April 9, 1946. E. BARTHOLOMEW 2,398,282

' ANTIKNOGK AGENT 7 Filed ‘Nov’. 27, 1944

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INVENTOR. Patented Apr. 9, 1946 2,398,282

UNITED STATES ‘PATENT OFFICE c

an'rnmocx AGENT Earl Bartholomew, Birmingham, Mich., asslgnor to Ethyl Corporation, New York, N. Y., a cor poration of Delaware : Application November ‘27, 1944, Serial No. 565,200 5 Claims. (Cl. 252-—386) This invention relates to antiknock compounds. bonyl is indicated as grams of‘ iron per gallon. Many attempts have been made to use iron car For convenience the corresponding volumes 0! bonyl as an antiknock agent in high compres tetraethyl lead and iron pentacarbonyl are shown sion engines, chie?y because it can be manufac in parentheses on the horizontal and vertical tured at a lower cost than the lead alkyls.~ Some scales respectively. of these attempts have included the use of lead Each line, A to M inclusive, indicates mixtures alkyls in very small proportional quantities. having a constant antiknock value. Mixtures in These attempts have not had any appreciable dicated by line A have the lowest antiknock value success and the reason for this has not been clear. and lines lying to the right of A indicate mix So far as I am aware these attempts have been 10 tures of progressively higher‘ antiknock value. based on a primary consideration of the use of Each of- these lines may be used in the following iron carbonyl, and other factors were wholly sec manner, taking line H as an example. This line ‘ ondary to this. starts from the horizontal axis at 1.32 grams of This application is a continuation-in-part of lead (1.25 c. c. of, tetraethyl lead) and 0.0 grams my application, Serial No. 490,659, ?led June 12, 15 of- iron per gallon of fuel, indicating that the fuel 1943, for Antiknock agent. , , r contains 1.32 grams of lead and no iron penta The use of either a lead alkyl or iron penta carbonyl. If 0.21 gram of iron (0.5 c. 'c of iron carbonyl alone in a motor fuel gives a bene?cial pentacarbonyl) is added to the base fuel, then, result and it would be presumed that the use of to keep the antiknock value of the curve con the two together would give a result which could 20 stant, one would expect that less than 1.32 grams be predetermined from a knowledge of the anti-‘ of lead would be required and therefore that a. knock properties of the individual compounds. point P on the curve having an ordinate of 0.21 However, the use of the two together may yield gram of iron should lie to the left of the starting a negative result in that the antiknock eil'ect of point of the curve,.as indicated on the chart. In a mixture of the two may be less than that of stead of passing'to‘ the left through point P, the one of them used alone. ' curve passes to the right of'it through P’. This I have found that by treating each of. the mix . shows that the addition of iron pentacarbonyl has tures of iron pentacarbonyl and a lead alkyl as decreased the e?ectiveness of the tetraethyl lead ‘basically a new single antiknock compound, de and more than 1.32 grams of lead must be used termining the intrinsic antiknock properties and 30 to obtain an antiknock effect equal to that of 1.32 then evaluating these intrinsic antiknock prop grams of lead alone per gallon. On this curve erties in the light of other characteristics of each 0.21 gram of iron and 1.46 grams of lead per of the components, I obtain a new and'di?’erent gallon are equal in antiknock effect to 0.0 c. c. of concept of the utility of mixtures of these two iron and 1.32 grams of lead per gallon. A mix antiknock compounds. ' ' ‘ 35 ture of 0.55 gram of iron (1.3 c. c. iron penta The object of the present invention is to pro carbonyl) and 1-32 grams of lead per gallon has vide useful antiknock mixtures of tetraalkyl lead and iron pentacarbonyl. the same effect as the 0.0 grams of iron and 1.32 ‘grams of lead per gallon. Between these two The single ?gure of the drawing is a chart points on the curve the compounds are so mutu illustrating the antiknock values of different mix 40 ally toxic that the addition of'the iron pentacar tures of tetraalkyl lead and iron pentacarbonyl bonyl results in a'loss of antiknock value and ‘when added to a widely used commercial base therefore the addition of iron pentacarbonyl is fuel. This fuel was the base for Standard Oil detrimental. No value is obtained from the iron Company of Indiana Red Crown gasoline as sold ~ pentacarbonyluntil more than 0.55 gram of iron from 1935 to 1941. The method oftest was the 45 per gallon is used. _ , A. S.» T. M. method D-357-39 T also known as the Following line H to its intersection with the A. S. T. M. motor method. The horizontal axis vertical axis, the chart shows that there is a OX indicates the quantity of lead alkyl in the similar mutually toxic eil'ect near this axis al ‘mixture per gallon of fuel and the vertical axis though it is ‘not as extensive as that near the OY'indicates the quantity of iron pentacarbonyl 50 horizontal axis. Between these two portions of in the mixture per gallon of fuel. Inasmuch as the curve each of the antiknock compounds pres~ the quantity of lead in a given volume of the dif-' ‘ent in the mixture gives a useful result but at no ferent lead alkyls is not constant, the quantity point on the curve is the value of the mixture of lead alkyl is indicated as grams of lead per equal to the sum of the values of the two con gallon. Likewise the quantity of iron pentacar stituents. The value of a mixture cannot be .2. 2,398,282 predicated upon a knowledge of the values of each the same result. However, when the iron penta carbonyl content approaches 4.0 c.. c. per gallon of the compounds in the mixtures. _ I find that‘Ti'useful mixtures of iron pentacar (line NR) it may be desirable to use ratios near bonyl and tetraalkyl-lead lie within the area line OT or to the right of it to inhibit engine " bounded by the lines OR, OS, and NR inclusive. wear. The mixture chosen depends on the cost of the It is well known that di?