Quaternary ammonium diester salt composition and lubricating oil containing same

A quaternary ammonium salt of a diester which can be represented by the formula: ##STR1## in which R.sup.i, R.sup.ii, R.sup.iii, R.sup.iv, R.sup.v and R.sup.vi represent hydrogen, alkyl or alkenyl radicals at least one of which is a hydrocarbyl radical having from 50-200 carbon atoms, R is a divalent radical having from 2-10 carbon, or carbon and oxygen atoms, R.sup.vii is hydrogen or a hydrocarbyl radical, z has a value from 0-4 and X is an anion is provided, as well as a method of preparation and a hydrocarbon lubricating oil composition containing same.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
Internal combustion engines operate under a wide range of temperatures 
including low-temperature stop-and-go service as well as high temperature 
conditions produced by continuous high speed driving. Stop-and-go driving, 
particularly during cold, damp weather conditions, leads to the formation 
of a sludge in the crankcase and oil passages of a gasoline engine. This 
sludge seriously limits the ability of the crankcase oil to lubricate the 
engine. In addition, the sludge tends to contribute to rust formation 
within the engine. The noted problems are compounded by lubrication 
service maintenance recommendations calling for extended oil drain 
intervals. 
It is known to employ nitrogen-containing dispersants and/or detergents in 
the formulation of crankcase lubricating oil compositions. Many of the 
known dispersant/detergent compounds are based on the reaction of an 
alkenylsuccinic acid or anhydride with an amine or polyamine to produce an 
alkenylsuccinimide or an alkenylsuccinamic acid as determined by selected 
conditions of reaction. 
It is also known to chlorinate alkenylsuccinic acid or anhydride prior to 
the reaction with an amine or polyamine in order to produce a reaction 
product in which a portion of the amine or polyamine is attached directly 
to the alkenyl radical of the alkenylsuccinic acid or anhydride. The 
thrust of many of these processes is to produce a dispersant having a 
relatively high level of nitrogen. The noted known processes generally 
result in the production of a dispersant reaction product typically 
containing from about 0.5 to 5% nitrogen. These dispersant additives 
exhibited a high degree of oil solubility and have been found to be 
effective for dispersing the sludge that is formed under severe low 
temperature stop-and-go engine operating conditions. However, it has 
become increasingly difficult to formulate lubricants with these additives 
which meet the present requirements with respect to the prevention or 
inhibition of the formation of varnish. 
2. Description of the Prior Art 
U.S. Pat. No. 3,522,179 discloses esters of hydrocarbon-substituted 
succinic acid which are prepared by reacting a chlorinated polyolefin with 
maleic anhydride to form an intermediate hydrocarbon-substituted succinic 
anhydride and then reacting the intermediate with a glycol, such as 
neopentyl glycol, or polyethylene glycol to form an acid ester. 
U.S. Pat. No. 3,778,371 discloses lubricant and fuel compositions 
containing N-hydrocarbyl-substituted quaternary ammonium salts prepared by 
reacting a high molecular weight aliphatic hydrocarbon halide with a 
tertiary amine. 
A copending application, Ser. No. 053,010, filed June 28, 1979, discloses 
quaternary ammonium diester salts formed from non-halogenated precursors. 
SUMMARY OF THE INVENTION 
The quaternary ammonium diester salt of this invention can be represented 
by the formula: 
##STR2## 
in which R.sup.i, R.sup.ii.R.sup.iii, R.sup.iv, R.sup.v and R.sup.vi 
represent hydrogen, alkyl or alkenyl radicals at least one of which is a 
hydrocarbyl radical having from 50-200 carbon atoms, R is a divalent 
radical having from 2-10 carbon, or carbon and oxygen atoms, R.sup.vii is 
hydrogen or a hydrocarbyl radical, z has a value from 0-4 and x is an 
anion selected from the group consisting of halides, sulfates, carbonates, 
sulfites, borates, carboxylates and phosphates. 
