US3389980A - Gasoline fuel containing alkyl orthophosphates of nu-aminoalkyl-substituted 2-amino-alkane detergents - Google Patents

Description

United States Patent GASGHNE FUEL CONTAINING ALKYL ORTHO- PHOSPHATES 0F N-AMINOALKYL-SUBSTI- TUTEE) Z-AMINO-ALKANE DETERGENTS George J. Kautsky, El Cerrito, Calif., assignor to Chevron Research Company, a corporation of Delaware No Drawing. Filed June 8, 1964, Ser. No. 373,515 Claims. (Cl. 44-69) ABTRACT OF THE DISCLOSURE Leaded gasoline composition containing alkyl orthophosphates of N-aminoalkyl-substituted 2-aminoalkanes in which the alkane is a straight chain containing from about 9 to 24 carbon atoms and each alkyl group of the orthophosphate contains from 8 to 18 carbon atoms.

This invention relates to improved gasoline fuels for spark ignition internal combustion engines. More particularly, the invention concerns gasoline fuels containing additives which function as detergents and deicers, thereby substantially reducing carburetor deposits commonly occurring in spark ignition internal combustion engines.

In the operation of spark ignition internal combustion engines there have been problems of rough idling and engine stalling, and carburetor adjustments and reconditioning are often necessary to provide satisfactory service. It is found, particularly in the case of stop-and-go driving in metropolitan areas, that such stalling and idling problems are more frequent, especially in the case of multithroat carburetors of the type employed in many present-day automobiles. It has been determined that the rough idling and engine stalling are primarily due to the accumulation of deposits in the throttle body section of the carburetors. As the deposits build up, the amount of air for given amount of fuel is impeded and greatly reduced, and the air-fuel mixture is overly rich for satisfactory engine operation. Frequent adjustments of the carburetor are needed to overcome the effect of this deposit buildup, and finally it becomes necessary to replace the carburetor or give it a complete overhaul.

In addition to the accumulating carburetor deposits of the above type, it has also been found that internal combustion engines operating at certain commonly encountered temperatures and humidity conditions and at certain speeds frequently have trouble with deposits of ice in the throttle body section of the carburetors, particularly on the throttle plate and the surrounding walls. Such ice deposits, although not permanent, cause problems of rough idling and engine stalling which are the equivalent of the problems due to the buildup of deposits as already described.

Various additives have been suggested for use in gasoline to cut down on the buildup of carburetor deposits. However, such additives have usually suffered certain disadvantages as to overall effectiveness, and the search has continued for more suitable compositions.

It has now been found that deposits in the carburetors of spark ignition internal combustion engines are substantially reduced by an improved gasoline fuel comprising a major proportion of a hydrocarbon base fuel boiling in the gasoline boiling range and from about 0.0001 to 1.5% by weight of alkyl orthophosphoric acid salt of branched-chain alkyl amine, the alkyl group of the orthophosphoric acid containing from 8 to 18 carbon atoms and the alkyl group of the amine containing from about 9 to 24 carbon atoms.

The alkyl orthophosphoric acids are preferably branched-chain primary alkyl acid esters, also known as acid monoand dialkyl esters of orthophosphoric acid or alkyl, monoand dihydrogen phosphates. In these compounds one or two of the three available acidic hydrogens of orthophosphoric acid have been replaced by alkyl groups of 8 to 18 carbon atoms.

The branchedchain alkyl amines are characterized by the formula in which one of the branches, R is a straight-chain alkyl group of from 1 to 3 carbon atoms and the other branch, R is a straight-chain alkyl group of 5 to 22 carbon atoms. R is selected from the class consisting of hydrogen and alkyl groups of 1 to 6 carbon atoms and hydroxyalkyl, aminoalkyl, polyaminoalkyl, hydroxyalkylaminoalkyl and polyethoxyamino groups, said alkyl groups containing from 2 to 6 carbon atoms, and R is hydrogen or alkyl groups of 1 to 6 carbon atoms or hydroxyalkyl, aminoalkyl, polyamino'alkyl, hydroxyalkylaminoalkyl or polyethoxyamino groups from 2 to 6 carbon atoms in each alkyl group. In the case of the tertiary amines where R and R are both substituents of the foregoing classes, they may be either alike or different. The polyaminoalkyl substituent groups have the general formula in which R is an alkylene or cyclic ralkylene group of 2 to 6 carbon atoms, R and R are hydrogen or alkyl groups of 1 to 6 carbon atoms and n is a number from 1 to 7.

