Amine phosphate salts and phosphoramides

A mixture containing a major proportion of amine phosphate salts and a minor proportion of phosphoramides is prepared by reacting a triaryl phosphate and an aliphatic amine in the presence of a catalytic amount of a trialkyl borate. Certain of these mixtures are useful as additives for lubricating oils.

FIELD OF THE INVENTION 
This invention relates to a process for preparing lubricating oil additives 
and to the products prepared by this process. This invention also relates 
to lubricating oil compositions containing the products prepared by the 
process of this invention. 
BACKGROUND OF THE INVENTION 
Amine phosphate salts have been prepared by heating an amine and the 
corresponding O,O-dihydrocarbyl phosphoric acid. When trialkyl phosphates 
are reacted with amines, they act as alkylating agents with the product 
forming as illustrated below, where R and R.sup.1 are alkyl: 
EQU (RO).sub.3 PO + R.sup.1 NH.sub.2 .fwdarw. (RO).sub.2 PO.sub.2 NRR.sup.1 
H.sub.2 
this type of reaction is illustrated in U.S. Pat. No. 2,563,506. 
When R in the above reaction sequence is aromatic, no reaction between the 
amine and the phosphate occurs. 
SUMMARY OF THE INVENTION 
It has now been found that the reaction between a triaryl phosphate and a 
primary or secondary aliphatic amine is catalyzed by trialkyl borate to 
yield a mixture of amine phosphate salts and phosphoramides. Certain of 
these mixtures are particularly useful as anti-oxidants, anti-wear agents 
and friction-modifying additives for lubricating oils.

DETAILED DESCRIPTION OF THE INVENTION 
Starting Materials 
Preferred triaryl phosphates for use within the scope of this invention are 
those of the formula 
##STR1## 
where R is alkyl, halo, alkoxy, nitro, trifluoromethyl, or 
dihydrocarbylamine and n is 0, 1 or 2. 
Preferred primary or secondary aliphatic amines are those in which the 
aliphatic radical contains from 4 to 18 carbon atoms. 
Particularly preferred starting-material phosphates and amines for 
preparing the lubricating oil additives are those where R is alkyl and the 
aliphatic amine is a primary alkyl amine containing 12-18 atoms. 
As used herein, the following terms have the meaning set forth below. 
"Aryl" means a compound containing at least one aromatic, 6-carbon-membered 
ring. It may contain other cycloaliphatic rings and/or any substituent 
groups that do not adversely affect the desired reaction path. 
"Primary amine" means an amine having two hydrogen substituents and one 
non-hydrogen substituent that is bonded by a carbon bond to a nitrogen 
atom. 
"Secondary amine" means an amine having one hydrogen substituent and two 
non-hydrogen substituents that are bonded by a carbon bond to a nitrogen 
atom. 
"Aliphatic" means a non-aromatic, carbon-containing radical which is either 
saturated or unsaturated, that is, it contains one or more olefinic or 
acetylenic sites of unsaturation. The aliphatic radical may not contain 
any substituents that would adversely affect the reaction of this 
invention. Preferably the aliphatic group contains only carbon and 
hydrogen and consists of 3 to 30 carbon atoms. 
"Alkyl" means a saturated aliphatic carbon chain of 1 to 30 carbon atoms 
which contains only carbon and hydrogen atoms. 
"Halo" means fluoro, chloro, bromo or iodo. 
"Alkoxy" means the radical alkyl-O- where alkyl is as defined above. 
"Hydrocarbyl" means a C.sub.1 -C.sub.30 aliphatic or C.sub.6 -C.sub.30 
aromatic hydrocarbon radical containing only carbon and hydrogen atoms. 
Reaction Conditions 
The reaction is preferably carried out by combining in the reaction mixture 
from 1 to 20 mols of amine per mol triaryl phosphate. Generally the 
reaction proceeds most efficiently when the molar ratio of reactants is 
2-3 mols of amine per mol triaryl phosphate. 
The reaction usually proceeds to completion in from 0.5 to 30 hours when a 
reaction temperature of 100.degree.-200.degree. C. is employed. 
Excess amine, aromatic by-products and catalyst can be removed, if desired, 
from the reaction product by vacuum distillation at 100-1000 Pa (0.75-7.5 
mm Hg) and a pot temperature of about 100.degree.-170.degree. C. 
A catalytic amount of trialkyl borate must be present in the reaction 
mixture. The trialkyl borate has the formula (R.sup.3 O).sub.3 B, wherein 
R.sup.3 is alkyl of 2 to 6 carbon atoms. Preferably the alkyl group is 
ethyl, propyl, amyl, butyl, or hexyl. Most preferably the alkyl group is 
butyl. Preferably 1 to 5 weight percent, based on the total weight of 
amine and phosphate, and most preferably 3 to 5 weight percent, of the 
borate catalyst is used. 