The novel quaternary diester salt is prepared by reacting a 
hydrocarbyl-succinic anhydride with a haloalcohol, employing a mole ratio 
of one mole of a hydrocarbon-substituted anhydride with two or more moles 
of a halogenated monohydric alcohol in the presence of an acid-reacting 
catalyst followed by a reaction with a heterocyclic tertiary amine to 
produce the prescribed quaternary ammonium salt. 
The dispersant detergent lubricating oil composition of the invention 
comprises a lubricating oil base and an effective amount of the prescribed 
quaternary ammonium salt. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The quaternary ammonium salt of a diester of this invention can be 
represented by the formula: 
##STR3## 
in which R.sup.i, R.sup.ii, R.sup.iii, R.sup.iv, R.sup.v and R.sup.vi 
represent hydrogen, alkyl or alkenyl radicals at least one of which is a 
hydrocarbyl radical having from 50-200 carbon atoms, R is a divalent 
radical having from 2-10 carbon, or carbon and oxygen atoms, R.sup.vii is 
hydrogen or a hydrocarbyl radical, z has a value from 0-4 and X is an 
anion selected from the group consisting of halides, sulfates, carbonates, 
sulfites, borates, carboxylates, and phosphates. 
In the above formula, the divalent radical represented by R can be an 
aliphatic hydrocarbon radical or it can be an ether or a polyether radical 
represented by the formulas: 
EQU --R.sub.a --O--R.sub.b -- and --R.sub.a --O--R.sub.b --O--R.sub.c- 
wherein R.sub.a, R.sub.b and R.sub.c are aliphatic hydrocarbon radicals 
having from 2 to 4 carbon atoms each. 
The hydrocarbon radical represented by R.sup.vii in the above formula can 
be an aliphatic hydrocarbon radical or an aromatic radical, or one or two 
pairs of R.sup.vii can be interconnected to form one or two fused aromatic 
rings respectively with the principal heterocyclic aromatic ring. 
When X is a halide it is preferably a chloride or a bromide ion. 
A preferred quaternary ammonium diester salt can be represented by the 
formula: 
##STR4## 
in which R.sup.i, R.sup.ii, R.sup.iii, R.sup.iv, R.sup.v or R.sup.vi is a 
hydrocarbyl radical having from 50 to 200 carbon atoms; and the remaining 
substituents are lower alkyl or alkenyl groups of ten carbon atoms or less 
or are hydrogen atoms, R is a divalent hydrocarbon radical having from 2 
to 6 carbon atoms, X is an anion selected from the group consisting of 
chloride, bromide, sulfate and borate ions, R.sup.vii is hydrogen or an 
aliphatic hydrocarbon radical having from 1 to 3 carbon atoms and z has a 
value from 0-2. 
The prescribed quaternary ammonium diester salt of the invention is 
prepared in a two-step reaction. In general, a hydrocarbyl succinic 
anhydride is reacted with a halogenated alcohol in the presence of an 
acidic catalyst to produce the intermediate diester. This, in turn, is 
reacted with a heterocyclic tertiary amine to produce the quaternary 
ammonium salt of the diester. 
Numerous methods for the preparation of hydrocarbyl-succinic acid 
anhydrides are known to those skilled in the art. The hydrocarbyl succinic 
anhydrides useful in this invention are those prepared by heating a 
chlorinated polyolefin with maleic anhydride. Spectral and chemical 
evidence suggest that a hydrocarbyl succinic anhydride of the following 
formula: 
##STR5## 
in which R.sup.i, R.sup.ii, R.sup.iii, R.sup.iv, R.sup.v and R.sup.vi have 
the same values as noted above for the finished salt, is the predominant 
product formed. 
The chlorinated polyolefin employed in this reaction is one obtained by 
chlorinating to 1.0 to 6.0% chlorine the product derived from the 
polymerization of a C.sub.2 to C.sub.6 monolefin or a mixture of 
monoolefins under conventional polymerization conditions. The optimum 
chlorine content is inversely proportional to the molecular weight of the 
polyolefin. The initial polymer will be an unsaturated polymer having a 
molecular weight corresponding to the desired molecular weight of the 
hydrocarbyl radical in the prescribed quaternary ammonium diester salt, 
i.e., a molecular weight from about 700 to 2800 as determined by vapor 
pressure osmometry. 
