US 3004838 A
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United States Patent 3,004,838 ANTIKNO'CK COMPOSITIONS Melvin L. Larson, Royal Oak, Mich., assignor to Ethyl Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed Oct. 24, 1956, Ser. No. 617,926 6 Claims. (Cl. 44-69) This invention relates to improved liquid fuel for spark ignition internal combusion engines and to composite additives for such fuel.
In recent years there has been a marked trend in the automotive industry of utilizing high compression, spark ignition engines in passenger cars and trucks. With such engines the accumulation of engine deposits results in a number of serious problems, including spark plug fouling and surface ignition (also known as deposit-induced autoignition or wild ping). Spark plug fouling results from the formation of conductive deposits on the firing end of spark plugs which provide a conductive surface for the electrical charge so that the decrease in resistance results in an insufficient potential across the spark plug electrodes. Under such circumstances the production of a spark at the spark gap is prevented. Surface ignition is erratic ignition produced by glowing engine deposits and manifests itself in reduced efiiciency of operation, loss of power and of fuel economy and in increased wear of engine parts.
A critical limitation imposed upon any additive to be used in alleviating spark plug fouling or controlling surface ignition is that it must not destroy an appreciable amount of the alkyllead antiknock compounds which are employed in gasoline. Failure to meet this limitation causes, among other things, loss of gasoline octane quality, a property which is needed in these days of the high compression engine. Another adverse effect caused by an additive which destroys the antiknock effectiveness of alkyllead antiknock agents is the substantial economic waste caused thereby.
On object of this invention is to provide composite additives for gasoline capable of substantially reducing spark plug fouling and surface ignition without causing loss of antiknock effectiveness. Another object is to provide improved gasoline compositions having the above properties. Other objects of this invention will be apparent from the ensuing description. I
The above and other objects are accomplished by pro viding a gasoline additive consisting essentially of an alkyllead'antiknock agent, a scavenging amount of an organic halide scavenger capable of reacting with the lead during combustion in a spark ignition internal combustion engine to form relatively volatile lead halide, and a dialkyl phosphoramidate in which each alkyl group contains from 2 to carbon atoms, the phosphoramidate being present in the additive in amount such that the phosphorus-to-lead atom ratio is from about 0.123 to about 1.6:3. Also provided by this invention is gasoline containing from about 0.02 to about 6.5 grams of lead per gallon as an alkyllead antiknock agent, a scavenging amount of organic halide scavenger capable of reacting with the lead during combustion in a spark ignition internal combustion engine to form relatively volatile lead halide and a dialkyl phosphoramidate as defined above which is present in amount such that the phosphorus-tolead atom ratio is from about 0.1:3 to about 1.6:3.
The dialkyl phosphoramidates used according to this invention have the general formula v R,o-i: on,
wherein R and R are alkyl groups containing from 2 to 3,004,838 Patented Qct. 1'1, 1961 10 carbon atoms. Preferred dialkyl phosphoramidates used in this invention are those in which the alkyl groups contain from 4 to'lO carbon atoms. These particular phosphoramidates are preferred because they possess ideal solubility characterisitcs; they are infinitely soluble in most present-day gasolines and have'an exceptionally low solubility in water. Low water solubility is a very important feature of an additive for gasoline because gasoline normally comes in contact with or contains water and since the preferred dialkyl phosphoramidates have such low solubility in water, their continued presence in the gasoline is assured.
Particularly preferred dialkyl phosphoramidates are those in which the alkyl groups both contain the same number of carbon atoms .and in which the total number of carbon atoms in the molucule is from 8 to 20. These are particularly preferred because not only do they have all of the eficacious attributes of the preferred type disclosed above, but they are very inexpensive and easily made from readily available starting materials.
The compositions of this invention are capable of (1) obviating ordinary knock, (2) substantially reducing surface ignition and (3) alleviating spark plug fouling because of the cooperation among the several ingredients. Moreover, these important benefits are obtained with virtually no loss in antiknock effectiveness of the alkyllead ingredient.