If desired, the reaction may be carried out in the presence of a 
hydrocarbon diluent; however, the reaction usually proceeds satisfactorily 
in the absence of any solvent or diluent. Excess amine used in the 
reaction and volatile reaction products, such as phenols, may be distilled 
off at about 200.degree.-200.degree. C. under vacuum of 1-10 mm Hg. 
Uses 
The mixtures prepared by the process of this invention have a variety of 
uses, such as lubricating oil additives, thickening agents, and biocides. 
Lubricating Oil Compositions 
The peferred mixtures for use in lubricating oil compositions are described 
above. These mixtures are particularly useful as anti-oxidant, anti-wear 
and friction-modifying additives for lubricating oils. Their use in oils 
reduces the power lost between sliding parts and can increase the number 
of miles per gallon of fuel that an engine can produce. 
The lubricating oil compositions of this invention can be prepared by 
mixing an oil of lubricating viscosity with from 0.01 to 10% by weight of 
the desired mixture prepared according to this invention. The amount of 
mixture which may be present in the lubricating oil in order to impart the 
desired properties varies with the type of mixture, the type of 
lubricating oil, and the presence of other additives. This type of 
variation is well known in the art. In general, the preferred additive 
concentration is 0.05-2% by weight based on the weight of the final 
lubricating oil composition. 
The lubricating oil which may be employed in the practice of this invention 
includes a wide variety of hydrocarbon oils. Other oils include 
lubricating oils derived from coal products and synthetic oils, e.g., 
alkylene polymers such as polypropylene, polybutylene, etc., and mixtures 
thereof), alkylene oxide-type polymers (e.g., alkylene oxide polymers 
prepared by polymerizing alkylene oxides such as propylene oxide, etc., in 
the presence of water or alcohol, e.g., ethyl alcohol), carboxylic acid 
esters (e.g., those which were prepared by esterifying carboxylic acids 
such as adipic acid, azelaic acid, suberic acid, sebacic acid, 
alkenylsuccinic acid, fumaric acid, maleic acid, etc., with the alcohol 
such as butyl alcohol, hexyl alcohol, 2-ethylhexyl alcohol, 
pentaerythritol, etc., liquid esters of phosphorus, such as trialkyl 
phosphate (tributyl phosphate), dialkylaryl phosphate, triaryl phosphate 
(tricresyl phosphate), etc., alkylbenzenes, polyphenols (e.g., bisphenols 
and terphenols), alkylbiphenylethers, esters and polymers of silicon, 
e.g., tetraethyl silicate, tetraisopropyl silicate, 
hexyl-(4-methyl-2-pentoxy) disilicate, poly(methyl)siloxane and 
poly(methylphenyl)siloxane, etc. The lubricating oils may be used 
individually or in combinations whenever miscible or whenever made so by 
use of mutual solvents. The lubricating oils generally have a viscosity 
which ranges from 50 to 5000 SUS (Saybolt Universal Seconds) and usually 
from 100 to 1500 SUS at 100.degree. F. (38.degree. C.). 
In addition to the mixture of this invention, other additives may be 
successfully employed within the lubricating compositions of this 
invention without affecting their high stability and performance over a 
wide temperature scale. One type of additive is an anti-oxidant or 
oxidation inhibitor. This type of additive is employed to prevent varnish 
and sludge formation on metal parts and to inhibit corrosion of alloyed 
bearings. Typical anti-oxidants are organic compounds containing sulfur, 
phosphorus or nitrogen, such as organic amines, sulfides, hydroxysulfides, 
methanols, etc., alone or in combination with metals such as zinc, tin or 
barium. Particularly useful antioxidants include 
phenyl-alpha-naphthylamine, bis(alkylphenyl)phenyl)amine, 
N,N'-diphenyl-p-phenylenediamine, 2,2,4-trimethyldihydroquinoline 
oligomer, bis(4-isopropylaminophenyl) ether, N-acylaminophenol, 
N-acylphenothiazines, N-hydrocarbylamides of ethylenediamine tetraacetic 
acid, alkyl-phenol-formaldehyde-amine polycondensates, etc. 
Another additive which may be employed is a rust inhibitor. The rust 
inhibitor is employed in all types of lubricants to suppress the formation 
of rust on the surface of metallic parts. Exemplary rust inhibitors 
include sodium nitrite, alkenylsuccinic acids and derivatives thereof, 
alkylthioacetic acid and derivatives thereof, substituted imidazoles, 
amine phosphates, etc. Another additive which may be incorporated into the 
lubricant composition of this invention is an anti-corrodant. The 
anti-corrodant is employed to inhibit oxidation so that the formation of 
acidic bodies is suppressed and to form films over the metal surfaces 
which decrease the effect of corrosive materials on exposed metallic 
parts. Typical anti-corrodants are organic compounds containing active 
sulfur, phosphorus or nitrogen, such as organic sulfides, phosphides, 
metal salts of thiophosphoric acid, cyclic and acyclic epoxides and 
sulfurized waxes, barium phenates and sulfonates, etc. A particularly 
effective corrosion inhibitor is ammonium dinonylnaphthylene sulfonate. 
