US3468639A - Gasolines containing deposit-reducing monoamides of polyamines characterized by improved water tolerance - Google Patents

Description

United States Patent 3,468,639 GASOLINES CONTAINING DEPOSIT-REDUCING MONOAMIDES 0F POLYAMINES CHARAC- TERIZED BY IMPROVED WATER TOLERANCE Eddie G. Lindstrom, Martinez, and Maurice R. Barusch,

Richmond, Calif., assignors to Chevron Research Company, San Francisco, Calif., a corporation of Delaware No Drawing. Filed Aug. 6, 1965, Ser. No. 477,955 Int. Cl. C101 1/22 US. CI. 44-66 3 Claims ABSTRACT OF THE DISCLOSURE An improved engine fuel for use in spark-ignition engines, comprising a major proportion of gasoline and in combination therewith a small amount of from about 0.0001 to about 0.1% by weight of an oil-soluble, emulsion-resistant monoamide reaction product of a polyamine and a hydrocarbon monocarboxylic acid The present invention relates to an improvement in motor fuels, specifically gasolines.

A large number of additives to gasoline have been proposed in the past. Among them, additives aiming at preventing, or at least substantially reducing, formation and accumulation of deposits in the induction system of automotive spark-ignition engines have been particularly numerous. Some of these additives were found to be quite effective in minimizing deposits, particularly those deposits in the throttle body section of the engines carburetor, in the intake manifold, in the ports and on the undersides of the valves. A number of these additives, however, while effective in reducing deposits, introduced new problems which hampered their acceptance by the industry.

Many aminoalkylene amides and some of their salts, found to be very effective as deposit-reducing additives to gasoline, on being blended therewith in the presence of water (and small quantities of moisture are practically always present in systems for handling gasoline), frequently cause a water haze because of the emulsification occasioned by the additive. Particularly, at higher concentrations of the additive, if moisture is present with the fuel, blending is often apt to cause formation of an emulsion which separates on standing but very slowly.

A very striking example is presented by the blending of monooleoylarnide of N-Z-hydroxyethyl-1,2-ethylenediamine (oleic acid monoamide of N-2-hydroxyethyl-l,2- ethylenediamine), an excellent, widely accepted, depositreducing additive to motor gasolines. When this additive is present in the rather small amount of 60 ppm. (60 parts per million parts of the base gasoline), haze occurs when the fuel is mixed vigorously with water, although the fuel settles bright within a period which may range from a few minutes to several hours. A number of factors influence the length of the time necessary for the restoration of brightness, namely, the kind of base gasoline, the amount and the quality of water present (e.g., pH and concentrations of salts), as well as the intensity of agitation in blending.

At higher concentrations, this difficulty becomes more serious: the emulsion formed by agitation tends to persist. At 250 ppm. concentration of the amide in the fuel, several days often may be required for the separation of distinct phases: an upper gasoline phase and a lower clear aqueous phase at the bottom of the blending or storage tank.

One can readily perceive that the production of haze in blending an additive into gasoline may be further accentuated by its motion while being transported by truck, ship or tank car from the refinery to distribution outlets. Consequently, the gasoline must be settled to be satisfactorily bright before it can be delivered to the customer, and the time required for settling or brightening ties up tankage and delays the overall operations at the distribution points.

For this reason, effort has been continued towards discovery of new deposit-reducing additives to gasoline which would be substantially free of the aforementioned emulsion-forming propensity or at least would require but a short time for phase separation after the blending or agitation during transportation and transfer of gasoline to storage tanks.