The synthesis of the subject hydrocarbyl succinic anhydride is described in 
the following U.S. patents, namely, U.S. Pat. Nos. 3,272,746, 3,284,410, 
3,346,493 and 3,522,179 the disclosures of which are incorporated herein 
by reference. 
Examples of specific hydrocarbyl succinic acid anhydrides which can be 
employed for preparing the prescribed quaternary ammonium diester salts of 
this invention include those prepared by the reaction of maleic anhydride 
with chlorinated polybutene, chlorinated polypropylene and chlorinated 
polypentene. 
The haloalkanol, which can be employed for preparing the intermediate 
diester salt, is represented by the formula X--R--OH in which X is a 
halogen atom and R is a divalent radical having from 2 to 10 carbon, or 
carbon and oxygen atoms. The halogen atom can be a chlorine, bromine or an 
iodine atom, with the chlorine atom being preferred. Typical examples of 
suitable haloalkanol compounds include 2-chloroethanol, 2-bromoethanol, 
3-chloropropanol, 3-bromopropanol, 4-chlorobutanol, 4-bromobutanol, 
4-iodobutanol, 5-chloropentanol, 5-bromopentanol, 6-chlorohexanol, 
6-bromohexanol, and 2-(2-chloroethoxy)-ethanol. 
The mole ratio of haloalkanol to hydrocarbyl succinic anhydride which can 
be used to prepare the intermediate product necessary in the reaction 
leading to the prescribed quaternary ammonium salt of a diester is from 
2.0 to 10.0 moles of haloalkanol to 1 mole of hydrocarbyl succinic 
anhydride with the preferred ratio being from 2.0 to 2.5 moles of the 
haloalkanol to a mole of hydrocarbyl succinic anhydride. The lower mole 
ratio of 2 moles of haloalkanol to 1 mole of the anhydride is a critical 
limitation in the process leading to the preparation of the prescribed 
diester salts. High mole ratios of the haloalkanol have no significant 
effect on the amount of the intermediate product produced. 
The reaction of a hydrocarbyl succinic anhydride with a haloalkanol to form 
the diester precursor of the prescribed quaternary ammonium diester salt 
must be conducted either concurrently or sequentially in the presence of 
an acid-reacting catalyst. This catalyst serves to promote the 
esterification reaction. Suitable acid-reacting catalysts include sulfuric 
acid, phosphoric acid, polyphosphoric acid, sulfonic acid, p-toluene 
sulfonic acid, phosphonic acid, hydrogen chloride, hydrogen bromide, 
sulfonated cation exchange resins and crystalline alumino-silicate in the 
acid form. 
The amount of the acid-reacting catalyst used is not critical. In general, 
from about 0.2 to 5.0 weight percent of the acid-catalyst based on the 
amount of the hydrocarbyl succinic acid anhydride will promote the 
esterification reaction. 
This reaction can be conducted over a broad range of temperatures. Useful 
temperatures range from about 20.degree. to 150.degree. C. with the 
preferred reaction temperature being from about 80.degree. to 120.degree. 
C. 
The intermediate diester product produced in the first step of this process 
leading to the prescribed quaternary ammonium salt can be represented by 
the formula: 
##STR6## 
in which R, R.sup.i, R.sup.ii, R.sup.iii, R.sup.iv, R.sup.v, and R.sup.vi 
have the same values noted above for the finished salt, and X is a halogen 
atom. 
The intermediate diester product is reacted with a tertiary heteroaromatic 
amine in order to form the prescribed quaternary ammonium salt. The 
effective tertiary heteroaromatic amine is represented by the formula: 
##STR7## 
in which z is a number from 0 to 4 and R.sup.vii is hydrogen, or a 
hydrocarbyl radical having from 1 to 8 carbon atoms, or one or two pairs 
of "R"s are interconnected to form one or two fused aromatic rings 
respectively. 
The preferred heteroaromatic amine is one in which R.sup.vii is hydrogen or 
a lower aliphatic hydrocarbon radical having from 1 to 4 carbon atoms. 