The amines of the above type may also be described as N-substituted aminoalkanes, for example, N-hydroxyethyLZ-aminoalkane, N-aminoethyl-3-aminoalkane, N- aminopropyl-2-aminoalkane, N-aminoethylaminoethyl-4- aminoalk-ane, N-triethylenetetramineethyl-2-:aminoalkane and the reaction product of N-aminoethylpiper-azine with 3-chloroalkane in which the alkane is straight-chain and contains 9 to 24 carbon atoms.

The salts of the alkyl orthophosphoric acid :and primary amines with secondary attachment and substituted amines with secondary attachment are satisfactorily employed in any amounts sufficient to impart detergency to the gasoline fuel or improve its resistance to carburetor icing. In general, it is preferred that the salt be present in the gasoline in amounts from about 0.0001 to 1.5% by weight as previously mentioned. However, for present purposes amounts in the range from about 0.003 to about 0.05% by weight are most satisfactory from the standpoint of effectiveness and cost.

To facilitate handling, it is customary to formulate the improved detergent anti-icing additives of this invention as concentrates. Since the additives are stable and possess good solubility characteristics, these concentrates represent a particular embodiment of the invention. In the preparation of the concentrate, the additive is dissolved in a suitable hydrocarbon or alcohol solvent boiling in the range from about 150 to 400 F., preferably an aromatic hydrocarbon solvent such as benzene, toluene, xylene, or higher boiling aromatics or aromatic thinners. Aliphatic alcohols of about 3 to 8 carbon atoms, such as isopropanol, isobutylcarbinol, n-butanol and the like, as well as mutually compatible mixtures of such alcohols and hydrocarbon solvents, are also suitable for use with the detergent additive. The amounts of detergent anti-icing additive in the concentrate are ordinarily at least by weight, and may vary up to about 70% by Weight.

In addition to the detergent anti-icing additive, other fuel additives may be used in the gasoline compositions of the invention. The deposit-reducing benefits are obtained in combination With lead alkyl antiknock agents, such as tetramethyl lead or tetraethyl lead. Such antiknock agents are ordinarily employed in amounts sulficient to enhance the octane number, usually from about 0.5 to 4 ml./ gal.

A nonvolatile light mineral lubricating oil, such as petroleum spray oil, is also a suitable additive for the gasoline compositions of the invention. These oils are believed to act as a carrier for dispersed deposits. They are employed in amounts from about 0.05 to 0.5% by volume based on the final gasoline composition.

The branched-chain alkyl amines of this invention are available from a number of sources. For example, straightchain olefinic hydrocarbons of the desired chain length may be converted by conventional methods to haloalkanes having halogen in the 2-, 3- or 4-positions, and the resulting haloalkanes may then be reacted with ammonia or an amine to give the corresponding branched-chain alkyl amine. Suitable amines include alkyl amines, hydroxyalkyl amines, aminoalkyl amines and polyalkylene polyamines as illustrated by monomethyl amine, benzyl amine, diethanol amine, piperidine, ethylene diamine, hexamethylene diamine, piperazine, tetraethylene pentamine and higher polyethylene amines and polyethyleneoxy amines containing as many as 7 and 8 or more ethylene or ethyleneoxy amine units.

In accordance with the present invention, a preferred class of branched-chain alkyl amines and mixtures thereof is obtained by converting cracked wax olefins to the corresponding haloalkanes and then to the corresponding aminoalkanes. The cracked wax olefins contain from about 9 to 24 carbon atoms, and preferably from about to carbon atoms. Mixtures of cracked Wax olefins obtained by the thermal cracking of parafiin waxes are particularly suitable. Such mixtures and their preparation are described in various publications, including U.S. Patent No. 2,172,228 on Process for the Manufacture of Olefins. The primary, secondary and tetriary amines produced from these olefins have the amino group attached to the branched-chain alkyl at the 2-, 3- or 4-positions to provide a mixture of branched-chain alkyl groups, i.e., secondary alkyl groups.