We have found that oil-soluble monoamides of certain polyamines and certain organic acids are both effective in reducing the aforediscussed deposit formation in spark-ignition engines and are substantially free of the emulsion and haze-forming tendencies of many other oil-soluble amides; in other words, our monoamides are emulsion-resistant. These particular monoamides are distinguishable from other oil-soluble amide additives of the prior art by having been prepared by reacting alkylene polyamines or hydroxy-terminated alkylene polyamines, in each case containing from 2 to 10 carbon atoms and at least two amino groups, with high molecular weight organic monocarboxylic acids in which the hydrocarbon part of the acyl group is non-linear and nonaromatic. More specifically, the amide additives of our invention are produced by reacting a polyamine with either a highly branched (multiple branched-chain) aliphatic hydrocarbon monocarboxyilc acid of 12 to 30, and preferably 15 to 30, carbon atoms in the molecule and with at least two aliphatic radicals branching off the main carbon chain, or with an alicyclic hydrocarbon monocarboxylic acid of 12 to 30, and preferably 15 to 30, carbon atoms in its molecule having one or more non-aromatic hydrocarbon rings. Suitable preferred multiple branched-chain 0 41 hydrocarbon aliphatic acids may carry two or more methyl or larger alkyl radicals and may be either saturated or unsaturated. The preferred alicyclic 0 -0 hydrocarbon monocarboxylic acids suitable for the making of the monoamides preferably contain more than one hydrocarbon non-aromatic ring, usually with 5 to 6 carbon atoms in the ring. The alicyclic hydrocarbon part of the acyl portion of these acids may be attached to the carbonyl carbon by a hydrocarbon chain, may carry alkyl substituents and may be in the form of condensed rings.

As illustrative examples of the aforementioned multiple branched-chain aliphatic acids, there may be listed: 2,2- dimethyltetradecanoic acid, 2,3,5,7,9,11-hexamethyl octadecanoic acid, 2,3,5,7,9,l1,13-heptamethyleicosenoic acid, 9,12-diethyloctadecanoic acid and the like. These acids may be obtained, for instance, by reacting branched-chain polybutene or polypropene, e.g., their trimers, tetramers, pentamers or hexamers, with an ester of acrylic or methacrylic acid, as described in detail in British Patent No. 876,450, published Aug. 30, 1961. Another way to obtain the multiple branched-chain aliphatic acids is by oxidizing in a known manner the aldehydes formed in the reaction of carbon monoxide with branched-chain olefins.

The C -C hydrocarbon .alicyclic non-aromatic acids suitable for the preparation of monoamides operative in accordance with our invention are exemplified by naphthenic acids, such as are recoverable from petroleum, rosin acids (e.g., abietic acid), dihexylcyclohexane carboxylic acid, 9-cyclohexyloctadecanoic acid, dextropimaric acid, cholanic acid, and the like.

The polyamines suitable for the preparation of the monoamide additives of the invention include ethylenediamine,

2-hydroxyethylethylen ediamine, diethylenetriamine,

tetraethylenep entarnine, trimethylenediamine,

propylene diamine,

butylaminoethylamine, 1,3-diamino-2-hydroxypropane, N-hydroxyethyl-1,3-diaminopropane,

di- (trimethylene) triamine,

N,N-di- (Z-hydroxyethyl) ethylenediamine, N-methyl-N- 3 -aminopropyl trimethylenediamine, 2-hydroxypropylethylenediamine, N-isopropylpropylene diamine,

N- 2-hydroxypro pyl isobutylenedi amine, N- (hydroxy-t-butyl) isobutylenediamine, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, 1-amino-2-hydroxy-3 -dimethyl aminopropane, N-Z-amino ethylpiperazine,

2-piperazinyl ethanol,

and the like. For practical purposes, because of their availability in the trade, we prefer to use ethylenediamine, diethylenetriamine, propylenediamine, trimethylenediamine, and tetraethylenepentamine for the preparation of the amide additives of the invention.

We have found that by introducing into the gasoline (whether leaded or unleaded) intended for use in automotive engines from about 0.0002 to about 1.5% by weight, and preferably from about 0.0005 to about 1.0% by weight, of our particular kind of monoamide, the deposit-forming tendencies of the gasoline can be substantially reduced. At the same time the haze and emulsionformation difliculties likely to arise in using other amidetype additives are noted to be essentially obviated. If any emulsification takes place at all, the emulsion breaks rapidly, gasoline becomes bright again, and water drops to the bottom of the blending tank in a matter of minutes, in all events in less than about 1 hour.

In actual practice we prefer to add the amide additive of our invention to gasoline in amounts from about 0.001 to about 0.1% by weight, that is, in proportions from about to about 1,000 parts of the additive per 1 million parts of the gasoline.

