Multipurpose lubricating oil additive and compositions containing same

A new class of compositions, tetrahydropyrimidyl-substituted compounds, useful as ashless bases and rust inhibitors, is prepared by reacting a C.sub.3 - to C.sub.50 amine containing a 1,3-diaminopropane group with ethylenediamine tetraacetic acid or nitrilotriacetic acid at a temperature of 150.degree. to 250.degree. C. for 10 to 100 hours.

BACKGROUND OF THE INVENTION 
Varnish, sludge, rust and corrosion seriously reduce the efficiency of an 
internal combustion engine by clogging restricted openings and reducing 
the clearance of moving parts. A high-quality motor lubricating oil must 
incorporate detergents capable of controlling varnish formation and 
corrosion. This function has heretofore been mainly performed by certain 
metallo-organic salts and bases in the lubricating composition. However, 
the present trend to unleaded fuels and ashless lubricating compositions 
brought about by certain important environmental concerns necessitates the 
search for non-metallic (ashless) substitutes for the metallo-organic 
detergents. These non-metallics must fulfill a host of requirements, 
primary among which are basicity and thermal stability. 
DESCRIPTION OF THE PRIOR ART 
U.S. Pat. No. 2,844,446 discloses bis-tetrahydropyrimidines wherein the 
rings are joined by a hydrocarbon radical of at least 2 carbon atoms. The 
bis-tetrahydropyrimidines are prepared by condensing 2 mols of an alkaline 
polyamine having at least 1 primary amino group separated from another 
primary or secondary amino group by 3 carbon atoms with 1 mol of a 
dicarboxylic acid at a temperature above 175.degree. C. 
1,3-Propylenediamine is disclosed as a suitable amine. Suitable 
polycarboxylic acids include oxalic, glutaric, adipic, higher polybasic 
carboxylic acids, and the like. The bis-tetrahydropyrimidines of this 
invention are useful in hydrocarbon distillates for retarding or 
preventing discoloration, oxidation, rust or corrosion, and in addition to 
impart detergent properties. In lubricating oils, the additive may 
function as a pour-point depressant, viscosity-index improver, etc. 
U.S. Pat. No. 3,325,496 teaches the use of triaminopyrimidines as 
high-temperatures lubricant fluids. 
U.S. Pat. No. 2,830,019 teaches the production of amine salts from the 
reaction of an aliphatic or heterocyclic amine with a nitrogen-containing 
polycarboxylic acid such as ethylenediamine tetraacetic acid. 
SUMMARY OF THE INVENTION 
It has been discovered that tetrahydropyrimidyl-substituted compounds 
prepared from a C.sub.3 to C.sub.50 amine containing a 1,3-diaminopropane 
group and ethylenediamine tetraacetic acid (EDTA) or nitrilotriacetic acid 
(NTA) are exceptionally superior ashless base additives for lubricating 
oil having good thermal stability as well as basicity. 
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
The tetrahydropyrimidyl-substituted compounds of this invention are 
prepared by reacting ethylenediamine tetraacetic acid or nitrilotriacetic 
acid with a compound of Formula I: 
##STR1## 
wherein each of R, R.sup.1, R.sup.2 and R.sup.3 is independently hydrogen 
or hydrocarbyl. The reaction is carried out at a temperature of 
150.degree. to 250.degree. C. for 10 to 100 hours. The reaction product 
may be used directly in the lubricating compositions of this invention, or 
it may be purified by methods well known in the art to substantially 
isolate the primary polytetrahydropyrimidine product. In generally, the 
use of the reaction product per se is preferred. 
The compositions of this invention are found to function as superior 
ashless additives for lubricating oil compositions in that they retain 
substantial alkalinity values under conditions of sustained high 
temperatures and they are highly rust-inhibitory. 
The products of this invention are composed of compounds of the following 
formulas, wherein Formula II represents the primary product from the 
reaction of nitrilotriacetic acid with the 1,3-diaminopropane compound of 
Formula I. Formula III represents the primary product from the reaction of 
ethylenediamine tetraacetic acid with the 1,3-diaminopropane compound of 
Formula I. 
##STR2## 
In the above formulas, each of R, R.sup.1, R.sup.2 and R.sup.3 is hydrogen 
or hydrocarbyl. As used herein, hydrocarbyl represents a radical composed 
primarily of carbon and hydrogen and containing from 1 to about 50 carbon 
atoms per hydrocarbyl group. The hydrocarbyl group is preferably 
saturated; however it may contain 1 or 2 sites of olefinic unsaturation. 