Other types of lubricating oil additives which may be employed in the 
practice of this invention include anti-foam agents (e.g., silicones, 
organic copolymers), stabilizers, anti-stain agents, tackiness agents, 
anti-chatter agents, dropping point improvers, anti-squawk agents, 
lubricating color correctors, extreme-pressure agents, odor control 
agents, dispersants, detergents, etc., as well as other anti-wear agents 
such as tricresyl phosphate and zine dithiophosphate esters. 
In many instances, it may be advantageous to form concentrates of the 
mixture of this invention within a carrier liquid. The employment of 
concentrates provides a convenient method of handling and transporting the 
mixtures of this invention for their subsequent dilution and use. The 
concentration of the mixture of this invention within the concentrates may 
vary from 10 to 90 weight percent, although it is preferred to maintain 
the concentration between about 20 and 80 weight percent. 
ILLUSTRATIVE EXAMPLE 
To a 1-liter flask was added 109 g (1/3 mol) triphenyl phosphate and 215 g 
(1 mol) cocoamine (96% n-dodecylamine). The reaction mixture was heated 
with stirring at 150.degree. C. under nitrogen for 4 hours. Analysis by 
infrared at the end of 4 hours indicated that little to no reaction had 
taken place. 
EXAMPLE 1 
To a 1-liter flask was added 326.3 g (1 mol) triphenyl phosphate, 430 g (2 
mols) cocoamine (96% n-dodecylamine) and 38 g (5% by weight) tri-n-butyl 
borate. The reaction mixture was stirred at 120.degree. C. for 10 hours 
and at 130.degree. C. for 5 hours. 
EXAMPLE 2 
To a 2-liter flask was added 645 g (3 mols) cocoamine (96% n-dodecylamine), 
326 g (1 mol) triphenyl phosphate and 49 g (5% by weight) tri-n-butyl 
borate. The reaction mixture was stirred at 120.degree. C. for 10 hours 
and then stripped to 150.degree. C. at 2-3 mm Hg. Product analysis: 5.3% 
P, 2.9% N, acid number 86 mg KOH/g, alkalinity value 103 mg KOH/g 
EXAMPLE 3 
To a 3-liter flask were added 967.5 g (4.5 mols) cocoamine (96% 
n-dodecylamine), 489 g (1.5 mols) triphenyl phosphate and 73.5 g (5% by 
weight) tri-n-butyl borate. The reaction mixture was stirred under 
nitrogen at 120.degree. C. for 10 hours and then stripped to 150.degree. 
C. at about 2 mm Hg. Product analysis: 5.4% P, 2.3% N, acid number 79 mg 
KOH/g, alkalinity value 96 mg KOH/g. 
The analysis of the products of Examples 1-3 is presented in Table I, which 
shows the percent distribution of products prepared as determined by 
phosphorus nuclear magnetic resonance. 
TABLE I 
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Molar percentage 
distribution in final 
product prepared in Example 
Products 1 2 3 
______________________________________ 
##STR2## 5 2 3 
##STR3## 2 3 2 
##STR4## 62 81 74 
##STR5## 31 14 21 
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EXAMPLE 4 
The coefficient of friction of a lubricating oil containing the additive 
prepared by the process of Example 2 is tested in the Kinetic Oiliness 
Testing Machine (KOTM) manufactured by G. L. Neeley of Berkeley, 
California. The procedure used in this test is described by G. L. Neeley, 
Proceedings of Mid-Year Meeting, American Petroleum Institute, 1932, pp. 
60-74. Friction was measured in this test under boundary conditions with a 
load of 100 pounds (12 MPa), speed of 0.1 rpm (0.5 mm/sec). The oil being 
tested is an SAE 10W40 oil containing 8.4% of a polyacrylate viscosity 
index improver and also containing a conventional polybutene succinimide 
dispersant, zinc dialkyl dithiophosphate and overbased magnesium 
sulfonate. The results in Table II below show good reduction in the 
coefficient of friction on both metal combinations tested and at all 
temperatures tested. 
TABLE II 
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Effect of Product of Example 2 on Coefficient of Friction 
Wt. % 
Prod- Coefficient of 
ucts of 
Friction at 
Metal Surfaces 
Ex. 2 50.degree. C 
100.degree. C 
150.degree. C 
200 .degree. C 
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52100 Steel sliders on 
0 0.13 0.14 0.15 0.16 
52100 steel track 
1 0.55 0.038 0.038 0.071 
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This reduction in coefficient of friction results in a fuel savings in a 
V-8 engine of the following percents at the speeds noted: 
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Speed, mph Savings, % 
______________________________________ 
0 (idle) 1.2 
15 13 
30 6.5 
55 2.1 
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