-6 and Z is --OH or --NH.sub.2, the amine may typically be 
one of the following: 
TABLE 
______________________________________ 
##STR5## 
##STR6## 
##STR7## 
______________________________________ 
When the amine has the formula (HOCH.sub.2 CH.sub.2).sub.x NH.sub.3-x 
wherein x is 2 the amine may typically be one of the following: 
TABLE 
______________________________________ 
(HOCH.sub.2 CH.sub.2).sub.2 NH 
______________________________________ 
When the amine has the formula H.sub.2 NCH.sub.x (CH.sub.2 OH).sub.3-x 
wherein x is 0-1, the amine may typically have the formula: 
TABLE 
______________________________________ 
H.sub.2 NCH(CH.sub.2 OH).sub.2 
H.sub.2 NC(CH.sub.2 OH).sub.3 
______________________________________ 
When the amine is an imidazoline, it may typically be 2-imidazoline. 
When the amine is an oxazoline, it may typically be 4-oxazoline. 
The preferred amine may be monoethanolamine. 
Amidation of the keto acid with the amine may be carried out by adding the 
keto acid in solution in inert solvent to a reaction vessel. Typical inert 
solvents may include hydrocarbons having a boiling point above about 
100.degree. C. A preferred inert hydrocarbon solvent is 100E Pale Stock 
HF. The keto acid may be present in amount of 50-500 parts, say 200 parts 
per 100 parts by weight of solvent. 
To the mixture of keto acids, there is added the amine over 1-12, 
preferably 2-5, say 2 hours as the reaction mixture is heated to 
80.degree. C.-200.degree. C., preferably 100.degree. C.-150.degree. C., 
say 110.degree. C. Preferably, the amine is added in amount equivalent to 
the acid. In the case of the preferred monoamines, this is one mole of 
amine per one mole of keto acid. 
After the amine addition is completed, the reaction mixture is maintained 
at the elevated temperature for 2-10 hours, say 2 hours to remove the 
water formed by this reaction and it is thereafter cooled to room 
temperature. 
Typical of the keto amides of this invention may be those formed from the 
following: 
TABLE 
______________________________________ 
Acid Amine 
______________________________________ 
A. Cyclized tetradecenyl- 
monoethanolamine 
succinic acid anhydride 
(1 mole) 
(one mole) 
B. Cyclized tetradecenyl- 
ethylene diamine 
succinic acid anhydride 
(1 mole) 
(one mole) 
C. Cyclized buten-2-yl 
monoethanolamine 
succinic acid anhydride 
(1 mole) 
(one mole) 
D. Cyclized buten-2-yl 
monoethanolamine 
succinic acid anhydride 
(1 mole) 
(one mole) 
______________________________________ 
Products may include those having the following formula 
##STR8## 
The lubricating oils which may be improved by the process of this invention 
may include hydrocarbon lubricating oils generally in use for internal 
combustion engines. 
A preferred standard non-fuel-economy hydrocarbon motor oil maybe one 
containing additives including: 
(i) 0.08-0.20% zinc from zinc dithiophosphate; 
(ii) 0.05-1.0% methyl methacrylate pour depressant; 
(iii) 0.05-0.50% of an ashless antioxidant; 
(iv) 0.01-0.50% of polyethoxylated alkylphenol; 
(v) 0.01-0.20% nitrogen from nitrogen-containing dispersant such as a 
polyalkenyl succinimide or a polyalkenylpolyamine; 
(vi) 0.05-0.35% calcium from calcium sulfonate, calcium phenolate, 
sulfurized calcium phenolate (or combinations thereof); 
(vii) 5-15% of ethylene-propylene copolymer or methacrylate ester polymer 
as viscosity index improver. 
It is preferred to add 0.01-10 W % preferably 0.5-5 w %, say 1 w % of the 
friction improver of this invention to the hydrocarbon lubricating oil 
with agitation. The frictional improvement imparted by these additives 
results in enhanced fuel economy. 
This may be observed by testing the lubricating oil compositions containing 
the additives in The Small Engine Friction Test. 
The Four Ball Wear Test is carried out by securely clamping three highly 
polished steel balls (each 0.5 inch in diameter) in a test cup in an 
equilateral triangle in a horizontal plane. The fourth highly polished 
steel ball, resting in the three lower balls to form a tetrahedron is held 
in a chuck. A weight lever arm system applies weight to the test cup, and 
this load holds the balls together. In the standard test, the speed of 
rotation is 1800 rpm; the load is 5 kilograms. The assembly is submerged 
in the liquid to be tested. The standard test is carried out at ambient 
temperature for 30 minutes. As the chuck and upper ball rotate against the 
fixed lower balls, the friction of the upper ball rotating in relation to 
the lower balls produces a wear-scar the diameter of which (i.e. the depth 
along a diameter of the ball) is measured. The average of the wear on the 
three lower balls is the rating assigned (in millimeters). 