The alkyl orthophosphoric acids and mixtures of them are also available from a number of sources. They may be conveniently obtained by reacting an alcohol having the desired alkyl group with phosphorus pentoxide. Ordinarily at least 2 moles of the alcohol will be used for each mole of the phosphorus pentoxide, but preferably from about 3 to 4 moles of alcohol per mole of phosphorus pentoxide is employed. A particularly suitable mixture of alkyl orthophosphoric acids is obtained by reacting alcohol and phosphorus pentoxide in a molar ratio of about 3:1. Such mixtures are comprised of monoalkyl esters and dialkyl esters in proportions of about 40 to about 60 mole percent of each.

In the preparation of the desired alkyl orthophosphoric acids, aliphatic monohydric alcohols of from 8 to 18 carbon atoms are employed. Mixtures of such alcohols are also suitable. For present purposes, branched-chain primary alkyl alcohols are preferred. A particular class of such alcohols are those obtained by the Oxo process from branched-chain olefins, carbon monoxide and hydrogen, the branched-chain olefins themselves being suitably derived from polymerization of low molecular weight unsaturated hydrocarbons, such as propylene and butylene.

As an illustration of the preparation of amines in accordance with the invention, a mixture of alkyl bromides is first prepared by hydrobromination of the thermally cracked wax olefin mixture containing from about 15 to 20 carbon atoms per molecule. This gives a mixture of secondary alkyl bromides, i.e., 2-, 3- and 4-bromoalkanes, which is substantially (about 95% by weight) pure 2-bromowith the remainder being 3- and higher. One mole of the alkyl bromides is reacted with about 5 moles of hydroxyethyl ethylenediamine at about 160 C. under autogenous pressure in an autoclave. Reaction time is about 10 hours. Two layers are formed, the top layer containing the reaction product and the bottom layer containing unreacted hydroxyethylenediamine, which is recovered and recycled as desired. The top layer is washed with an aqueous 25% caustic solution and then with water. The yield is N-hydroxyethylaminoethyl-Z-aminoalkane.

The salts of the foregoing amines and the alkyl orthophosphoric acids are prepared by reacting the amine and acid using conventional neutralization procedures. In the neutralization, one equivalent of amine is ordinarily reacted with one equivalent of the acid phosphate to produce a substantially neutral salt. Ordinarily the mole ratio of a monofunctional amine to alkyl orthophosphoric acid will range from about 1:0.9 to about 1:0.4 consistent with the above described preparation of the monoand dialkyl orthophosphoric acid amine salts. In the case of polyamines, all amine groups and/or each amine group individually may be 40 to neutralized with the alkyl phosphoric acid.

The improved gasoline compositions containing the branched-chain alkyl amine phosphates in accordance with the invention provide excellent detergent performance compared to gasoline compositions containing other alkyl amine phosphates. Such detergent properties are determined by the generally accepted method of appraising the gasoline compositions in the glass throttle body engine test, which has been especially developed to observe and to evaluate deposits in the carburetors of typical gasoline engines.

In the Glass Throttle Body Test, a 6-cylinder Plymouth automobile engine is set up in the laboratory and is provided with a conventional carburetor modified by the replacement of the metal throttle body section by a removable glass throttle body section. This glass throttle body is a section of glass tubing A thick, of approximately 1%" outside diameter and about 1% long. An automatic cycler or timer, which consists of a constant-speed electric motor and a magnetic clutch, is provided for insuring cyclic operation of the engine with 7.5 min. idle periods followed by five accelerations to 2000 rpm. Crankcase fumes are vented to the carburetor air inlet, since these fumes are now known to be responsible for the larger portion of the deposits. The engine is started up, using leaded gasoline containing a conventional amount of tetraethyl lead (1.5 ml./gal.), but no surface active additives of any kind. It is run for 4 hours with the blowby fumes being drawn in at the air intake. The engine is then stopped, the glass body is removed, and both sides of it are photographed. Thereupon the dirty glass body is again installed on the engine and run for one hour on the same leaded base gasoline compounded with the detergent-action additive. This time the blowby fumes are not piped to the carburetor. After the run is completed, the glass throttle body is again photographed, and the effectiveness of the detergent-containing gasoline (the percentage of cleanup of deposits) is visually estimated.