Examples of suitable tertiary heteroaromatic amines include pyridine, 
3,4-dimethylpyridine, 4-methylpyridine, quinoline, isoquinoline and 
phenazine. 
Procedure A, following, describes the method that was employed for 
preparing the diester intermediate used in the preparation of the 
prescribed quaternary ammonium salt compounds of this invention. 
PROCEDURE A 
A chlorinated polyisobutene/maleic anhydride derived hydrocarbyl succinic 
anhydride, the haloalcohol and the acid catalyst are charged to an 
appropriate sized flask equipped with a reflux condenser, stirrer and 
thermometer. The mixture is heated at the specified temperature for the 
indicated time period. The reflux condenser is removed and a distillation 
head is installed after which the mixture is further heated at 
120.degree.-130.degree. C. under reduced pressure in order to remove small 
amounts of volatile materials (primarily unreacted alcohol) and to 
complete formation of the product. The product is then subjected to 
infrared analysis. Ester formation is indicated by a strong absorption at 
the 1740 cm.sup.-1 wavelength.

The following Table gives the details of preparation and the results 
obtained in Examples 1 through 3 for the diester intermediate product. 
TABLE I 
__________________________________________________________________________ 
INTERMEDIATE DIESTER 
REACTANTS ANALYSIS OF PRODUCT 
Moles of Reaction 
Hydrocarbyl Moles of 
Moles of Mole Ratio 
Conditions 
Succinic 
Halo- 
Sulfuric Anh./Alc./ 
Temp. 
Time 
Example 
Anhydride.sup.(1) 
alkanol.sup.(2) 
Acid Procedure 
Acid .degree.C. 
Hr. 
% Chlorine 
__________________________________________________________________________ 
1 0.17 1.7 0.04 A 1-10-0.25 
115 18 4.10 
2 1.6 17.0 0.17 A 1-10.8-0.11 
115 8 5.17 
3 0.30 2.0 0.03 A 1-6.7-0.1 
80 5 5.52 
__________________________________________________________________________ 
.sup.(1) The anhydride of Example 1 was prepared from chlorinated 
polyisobutene of about 1300 m.w. and had 0.17% Cl and a 75.9 sap. no. The 
anhydride of Examples 2 and 3 was prepared from chlorinated polyisobutene 
of about 1100 m.w. and had 0.51% Cl and a 90.8 sap. no. 
.sup.(2) 2chloroethanol was used in Examples 1 and 2; 4chlorobutanol was 
used in Example 3. 
EXAMPLES 4-6 
The prescribed quaternary ammonium diester salts of this invention were 
prepared by one of the following procedures. 
The appearance of the additive can often be beneficially modified by 
conducting the ester/amine reaction in the presence of a base to 
neutralize amine hydrochloride and/or boric acid to minimize color body 
formation. In addition, it will be appreciated that the performance and/or 
appearance of the additive can often be beneficially modified by 
exchanging the halide in the compound with another anion, such as a 
borate, sulfate, phosphate, phosphonate, sulfite or sulfonate, disclosed 
above. In general, the original quaternary ammonium diester salt is mixed 
with an acidic compound having the desired anion prescribed hereinabove 
and reacted therewith at a moderately elevated temperature ranging from 
about 80.degree. to 120.degree. C., while removing the displaced hydrogen 
halide under reduced pressure. The resulting modified salt is 
significantly improved as a lubricating oil additive. 
PROCEDURE B 
The ester and the tertiary amine are charged to an appropriately sized 
flask equipped with a reflux condenser, stirrer, nitrogen inlet tube, and 
thermometer. The mixture is stirred and heated under a nitrogen atmosphere 
at the specified temperature for the indicated time period. The mixture is 
diluted with a light hydrocarbon, (heptane or isooctane) and a measured 
amount of mineral oil, filtered through diatomaceous earth, and then 
stripped at 90.degree.-100.degree. C. under a vacuum of from 1-25 mm of 
mercury to remove the light hydrocarbon and the unreacted amine and yield 
the product. 