The significant common property of the deposit-reducing monoamide additives of the present inventionwhether the C C hydrocarbon portion of their acyl group is an aliphatic radical of .at least two (and preferably more) alkyls branching off the main carbon chain or is an alicyclic configuration formed by one or more non-aromatic hydrocarbon ringsis their emulsion resistance, that is, their proneness to facilitate a rapid separation of two distinct clear phases from aqueous emulsions which may be formed by agitating gasoline in the presence of water. This ability to permit a rapid phase separation is considered to be a unique characteristic of our monoamides as compared with analogous straightchain aliphatic aminoamides mentioned in the art.

This surprising property of the aminoamide additives of our invention in not producing persistent, stable emulsions or haze when added to gasoline in the presence of water is persuasively demonstrated in a modification of the known ASTM D-1094 Test of Water Reaction or Water Tolerance. In this modified procedure, 80 ml. of gasoline and ml. of distilled water in a 100 ml. graduate are thoroughly mixed by vigorous shaking for one minute; the time required for the two distinct bright phases (gasoline and water) to separate is then observed.

The preparation of the new emulsion-resistant monoamides for use in this test, efiective in gasoline according to our invention, by reacting an alkylene polyamine or a hydroxy-substituted (or terminated) alkylene polyamine 4 with a multiple branched-chain aliphatic monocarboxylie acid derived from trimers, tetramers, pentamers and hexamers of propene and butene is illustrated by the following example.

50 g. of methylacrylate is charged into a dry reaction flask provided with a reflux condenser protected with a CaCl moisture trap, and 10 g. of anhydrous aluminum chloride is rapidly .added while stirring. The aluminum chloride dissolves as the temperature is raised from 25 to 50 C. Then, g. of a polypropene fraction boiling between 100 and 124 C. at 10 mm. Hg and averaging five propene groups per polymer molecule is added to the flask, and the contents are heated to 70-75 C. for five hours. Upon cooling to 30 C., 2 ml. of water .and an excess of anhydrous sodium carbonate are added to destroy the aluminum chloride complex. The mixture is filtered through a Biichner funnel. To prevent polymerization of methylacrylate, 0.1 g. of hydroquinone is added, and volatiles are distilled to a bottoms temperature of C. at a pressure of 5 mm. Hg. The remaining mixture is dissolved in 50 ml. of benzene, and saponified using 10 g. of sodium hydroxide, 20 ml. of water .and 100 ml. of ethyl alcohol, and refluxed for three hours. The saponified mixture is acidified and extracted with hexane. Then, the hexane extract is water-washed to neutrality, and hexane is removed by distillation, leaving a mixture of carboxylic acids whose equivalent weight is 302 compared with 282 calculated for a mixture of acids averaging 18 carbon atoms. 16.6 g. of this acid product is mixed with 6.1 g. of hydroxyethylethylenediamine in a flask arranged for refluxing. The amine is used in a slight molar excess. Next, toluene is added to the flask, and the mixture is refluxed for six hours. As a result, 2.0 ml. of water is removed, whereupon toluene is distilled 01? and the contents of the flask stripped to C. at 5 mm. Hg. After cooling, water is added (2.0 ml.), and the mixture is held eight hours at 60 C., during which time the imidazoline which is first formed is converted to the monoamide having an actual equivalent weight of 400 as a base. This compares favorably with the calculated value of 406 (388 plus a mole of free water present in the mixture).

Amides of hydroxyethylethylenediamine and a branched-chain heneicosenoic acid are obtained in a like fashion, starting with a cut of hexamer of propene and methylacrylate. Analysis shows the multiple branchedchain acid intermediate obtained to be 77% pure acid having an equivalent weight of 420. It is next converted to the effective amide additive of the invention by reacting it with hydroxyethylethylenediamine. The monoamide product has an equivalent weight of 443 as compared with the theoretical value of 410 for a pure heneicosenyl monoamide.

