Petroleum Acids and Bases H. L. LOCHTE
The University of Texas, Austin, Tex.
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sist of nearly equal amounts of compounds that can be extracted from refinery products with dilute acids and those that cannot be so extracted. The so-called nonbasic compounds are thought t o include pyrroles and similar compounds that can be removed by treatment with solid potassium hydroxide but very little is known in regard t o these compounds. The basic compounds are known t o include alkylated and cyclic substituted pyridines and alkylated quinolines and probably isoquinolines. The alkyls in the quinolines have so far been shown to be located a t positions 2, 3, 4, and 8 with alkyls higher than ethyl only a t position 8. In addition to industrial interest in these compounds, they should be considered in connection with theories on the origin of petroleum.
This review of petroleum acids and bases is presented in a single paper since most operations in the study of both classes of compounds are identical or analogous. The acidic compounds in petroleum consist of a mixture of phenols and carboxylic acids which are of aliphatic and cyclic types. The cyclic acids consist of ones containing the cyclopentane and those with a cyclohexane ring along with traces of aromatic acids. The carboxyl group is sometimes attached directly to the ring and sometimes one or more CH2 groups lie between carboxyl and ring. In addition to the monocyclic acids, those with 10 or more carbons include some with two or more rings but practically nothing is known in regard to their structure. The nitrogen compounds in petroleum are known to con-
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WILL become apparent later, there are so many points of similarity between petroleum acids and bases and their study, t h a t the presentation of both subjects in a single paper appears t o be desirable for logical reasons as well as to conserve space. While a single case does not establish this as a fact, there may be a genetic relationship between these acids and bases since, in the case of California petroleum it has been found that 2,4dimethyl-6-(2,2,6-trimethylcyclohexyl)pyridineand what may be considered as an oxidation product of the base, namely, 2,2,6trimethylcyclohexanecarboxylic acid, have been isolated among the most abundant bases and acids, respectively. Finally, any theory or theories in regard to the origin of petroleum cannot ignore these classes of compounds. ISOLATION
Petroleum acids and bases have both been isolated from crude oil and from natural gas but the concentration of these compounds in viscous crude oil is so low that it is difficult to isolate considerable amounts of either class in this way. The bases can be extracted from crude oil by means of concentrated sulfuric acid or by liquid sulfur dioxide (Edeleanu process) while the acids can be extracted with aqueous or alcoholic sodium hydroxide solution, but the procedure is unsatisfactory and, in practice, both classes of compounds are isolated by extracting the proper refinery fraction with acid or alkali. In both cases the compounds are then fractionated by distillation of the free acids or their methyl or ethyl esters and as the free base. Modern efficient columns are used to avoid the tedious redistillations formerly required. Fractional distillation may or may not yield cuts containing individual compounds in such high concentration that crystalline salts or derivatives can be obtained, but the yield of pure compound that can be obtained in this way is so low that it is almost always advisable to use some other physical method of separation before attempting to isolate pure compounds by recrystallization of salts or derivatives. Fractional neutralization or liberation of acids or bases has been most commonly applied to effect further separations, since these methods used with modern countercurrent equipment lead to numerous fractions from which crystalline derivatives can be obtained and recrystalNovember 1952
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lized to a state of purity. Determination of structure then follows the usual methods of organic chemistry. PETROLEUM ACIDS
By 1930 after half a century of tedious and often discouraging study of mixtures of acids isolated from refinery products and, in some cases, from crude oil, chemists were able to state that:
1. Phenols and carboxylic acids are found in all acidic mixtures. 2. The carboxylic acids consist of a mixture of the lower liquid and a few higher solid aliphatic acids and alicyclic acids which are known as naphthenic acids. 3. The naphthenic acids range from 6 to more than 20 carbon atoms, show no unsaturation, and ap ear to contain normally only minor concentrations of cyclohex y?acids. 4. While rings with 4 carbon atoms and with 7 or more such atoms are not excluded they are considered to be unlikely; consequently, the naphthenic acids consist predominatingly of cyclopentyl acids. I n 1928 von Braun (3) began a long series of studies in the chemistry of the naphthenic acids. These gave more information on the reactions of these acids than had been obtained in all previous work, but, since he separated almost entirely by distillation, as had been done in vain by earlier workers, he was not able to isolate a single pure naphthenic acid. Von Braun concluded as a result of his research that: 1. Acids with less than 8 carbons are almost entirely aliphatic in nature. 2. Monocyclic acids start a t CSand predominate between Cs and Cla. 3. Bicyclic acids start a t CLZ and predominate above CI4except in cases of the Galician acids in which no bicyclic acids were detected. 4. His “chlorine number’’ determinations ( 4 ) showed that most fractions of naphthenic acids had two a1 ha hydrogen atoms (chlorine number, 200) and so must have a t feast one CH2 group between the ring and the carboxyl group. 5. In a few cases he was able t o form a lactone after converting the acid to one with beta-gamma unsaturation and so concluded that in these the carboxyl grou had a t least three carbons between it and the ring. He concluied, however, that in most cases there was only one carbon between the ring and carboxyl. 6. The amines formed in good yield by the K. F. Schmidt degradation of the acids appear t o be more easily separated by distillation or by recrystallization of the oxalates than the parent acids.