PROCEDURE C 
The reaction product obtained according to Procedure B (100 parts) is 
diluted with a light hydrocarbon (heptane or isooctane, 200 parts) and the 
resulting solution is extracted with methanol (100 parts). The methanol 
layer is allowed to separate and is then removed from the vessel and 
discarded. The remaining light hydrocarbon solution is stripped at 
90.degree.-100.degree. C. under a 1-25 mm Hg vacuum to yield an oil 
concentrate of the product. The extraction removes residual amine and some 
low molecular weight quaternary salts from the initial product. 
The reactants, reaction parameters and product analyses for Examples 4 
through 7 are summarized in Table II below: 
TABLE II 
__________________________________________________________________________ 
Diester 
Ex. No. Mole Ratio 
in Amine/ 
Prep. 
Ex. 
Table Tertiary Amine 
Chloride 
Proce- 
Product Analyses (2) 
No. 
I Gr. 
Identity 
Grams 
in Diester 
dure (1) 
% Chlorine 
% Nitrogen 
__________________________________________________________________________ 
4 1 190 
4-Picoline 
96 4.7 C (3) (3) 
5 2 276 
4-Picoline 
215 5.8 B 2.30 0.93 
6 2 276 
4-Picoline 
215 5.8 C 1.66 0.51 
7 3 200 
4-Picoline 
143 5.0 C 1.30 0.49 
__________________________________________________________________________ 
(1) Reaction conditions: Example 4: 130.degree. C. (7 hrs.); Examples 5 
and 6: 130.degree. C. (8 hours); Example 7: 130.degree. C. (7 hours), 
mixture contained 20 gr. of sodium carbonate. 
(2) Samples contained 50% diluent oil. 
(3) Not determined. 
The lubricant composition of the invention comprises a major amount of a 
mineral, hydrocarbon oil or synthetic oil of lubricating viscosity and an 
effective detergent-dispersant amount of the prescribed quaternary 
ammonium salt of a diester. Advantageously, in the finished lubricating 
oil composition, the prescribed quaternary ammonium diester salt content 
ranges between about 0.1 and 10 percent by weight, preferably between 
about 0.5 and 5 weight percent. In the lubricating oil concentrates, from 
which the finished lubricating compositions are derived via the addition 
of added lubricating oil, quaternary ammonium diester salt contents 
between about 10 and 50 weight percent are found. 
The hydrocarbon oil in the finished lubricating composition advantageously 
constitutes at least about 85 weight percent and preferably between about 
90 and 98 weight percent of the composition, and in the lube oil 
concentrates between about 50 and 90 weight percent of the composition. It 
is to be noted that even in the lubricating oil concentrates the 
prescribed quaternary ammonium diester salt will exhibit 
detergent-dispersancy as well as varnish inhibition. 
Examples of the hydrocarbon base oil contemplated herein are the naphthenic 
base, paraffinic base and mixed base mineral oils, lubricating oils 
derived from coal products and synthetic oils, e.g., alkylene polymers 
such as polypropylene and polyisobutylene of a molecular weight of between 
about 250 and 2500. Advantageously, a lubricating base oil having a 
lubricating oil viscosity at 100.degree. F. of between about 50 and 100, 
preferably between about 100 and 600, are normally employed for the 
lubricant compositions and concentrates thereof. (SUS basis) 
In the contemplated finished lubricating oil compositions other additives 
may be included in addition to the dispersant of the invention. The 
additives may be any of the suitable standard pour depressants, viscosity 
index improvers, oxidation and corrosion inhibitors, anti-foamants, 
supplementary detergent-dispersants, etc. The choice of the particular 
additional additives to be included in the finished oils and the 
particular amounts thereof will depend on the use and conditions desired 
for the finished oil product. 
Specific examples of the supplementary additives are as follows: 
A widely used and suitable VI improver is the polymethacrylate having the 
general formula: 
##STR8## 
where R.sup.2 is an aliphatic radical of from 1 to 20 carbons and n is an 
integer of between about 600 and 35,000. One of the most suitable VI 
improvers is the tetrapolymer of butyl methacrylate, dodecyl methacrylate, 
octadecyl methacrylate, and dimethylaminoethyl methacrylate having a 
respective component weight ratio in the polymer of about 4:10:5:1. 
