US2800401A - Hydrocarbon compositions - Google Patents

Description

Patented July 23, 1957 HYDROCARBON COMPOSITIONS Theodore R. Lusebrink, Concord, and Stanley L. Cosgrove, Martinez, Calif., assignors to Shell Development Company, New York, N. Y., a corporation of Delaware No Drawing. Application August 24, 1955, Serial No. 530,418

7 Claims. (CI. 4462) This invention relates to improved hydrocarbon compositions -boiling substantially within the gasoline boiling range, particularly such compositions designed to be used as fuels in internal combustion engines.

Commercial hydrocarbon compositions boiling in the gasoline boiling range invariably contain small amounts of water, either dissolved or dispersed in the product. This is because it is virtually impossible to prevent contact of the product with water during blending operations, storage and transportation to the consumer. Also, even if the greatest precautions to prevent any such contact were taken, water would still be absorbed from the atmosphere. The presence of a small amount of water as such is not normally deleterious; however, when the product is cooled, ice particles are often formed.

The formation of ice in such hydrocarbon products is usually at least troublesome and often is extremely dangerous. For example, all gasoline-powered vehicles are normally provided with filters, such as filter screens and micronic filters, in the fuel system, so as to prevent the passage of solid contaminants, for example, small particles of rust, into the engine. When ice is formed in the gasoline used, it will often plug the filters, thus stopping the flow of fuel to the engine. In the case of vehicles operating on the ground or Water surface, this is at least inconvenient; but in aircraft such stoppage, of course, involves a grave risk to human life. Because of this danger, most aircraft are provided with an automatic bypass around the filters. However, on the opening of the -by-pass, the ice is passed through to injector mechanisms and the like, which contain close and critical tolerances. Here, the ice causes still further difiiculties, including malfunctioning of these mechanisms.

Another fuel system mechanism which is particularly prone to malfunctioning due to plugging with ice is the carburetor. At this point in the fuel system, additional moisture is introduced from the air for combustion. Even though both liquid fuel and air temperatures are above 32 F., the evaporation of the fuel in the carburetor will often cool the system to 32 F. or below, especially soon after starting the engine, whereupon ice will form and will frequently cause the engine to stall because of the blocking of fuel and air passages by the ice.

Other hydrocarbon products boiling within the gasoline boiling range besides gasoline itself are susceptible to difiiculties due to the formation of ice therein, for example, mineral spirits, cleaners naphtha, VM&P naphtha and other specialty products such as benzene, toluene and xylenes, isopentane and the like.

Heretofore, these difficulties have sometimes been alleviated by incorporating into the hydrocarbon product certain water-soluble freezing point depressants, such as alcohols, including glycols, or the like. However, this requires relatively large concentrations of the freezing point depressant, for example, from about 0.1% to as high as 2 or 3% by volume. These large concentrations are not only uneconomical but also often adversely affect the chemical and physical properties of the product. Ad-

cooled. However,

ditionally, the high water solubility of these compounds makes them susceptible to removal from the hydrocarbon product by the leaching action of the free Water with which the product usually comes in contact during storage. Furthermore, such water-soluble products, when incorporated into the hydrocarbon product, act as solubilizers for water, thus actually increasing the amount of water which the product will absorb during commercial handling. Although this is by no means desirable, the alcohols, for example isopropyl alcohol, still are somewhat effective in decreasing the incidence of stalling of automobiles due to carburetor icing. But in the case of aircraft applications, wherein filter clogging is particularly critical, and temperatures are unusually low, the increased concentration of water in the gasoline over-balances the benefit of the freezing point depressant, so the addition of the latter often aggravates rather than alleviates the problem.

It is accordingly a principal object of this invention to provide an improved composition of hydrocarbons boiling within the gasoline boiling range. A more particular object is to provide such a composition which has improved characteristics with respect to ice formation therein. A further object of the invention is to provide a gasoline fuel composition with improved anti-icing characteristics. Still further an object of the invention is to provide a hydrocarbon composition with improved characteristics with respect to ice formation therein and which requires neither a water soluble anti-icing additive nor a high concentration of an anti-icing additive. Other objects will be apparent from the description of the invention.

