AGENT FOR RAISING THE OCTANE NUMBER OF GASOLINE AND PROCESS FOR PREPARING THE AGENT

Abstract: Agent for increasing the octane number of gasoline. The agent is a reaction product between iron pentacarbonyl, one or more aliphatic di- and/or polyketones, one or more esters of aliphatic ketocarboxylic acids, one or more esters of orthophosphoric acid with aliphatic alcohol, and one or more esters of acetic acid with aliphatic alcohol. The invention also relates to a process of preparing the agent, the components being mixed and stored under access of air and ultraviolet light.

Description: AGENTFORRAISINGTHEOCTANENUMBEROFGASOLINE A N D PROCESSFORPREPARINGTHEAGENT This invention is concerned with an agent for increasing the octane number of gasoline. The invention also relates to a process for preparing such an agent. In order to obtain a good power fuel economy, modern internal combustion motors have been constructed with ever higher compression ratios. These motors require a fuel with a high octane number to prevent knocking. Therefore various additives to the fuels increasing the octane number have been used for a long time. It is also possible to conduct the refining of "the crude oil in such a direction and to convert the resulting petroleum products in such a way that a fuel with a high octane number is obtained without any additives. However, this is expensive, as large-scale redesigns of the existing refineries are necessary. Moreover, the yield of high-octane fuel will be considerably reduced, which brings increased costs and is un¬ suitable in times 'of a threatening depletion of oil. The additives mostly used for increasing the octane number are at present lead alkyl compounds , primarily tetraethyl lead and tetramethyl lead. These compounds provide a very good octane increasing effect, but they also have considerable disadvant¬ ages. The lead alkyl compounds as such are highly toxic, so that special precautions are required when handling them and the gasoline in which they are included. Another serious short¬ coming is that at their combustion in the engine, lead compounds in a finely divided form such as lead oxides are given off to the atmosphere and may have toxic effects there. According to recent research results, these toxic effects seem to be more serious than what has previously been assumed, especially against growing children. For these reasons, the authorities in several countries have decided to reduce the maximal permitted lead content in gas¬ oline, and it is desirable to exclude lead compounds completely, A compound which has been known for a long time to have octane raising effects on gasoline is iron pentacarbonyl, FeCCO)^. This compounds is less toxic as such than the lead alkyl compounds and at combustion in a motor gives iron compounds, which have no highly toxic effects. However, iron carbonyl has not Jbeen used to any considerable extent, as it is unstab in a pure form as well as in admixture with gasoline hydro¬ carbons. Already after storage for a short time, precipitates of iron oxides are formed, and finally all the iron has pre¬ cipitated as oxide. This decomposition is accelerated by lig air and humidity. Several attempts have been made to stabilize solutions of ir carbonyl in gasoline hydrocarbons against decomposition, var ous additives being used. Thus, according to British .Patent 260 639 and German Auslegeschrift No. 1 172 261, various colo ed additives are used to prevent the light-induced degradatio Moreover, according to US Patent No. "2 493 714, certain este amides are used as stabilizers. However, the stabilizing effe of such, additives have not been found to be sufficient in or that iron carbonyl might be used in practice as an agent rais "the octane number. Furthermore, it is known from Swedish Patent No. 362 261 and Patent No. 3 880 612 to stabilize solutions of iron carbonyl gasoline hydrocarbons by the addition of organic aluminium compounds, especially reaction products between aluminium alkoxides and keto. compounds with one or more carbonyl groups An excellent stabilizing effect has been obtained by these compounds. However, as additional metal has been added in the form of the organic aluminium compounds, problems may arise i the elimination of the combustion resid ues in the motor. The present invention is based on further developments of these stabilizers. According to the • inventio , there is provided an agent increa ing the octane number of gasoline, which is characterized in that it is a conversion'product between iron pentacarbonyl, o or more aliphatic di- and/or polyketones, one or more esters of aliphatic keto carboxylic acids, one or more esters of orthophosphoric acid with aliphatic alcohol, and one or more esters of acetic acid with aliphatic alcohol. The aliphatic di- and/or polyketones are compounds in which the carbonyl, groups are in a conjugated position. It is intended by "conjugated position" that two carbonyl groups are separated by a ethylene group, which is optionally alkyl substituted. The ketones preferably contain up to 6 carbon atoms , but this limit is not critical. Ketones with a greater number of carbon atoms in the chain may also