In these tests, salts of 56.7/43.3 (mixtures of monoand di(tridecyDorthophosphoric acid and branched-chain alkyl amine mixtures obtained from cracked wax olefins as described above were evaluated in the gasoline composition at a concentration of 0.003% by weight. They were additive was determined in a 70/30 isooctane/ toluene mixture stored at --20 F. for one week.

TABLE III Concentration, p.p.m. Compound l-emino Cir-C alkane White precipitate White precipitate White precipitate. 2-amino (Du-C alkane Clear Clear Trace of white floc. C mono-dialkyl orthophosphoric acid salt of do do Clear.

2amino Ora-C20 alkane.

Hydroxyetl1yl-2-amino CHF'CZO alkane do do Trace of white fioc. C13 mono-dialkyl orthophosphoric acid salt of do lear.

ane.

found to give excellent carburetor cleanups as set out in the following table.

The above test results show that the alkyl orthophosphoric acid salts of branded-chain alkyl amines are effective as detergents in typical gasoline compositions in accordance with recognized methods of quality appraisal. In particular, the hydroxyalkyl and aminoalkyl substituted amine phosphates, especially the latter, give surprisingly high cleanup values.

The phosphate salts of the branched-chain alkyl amines act as excellent rust inhibitors in gasoline and other petroleum distillate fuels. In a series of conventional rusting tests using a modified ASTM D665 procedure, the phosphate salts were evaluated at a concentration of 5 ppm. in a typical commercial gasoline as previously described. Polished mild steel specimens in the form of probes were immersed into 300 ml. of the gasoline containing an aqueous phase consisting of 30 ml. sea water. The aqueous and gasoline phases were stirred at room temperature for 17 hours. At the end of the test, the probes were rated and compared with the base fuel on a visual performance scale of 1 to 5, in which 1 indicated no corrosion and 5 indicated very heavy corrosion. The results are shown in the following table.

TABLE II Fuel: Rating Base Fuel 4.5 Z-amino C -C alkanes 3.0 I-Iydroxyethyl-2-amino C -C alkanes 3.5

C mono-dialkyl orthophosphoric acid salt of Z-amino C15'C20 alkanes 1 C mono-dialkyl orthophosphoric acid salt of hydroxyethyl-Z-amino C -C alkanes 1.5 Aminoethyl-2-amino C -C alkanes 1 The effectiveness of gasoline additives is also dependent upon solubility at low temperatures. It is desirable that the additive remain in solution at low temperatures, for example, at -20 F. The branched-chain alkyl amine phosphates are found to possess a decided advantage in this respect, as indicated by the following test results. In these tests, the solubility of various concentrations of the As mentioned above, deposits of a temporary but critical nature are also formed in carburetors due to icing conditions. Such ice deposits are a particular problern in a number of European-manufactured automobiles, the more problem prone being those in which the carburetor is isolated from engine heat.

Tests were carried out to evaluate the effect of the gasoline compositions of this invention in preventing stalling and loss of engine power due to ice deposits in the carburetor. In these tests, a 1963 Volkswagen equipped with Solex 28 PCIT carburetor was employed. It was operated on a chassis dynamometer in an air-conditioned room at 40 F. and 100% relative humidity. A speed of 60 m.p.h. with athrust at the rear wheels of lbs. to approximate road load was maintained for 30 minutes. The base gasoline tested was a typical volatile gasoline having an ASTM D86 initial boiling point of 102 F., a 50% boiling point of F. and a final boiling point of 383 F. with a residue of 1.5%.

The high speed icing test described above showed that the base gasoline by itself sustained a 26% power loss due to the formation of ice deposits in 30 minutes. By comparison, the same base fuel containing 30 p.p.m. of C mono-dialkyl orthophosphoric acid salt of 2-amino C C alkane sustained a power loss of only 8%. On the other hand, a well known anti-icing agent for gasolines, isopropyl alcohol, was evaluated in the same tests and found to be decidedly less effective. At 0.5% by Weight concentration, the isopropyl alcohol sustained a power loss of 23%, while at 1.0% the power loss was 12%.

Although the salts of C mono-dialkyl orthophosphoric acid have been employed in the foregoing examples to illustrate the mono-dialkyl orthophosphoric acids in general, it is obvious that other monoand dialkyl esters may be employed. Illustrative alkyl groups for such esters include the octyl, nonyl, decyl, undecyl, dodecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl and octadecyl groups and the like which may be either straight-chain or branched-chain.