It has now been discovered that these and other objects are attained by the addition, to a hydrocarbon product boiling within the gasoline boiling range, of an extremely small concentration, for example, less than 100 parts per million (wt), organic polymers, to be described with particularity hereinafter.

The exact way that the polymeric additive alleviates icing difiiculties is not known. Since the additive is not water soluble, it probably does not act strictly as a freezing point depressant, and so it may not actually prevent the formation of ice when the hydrocarbon product is even if the ice still forms, it is clear that the presence vents, or at least reduces, plugging of screens and interference with the operation of pumps, injector mechanisms, carburetors, and the like.

The hydrocarbon base material which is the major component of the composition of the invention can be any hydrocarbon or mixture of hydrocarbons boiling substantially within the gasoline boiling range; that is, those with normal boiling points from about 30 F. to about 450 F. The invention is particularly directed to mixtures of hydrocarbons within an ASTM boiling range of from about F. to about 425 R, such as gasoline, and especially such as aviation gasoline, which normally has an ASTM boiling range of from about F. to about 350 F.

The polymeric additive of the invention is a hydrolyzed reaction product of a vinyl ester of a lower molecular weight allkyl carboxylic acid, or a mixture of such esters, and 'an acyclic alpha-monoolefinic hydrocarbon containing a terminal CH2=CH group and containing at least 10 and no more than 42 carbon atoms, or a mixture of such alpha-olefins. The hydrolyzed reaction product is a mixture of compounds having an average molecular weight of from about 4000 to about 100,000, each molecule thereof containing a linear backbone hydrocarbon chain of from about 40 to about 4000 carbon atoms substituted on about half the carbon atoms of this chain of certain highly-branched oil-soluble of the additive of the invention preby randomly or uniformly located polar and non-polar groups, the polar groups being hydroxyl groups and alkanoyloxy where R=H or alkyl) groups, the alkyl subgroup of the latter containing no more than 4 carbon atoms, at least about 30% of the polar groups being hydroxyl groups, and the non-polar groups being acylic hydrocarbyl groups containing from 8 to 40 carbon atoms, wherein the ratio of the number of polar groups to the number of nonpolar groups is from about 0.511 to about 10:1.

The alkyl groups of the copolymer are, of course, determined by the particular acyclic alpha-monoolefin used. Since the terminal CH2=CH- group of this monomer enters the backbone chain of the copolymer, the alkyl group derived from a particular olefin molecule will be the remainder of the molecule. It is preferred that these alkyl groups be straight chain groups and it is also preferred that they contain'at least 10 carbon atoms, especially at least 12 carbon atoms. However, these groups should not be too long and preferably should contain no more than 30 carbons. Still better results will be obtained with alkyl groups containing no more than about 20 carbon atoms.

The acid from which the vinyl ester is derived can generally be any of the lower molecular weight alkyl carboxylic acids, preferably mono-carboxylic acids, containing up to 5 carbon atoms. The vinyl ester can thus be vinyl formate, vinyl acetate, vinyl propionate or the like. Vinyl acetate is a cheap, readily available and especially preferable ester for the purposes of the invention.

It is preferred that the average molecular weight of the hydrolyzed copolymer be at least 8000 and even better results will be generally obtained with molecular weights above about 10,000. Oh the other hand, although molecular weights up to about 100,000 can be used, better results will be generally obtained with average molecular weights no greater than about 50,000, and especially no greater than 25,000.