be used. Consequently, suitable aliphatic di- and polyketones have the general formula wherein R 1 and R„ are the same or different and each represents straight-chained or branched alkyl or alkenyl with 1-3 carbon atoms, Ra is hydrogen or alkyl or alkenyl with 1-3 carbon atoms, preferably hydrogen, and X has the value of 0, 1 or 2 . R. , R_ and R thus represent methyl, ethyl, propyl, isopropyl, vinyl, propenyl or isopropenyl. The acid portion of the aliphatic keto carboxylic acid esters is mainly * -keto carboxylic acids with at least 3 and up to 6 carbon atoms in the carbon chain. The alcohol portion of the esters is in the first place alkyl rests with up to 6 carbon atoms, and preferably methyl or ethyl. The acid portion as well as the alcohol portion in the esters may contain more than 6 carbon atoms without the applicability of the invention being risked, but this gives no additional advantages. Thus, suitable esters of aliphatic keto carboxylic acids have the general formula R 5 ~ C - CH 7 - C00R, II - 4 0 wherein R 3 is alkyl or alkenyl with 1-3 carbon atoms, and R^ is alkyl or alkenyl with 1-6 carbon atoms. The groups R- and R 4 can be straight-chained or branched. The esters of orthophosphoric acid, H-PO^, are esters of alco hols with preferably 2-5 carbon atoms in their chain, but als alcohols with more carbon atoms can be used. The monoesters a well as the di- and triesters can be used. Examples of suitab esters are monoethyl orthophosphate, diethyl orthophosphate, triethyl orthophosphate and the corresponding esters of propy butyl and amyl alcohol. The useful alcohols can be primary, secondary or tertiary and have straight or branched carbon chains, and may contain one or more double bonds in the carbo chain. In the di- and triorthophosphates the two or three bon alkyl groups may be the same or different. Thus, suitable esters of orthophosphoric acid ave the genera formula wherein the groups Rr , g and R are the same or different an each represents hydrogen or straight-chained or branched alk or alkenyl with 2-5 carbon atoms, at least one of the groups c -Ry being different from hydrogen. The esters of acetic acid and aliphatic alcohol preferably co tain up to 6 carbon atoms in the alcohol portion. The alcohol portion can also contain more than 6 carbon atoms, but this gives no additional advantages of the invention. In the reaction mixture, the esters of acetic acid and alipha alcohol are preferably ' included in a concentration of 20-25 % by volume. In the reaction to the agent according to the invention, iron pentacarbonyl is included in an amount of 5-10 % by volume an preferably 8-10 % by volume, calculated on the starting mixtu for the reaction. A content of 10 % by volume should not be exceeded. The esters of orthophosphoric acid should be present in the reaction in such amounts that the number of gram atoms of pho phorous always exceeds the number of gram atoms of iron. The atomic ratio Fe:P is preferably within the range of 5-15:15- the preferred ratio being about 11:18. / "fOR { 0: - The aliphatic di- and/or polyketones are present in the reaction -mixture.in a total concentration of at least 3 % by volume, preferably 4-10 % by volume. The esters of the aliphat¬ ic keto carboxylic acids are present in the reaction mixture in a concentration of a least 27 % by volume and preferably 27-35 % by volume. These percentages are based on the starting volume of the reactants of the reaction mixture. The agent of the invent on can easily be prepared by mixing and storing the components indicated above for a sufficient time to achieve reaction. This time is at least 60 days at room tem¬ perature, but may be longer. The reaction is to be carried out under access of air and ultraviolet light and substantially at room temperature. As a source of ultraviolet lightsdaylight has been found to be sufficient, but stronger UV light, e.g. from a quartz lamp, gives a more rapid reaction.- Also the light from conventional fluorescent tubes has been found to contain a sufficient portion of UV light for the reaction to take place. An elevated temperature also brings a more rapid reaction. However, it is less suitable to work at temperatures in excess of about 50 C as the iron pentacarbonyl can then be thermally decomposed in a too great extent. If desired, the reaction mixture may be diluted before the reaction with an inert diluting agent, preferably gasoline hydrocarbons. The concentration values indicated above are cal¬ culated on a non-diluted reaction mixture. The reaction process can be followed by taking samples and analyzing them in respect of the existence of iron penta¬ carbonyl, e.g. by means of an IR spectrum. It appears that in the course of the reaction, the content will decrease of the iron pentacarbonyl, which is converted into stable, iron- -containing organic compounds with the included keto compounds , and it is probable that the compounds formed are cyclic with up to three rings. Finally, no iron pentacarbonyl can be detected, and the reaction is then complete. It is suitable to conduct the reaction as far as possible, so that all iron car bonyl is reacted and cannot be decomposed later when it has