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7 . The CsH1,O ketone m o d comnionlv obtained on degradation of GI" naphthenic acids forms a di-p-nit1 obenzylidene derivative; therefore, it must have both alpha carbons unsubstituted. This CS ketone was the subject of a considerable amount of study as a result of which von Braun concluded that it was 3,3,4trimethylcyclopentanone (6). He arrived a t this conclusion after synthesizing those ketones with unsubstituted alpha carbon atoms which were not knonn and nhich contained either a cyclopentane or a cyclohexane ring (except 3,3,4-cyclopentanone vhich he was unable t o prepare) and with the cis-trans isomers of 3-ethyl-4-methylcyclopentanonewhich were apparently overlooked. Since none of the known or newly synthesized ketones was found identical with his petroleum ketone he decided that the unknon n 3,3,4-trimethylcyclopentanone(5) was the one obtained from naphthenic acids. On the assumption that this was the correct structure, he synthesized the corresponding acetic acid from the petroleum ketone and decided that it was the acid from which his ketone was obtained, again ignoring the fact that cis-trans isomers are to be expected and the one synthesized might turn out to be not the one found in petroleum (6). Buchmann and Sargent (9) synthesized 3,3,4-trimethylcyclopentanone and found the melting points of its derivatives, particularly that of the semicarbasone which had been prepared a number of times by von Braun, to differ so far from those reported by von Braun that they concluded that von Braun's ketone could not have had the structure of 3,3,4-trimethylcyclopentanone and therefore all conclusions based on this structure were worthless. Mukherji (23)' apparently unaware of the work done a t the University of Texas and by Buchmann and Sargent. also reported the synthesis of the same ketone. She also found rather poor agreement in the melting point of the semicarbazone but, contrary to Buchmann, decided that her ketone was identical with von Braun's and then synthesized the corresponding acetic acid n-hich she thought constituted the first total synthesis of a naturally occurring naphthenic acid, Ruzicka and coworkers (33) also obtained this ketone in the course of work not related to petroleum. They proved its structure by degradation but unfortunately did not prepare the semicarbazone or otherwise characterize it sufficiently t o permit comparison with the petroleum ketone. The properties reported differed radically from von Braun's ketone and they obtained it from the same substituted adipic acid that was prepared by Buchmann and Sargent, thus confirming their structure. Baumgarten and Gleason ( 1 ) noted the discrepancy between the properties of 3,3,4-trimethylcyclopentanoneas reported by Buchman and Sargent and by Mukherji and repeated the synthesis using a slightly different synthesis. Their ketone was obviously identical with the one obtained by Buchmann and Sargent and not with von Braun's ketone from naphthenic acid, so von Braun's naphthenic acid ketone could not have had the structure he assigned to it. Meanwhile, Goodman (18) found that von Braun reported the synthesis of a 3-ethyl-4-methylcyclopentanonewhich was found to be different from the ketone derived from naphthenic acids but did not mention its cis-trans isomer which might prove to be the correct one. Goodman synthesized the ketone by a different route and was able to obtain the synthetic ketone of von Braun in good yield and to obtain the other form as a byproduct. The main synthetic ketone was reduced to a l-ethyl2-methylcyclopentane that had the properties of the cis form so the other ketone must be the trans form; its derivatives appear to be identical with those of the petroleum ketone of von Braun. Tentatively, von Braun's petroleum acid may be assigned one of the two possible forms of 3-ethyl-4-methylcyclopentylacetic acid having the alkyls trans with respect to each other. In 1939 following publication of von Braun's main papers, Tchitchibabine (41) published a progress report on a long-range