Generally, superior results are obtained with hydrolyzed 'copolymers of the invention wherein the ratio of the number of polar groups to the number of non-polar groups (i. e., the mole ratio of the vinyl ester to the alpha-olefin in the copolymer before hydrolysis) is at least 1: 1, especially at least 3: 1. On the other hand, this ratio is preferably not greater than 8:1, 'and especially not greater than 5:1. i

The degree of hydrolysis of the copolymer, of course, determines the proportion of the polar groups which will be hydroxyl groups. It is preferred that at least 50%, and especially at least 80%, of the polar groups be bydroxyl groups. Generally, best results will be obtained if nearly all are hydroxyl groups; however, practical considerations in the hydrolysis of the copolymer will usually limit the economic proportion of hydroxyl groups to about 90 or 95% of the total of the hydroxyl and alkanoyloxy groups of the hydrolyzed copolymer.

The copolymer can be readily prepared by reacting the vinyl ester with the alpha-olefin in the presence of a free radical catalyst or initiator. Generally, an oxygencontaining catalyst is preferred, i. e., a compound containing two directly linked oxygen atoms, preferably an organic peroxide, for example, ditertiarybutyl peroxide, benzoyl peroxide or dichlorobenzoyl peroxide, but other free radical catalysts, for example, :,0c-3Z0dilSOblltY1'O- nitrile and the like, have been found to be effective. Also, the reaction can be made to progress by the use of actinic radiation, such as ultraviolet light. The concentration of the catalyst in the reaction mixture can be varied widely, for example, from as low as 0.01% wt. to wt. or more, based on the weight of the reactants initially added. As a general rule, the larger the concentration of catalyst 7 should be at least about 0.1:1 in order to provide a sufiicient ratio of polar to non-polar groups in the copolymer. Best results are obtained if this ratio is at least about 05:1 and especially at least about 1.5:1. However, to avoid too high a ratio of polar to non-polar groups in the copolymer, this ratio should generally be not greater than about 10:1 and best results are obtained if this ratio is not greater than 5:1, especially not greater than 2.521. The amounts of excess monomer recovered after the polymerization reaction will, of course, indicate the ratio of the original monomers which have entered the copolymer. Accordingly, the ratio of the number of alkanoyloxy groups to the number of alkyl groups in the copolymer can be adjusted at will by varying the original ratio of the two monomers initially charged to the reaction.

The temperature of the reacting mixture can be selected for convenience in order to effect a substantial conversion of the monomers into the copolymer in a reasonable length of time. Ordinarily, the reaction will progress satisfactorily at temperatures of from about 50 C. to about 200 0., preferred temperatures being from about 70 C. to about C. The reacting pressure should be sufficient to keep the reactants substantially in the liquid phase at the reaction temperature employed. The unreacted monomers and any solvent used can then be distilled off from the copolymer product.

Either a batch or a continuous process for the polymerization reaction can be used. Especially suitable copolymers are obtained when the ratio of the unreacted monomers is kept approximately constant throughout the reaction, as is of course the case in the normal continuous process technique. The same advantage can be attained in a batch process by continuous or intermittent addition of further amounts of one of the monomers, usually the ester, to the reacting mixture of monomers and copolymers.

After this copolymer is formed and separated, it must be hydrolyzed to a substantial extent, otherwise it will not be suitable for the purposes of the invention. By hydrolyzed, we mean that a substantial proportion of the alk anoyloxy groups of the copolymer chain must be converted to hydroxy groups. The way this is accomplished is generally not important so long as the resulting hydrolyzed copolymer is not contaminated to any great extent with the other products of the hydrolysis reaction. An especially convenient and effective method of effecting the hydrolysis of the copolymer is to react it with a lower molecular weight alcohol, such as methanol or ethanol, in the presence of a small amount of a hydrolysis catalyst such as an alkali metal alkoxide, or alcoholate, for example, sodium methoxide (i. e., sodium methylate), and preferably also in the presence of a solvent, which can be, for example, either an excess of the alcohol or an ester of the alcohol and the acid group of the vinyl ester monomer, or both. After the hydrolysis reaction has progressed to the desired extent, the alkali metal alcoholate is neutralized, for example, with an equivalent amount of glacial acetic acid, and the solvent and the hydrolysis products can then be distilled off from the hydrolyzed copolymer. Other well known methods of hydrolyzing polyvinyl esters are generally suitable, such as those described in U. S. Patents Nos. 2,266,996; 2,464,290; and 2,668,809. Saponification with aqueous sodium hydroxide is efifective but less desirable because of the necessity of removing from the hydrolyzed copolymer the high concentrations of excess sodium hydroxide and the resulting sodium salt of the acid group of the vinyl ester.

than 100 parts per million (wt.).

parts per million.