been added to &e gasoline. The resulting reaction mixture need not be especially worked but can -be added directly to gasoline hydrocarbons. This is usually done in such a way that a concentrated stock solution is prepared, which is then added to the gasoline in the requi amount. It has been found in tests that an addition of about 1,5 % by volume of the reaction product, calculated as non-diluted, to a normal gasoline gives an increase of the octane number by about 2 units according to the research method. The product c also be diluted with aromate-containing platformate gasoline a dilution degree of 1:200 without any decomposition being ob served. The resulting mixtures are stable for at least 6 mont The invention is illustrated more in detail by the following examples. EXAMPLE 1 : A mixture of 225 ml of orthophosphoric acid ethyl ester and 225 ml of acetic acid-n-butyl ester is added to a mixture of 36 ml of 2 , -diketopentane and 324 ml of ethyl acetoacetate ("aceto-acetic acid ethyl ester"), and the volum of the mixture is adjusted to 910 ml by addition of 100 ml of straight-run gasoline. Mixing is carried out at usual room temperature of about ' 20°C and no increase of the temperature can be detected. 90 ml of iron pentacarbonyl is rapidly added to the resulting mixture. The initially pale yellow mixture rapidly becomes darker, and a development of free carbon monoxide can be detected. On the other hand, no temperature rise or turbidity occurs. The reaction mixture is kept in a clear glass bottle of 1.51, which is exposed to usual daylight from all sides and in a ro which is illuminated from the ceiling by conventional fluor¬ escent tubes at night. During the storage time of the first days at about 20 C, development of carbon monoxide can still be detected. After about 60 days of storage time, the reactio mixture has darkened to a reddish-brown color but is complete O c clear. No iron pentacarbonyl can any longer be detected. When 15 ml of this product were added to 1 litre of straight- -run gasoline, an increase of the octane number of 2 units according to the research method was obtained, in spite of the absence .of iron pentacarbonyl. After about 6 months storage, no turbidity or another indication of decomposition could be detected. EXAMPLE 2: A mixture of 450 ml of orthophosphoric acid ethyl ester and 450 ml of acetic acid n-amyl ester is added to a mixture of 72 ml of 2 } 4-diketopentane and 648 ml of 1-O -keto- -propionic acid ethyl ester, and the volume of the mixture is adjusted to 1820 ml by addition of 200 ml of straight-run gasoline. Mixing is carried out at usual room temperature of about 20°C, and no rise in temperature can be detected.180 ml of iron carbonyl are rapidly added to the resulting mixture. The initially pale yellow mixture rapidly becomes darker and a devlopment of free carbon monoxide can be detected. On the other hand, no temperature rise or turbidity occurs. The reaction mixture is kept in a clear glass bottle of 3.01 volume, which is exposed to usual daylight from all sides, and in a room which is illuminated by conventional fluorescent tubes from the ceiling at night. During the storage of the first days at about 20 C, development of carbon monoxide can still be detected. After about 60 days storage, the reaction mixture has darkened to reddish-brown color but is completely clear. No iron pentacarbonyl can any longer be detected. When 15 ml of this product are added to 1 litre of straight-run gasoline, a rise of the octane number by 2 units is obtained according to the research method, in spite of the absence of iron pentacarbonyl. Also after a storage time of 6 months, no turbidity or other indication of decomposition could be detected. EXAMPLE 3: A mixture of 337.5 ml of orthophosphoric acid ethyl ester and 337.5 ml of acetic acid n-amyl ester is added to a mixture of 54 ml of 2. -diketohexane and 486 ml of ethyl- acetoaceτate ("aceto-acetic acid ethyl ester"), and the volume of the mixture is adjusted to 1365 ml by the addition ml of straight-run gasoline. Mixing is carried out at a usual room temperature of about 20 C, and no rise in temperature occurs. 135 ml of iron pentacarbonyl are rapidly added to the resulting mixture. The initially pale yellow mixture rapidly becomes .darker and free carbon monoxide is devloped. On the other hand, no temperature rise or turbidity occurs. The reaction mixture is stored in a clear glass bottle of 2.0 volume, which is exposed to usual daylight from all sides in room which is illuminated freo the ceiling by conventional fluorescent tubes at night. During the storage time of the first days at about 20°C, development of free carbon monoxide can still be detected. After about 60 days storage time the reaction mixture has darkened to a reddish brown color but is completely clear. No iron pentacarbonyl can any longer be de- detected. At the addition of 15 ml of this product to 1 litre of straig -run petrol a rise of the octane number by 2 units is obtaine according to the research method, in spite of the absence of iron pentacarbonyl. After a storage time of about 6 months.no turbidity or another indication of decomposition could be detected.