In the foregoing illustrations of the invention, the effectiveness of phosphates of amines derived from mixtures of olefins, such as thermally cracked wax olefin fractions, is particularly apparent. The typical C -C olefins which were employed have the following weight composition:

Percent C 0.6 C 11.2 C 19.3 17 18.5 G 18.4 C 17.3 C 14.0 2 0.7

Such a mixture contains about 92% by weight of straightchain a-olefins, 3% a,w-diO16finS, 3% internal olefins and 2% branched-chain, naphthenic and other hydrocarbons. In the hydrohalogenation of these olefins a catalyst, such as ferric chloride, is conveniently employed to direct the addition such that the halogen atom attaches to nonterminal carbon atoms, thereby providing the branchedchain alkyl structure for the amine final product. The hydrohalogenation is also customarily carried out at temperatures, such as 30 to 40 C., which are not high enough to cause rearrangement of the olefin double bond. The 2-haloalkanes thus obtained are readily converted to amines by conventional procedures as previously indicated. Small amounts (about or less) of 3- and 4-haloalkanes are also present and lead to the corresponding 3- and 4-amines.

While the character of this invention has been described in detail with numerous examples, this has been done by way of illustration only and without limitation of the invention. It will be apparent to those skilled in the art that numerous modifications and variations of the illustrative examples may be made in the practice of the invention within the scope of the following claims.

I claim:

1. An improved detergent gasoline composition comprising a major proportion of a hydrocarbon base fuel boiling in the gasoline boiling range, lead alkyl antiknock agent in amount sufficient to enhance the octane number and from about 0.0001 to 1.5 percent by weight of an alkyl orthophosphoric acid salt of a branched-chain alkyl amine containing from about 9 to 24 carbon atoms in the alkyl group and having the formula:

in which one of the branches, R is a straight-chain alkyl group of from 1 to 3 carbon atoms and the other branch, R is a straight-chain alkyl group of 5 to 22 carbon atoms, R is selected from the class consisting of aminoalkyl and polyaminoalkyl groups, said alkyl groups containing from 2 to 6 carbon atoms and said polyaminoalkyl groups having the general formula:

in which R is selected from the group consisting of alkylene and cyclic alkylene groups of 2 to 6 carbon atoms, R and R are selected from the group consisting of hydrogen and alkyl groups of 2 to 6 carbon atoms and n is a number from 1 to 7, and R is hydrogen, the alkyl groups of said orthophosphoric acid containing from 8 to 18 carbon atoms each.

2. The composition of claim 1 in which the branchedchain alkyl amine has the branched-chain alkyl portion identified by the formula:

OH- R! derived from thermally cracked wax olefin mixtures having about 15 to 20 carbon atoms per molecule.

3. The composition of claim 1 in which the branchedchain alkyl amine is characterized by having R as an aminoalkyl group containing from 2 to 6 carbon atoms and R; as hydrogen.

4. The composition of claim 1 in which the branchedchain alkyl amine is characterized by having R as a polyaminoalkyl substituent group of the general formula:

in which R is selected from the group consisting of alkylene and cyclic alkylene groups of 2 to 6 carbon atoms, R and R are selected from the group consisting of hydrogen and alkyl groups of 2 to 6 carbon atoms and n is a number from 1 to 7, and R is hydrogen.

5. An improved detergent gasoline concentrate consisting essentially of a hydrocarbon solvent and from about 10 to percent by weight of the branched-chain alkyl amine alkyl orthophosphate of the gasoline composition of claim 1.

References Cited UNITED STATES PATENTS 1,787,789 1/1931 Lovell et al. 44-72 1,954,939 4/ 1934 Magness 4480 2,021,088 11/1935 Pevere 4472 2,684,292 7/1954 Caron et al. 44--63 2,706,677 4/1955 Duncan et al. 44-63 2,840,461 6/1958 Duncan et al. 4472 2,863,904 12/1958 Cantrell et al. 44--69 2,905,542 9/1959 Gottshall et al. 44-72 3,007,782 11/1961 Brown et al. 44-72 3,228,758 1/1961 Bauer 4472 DANIEL E. WYMAN, Primary Examiner.

Y. H. SMITH, Assistant Examiner..