‘erent fuels have di?er components of the mixture, the increment of ent susceptibilities to antiknock compounds and antiknock value desired from the mixture, the the measurement of the susceptibility is a stand nature of the base fuel, the type of engine,~the ard procedure. Different fuels also have differ conditions of engine operation and the increased 10 ent effects on the mutual toxicity of tetraethyl rate of engine wear attributable to the anti lead and iron pentacarbonyl. In general this mu knock mixture. tual toxicity is at a maximum in highly aromatic Because of the lower cost of iron pentacarbonyl base fuels and at a minimum in highly volatile it would appear that all mixtures should be paramnic fuels. The mutual toxicity tends to chosen near the line 05. The lower boiling point, -15 become greater as the unsaturation is increased. of iron pentacarbonyl also suggests this inas In all fuels this effect is readily determined by much as the antiknock mixture will be more the same standard procedure as is used in meas evenly distributed during periods of poor fuel uring antiknock susceptibility. With all of these distribution. When operating engines which tend fuels my mixtures are those described above and to preignite I prefer to use mixtures having a 20 de?ned on the chart by the lines OR, OS, OT, and relatively high iron pentacarbonyl content be NR, however, in the case of fuels giving unusually cause I have found that products of combustion high mutual toxicity, I prefer to use, mixtures ly of iron pentacarbonyl which remain in the com- . ing fairly close to line OT. bustion chamber have less tendency to cause pre The curves for mixtures containing other lead ignition than those of tetraethyl lead. Where en 25 alkyls with iron pentacarbonylv may vary from gines are run on rich fuel-air mixtures (high fuel ‘ those for‘ mixtures containing iron pentacarbonyl content) as during take-oil‘ of airplanes. a rela and tetraethyl lead but if they vary the differ tively high iron pentacarbonyl content is desir ences are not material as to a choice of the mix able because of the increased effectiveness of iron ture to be used. pentacarbonyl relative to tetraalkyl lead com 30 Tetraethyl lead is used more widely than any pounds under these conditions. other lead compound as an antiknock and for this . I find, however, that certain conditions of en reason its use with iron pentaoarbonyl has been gine operation call for a wider range of mixtures described above. The more useful range of lead than those near the, line OS. If an engine may alkyls for admixture with iron pentacarbonyl operate‘under knocking conditions at high speed 35 appears to extend from ‘lead dimethyl diethyl to or at high mixture or cylinder temperature at ‘the heavier alkyls such as lead tetra-n-butyl. low speed, it is desirable to choose mixtures ly The usefulness of tetramethyl lead and trimeth ing farther to the right of line OS on the chart ylethyl lead for antiknock purposes is small in because of the relatively low effectiveness of iron comparison with the other alkyls. Any other lead pentacarbonyl and high effectiveness of tetra alkyl can be used in place of or with tetraethyl ethyl lead under such conditions when used in lead in my mixtures. I . admixture. The decrease in effectiveness of iron It is well known that halides are used with pentacarbonyl under these conditions is so great lead alkyl antiknockcompounds and- they may as to suggest the possibility of premature decom be used in my mixtures in accordance with the position. Under these conditions tetraethyl lead‘ 45 content of lead alkyls present. retains its e?ectiveness. . I claim: ~ On the chart I have shown the effectiveness of 1. An antiknock mixture of iron pentacarbonyl mixtures of iron pentacarbonyl and tetraethyl and a tetraalkyl lead whose proportions, on a lead up to concentrations of 2.52 grams of iron chart having grams of lead per gallon of fuel (6.0 c. c. of iron pentacarbonyl) per gallon so as 5? as its scale of abscissae and grams of iron .as to indicate the nature of the curves. Iron oxide,” its scale of ordinates, lie within an area bounded formed by the combustion of iron pentacarbonyl, by straight lines drawn through the origin and is an abrasive and produces engine wear. I have points R and S, having coordinates respectively discovered that this abrasive action is decreased 3.18 grams lead, 1.68 grams iron and 1.06 grams by the use of substantial amounts of lead alkyl 65 lead, 2.52 grams iron, and horizontal line NR, antiknock compounds with the iron pentacar whose equation is 3/ equals 1.68, inclusive. bonyl. This effect is barely discernible with ra 2. An antiknock mixture of iron pentacar tios near line OS, is pronounced with ratios near bonyl and a tetraalkyl lead whose proportions. line OT, and still greater with ratios near line OR. on a chart having grams of lead ‘per gallon of However, because of excessive engine wear asso 60 fuel as its scale of abscissae and grams of iron ciated with the use of large amounts of iron pen as its scale of ordinates, lie within an area tacarbonyl, even when tetraethyl lead is present, bounded by straight lines drawn through the I employ mixtures having an iron pentacarbonyl the origin and points T and S, having coordinates content of not more than 4.0 c. 0. per gallon, respectively 2.65 grams lead, 2.52 grams iron and equivalent to 1.68 grams of iron, as indicated by 65 ‘1.06 grams lead, 2.52 grams iron. and horizontal line NR. ' > line NR, whose equation is y equals 1.68, in