Claims: CLAIMS 1. An agent for raising the octane number of gasoline, charac¬ terized in that it consists of a reaction product between a) iron pentacarbonyl in an amount of 5-10 % by volume; b) at least 3 % by volume of one or more aliphatic di- and/or polyketones of the general formula wherein R 1 and R„ are the same or different and each represent straight-chained or branched alkyl or alkenyl with 1-3 carbon atoms, R 3. is hydrogen or alkyl or alkenyl with 1-3 carbon atoms, and x has the value of 0, 1 or 2; c) at least 27 % by volume of one or more aliphatic keto- carboxylic acid esters of the general formula wherein R- is alkyl or alkenyl with 1-3 carbon atoms, and R^ is alkyl or alkenyl with 1-5 carbon atoms; d) one or more esters of orthophosphoric acid with aliphatic alcohol and of the general formula 0=P 0R 6 ^0R ? wherein the grouDS R c , R„ and R-, are the same or different and each is hydrogen or straight-chained or branched alkyl or alkenyl with 2-5 carbon atoms, and at least one of the groups R.--R- is different from hydrogen, these ' esters being included in such an amount that the phosphorous content is greater than the iron content, calculated as gram atoms and the atomic ratio Fe:P is within the range of 5-15:15-20; and e ) 20-25 % by volume of one or more esters of acetic acid with aliphatic alcohol with up to 6 carbon atoms in the alcohol portion, the reaction being carried out in such a way that th components a)-e) have been mixed and stored for a period of a least 60 days under access of air and ultraviolet light and a temperature of maximum 50 C. 2. The agent of claim 1, characterized in that the aliphatic di- and/or polyketones contain up to 6 carbon atoms . 3. The agent of claim 1 or 2, characterized in that the alcoh portion in the esters of ketocarboxylic acids is methyl or et 4. The agent of any one of claims 1-3, characterized in that the iron pentacarbonyl is included in a concentration of 8-10 by volume. 5. The agent of any one of claims 1-4, characterized in that the esters of orthophosphoric acid are included in such a con centration that the atomic ratio of Fe to P is about 11:18. 6. ' The agent of any one of claims 1-5, characterized in that the aliphatic di- and/or polyketones are included in a con¬ centration of 4-10 % by volume. 7. The agent of any one of claims 1-6, characterized in that the esters of the aliphatic ketocarboxylic acids are included in a concentration of 27-35 % by volume. 8. A process for preparing an agent according to any one of claims 1-7 for raising the octane number of gasoline, charact ized in that iron pentacarbonyl in a concentration of 5-10 % volume, one or more aliphatic di- and/or polyketones in a con¬ centration of at least 2 % by volume, one or more esters of aliphatic ketocarboxylic acids in a content of at least 27 % by volume, one or more esters of orthophosphoric acid with aliphatic alcohol in such a concentration that the phosphorou content will be greater than the iron content calculated as gram atoms, the atomic ratio Fe:P being 5-15:15-20, and one o more esters of acetic acid with aliphatic alcohol in a con¬ centration of 20-25 % by volume are mixed with each other and stored under access of air and ultraviolet light for a period of at least 60 days at a temperature of maximum 50°C. 9. The process of claim 8, characterized in that the iron pen¬ tacarbonyl is incl-uded in a concentration of 8-10 % volume, the aliphatic di- and/or polyketones are included in a concentration of 4-10 % by volume, the esters of aliphatic ketocarboxylic acids are included in a concentration of 27-35 % by volume and the esters of orthophosphoric acid are included in such a con¬ tent that the atomic ratio Fe:P becomes about 11-18, and the mixture is stored at room temperature.

Inventors: REISINGER K
Applicants: OESTERGREN J, REISINGER K
Application year: 1981
Main classification: C10L1
IPC codes: C10L1