Besides the hydrolyzed copolymer, the hydrocarbon compositions of the invention can, and ordinarily will,

contain other additives, such as the usual commercial additives, for example, antidetonants, such as tetraethyl lead, iron carbonyl, dicyclopentadienyl iron, xylidene and N-methyl aniline, lead scavengers, such as ethylene dibromide and ethylene dichloride, dyes, spark plug antifoulants, such as tricresyl phosphate and dimethyl xylyl phosphate, combustion modifiers, such as alkyl boronic acids and lower alkyl phosphates and phosphites, oxidation inhibitors, such as N,Ndisecondarybutyl-phenylenediamine, N-n-butyl-p-aminophenol and 2,6-ditertiarybutyl-4-methylphenol, metal deactivators, such as N,N'-

disalicylal-1,2-propanediamine, and rust inhibitors such as polymerized linoleic acids and N,C-disubstituted imidazolines.

The invention is illustrated in the following examples, which, however, should not be considered limitations thereof.

EXAMPLE I A hydrolyzed copolymer additive suitable for the purposes of the invention was prepared as follows:

Freshly distilled vinyl acetate was added to a mixture of straight chain alpha-olefin hydrocarbons containing 4% v. (3131126, 19% V. C14H2s, 4% v. C15H30, 45% v. Ciel-132, 3% V. C1'1H34 and V. C18H36, With the remainder being minor amounts of saturated hydrocarbons in the same carbon number range, in the proportion of 1.9 mols of the acetate per mol of the olefin. To this mixture was added 1% w. benzoyl peroxide as an initiator. The mixture was then stirred at 80 C. for 16 hours. At this time the unreacted material was distilled off to a temperature of 200 C. at 18 mm. Hg absolute pressure. The remaining copolymer amounted to approximately 61% by weight of the monomers initially charged. The copolymer was cooled and analyzed. The acetate to olefin mol ratio in the copolymer was 3.95 to l, and the ester value was 0.71 equivalent per 100 grams.

The copolymer was then hydrolyzed as follows: To 100 parts by weight of the copolymer was added 72 parts of anhydrous mefllyl alcohol, 0.72 part of water and 1 part of sodium methylate. This mixture was heated and maintained at 65 C. with refluxing for 2 hours. The mixture was then cooled and to it was added approximately 10% excess of glacial acetic acid, based on the stoichiometric ratio of acetic acid to the sodium methylate previously added. The excess methanol and the hydrolysis product methyl acetate were distilled off and the hydrolyzed copolymer recovered. The product was analyzed and found to have a hydroxyl value of 0.64 equivalent per 100 grams,

and a ratio of hydroxyl groups to ester groups of about 4 to 1. Thus, the copolymer had been about 80% hydrolyzed. The product was a clear, light brown, oil

soluble solid with a molecular weight of about 15,000.

EXAMPLE H filled with water. The waiter thus displaced is introduced into a second glass vessel, initially filled with the hydrocarbon product to be tested. The hydrocarbon product thus displaced from the second glass vessel is passed through a heat exchanger, where its temperature is reduced to the desired level, usually between about 0 F. and 20 F., and immediately thereafter through a 10 micron paper filter (Bendix Skinner Division, Bendix Aviation Corporation, Part No. 568,509). In this manner the hydrocarbon product is kept in contact with water, and air is excluded, thus avoiding any change in water concentration in the hydrocarbon product. The flow rate of the hydrocarbon product through the filter was held constant in all tests at 38 cc. per minute. The pressure difierential across the filter at any time is therefore a measure of the degree to which the filter is plugged with ice.