Preferably the hydrocarbyl group is an alkyl group of from 1 to 30 carbon 
atoms, and more preferably of from 1 to 20 carbon atoms. Suitable 
substituents include methyl, hexadecyl, tetrapropenyl, hexabutenyl, 
ethylbenzyl, and the like. Without altering the basic performance 
characteristics of the compositions of this invention, each of R, R.sup.1, 
R.sup.2 and R.sup.3 can be a hydrocarbyl group which is substituted by 1 
to 2 alkylamino, alkyloxy or hydroxyalkyl groups, e.g., ethylamino, 
hydroxyethyl, ethyloxy, and the like. Preferred compositions are those 
prepared from an N-substituted 1,3-diaminopropane, i.e., those compounds 
wherein R is hydrocarbyl and R.sup.1, R.sup.2 and R.sup.3 are each 
hydrogen. The preparation of the compositions of this invention is carried 
out by mixing EDTA or NTA and the amine in a suitable solvent, such as 
xylene, while maintaining the temperature at about 150.degree. to 
250.degree. C. for about 10 to about 100 hours, preferably from about 20 
to about 40 hours. The reaction temperature is, of course, generally 
limited by the reflux temperature of this solvent or the decomposition 
temperature of the reactants or product. It is preferred to react all of 
the carboxylic acid groups; therefore it is preferred to operate with an 
excess of amine over the stoichiometric requirement. Broadly, from 0.9 to 
3 mols of amine per carboxylic acid group is utilized, and preferably 1.5 
to 2 mols. The product is complex, containing intermediate amides and 
other compounds in addition to mixed tetrahydropyrimidino compounds.

EXAMPLES 
The preparation of illustrative compositions in the scope of this invention 
is illustrated by the following examples. It is not intended that these 
examples represent limitations on the embodiments of this invention. 
EXAMPLE 1 
Into 600 ml of xylene were placed 57 g (about 0.3 mol) of nitriloacetic 
acid and 360 g (about 0.9 mol) of N-oleyl-1,3-diaminopropane. The mixture 
was held at about 150.degree.-200.degree. C. for about 27 hours and a 
total of 30 ml of water was evolved (calculated, 35 ml). The 431 g of 
product had 7.4 weight percent of nitrogen and an alkalinity value of 160 
mg KOH/g. The infrared spectrum showed the strong C.dbd.N band at 1640 
cm.sup.-1, and nuclear magnetic resonance (NMR) confirmed the presence of 
the methylene-ring hydrogens of the tetrahydropyrimidinyl group. 
EXAMPLE 2 
N-oleyl-1,3-diaminopropane (2400 g, about 6 mols) and nitrilotriacetic acid 
(282 g, about 2 mols) were mixed under nitrogen with stirring to 
200.degree. C. over a 2-hour period. The mixture was maintained at this 
temperature for about 18 hours, stripped under vacuum and nitrogen to 
150.degree. C., and 2661 g of product was recovered having an alkalinity 
value of 176 mg KOH/g. The product is 
tris-(3-oleyl-3,4,5,6-tetrahydro-2-pyrimidylmethyl)amine with some 
intermediate amides. 
EXAMPLE 3 
Into 300 ml of xylene were mixed 146 g of ethylenediamine tetraacetic acid 
(about 0.5 mol) and 800 g of N-oleyl-1,3-diaminopropane. The mixture was 
heated at 150.degree.-200.degree. C. for about 48 hours, and 69 ml of 
water was evolved (72 ml calculated). The 904 g of product had an 
alkalinity value of 180 mg KOH/g and showed the infrared absorption at 
1630 cm.sup.-1 typical of C.dbd.N. The product is 
N,N,N',N'-tetrakis-(3-oleyl-3,4,5,6-tetrahydro-2-pyrimidylmethyl) 
ethylenediamine, mixed with some amido intermediates. 
EXAMPLE 4 
In 100 ml of xylene were mixed 56 g (about 0.29 mol) of nitrilotriacetic 
acid and 212 g (about 0.88 mol) of N-tallowalkyl-1,3-diaminopropane. The 
mixture was heated to about 200.degree. C. for about 27 hours. 31 ml of 
water was evolved (31 ml calculated). The 330 g of product contained an 
infrared absorption at 1640 cm.sup.-1. The product is 
tris-(3-tallowyl-3,4,5,6-tetrahydro-2-pyrimidylmethyl)amine with some 
amido intermediates. 
EXAMPLE 5 
To 20 ml of xylene were added 191 g (about 1 mol) of nitrilotriacetic acid 
and 834 g (about 3 mols) of N-coco alkyl-1,3-diaminopropane. The mixture 
was heated for about 29 hours at about 200.degree. C. 101 ml of water 
evolved (108 ml calculated). The 911 g of product had an alkalinity value 
of 187 and contained 3.5 weight percent of nitrogen. The product contained 
a sharp infrared absorption at 1630 cm.sup.-1. It is 
tris-(3-coco-2,4,5,6-tetrahydro-2-pyrimidylmethyl)amine. 