Among the features of this invention is that the dialkyl phosphoramidate ingredients have unusually great effectiveness in reducing surface ignition rate and alleviating spark plug fouling. In addition to this, these phosphoramidates cooperate with the alkyllead antiknock agent during engine combustion in some currently unexpected manner so that'there is almost no loss in the antiknock effectiveness of the entire composition. In other words, the'dialkyl phosphoramidates have the very unusual property of exhibiting very little destruction of or antagonism toward the antiknock eifectiveness of the alkyllead antiknock agent. This represents a substantial advance in the art inasmuch as phosphorus compounds in general have heretofore been reported as being among the most serious antagonists for tetraalkyllead antiknock agents. Other important features of this invention are that the dialkyl phosphoramidates are easily made and have a high phosphorus content, the amount of phosphorus in the molecule ranging as high as over 20 percent by weight. Thus, the petroleum refiner is provided with not only an inexpensive, highly effective and eminently useful composition, but one in which only a small amount of the phosphoramidate ingredients need be added to achieve the desired phosphorus-to-lead atom ratio. This further reduces his costs vand simplifies his handling, storage and blending operations. Thus, the present invention not only provides highly unexpected results but is an important contribution to the art.
To prepare the improved composite additives of this invention, the desired proportions of the ingredients are placed in a suitable container, such as a blending tank, and mixed. To insure homogeniety, use is made of conventional physical agitation, such as stirring, shaking or the like. The order of addition of the ingredients during formulation is not critical.
Representative alkyllead antiknock compositions of this invention-i.e., composition additivesare presented in Table I. The figures following the representative ingredients are parts by weight. The two figures following t 1. a 3 composition having a phosphorus-to-lead atom ratio of 0.413. For other phosphorus concentrations, the proper adjustments are evident.
Tab7e'I..-Antik1i0ck fluid compositions Antiknock agent" Scavenger Dialkyl phosphorcomprising isopentane, alkylate, aromatics and straightrun gasolines. 'Initial boiling point, 82 F.; endpoint, 330 F. g
Base Fuel D--A blend of light catalytically cracked naphtha, polymer stock, catalytic reformate and light straight-run naphtha. containing butane to the proper Reid vapor pressure Initial boiling point, 90 F.;
Ethylene dibromide Ethylene dibromide 94 and ethylene dichloride 99.
Diethyl phosphoramidate 5.1-8L6. Dipropyl phosphoramidate til-96.5.
Y endpoint, 368 F. V
Table Il.Antik-nvck fuel compositions Antilrnock agent Scavenger Dialkyl phosphoramidate enes l25'and ethyl- 'phoamldate 10.7.
ene dichloride 99. 17 Mixed dibromotolu- Didecyl phosphorenes 150'and 1,2,4- amidate 126-2011. ggiehlorobenzenes 5. Do Ethylene dibroruide Butyl isobutyl phos- 94 and mixed triphoramidate 7.0
ehlorobenzcnes 146. 111.5. Do 1',4- iibromobutane 216. Propyl'isopropyl phosphgramidate 6.0- 96. .Do 1,4-dibromobutane 108. Propyl heptyl phosand 1,4-dichlorophoramidate 7.9-.
. butane 127. 126.4. Tetrapropyllead 379. Acetylene tetrabro- Diisopropyl phosphormide 346. amida'te (LO-96.5.
Dimethyldiethyllead B,fi'-dibromodiethyl- Dine-open tyl phos- 295.. ether 232. plgo liarnidate 7.9- r 12 l Methyltriethyllcad flfl-dibromodiisopro- Dioctyl phosphorami- 309. V pyl ether 130 and date 10.7171;2.
p fli-diehlorodiethyl ether 143.
I 'l-he antiknockfluid compositions shown in; Table I are presented for illustrative purposes only. Other antikriock fluid; compositions will now be apparent to one skilled in. the art. r V I V V Many'blending procedures are available to prepare the improved fuel compositions of this invention. For example,. a composite; additive of this invention, suchv as described in 'lEable I; can be: blended; in appropriate concentration with gasoline to provide a finished fuel of this invention containing; from about 0.02. to, about 6.5 grams of-lead per' gallon. Another method is to add anappropriate concentration of a dialkyl phosphoramidate separately to the fuel-before, after or at the same time a conventional' alkyllead antiknock fluid composition is blended with the fuel. Still-another procedure is to blend with the fuel each of theingredients of the above composite' additives separately or in various combinations in any sequence; a
Illustrative improved fuel compositions. of this invention areshown in Table II. The two figures following each of the ingredients are weights in' grams thereof. By blending each of the ingredients in the amounts of the respective lower figures with gallons of gasoline, a fuel composition of-this invention containing about 0.5 gram of lead per gallon as the leadalkyl antiknock agent is prepared. The respective higher figures following each ingredient show the amount in grams thereof which are blended with 10 gallons, toprovide a lead content of about 6.5 grams per gallon. 1 These illustrative fuels have a phosphorus-to-lead atom ratio of 0.4:3. The characteristics of the base fuels represented in Table II as A,
B, C and D are as followsr Base j Fuel AA blend of straight-run, catalytically cracked andpolymer stocks. Initial boiling point, 98 F.; endpoint, 402 F.