The following Table I shows the results of several Water Reaction tests of gasoline compounded with a number of representative aminoamide additives of this invention. The base gasoline used in these tests was a conventional commercial leaded regular-grade gasoline, free of any other surfactant. The monoamide was added in a concentration of 250 ppm.

TABLE I.WATER REACTION TESTS WITH MONOAMIDES In all instances, a perfect phase separation and a clear gasoline phase were obtained without any cloud or floc remaining in less than one hour. This rapid clean separation into a bright gasoline phase and a clear water phase represented an unexpected improvement as compared with the results obtained with a otherwise excellent additive, namely, monooleoylamide of hydroxyethylethylenediamine, which, when used in the same concentration, imposed a delay of at least several hours for the separation of emulsion and disappearance of haze.

A similar improvement was observed in Water Tolerance Tests which used other base gasoline fuels compounded with the amide additive of the invention, at either lower or higher concentrations.

Samples of the same base gasoline, compounded with representative aminoamide additives, such as are shown in Table I, were subjected to the Glass Throttle Body Test in order to confirm their elfectiveness as depositreducing agents, particularly with reference to the deposits which occur in the throttle body section of the carburetor.

In this test a glass throttle body is inserted between the float section and the cast iron throttle body of a conventional carburetor. The throttle plate and shaft are removed from the cast iron body, and the shaft holes are brazed shut. The glass body represents a section of glass tubing 4" thick, 1%" in diameter and 2" long. Some from the upper edge, holes are drilled diametrically in the tubing to receive a conventional metal throttle plate and shaft. The carburetor and engine are those of a Plymouth automobile. Two small tubes carry the idle fuel mixture from the float section to appropriate passages in the cast iron throttle body.

In testing, the engine is run one hour on the base fuel without any detergent additive being present, at about 500 r.p.m. idle with full throttle, and no-load accelerations up to about 3,000 r.p.m. every 15 minutes, while the blowby is piped to the air cleaner above the carburetor. After one hour, the engine is made to operate on the same fuel but this time containing a specified amount of the deposit-removing additive. Before beginning this second phase of the test, the glass body is photographed to record the appearance of deposits formed in the first hour of running. Then the glass body is reinstalled without removing the deposits. The engine is run again for four hours without returning blowby to the air cleaner. Finally, the engine is shut down, the glass body is removed, and the percentage of deposits removed in this phase of the run is determined. This procedure is designated Clean-Up Procedure.

In a representative run, the same base gasoline, that is, a commercial leaded, regular-grade gasoline was used. The amide was a monoamide of hydroxyethyl ethylenediamine and multiple branched-chain aliphatic acids produced by reacting propene pentamer with methylacrylate. The concentration employed was 30 ppm. The percentage of clean-up observed after the termination of the run was 53%. This figure represented an average of a six-run series.

In another test series, we used the same gasoline and a monoamide additive of hydroxyethyl ethylenediamine and alicyclic naphthenic acids from petroleum in a concentration of 50 ppm. The series consisted of six runs, and the average clean-up recorded was 56%. These two figures obtained in the Glass Throttle Body Test favorably compare with the clean-up in the range of 40 to 60% obtainable with the oleic acid monoamide of hydroxyethyl ethylenediamine, recognized as satisfactory in the automobile engine practice.

In addition to being satisfactory as deposit-removing additives, the monoamides of our invention have the advantage of reducing the stalling of automobile engines due to ice formation in the carburetor. When used in the amounts specified, and preferably in amounts from to 1,000 p.p.rn., they enhance the operation of the engines under cool and humid atmospheric conditions.

It may be also added that the monoamides of this invention minimize ferrous corrosion which does occur when the metal parts of the engine come into contact with gasoline contaminated with moisture. The same action is exerted by them in fuel distribution systems, and thus they are applicable for preventing rusting of tanks, pipelines and tankers.