The elapsed time before this differential pressure has reached 16 cm. Hg was selected as a'measure of the ability of the hydrocarbon product to avoid plugging of the filter with ice. The higher this figure, of course, the better the hydrocarbon product.

It has been found that variations in filter temperature between about 0 F. and 20 F. do not have a substantial effect on the elapsed time before filter plugging in this test.

The base product selected for the tests in this example was a specification MIL-F-5572 115/145 grade aviation gasoline, containing only the specification additives, tetraethyl lead, ethylene dibromide and 2,6-ditertiarybutyl-4 methylphenol oxidation inhibitor.

The results btained in these tests are presented in Table I, listed in the chronological order obtained. Additive A, listed in Table I, is the hydrolyzed copolymer obtained in Example I. Additive B is a C,N-disubstituted imidazoline of the general structural formula:

/NOH2 C :4( 2)1uC N-CHa HOCHr-CHz which compound is a corrosion inhibitor.

40 Table I Concentration,

p. p. 111. (wt) Average Temperature at Filter, F.

Time, Minutes, To 16 cm. Hg Ap Test No. Additive The compositions of the invention are thus seen to be superior to the usual commercial gasoline by several magnitudes, and that the presence of a corrosion inhibitor does not detract this benefit.

EXAMPLE I III In order to prove the benefits of the compositions of the invention in commercial equipment, they were tested in a full-scale mock-up of the fuel system of the model 1049C Super Constellation aircraft. The equipment and procedure for this test is as follows: The fuel to be tested is contained in a well-insulated 1000 gallon tank equipped with internal cooling coils and fuel booster pump. A oneinch aluminum fuel line is led into an insulated cold box approximately 20 x 3 x 3 feet which contains all other components of the system. The atmosphere within the box is maintained at a low temperature by circulation of carbon dioxide through the box via a fan and duct system. The fuel line is feet long and is connected to a 10 micron paper filter which is provided with a by-pass which mate opens a t about 19 cm. Hg differential pressure. The line t n ead i hrqug a e hani ally d e e p mp, through a flowjrneter, to a 200 mesh wire screen filter, also provided witha by pass opening at about 16 cm. Hg, then through the fuel master control and finally from the cold box tounderground storage tanks. The fuel is tested on a once-through basis.

The base fuel in each test was a specification MIL-F- 5572 115/145 grade aviation gasoline, containing only the specification additives, tetr-aethyl lead, ethylene dibromide and 2,6-ditertia-ry-butyl-4-methylphenol oxidation inhibitor. The 1000 gallons of test fuel is first agitated with gallons of water and the air in the space above the fuel is saturated with water for.8 to 12 hours before a test. The water is then drawn off and the fuel is pumped to the 1000 gallon test tank through a 10 micron bronze filter. This treatment saturates the fuel with water at the desired temperature but excludes any entrained separate water. The fuel is-then cooled without stirring, to avoid ice crystallization on the cooling coils or the sides of the tank. The refrigerant is turned off when the fuel is at the desired test temperature (-10 F. for these tests) to eliminate dehumidification of the fuel by the exposed coils as the fuel is used in the test. The fuel is then pumped through the system in the cold box, with the temperature of the carbon diox ide atmosphere therein being set at 40 F., all variables being controlled exactly as in a commercial aircraft under the selected conditions. A constant fuel flow is maintained at 1900 pounds per hour by adjustment of the throttle valve on the outlet of the cold box. It has been found that no icing occurs anywhere downstream of the 10 micron filter until it has iced and the bypass is opened.

With the base gasoline the time required to plug the 10 micron filter sufliciently to open its bypass was 57 minutes. In only 2 additional minutes the 200 mesh screen plugged sufliciently to open its bypass.

When the same base gasoline, but now containing 10 parts per million by weight of the copolymer of Example I, was used in this test, the time before the 10 micron filter was plugged sufficiently to open its bypass was 99 minutes, nearly double the time with the base fuel alone. More surprising, however, was the fact that the additional time necessary to plug the 200 mesh screen sufficiently to open its bypass was extended to 45 minutes, over times the time with the base gasoline alone.