Another VI improver is a copolymer of ethylene and propylene having a 
molecular weight of 20,000 to 50,000 containing 30 to 40 percent 
propylene in the copolymer in admixture with solvent neutral oil (100 E 
Pale Oil) comprising 13 weight percent copolymer and 87 weight percent 
oil. The VI improvers are normally employed in the finished lubricant 
compositions in quantities between about 0.1 and 10 percent by weight. 
One of the commonly employed lube oil corrosion inhibitors and antioxidants 
are the divalent dialkyl dithiophosphates resulting from the 
neutralization of a P.sub.2 S.sub.5 -alcohol reaction product with a 
divalent metal or divalent metal oxide. Barium and zinc dialkyl 
dithiophosphate are specific examples. Another class of antioxidants are 
the polyalkylated diphenylamines, such as a mixture of 
2,2'-diethyl-4,4'-dioctyldiphenylamine and 
2,2'-diethyl-4-octyldiphenylamine. The corrosion and oxidation inhibitors 
are usually present in the finished lubricating oil compositions in 
concentrations of between about 0.1 and 3 weight percent. 
Examples of supplementary detergent-dispersants which can be employed are 
the monoethoxylated inorganic phosphorus acid-free, steam hydrolyzed 
polyalkylene (500-50,000 m.w.)-P.sub.2 S.sub.5 reaction product, alkaline 
earth metal alkylphenolates, such as barium nonylphenolate, barium 
dodecylcresolate, calcium dodecylphenolate and the calcium carbonate 
overbased calcium alkaryl sulfonates formed by blowing a mixture of 
calcium hydroxide and a calcium alkaryl sulfonate, e.g., calcium 
alkylbenzene sulfonate of about 900 m.w. with carbon dioxide to form a 
product having a total base number (TBN) of 50 to more, e.g., 300 to 400. 
If antifoamants are employed in the finished compositions, one widely used 
class which is suitable are the dimethyl silicone polymers employed in 
amounts of between about 10 and 1000 ppm. 
The following test was employed to determine the dispersancy and varnish 
inhibiting effect of the lubricant composition of the invention: 
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 of oils of 
increasingly poor dispersancy. 
EXAMPLE 8 
A fully formulated SAE Grade 10W-40 lubricating oil composition containing 
the quaternary ammonium salt of a diester of the invention was tested for 
its dispersing effectiveness in the Bench VC Test in comparison to a fully 
formulated base oil without the amine salt dispersant, and to fully 
formulated lubricating oil compositions containing a commercial 
succinimide dispersant. 
The base blend employed contained the following conventional additives: 
0.15 weight % zinc as zinc dialkyldithiophosphate 
0.23 weight % calcium as overbased calcium sulfonate 
0.25 weight % alkylated diphenylamine antioxidant 
11.5 weight % ethylene-propylene copolymer VI improver 
0.15 weight % ethoxylated alkylphenol 
0.10 weight % methacrylate pour depressant 
150 ppm silicone antifoamant 
mineral oil--balance 
The quaternary ammonium diester salt dispersant of the invention was added 
to the base blend at two concentrations on an oil-free basis and then 
tested in the Bench VC Test. 
The results are set forth in the table below: 
TABLE III 
______________________________________ 
BENCH VC TEST 
Run Wt. % of Additive in Base Blend 
Turbidity 
______________________________________ 
1 Base Blend (no dispersant) 
97.5 
2 Example 4 - 4.0 2.0 
3 Example 4 - 3.0 2.5 
4 Example 5 - 4.0 2.5 
5 Example 5 - 3.0 6.5 
6 Example 6 - 4.0 2.0 
7 Example 6 - 3.0 5.0 
8 Example 7 - 4.0 2.0 
9 Example 7 - 3.0 2.5 
10 Succinimide Dispersant - 4.0 
4.0 
11 Succinimide Dipersant - 3.0 
9.5 
______________________________________ 
The foregoing tests demonstrate that the prescribed quaternary amine salts 
of diesters are excellent dispersants for a lubricating oil composition 
and exhibit superior effectiveness in comparison to a commercial 
succinimide dispersant.