EVALUATION 
The polytetrahydropyrimidinyl products prepared by the process of this 
invention display satisfactory anti-varnish detergency as additives in 
lubricating oils for the internal combustion engine as illustrated in the 
Ford V8 varnish test results of Table I. In this test, a Ford V8 engine of 
302 cubic inches displacement is operated in cycles of 500/2500/2500 rpm 
for periods of 45/120/75 minutes on a Chevron gasoline containing FCC 
heavy fraction (i.e., product of fluidized-bed catalyst cracking. 
TABLE I 
______________________________________ 
Ashless Base in Ford V8 Varnish Test 
Varnish Rating at (hours) 
20 40 60 80 
______________________________________ 
No base.sup.1 8.9 8.0 7.7 -- 
Mettallic base.sup.2 
9.7.sup.6 
9.4 9.1.sup.4 
8.8.sup.4 
Polytetrahydropuimidine.sup.3 
9.6 8.9 8.7 8.3 
______________________________________ 
.sup.1 All oils contained 6 weight percent polyisobutenyl succinimide of 
tetraethylene pentamine and 15 mM/kg of zinc dialkyldithiophosphate in a 
neutral petroleum oil. 
.sup.2 30 mM/kg of carbonated, sulfurized, calcium polypropylene phenate 
(9.25% calcium) and 30 mM/kg of over-based calcium sulfonate (11.4% 
calcium). 
.sup.3 Tris-(3-oleyl-3,4,5,6-tetrahydro-2-pyrimidylmethyl)amine at 2 
weight percent (63 meg/kg). 
.sup.4 Mean value of two runs. 
In the Ford V8 varnish test, the engine is disassembled at 20-hour 
intervals and the piston varnish is measured on a scale of 0-10, with 10 
being completely clean. The polytetrahydropyrimidine ashless base is found 
to give anti-varnish protection which is comparably satisfactory to the 
metallic base-containing, e.g., overbased, lubricating oil comprably in 
present use. 
The polytetrahydropyrimidines display excellent rust-inhibitory ability in 
the ASTM D1748 Humidity Cabinet Rust Test. In Table II, various low-ash 
and ashless lubricating oil compositions have been tested in the Humidity 
Cabinet Rust Test with and without the addition of 1% by weight of the 
product of Example 1. 
TABLE II 
______________________________________ 
Rust Inhibition of Polytetrahydropyrimidine (1%) 
Humidity Cabinet Rust Life 
(hours) 
Composition Without With 
______________________________________ 
Low-Ash.sup.1 &lt;24 (50) 
Low-Ash.sup.2 &lt;24 (90) 
Ashless.sup.3 24 (800) 
Ashless.sup.4 40 (700) 
Ashless.sup.5 130 &gt;2000) 
______________________________________ 
.sup.1 6 weight percent of polyisobutenyl succinimide of 
tetraethylpentamine and 18 mM/Ks of zinc dialkyl dithiophosphate. 
.sup.2 THe composition of Footnote 1 + 0.2 weight percent of 
tetrapropenylsuccinic acid. 
.sup.3 5 weight percent of polyisobutenylsuccinimide of 
triethylenetetramine, 1 weight percent of diisobornyldiphenylamine and 1% 
of bisalkylphenol sulfide. 
.sup.4 The composition of Footnote 3 + 0.2 weight percent of 
tetrapropenylsuccinic acid. 
.sup.5 6 weight percent polyisobutenylsuccinimide of 
tetraethylenepentamine, 1 weight percent sulfurized wax, 3 weight percent 
sulfurized alkylphenol and 1.5 weight percent hindered bisphenol (Ethyl 
702). 
The humidity cabinet rust lifetime in hours for the same composition 
containing 1% of the polytetrahydropyrimidines is given in parentheses in 
Table II. Even the low-ash and ashless compositions containing 
tetrapropenylsuccinic acid are found to be improved in rust inhibition by 
the addition of only 1% of the polytetrahydropyrimidine. 
TABLE III 
______________________________________ 
Rust Inhibition of Polytetrahydropyrimidine 
Humidity Cabinet Rust 
Additive at 1% Life (Hours) 
______________________________________ 
None.sup.1 &lt;24 
Example 2 300 
Example 4 270 
Example 5 200 
Example 3 250 
______________________________________ 
.sup.1 A neutral petroleum oil of about 480 SUS at 100.degree. F. 
The rust-inhibitory power of the polytetrahydropyrimidines of Examples 2-5 
is demonstrated in Table III. 