It behooves to mention at this point that salts of the effective aminoamides of our invention are likewise effective in reducing the deposits, preventing stalling, while being resistant to the formation of emulsions and haze when gasoline containing them is mixed with water. Among these salts, there may be mentioned carboxylates, in particular, salts of saturated C C aliphatic monocarboxylic acids. Likewise effective are various salts of phosphorus containing acids, such as oxyphosphorus acids and acids with one or two hydrocarbon radicals attached to the central phosphorus atom, e.g. phosphoric acids, phosphonic acids, and alkyl phosphoric and alkyl phosphonic acids. Particularly effective, both as regards the reduction of deposits and the resistance to emulsion formation are aminoamide salts of monoand dialkylphosphoric acids of 8 to 20 carbon atoms in each of their alkyl radicals.

Ordinarily it is desirable to prepare and distribute the additives of the invention, whether in the form of amides or their corresponding salts, as concentrates, so as to facilitate handling and to enhance a simple blending operation when adding them to gasoline. In preparing these concentrates, gasoline-compatible organic solvents having substantially the same boiling range of the gasoline, for instance, liquid hydrocarbon solvents or alcohols, may be used. Examples of hydrocarbo solvents are aromatic solvents, while examples of alcohols are C -C aliphatic alcohols, such as isobutanol, n-butanol, methylisobutylcarbinol, and the like. The additive is dissolved in such solvents within a wide range of concentrations from at least 10 up to at least 70% by weight. Before concluding this description, it is to be pointed out that the gasoline compositions compounded with the particular amides in accordance with the invention may contain other conventional gasoline additives in customary minor amounts, provided such additives do not interfere with or take away the advtanges imparted by the amide additives. Among such additional materials which may be present in the gasoline there may be mentioned lead antiknock agents, such as tetraethyl lead, lead scavengers, dyes, inhibitors of spark plug fouling, oxidation inhibitors, and so forth. An additional improvement may be achieved by introducing into the gasolines compounded with the additives of the invention a non-volatile oil, for instance, a light mineral lubricating oil or a petroleum spray oil. These oils act as carriers for the engine deposits dislodged by the action of the amide additive of our invention. One may incorporate from about 0.05 to about 0.5% by volume of such carrier oils in the gasoline.

It is to be understood that the invention is by no means limited to the particular examples offered in illustration thereof and by the recitals of any representative materials, but that many modifications, which come within the spirit and scope of the invention as defined in the following claims, are intended to be included in the definitions of these claims.

I claim:

What is claimed is:

1. An improved en ine fuel for use in spark-ignition engines, comprising a major proportion of gasoline, and, in combination therewith, a small amount of from about 0.001 to about 0.1% by weight of an oil-soluble, emulsion-resistant monoamide product of reaction of a polyamine from the group of C2C10 alkylene polyamines and hydroxy-terminated C C alkylene polyamines with a hydrocarbon monocarboxylic acid from the group of aliphatic C 'C hydrocarbon monocarboxylic acids with at least 2 alkyl groups branching off the main carbon chain of the acyl portion thereof and alicyclic (E -C hydrocarbon monocarboxylic acids.

2. An engine fuel as defined in claim 1 wherein said oil-soluble monoamide is present as a salt thereof from the group of salts of phosphorus-containing acids and saturated C C aliphatic rnonocarboxylic acids.

3. An additive concentrate intended for incorporation into gasoline, consisting essentially of an organic, gasoline-compatible solvent boiling in the gasoline range and selected from the group of hydrocarbon solvents and C -C saturated aliphatic alcohols, and, dissolved in said solvent, from about 10 to about 70% by weight of an oil-soluble, emulsion-resistant monoamide of a polyamine from the group of C C alkylene polyamines and bydroxy-terminated C -C alkylene polyamines, and a hydrocarbon rnonocarboxylic acid from the group of allphatic C -C hydrocarbon monocarboxylic acids With at least two alkyl groups branching off the main carbon References Cited UNITED STATES PATENTS V 1,692,784 11/1928 Orelup et al. 44-66 2,604,451 7/ 1952 Rocchini 44-71 2,718,503 9/1955 Rocchini 44-66 2,805,135 9/1957 Bell et a1 44-66 2,922,708 1/1960 Lindstrom et al. 44-66 2,975,133 3/1961 Gottshall et al. 44-66 DANIEL E. WYMAN, Primary Examiner Y. H. SMITH, Assistant Examiner U.S. Cl. X.R. 44-72, 71