- For the above reasons my preferred mixtures clusive. . ' i for overall-engine operation lie between lines OS 3. An antiknock mixture of iron pentacarbonyl and OT inclusive on the chart. For general use, and tetraethyl lead whose proportions. on a chart in all types of engines and base fuels under the 70 having‘grams of lead per gallon of fuel as its wide range of weather and driving conditions scale of abscissae and grains of iron as its scale‘ encountered in service, I prefer to use three parts of ordinates, lie within an area bounded, by iron pentacarbonyl by volume with one part tetra straight lines drawn through the origin and ethyl lead. This mixture is not critical and small points It and S, having. coordinates respectively variations in either direction give substantially 75 3.18 grams lead, 1.68 grams iron and 1.06 grams ,4 . spasms ' ' 3 lead, 252 grams iron, and horizontal line NR. whose equation is 1! equals 1.68, inclusive. points '1‘. and 8, having coordinates respectively 4. An antiknock mixture of iron pentaesl‘bonyl 2.65 grams load, 2.52 grams iron and 1.06 ms and tetraethyl lead whose proportions, on a chart lead, 2.52 grams iron,- and horizontal line NR, having grams of lead per gallon of tuel as its whose equation is 1; equals 1.88, inclusive. scale of abscissae and grams or iron as its scale 5. An antiknock mixture consisting of by vol of ordinates, lie within an area bounded by ume substantially three partsiron pentacarbonyl straight lines drawn through the origin and and one part tetraethyl lead. ' EARL BARTHOLOMEW.