Base Fuel BA 100% catalytically cracked gasoline hav- 'ing an initial boiling point of 105 F. and an endpoint of 425 F Base Fuel aviation gasoline of grade 100/130 'Ietramethyllead Tetraethyllead i. do
'lrimethylethyl-. lead (ts-38.2.
. 2.7-3.5.4 and ethylene dichlo- Mixed dibromotolu- Ethylene dichloride Ethylene dibromide 184.108.40.206'and ethylone dichloride Ethylene dibrornide' ride 2.4-3L1.
enes 3.6471. 1,3dibromobutane 5.267.8. 1,4-dihromobutane Mixed dlbromotoluenes 23.0-39.1 and 1,2,4-triehlorobcnzene 2.9-319:
Diethyl phosphoramidate 0.5-6.4.
Diisopropyl phosploramidate 0.6- l.
Dibutyl phosphoramidate 0.7-8.7;
Diamyl' phosphoramidate 0.8-9.9.
Dioctyl phosphoramidate Lil-13.4.
Dideeyl phosphoramidate 1.2-158.
Butyl isobutyl phosphoramidate 0.7- 8.8.
Ethyl octyl phosphoramidate 0.8- dichlorodiethyl 9.9. ether 3.5444).
To illustrate the great effectiveness of the compositions of this invention in suppressing surface ignition, recourse was had to engine tests. A- spark ignition internal combustion engine equipped with an electronic evice which automatically recorded surface ignitions was used in the tests.' This engine was operatedon a commercially available gasoline containing 3 milliliters 3 of totraethyll'ead per gallon as a conventional antiknock 40 mixture '(tetraethyllead, about-0.5 theory of bromine as ethylenedibromideand'about 1.0 theory of chlorine as ethylene dichloride). This established a baseline in terms of the number of surface ignitions which occurred per hour. Another portion of the same leadedfuel was then treated with atypical; preferred dialkyl-phosphoramidate of this invention--di'- -cthylhexyl phosphorarnidate.in amount such that the phosphorus-to-lead atom ratio-was 0.43. The engine was then operated on this fuel andthe-efi'ect ofthe presence of this phosphoramidate determined. It was foundthat-the phosphorus-free, leaded gasoline produced 115- surface ignitions per hour of engine operation, whereas the gasoline composition of this invention only exhibited 26 surface ignitions per hour. a In other words, the fuel composition of this invention resulted in a surface ignition ratewhich was only 5 23 percent of that of the 'untreated'leaded' fuel, a reduction in surface ignition rate of 77- percent-.havin'g'been achieved; These results are illustrative of; the enhanced surface ignition suppression properties of the compositions of this invention. Equally good results are obtained with other such compositions, such as 'those shown in Tables I and II. 7
My compositions also effectively alleviate spark plug fouling by beneficiallyniodifying the characteristics of deposits formed on spark plug electrodes and insulators.
Since my dialkyl phosphoramidate additives are highly effective in reducing surface ignition andspark plug fouling, they may housed at lower concentrations than additives suggested heretofore to obtain the same degree of effectiveness. On the other hand, they may be used at the same or higher concentrations itstill greater benefits re arding these problems are desired.
Another outstanding characteristic of my improved antiknock compositions is that in use there is no adverse effect on the antiknock'effectiveness of the alkyllead antiknock agent during the-cooperation of this'ag'ent and the dialkyl phosphoramidate additives of this invention... This exceptional characteristic of my phosphoramidate additives was clearly demonstrated by conducting a series of comparative engine tests.