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research project on Baku acids. Through fractional distillation followed by recrystallization of the amides he isolated &methylhexanoic and 3-ethylpentanoic acids but abandoned use of the amides because of a tendency toward mixed crystal formation. He obtained better results in the separation of aliphatic from cyclic acids through systematic fractional cadmium salt formation and was able to isolate cyclohexanecarboxylic acid. Like von Braun, Tchitchibabine carried out extensive degradation reactions on various fractions of naphthenic acids. The acids mere converted t o the alpha-hydroxy acids which were heated to obtain formic acid and an aldehyde or ketone, depending on the structure of the acid. I n the case of cyclic acids M ith the carboxyl directly attached to the ring, he concluded that dehydration takes place instead of degradation. Various fractions of Baku acids yielded mainly unsaturated acids and Tchitchibabine came to the conclusion that in the case of Baku acid the carboxyl group is usually attached to the ring instead of being one carbon removed from it as in the case of von Braun's Roumanian acids. Aside froin his work on the CIOacids and the ketone obtained from them, von Braun attempted for years to learn more about bicyclic acids which he found among the higher naphthenic acids. Correspondencewith the late J. R. Bailey indicated that he became very much discouraged with his lack of progress in this line, and aside from the indication that a t least some of these acids also are substituted acetic acids, since he obtained a ketone on removing two carbon atoms from the acids, he obtained no positive information in regard to the nature of these acids. I n 1938, Nenitzescu, Isacescu, and Volrap (24)reported the isolation and identification of a number of additional aliphatic acids, and the first series of naphthenic acids were identified. The acids Jvere obtained from Ploesti straight-run gasoline and contained high concentrations of phenols. After the usual purification steps the acids were converted to methyl esters and the distilled esters extracted with cold dilute sodium hydroxide to remove phenols. The acids were again liberated and esterified and now carefully fractionated-the only real fractionation employed in this work. Sixty-one fractions boiling over 1" C. ranges between 40" and 100" C. a t 20 mm. were collected. Each fraction was then treated with 1.5 volumes of 13 -1-ammonium hydroxide and set aside for a t least 2 weeks in stoppered flasks. 4 number of the fractions were converted into solid amides during this time and in some cases could be purified by recrystallization. Only about 8% of the acids present had been converted to solid amides but cyclopentanecarboxylic acid, cpclopentj-lacetic acid, and 3methylcyclopentylacetic acid were identified as 11. ell as 4-methylpentanoic and 5-methylhexanoic acids. Meanwhile, this author and cos-orkers were working on Signal Hill straight-run gasoline and kerosene acids a t the University of Texas and were able to isolate and identify a much larger number of naphthenic and aliphatic acids by taking advantage of the availability of a mixture of straight-run acids including the lowest naphthenic acids which should be most easily isolated and identified. Previous workers were generally not able to get a supply of such acids since commercial acids normally contain only traces of the lower naphthenic acids. The Macmillan Petroleum Co , which generously furnished the acids, a t that time used a peculiar refining system in which straight-run gasoline and kerosene were washed countercurrently in two alkali towers so arranged and operated that the first removed the carboxylic acids while the second removed practically only phenols. Advantage was also taken of development and use of countercurrent fractional neutralization or liberation of the acids as efficient separation methods to supplement fractional distillation of the acids and their esters (25). The aliphatic acids through Ce were carefully separated and the normal acids, which occurred in much the highest concentration, through Cg were identified. There was no indication that such acids do not occur above C p(51).