The alkalinity value (AV) of a base is an important indicator of the 
ability of the additives to inhibit corrosion, varnish formation and rust. 
The alkalinity value is obtained by titrating the material with perchloric 
acid in glacial acetic acid. The results are converted to mg KOH/g 
necessary to neutralize the titrated acid. Just as important as a high 
alkalinity value in a lubricating composition is the ability of the base 
to maintain its AV over a period of time under the extreme thermal 
conditions encountered in actual use. 
TABLE IV 
______________________________________ 
Thermal Stability 
Initial 
Alkalinity 
Additive.sup.1 Value (AV) Retention 
______________________________________ 
Polyisobutenyl succinimide 
of tetraethylene pentamine 
9.1 67% 
Polyisobutenyl ethylenediamine 
4.4 25% 
Example 2 16 72% 
Example 4 17 79% 
______________________________________ 
.sup.1 All additives are at 10 weight percent in a neutral mineral oil. 
The results of Table IV illustrate the outstanding thermal stability of the 
polytetrahydropyrimidines in comparison with other ashless bases. 
Lubricating oil compositions containing a neutral mineral oil and 10% of 
the additive in Table IV were maintained at 300.degree. F. for 24 hours. 
The initial and final AV was measured and the result expressed as a 
percent retention of AV under these conditions. The 
polytetrahydropyrimidines display an outstanding retention of alkalinity 
value. 
PRIOR ART EXAMPLE 
The example taught at Col. 5, lines 4-11, of U.S. Pat. No. 2,830,019 was 
substantially repeated as follows: 
Into a 1-liter flask were placed 251.3 g (0.86 mol) of ethylenediamine 
tetraacetic acid and 166.1 g (0.46 mols) of Duomeen S. The mixture was 
stirred and heated to 155.degree. C. for 20 minutes. The reaction product 
was solid and was insoluble in oil. IR, NMR and UV analyses indicated a 
product consisting primarily of amides with some salts. The 
rust-inhibitory ability of the product was tested using ASTM D1748 
Humidity Cabinet Rust Test as in Table II above. The humidity cabinet rust 
life was less than 24 hours. 
ADDITIVE MEDIUM 
The products of this invention may be used singly or in combinations of two 
or more in an oil of lubricating viscosity. The lubricating oil can be any 
relatively inert and stable fluid of lubricating viscosity. Such 
lubricating fluids are generally of viscosities of 35-50,000 Saybolt 
Universal Seconds (SUS) at 100.degree. F. (37.degree. C.). The fluid 
medium or oil may be derived from either natural or synthetic sources. 
Included among the natural hydrocarbonaceous oils are paraffin-base, 
naphthenic-base or mixed-base oils. Synthetic oils include polymers of 
various olefins, generally of from 2 to 6 carbon atoms, alkylated aromatic 
hydrocarbons, etc. Non-hydrocarbon oils include carboxylic acid esters, 
polyalkylene oxides, phosphates, aromatic ethers, silicones, etc. The 
preferred lubricating media are the hydrocarbonaceous media, both natural 
and synthetic. Preferred are those hydrocarbonaceous oils having 
viscosities of about 100-4000 SUS, and particularly those having 
viscosities of from 200 to about 2000 SUS at 100.degree. F. The 
lubricating fluids may be used individually or in combinations when 
intermiscible or made so by the use of mutual solvents. 
The lubricating oil will be present at 75 or greater percent by weight of 
the final composition. In concentrates, however, the oil may be present at 
1-84%, preferably 1-50%, by weight. These concentrates are diluted with 
additional oil prior to being placed in service to obtain the requisite 
concentration. 
Other additives may also be present in the compositions of this invention. 
Materials may be added for enhancing the EP properties of the composition, 
or providing other desirable properties to the lubricating medium. These 
include such additives as rust and corrosion inhibitors, anti-oxidants, 
oiliness agents, detergents, rust inhibitors, the viscosity-index 
improvers, pour-point depressants, etc. Usually these will be in the range 
of from about 0-5%, more generally in the range of from about 0-2%, of the 
total composition. Typical additional additives found in compositions of 
the present invention include phenolic and arylamine antioxidants and 
ashless dispersents such as the alkenylsuccinimides. The 
polytetrahydropyrimidines of the present invention may find use in 
lubricating compositions containing ash such as the metallo-organic 
detergents which are known in the art, e.g., the alkaline earth phenates 
or sulfonates. 
The additives of the present invention will generally be present in 
lubricating oils in functional amounts consistent with their use as 
ashless bases and rust inhibitors. Such functional amounts will generally 
range from about 0.05 to 15 weight percent of the total composition, more 
usually in the amount of about 0.1 to about 10 weight percent of the total 
composition.