W In the present tests the amount of tetraethyllead antagonism exhibited by typical dialkyl phosphoramidates of this inventiondiethyl phosphoramidate,'dibutyl phosphoramidate, diisoamyl phosphoramidate and di-2-ethylhexyl phosphoramidate-was determined by the standard ASTM 'Research Method, Test Procedure D908/5l (which can be found in the 1952 edition of ASTM Manual of Engine Test Methods for Rating Fuels). In these tests primary measurements were made of .the percent of the tetraethyllead effectiveness destroyed, if any, caused by these dialkyl phosphoramidates. For comparative purposes, identical tests were run using triethyl phosphate and triisobutyl phosphate, additives described heretofore as being useful in leaded gasolines. The experiments consisted of blending with individual portions of a standard base fuel, 3.0 milliliters of tetraethyllead per gallon as an anti-knock fluid consisting essentially of tetraethyllead, 0.5 theory of bromine as ethylene dibromide and 1.0 theory of chlorine as ethylene dichloride. To each of these fuel portions was added an amount of the phosphorus additive under test such that the phosphorus-to-lcad atom ratio was 04:3. The test fuel used had a volume percent composition as follows: diisobutylene, 20%; toluene, 20% isooctane, 20%; n-heptane, 40%. 5
Table'TII-eEfiect of phosphorus additives on tetraethyllead antiknock effectiveness Percent tetraethyllead Phosphorus additive: effect destroyed The above data clearly show that the tetraethyllead antagonism, if any, of the additives of this invention is extremely low. In fact, the tetraethyllead antagonism of the prior art additives is at least over several times that of the additives of this invention. Thus, triethyl phosphate produced 400 percent as much tetraethyllead antagonism as diethyl phosphoramidate and triisobutyl phosphate produced 700 percent as much as dibutyl phosphoramidate. It will be noted that diisoamyl phosphoramidate and di-Z-ethylhexyl phosphoramidate did not destroy any of the tetraethyllead antiknock efiectiveness.
The preeminence of the diakyl phosphoramidates of this invention from the standpoint of their compatibility with alkyllead antiknock agents during engine combustion was further demonstrated by conducting another series of engine/tests. In'this instance the standard ASTM Motor Method, Test Procedure D357 (which can be found in the 1953 edition of ASTM Manual of Engine Test Methods for Rating Fuels) was used. The gasoline used-had a motor octane number clear-is, unleaded of 71.4. Forthe present tests'the gasoline samples each contained 3 milliliters of tetraethyllead per gallon, 0.5 theory of bromine as ethylene dibromide and 1.0 theory of chlorine as ethylene dichloride. A sample of this leaded gasoline was subjected to the above ASTM test method and the octane number of the fuel determined. Then, representative fuels of this invention were subjected "to the same test procedure. These particular fuels contained diethyl phosphoramidate, dibutyl phosphoramidate or di-Z-ethylhexyl phosphoramidate in amount such that the phosphorus-to-lead atom ratio was 1:3. For comparative purposes another series of leaded gasm lines was prepared, these containing the same concen- 6 tration of phosphorus as tributyl phosphite, triethyl phosphate or triisobutyl phosphateadditives suggested in the prior artand were rated under the same conditions. The results of these tests are shown in Table IV.
Table I V.Efiect of phosphorus additives on tetraethyllead anziknock efiectiveness The data shown in TableIV establish-that the dialkylphosphoramidate additives of this invention exhibited practically no adverse efiect upon the antiknock effectiveness of tctraethyllead, whereas somewhat closely relatedaliphatic phosphorus compounds suggested in the prior art caused a substantial amount of this adverse effect. Thus, the compositions of this invention'result in the virtual elimination of deposit-induced engine problems without incurring any significant amount of alkylle'ad antagonism.
The alkyllead antiknock agents which are present in the compositions of this invention are represented by such compounds as tetramethyllead, tetraethyllead, tetrapropyllead, tetrabutyllead, diethyldimethyllead, tn'ethylmethyllead, andthe like, or mixtures thereof. Such compounds containing from 4 to about 16 carbon atoms, one atom of lead and a plurality of lead-to-carbon bonds, are capable of increasing the octane qua ity of gasoline when employed therein in antiknock quantities-about 0.02 to about'65. grams of lead per gallon. Of such compounds, tetraalkyllead compounds having 4 to about 12 carbon atoms have superior volatility characteristics from the standpoint of engine induction and are thus preferred. Halogen-containing alkyllead compounds, such as triethyllead bromide, may also be used in the compositions of this invention.