EXAMPLE IV In order to determine the benefits of the additives of the invention in respect to icing in carburetors, the following test was adopted:

A standard ASTM-CFR fuel research engine was fitted with a Chevrolet carburetor (Carter, Model No. WA- 1-4135). Intake air for the engine was adjusted for the tests to a constant temperature and humidity at the air inlet to the carburetor of 41 F. and 75 percent relative humidity, respectively, a combination of atmospheric conditions which is known to lead to carburetor icing very frequently in practice. Since it is also well known that stalling due to carburetor icing in automobiles most frequently occurs soon after a cold start and atr a time when the engine speed is reduced to idling, for example, as an automobile is stopped at a street intersection, these circumstances were simulated, and the test procedure standardized, by operating the test engine on the test gasoline with the throttle adjusted to open position until the temperature of the body of the carburetor is reduced to 36 F. With the base gasoline selected for thetests in this example, an automotive gasoline, having a 50% ASTM boiling point of 200 F. and containingfthe usual commercial additives but no alcohol or other antieicing agent, the time necessary to reduce the temperature of the body'of the carburetor to 36 F. was uniformly about 3 minutes. 'At this, time, the throttle valve was closed to the idling position. The time V 8 interval then expiring until the engine stalled is the measure of the tendencyof the test gasoline composition .to prevent stalling due to carburetor icing and is called the stall time of thetest gasoline composition. Compositions with greater stall times are, of course, .superior to those with lesser stall times.

To provide data which are more meaningful in respect to the value of the gasoline compositions of the invention, a large number of tests were made on the base gasoline alone and also on the base gasoline with 1% by volume of isopropyl alcohol (a well known freezing point depressant type of gasoline anti-icing additive). The stall time obtained with the base gasoline and an anti-icing additive was divided by the stall time obtained with the base gasoline alone, thus giving a stall time ratio which is a direct measure of magnitude of the anti-icing benefit of the additive. The results of these tests are shown in Table II.

Additive A of Table II is a hydrolyzed vinyl acetate/ l-octadecene prepared with the procedure of Example I except that the ratio of vinyl acetate to l-octadecene charged was 1.6:1, the polymerization reaction was allowed to progress for 24 hours, the yield of copolymer was 40.5%, and the hydrolysis was effected by refluxing the copolymer for 24 hours with parts of 3A denatured alcohol in which 0.25 part of metallic sodium had been dissolved for each parts by weight of copolymer. The ratio of polar groups (hydroxyl and acetate) to non-polar groups in the hydrolyzed copolymer was 3.5:1, the hydroxyl value was 0.72 equivalent per 100 grams, the degree of hydrolysis was 85.6% (i. e., 85.6% of the total number of hydroxyl and acetate groups consists of hydroxyl groups), and the molecular weight was about 16,500.

Additive B of Table II was also a vinyl acetate alpha- 'olefin prepared with the procedure of Example I, but in this case the alpha-olefin was l-dodecene, the ratio of vinyl acetate to l-dodecene charged was 0.835 :1, the polymerization reaction was allowed to progress for 24 hours, the yield of copolymer was 27%, and the hydrolysis was effected by refluxing the copolymer with 400 parts of methanol in which 0.25 part of metallic sodium had been dissolved for each 100 parts by weight of copolymer. The ratio of polar groups (hydroxyl and acetate) to non-polar groups in the hydrolyzed copolymer was 2:1, the hydroxyl value was 0.748 equivalent per 100 grams and the degree of hydrolysis was 96% (i. e., 96% of the total number of hydroxyl and acetate groups consists of hydroxyl groups).