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PETROLEUM-COMPOSITION I n the naphthenic acid range cyclopentanecarboxylic, 2-methylcyclopentanecarboxylic, 3-methylcyclopentanecarboxylic, cyclopentylacetic, 3-methylcyclopentylacetic, 2,3-dimethylcyclopentylacetic, and 1,2,2-trimethyIcyclopentanecarboxylic acids containing what is considered the typical cyclopentane ring were isolated as were cyclohexanecarboxylic, p-methyicyclohexanecarboxylic, and cis- and trans-2,2,6-trimethylcyclohexanecarboxylic acids (25). Dimethylmaleic anhydride was isolated from both Texas and California acids (14,36). The interesting, highly hindered 1,2,2-trimethylcyclopentanecarboxylicand 2,2,6-trimethylcyclohexanecarboxylic acids were very easily isolated by making use of the fact that they are not esterified by prolonged refluxing with methanol containing hydrogen chloride while the others are readily esterified (14,57). It will be noted that in this lower range of naphthenic acids both cyclopentyl and cyclohexyl acids are found and that some are substituted acetic acids while others have the carboxyl group attached directly to the ring. Whether the higher naphthenic acids are also mixtures of all types or whether, as believed by von Braun, they consist very largely of cyclopentaneacetic acids remains t o be seen. As pointed out before the nature of the bicyclic acids remains a mystery, Von Braun arrived a t no conclusion; Harkness and Bruun (15) analyzed Gulf Coast acids and found that they appeared t o consist of mixtures of acids with one to five rings and containing some aromatic acids. Goheen (11) decided that it might be easier to determine what rings and how many were present if he converted the acids to the corresponding hydrocarbons. These were studied by means of type analysis methods developed in hydrocarbon chemistry. He concluded that Gulf Coast acids contain bicyclic and some molecules with more than two rings in addition to the usual monocyclic acids. Wash (43) in a study of Texas acids also obtained fractions with unusually high n X d values of 1.52 t o 1.53, where n = index o€refraction a t T oC., and d = density a t T oC. Incomplete work a t present in progress a t the University of Texas indicates definitely that there are low concentrations of aromatic acids in naphthenic acids from northern California (less than 1% of the acids in the narrow boiling fraction) and that bicyclic acids occur even in the CIOand C1l range of acids, althoughtheconcentration of such acids in the C13t o CISrange seems to be much higher (22).
PETROLEUM BASES
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The occurrence of ammonia among the products obtained on the distillation of certain crude oils was observed in Europe about 75 years ago and a few analyses on crude oils and on refinery fractions were run soon thereafter. They showed that variable but definite amounts of nitrogen compounds are present in most crude oils. Since petroleum bases unlike the naphthenic acids are not commercial products, research was made difficult because the bases usually had to be isolated directly from crude oils or be specially extracted from refinery products. It was thus an expensive as well as tedious field of research. Between 1900 and 1920 Mabery and Wesson (10)studied basic compounds isolated from refinery fractions of California petroleum. They were the first to recognize that the ordinary Dumas method without special modifications is poorly suited for the analysis of crude oils and leads t o results which may be high by several hundred per cent. They, along with most of the earlier workeis, held the Kjeldahl method as unsuitable and modified the Dumas procedure until correct results (agreeing with Kjeldahl, however) were obtained (19). Mabery concluded that the bases consist of a mixture of alkylated quinolines and isoquinolines most of which are highly alkylated with side chains of not over four carbons. They were not able to identify any individual compound but later work has shown that their conclusions may have been essentially correct as far as the quinolines were concerned.