Typical dialkyl phosphoramidates useful in the practice of this invention include diethyl phosphoramidate, dipropyl 'phosphoramidate, diisopropyl phosphoramidate, ethylpropyl phosphoramidate, ethylisopropyl phosphoramidate, propylisopropyl phosphoramidate, ethylisoamyl phosphoramidate, propyl-B-hexyl phosphoramidate, ethyldecyl phosphoramidate,- andthe like; Preferred dialkyl phosphoramidates used according to this invention are typified by and include dibutyl phosphoramidate, diisobutyl'phosphoramidate, di-sec-butyl phosphoramidate, ditert butyl phosphoramidate, di-sec-amyl phosphoramidate, dihexyl phosphoramidate, diheptyl phosphoramidate, dioctyl phosphoramidate, dinonyl phosphoramidate, didecyl phosphoramidate, butylamyl phosphoramidate, hexyloctyl phosphoramidate, and the like. Of these preferred dialkyl phosphoramidates, those in which both alkyl groups contain the same number of carbon atoms are especially preferred because of their low cost and ease of manufacture. Mixtures of these dialkyl phosphoramidates can also be used.
The diallcyl phosphoramidates used according to this invention can be prepared by known chemical methods which are reported in the literature. One such method I is to react ammonia with a dialkyl phosphoryl chloride in which each alkyl group contains from 2 to 10 carbon atoms. The ammonia is added to the chloride in a 10 0 mole percent excess of the amount required to replace the phosphorus-bonded chlorine. In general, the above reaction is carried out at a temperature between about 0 and about 50 C. It is advantageous to carry this reaction 7 out in a suitable solvent such as diethyl. ether, petroleum ether, or the like.
The dialkyl phosphoryl chlorides are obtainable by reacting phosphoryl chloride with the appropriate monohydric alcohol or mixture of monohydric alcohols under known reaction conditions. About twomoles of the alcohol are reacted per mole of phosphoryl chloride using a Lewis acid catalyst and temperatures between about 80 and 140 C. a
V The organic halide scavengers used in the compositions ofthis'inyentionare compounds which react with the lead during combustion in the engine to form relatively volatile lead halides. The halogen of these. scavengers has an atomic weight between 35 and 80; that is, the active scavenging ingredient is chlorine and/or bromine. Such scavengers include ethylene dibromide; ethylene dichloride; carbon tetrachloride; propylene dibromide; 2-chloro- 2,3 dibromobutane; 1,2,3-tribromopropane; hexachloropropylene; mixed bromoxylenes; 1,4-dibromobutane; 1,4-
dichloropentane; fi,fi-dibromodiisopropyl ether; trichlorobenzene; fdibromotoluenes; tert butyl bromide; Z-methyl- Z-bromobutane; '2,3,3-trimethyl2-bromobutane; tert-butyl chloride; 2,3-dimeth-yl-2,3-dibromobutane; 2,3-dimethyl- 2,5-dibromohexane; Z-methyl- 2,3 dibromobutane; 2- methyl-2,3-dichloroheptane; 2-methyl-2,4-dibromohexane; 2,4-dibrornopentane; 2,5-dich1orohexane; 3-methyl 2,4-dibromopentane; l-phenyl 1' bromoethane; l-phenyl-lchloroethane; ethyla bromoacetate;diethyl-dibromo? malonate; propyl-ot-chlorobutyrate; 1,1-dichloro-1-nitroethane; 1,1-dichloro-2rnitroethane; 1,11-dibromo-1-nitrobutane; 2-chloro 4 nitropentane; 2,4-dibromo-3-nitropentane; l-chloro-Z-hydroxyetharie;, 1-bromo-3-hydroxypropane; 1'-bromo3-hydroxybutane; 3-methyl-2-bromo-4 hydroxyp'entane; 3,4-dimethyl-Zbromo-4-hydroxypentane;
and, in general, scavengers disclosed in US. Patents 1,- 592,954; 1,668,022; 2,364,921; 2,479,900; 2,479,901; 2,479,902; 2,479,903 and 2,496,983.
carbon and elements selected from the group consisting ofhydrogen, bromine, chlorine, nitrogen and oxygen, Particularly preferred scavengers are halohydrocarbons, that is, bromohydrocarbons, chlorohydrocabons, and
V In short, it is pre' ferred' to employ halogenated scavengers containing only.
bromochlorohydrocarbons having a vapor pressure from V 0.1 to 250 millimeters of mercury'at 50C. The total amount of scavenger used is preferably from about 0.5
to about 2.0 theories, a theory being defined as the quantity required to react with the lead to form lead halidei.e., 2 atoms of halogen per atom of lead. This amount can be inthe form of a single compound or a mixture of compounds. However, when I use mixtures of bromine-containing and chlorine-containing scavengers, particularly bromoand chlorohydrocarbons as the scavenger complement, I can employ a wider, range of concentrations in the proportions described in US. Patent,
2,398,281. Thus, the scavenger concentrations used are those which are sufiicient to control the amount of deposits formed in the engine, particularly on the exhaust valves.