Table II AVERAGE STALL TIME RATIOS [Stall time with anti-icing additive/Stall time with base gasoline] Average Ant1-Icmg Additive Concentration Stall Time Ratio Isopropyl alcohol 1 v 1. 7 Additive A 50 p m- 1. 8 Additive B 50 p. p m 1. 7

substantially in the gasoline boiling range and at least 1 and less than 100 parts per million by weight of an at least partially hydrolyzed reaction product of a vinyl ester of. a lower molecular weight alkyl carboxylic acid and an acyclic monoolefinic hydrocarbon material with a terminal CH2=CH group and containing from 10 to 40 carbon atoms per molecule, said reaction product, before hydrolysis, containing said vinyl ester and said monoolefinic hydrocarbon material in a mol ratio of from about 0.5 :1 to about 10:1, said hydrolyzed reaction product having an average molecular weight of about 4000 to about 100,000.

2. A gasoline composition in accordance with claim 1, wherein said hydrolyzed reaction product, containing polar groups consisting essentially of hydroXyl groups and alkanoyloxy groups, contains hydroxyl groups in a proportion of at least 30% of the total of said polar groups.

3. A gasoline composition in accordance with claim 2, wherein the vinyl ester is vinyl acetate.

4. A gasoline composition in accordance with claim 3, wherein the acyclic monoolefinic hydrocarbon material contains from about 10 to about 30 carbon atoms per molecule.

5. A gasoline composition in accordance with claim 4, wherein at least 80% of the polar groups of the hydrolyzed reaction product are hydroxyl groups and wherein the concentration of the hydrolyzed reaction product therein is from about 5 to about 50 parts per million by weight.

6. An aviation gasoline composition consisting essentially of a hydrocarbon base material boiling substantially in the aviation gasoline boiling range and from about to about 30 parts per million by weight of an at least 80% hydrolyzed reaction product of vinyl acetate and a mixture of monoolefinic hydrocarbons substantially most molecules of which hydrocarbons have a terminal CHz=CH- group and from about 14 to about 18 carbon atoms, said reaction product, before hydrolysis, containing said vinyl acetate and said mixture of monoolefinic hydrocarbons in a mol ratio of about 4:1 said hydrolyzed reaction product having an average molecular weight of from about 4000 to about 100,000.

7. A gasoline composition consisting essentially of a hydrocarbon base material boiling substantially in the gasoline boiling range and at least 1 and less than parts per million by weight of an at least partially hydrolyzed reaction product of vinyl acetate and a mixture of monoolefinic hydrocarbons substantially most molecules of which hydrocarbons have a terminal CH2=CH- group and from about 14 to about 18 carbon atoms, said reaction product, before hydrolysis, containing said vinyl acetate and said mixture of monoolefinic hydrocarbons in a mol ratio of from about 3:1 to about 5:1, said hydrolyzed reaction product having an average molecular weight of from about 10,000 to about 25,000.

References Cited in the file of this patent UNITED STATES PATENTS 2,213,423 Wiezevich Sept. 3, 1940 2,386,347 Roland Oct. 9, 1945 2,421,971 Sperati June 10, 1947 2,469,737 McNab et a1 May 10, 1949

Claims (1)

1. A GASOLINE COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR AMOUNT OF A HYDROCARBON BASE MATERIAL BOILING SUBSTANTIALLY IN THE GASOLINE BOILING RANGE AND AT LEAST 1 AND LESS THAN 100 PARTS PER MILLION BY WEIGHT OF AN AT LEAST PARTIALLY HYDROLYZED REACTION PRODUCT OF A VINYL ESTER OF A LOWER MOLECULAR WEIGHT ALKYL CARBOXYLIC ACID AND AN ACYCLIC MONOOLEFINIC HYDROCARBON MATERIAL WITH A TERMINAL CH2=CH- GROUP AND CONTAINING FROM 10 TO 40 CARBON ATOMS PER MOLECULE, SAID REACTION PRODUCT, BEFORE HYDROLYSIS, CONTAINING SAID VINYL ESTER AND SAID MONOOLEFINIC HYDROCARBON MATERIAL IN A MOL RATIO OF FROM ABOUT 0.5:1 TO ABOUT 10:1, SAID HYDROLYZED REACTION PRODUCT HAVING AN AVERAGE MOLECULAR WEIGHT OF ABOUT 4000 TO ABOUT 100,000.