BENCH VC TEST 
In the Bench VC Test, a mixture containing the test oil and a diluent are 
heated at an elevated temperature. After heating, the turbidity of the 
resultant mixture is measured. A low % turbidity (0-10) is indicative of 
good dispersancy while high results (20-100) are indicative oils of 
increasingly poor dispersancy. 
SMALL ENGINE FRICTION TEST 
The Small Engine Friction Test (SEFT) uses a single cylinder, air-cooled, 
6-horsepower engine driven by an electric motor. The engine has a 
cast-iron block and is fitted with an aluminum piston and chrome-plated 
rings. The electric motor is cradled-mounted so that the reaction torque 
can be measured by a strain arm. The engine is housed in a thermally 
insulated enclosure with an electric heater and is driven at 200 rpm. 
Prior to each test, the engine is flushed three times with 1-quart charges 
of test oil. During the test run, the engine and oil temperatures are 
increased continually from ambient until a 280.degree. F. oil temperature 
is reached. The heat comes from engine friction, air compression work and 
from the electric heater. The engine and oil temperatures and the engine 
motoring torque are recorded continually during the test. A SEFT run takes 
about 4 hours. Each test oil evaluation is preceded by a run on a 
reference oil for a like period of time. The torque reference level for 
the engine shifts very slowly with time as a result of engine wear. 
Therefore, the test oil results were recorded compared to a reference band 
consisting of data from up to three reference runs made before and three 
runs made after the test oil evaluation. 
The results are recorded in foot-pounds of torque at several temperatures. 
The results at 280.degree. F. correlate most closely with field 
experience. 
Use of the additive of this invention permits attainment of generally 
improved results as determined by these tests.

DESCRIPTION OF PREFERRED EMBODIMENT 
Practice of this invention will be apparent to those skilled in the art 
from the following wherein, as elsewhere in this specification, all parts 
are parts by weight unless otherwise specified. 
EXAMPLE I 
In this example which represents the best mode known to me of practicing 
the process of this invention, there is charged to a 500 ml round bottom 
flask equipped with an overhead stirrer, nitrogen inlet tube, and 
condenser 100 g of tetradecenylsuccinic anhydride, 23 g of activated 
Nafion acid resin and 200 ml of heptane. The mixture was refluxed for 24 
hr. cooled and filtered to remove the resin. The solvent was then removed 
by vacuum distillation yielding 79.5 g of a dark brown liquid. 
To a 250 ml flask (equipped with an overhead stirred, nitrogen inlet tube 
and Dean-Stark trap with condenser) is charged 60 g of the above product 
and 69 g of 100 E Pale Stock HF. Monoethanolamine (13 g) is added dropwise 
and the mixture heated at 110.degree. C. for 2 hrs. After cooling the 
mixture to room temperature, the mixture is filtered, yielding 108 g of 
product as a reddish-brown filtrate. 
EXAMPLE II 
A lubricating oil formulation is made-up by adding 1 w % of the product of 
Example I to the preferred standard non-fuel economy hydrocarbon motor 
lubricating oil. The formulation was subjected to the 4 Ball Wear Test, 
the Bench Dispersancy Test, and the Small Engine Friction Test. 
EXAMPLE III* 
A reference series was run on a comparable hydrocarbon lubricating oil 
composition which did not contain the additive of this invention, but 
contained a commercially used fuel economy additive. 
EXAMPLE IV* 
A second reference series was run on another comparable hydrocarbon 
lubricating oil composition which did not contain the additive of this 
invention or any fuel economy additive. 
The results were as follows: 
TABLE 
______________________________________ 
EXAMPLE 
TEST IV* III* II 
______________________________________ 
Four Ball Wear 0.43 0.38 0.39 
Test (mm) 
Bench Dispersancy 7.0 10.5 11.5 
Test 
Small Engine Friction Test 
-- 2.52 2.50 
(ft # torque at 280.degree. F.) 
Decrease in torque relative 
-- 6.1 6.9 
to a comparable hydrocarbon 
lubricating oil composition 
containing no fuel economy 
additive (%) 
______________________________________ 
Results comparable to those of Example I may be attained if there is added 
to the base oil, the keto acid of Example I which has been amidated by the 
following amines: 
______________________________________ 
EXAMPLE ADDITIVE 
______________________________________ 
IV ethylene diamine 
V diethanolamine 
VI imidazoline 
VII oxazoline 
______________________________________ 
Although this invention has been illustrated by reference to specific 
embodiments, it will be apparent to those skilled in the art that various 
changes and modifications may be made which clearly fall within the scope 
of this invention.