The compositions of this invention can contain other ingredients, such as dyes for identification purposes; metal deactivators, such as N,Nf disalicylidene-LZ-diamino propane, etc.; anti-icing and, anti-rust additives; upper cylinder lubricants; induction system cleanliness agents; antioxidants, such as N,N-di-sec-butyl-p-phenylenediamine, p-alkylamino phenols, alkyl phenols, etc.; and the like.
My antiknock fluids may be used in a variety of hydrocarbon base stocks boilingwithin or throughout the gasoline boiling range. to about 420 -F. formotor gasolines, while the endpoint of aviation fuels isv in theorder of'about 310-335 F. Thus, the improvements can be made in fuels resulting from thermal and catalytic cracking processes, reforming, hydroforming and alkylating procedures; in straight-run This range is from about 80' 8 gasolines; and in various blends of gasolinehydrocarbons'.
This application is a. cont-inuationrinpart of my prior copending application Serial: No. 526,317, filed August 3, 1955, now abandoned.
I claim: 4 1
' 1. Gasoline containing from about 0.02to about 6.5 grams of lead per gallon as, an alkyllead antiknock compound, a scavenging amount of an, organic halide scavenger capable of reacting with the lead, during combustion in a spark. ignition internal combustion engine to forrnrelatively volatile lead halide, and a. dialkyl phosphoramidate ester in which each alkyl group contains from 2 to '10 carbon atoms, said phosphoramidate ester being present in amount such that the phosphorus-to-lead atom ratio is from about 0.1:3 to about 1.6:3.
'2. Gasoline containing from about 0.02 to about 6.5 grams of lead per gallon as tetraethyllead, a bromohydrocarbon and chlorohydrocarbon scavenger complement present in amount suflicient to control the amount of deposits formed 'in the engine, and a dialkylphosphoramidate ester inwhich each alkyl group contains from 4 to 10 carbon atoms said. phosphoramdiate ester being present in amount such that the phosphorus-to-lead atom ratio is from about 0.1:3 to about 1.623.
3. An antiknock composition adapted for use as an additive for gasoline consisting essentially of an alkyllead antiknock' compound, a scavenging amount of an organic halide scavenger capable of reacting with the lead during combustion in a sparkignition internal combustion engine to form relatively volatilelead halide, and'a dialkyl phosphoramidate esten in'wh'ich' each alkyl' group contains from 2 to 10 carbon atoms, said phosphoramidate ester being present in amount such that the phosphorus-to-lead phosphoramidate is dibutyl phosphoramidate.
6. The antiknock composition of claim 3 in which said phosphoramidate is dibutyl; phosphoramidate- References Cited in the file of this patent UNITED STATES PATENTS 2,405,560v Campbell Aug. 13, 1946 2,765,220 Yust' et a1; Oct. 2, 1956 2,794,717 Gilbert June 4, 1957 2,797,153 Bereslavsky June 25, 1957 2,828,195 Yust et al. Mar. 25 1958 2,863,743 Pellegrini et al. Dec. ,9, 1958 2,878,255 Toy etjal. Mar. .17, 1959 2,897,068 Pellegrini et a1. July 28, 1959 FOREIGN PATENTS 683,405 Great Britain Nov. 26, 1952 708,006 Great Britain Apr. 28, 1954 709,471 Great Britain May 26, 1954 1,094,828 France Dec. 15, 1954 1,100,185 France Mar. 30, 1955 OTHER REFERENCES Ind. and Eng. Chem. March 1948, vol. 40, No. 3, Suitability of Gasolines as Fue by I ames and Morris, pp. 405-411. r
Ind. and Eng. Chem. March 1951, vol. 43, No. 3, Antiknock Antagonists, by Livingston, pages 663-670.