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RECENT RESULTS
It remained for API Project 20, under the direction of the late J. R. Bailey, to isolate and identify a whole series of bases from California distillates after a careful analytical survey of crude oil samples from a large number of American fields. I n the course of this study reliable methods of determination of nitrogen by a modified Kjeldahl procedure were developed and it was found that the crude oils from California show a higher nitrogen content (up to 0.8%) than other American oils (29). I n addition to careful fractional distillation using efficient columns they employed a remarkably effective solvent extraction scheme in which the hydrochlorides of the bases are distributed between water and chloroform. The quinolines accumulate in the chloroform and pyridines in the water layer, although it is possible to separate cyclic substituted pyridines from simple alkylpyridines since the latter now are found in the water layer and the cyclopyridines mainly in the chloroform layer (27). I n still more difficult separations Texas workers have used countercurrent fractional liberation or neutralization of the bases which were previously fractionally distilled and distributed between chloroform and water (3.4). Through use of these methods of separation it was possible to isolate and identify more than 24 alkylated quinolines and a few pyridines (55). Later work using very careful separation led to the identification of a number of new alkylpyridines and 3- and 4-cyclopentylpyridine (18). The most interesting compound isolated was one that is present in high concentration in bases boiling around 275" C. and was easily converted to its picrate. The Cl5HZ5Nbase is extremely stable to oxidation and has so many peculiar properties that Bailey and coworkers had great difficulty in determining its correct structure. It was finally identified, a few days before Bailey's death, through the fact that 2,2,6-trimethylcyclohexanecarboxylic acid is obtained on ozonolysis of the base and had just been isolated and identified as one of the main acids found in California naphthenic acids. Since this acid and its amide must have been obtained from the nitrogen and an adjacent carbon of the base, the cyclic portion of the acid must have been attached to this alpha carbon atom. The other alpha carbon was known t o carry a methyl group, as was the gamma carbon; consequently, the structure of the base was known to be 2,4-dimethyl-6-(2,2,6trimethylcyclohexy1)pyridine. Since the acid obtained on ozonolysis had been found to be one of the most highly hindered acids known, it is not surprising that this base should also be protected by this unit (YO, 38). Of the substituted quinolines isolated, all had a methyl group in position 2 and other groups present were located a t positions 3,4, and 8, while none were found a t 5 , 6 , or 7. CRACKING PROCESS BASES The main series of bases was obtained from straight-run products. Two studies on cracking process bases from California gasoline have also been reported (2, 13). Unfortunately, the bases isolated from gasoline boil lower than those obtained earlier from distillate and kerosene, and a direct comparison is not possible. The cracking process bases consist of most of the possible methyl- and some ethylpyridines. Hackman and Wibaut (13) also isolated isoquinoline and 1-'and 3-methylisoquinoline as well as some methylquinolines not alkylated in position 2. They also isolated 7-methylquinoline; all of these types had not previously been isolated from straight-run material. Whether these compounds were formed during pyrolysis or whether they were among the large number of bases undoubtedly present and not isolated by Bailey's group is not known.
NONBASIC NITROGEN COMPOUNDS Except in the case of gas-well products, among which ammonia and lower aliphatic amines have been reported (IO,467, only
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tertiary amines have been reported. These appear to consist entirely of heterocyclic bases like pyridines, quinolines, and isoquinolines. There is, however, another type of nitrogen compound which, in the case of California material studied by Bailey's group, amounts to almost half of the nitrogen compounds present and which has been studied only very slightly This is the class of nonbasic compounds which are not extracted from hydrocarbons by dilute acid. Positive qualitative tests for pyrroles have been reported and in the case of shale oil bases a few of these (22, 42) have been isolated. The Texas group found that the socalled nonbasic compounds can be extracted with concentrated sulfuric acid or by liquid sulfur dioxide by means of which (Edeleanu process) they were obtained from California distillate and kerosene. It remains to be seen from future studies whether these compounds are all pyrroles and similar heterocyclic compounds and nitriles or whether some of them may be derived from primary or secondary amines which are converted to AT-substituted amides of naphthenic or other carboxylic acids or to stable compounds with higher phenols (44). ORIGIN While it is now rather generally agreed that petroleum and its acids and bases are of animal or vegetable origin the steps by which the acids are formed are unknown. Tanaka and Kuwata (40)believed that whale and shark oil glycerides were hydrolyzed and the resulting acids as such or changed were present as petroleum acids. Von Braun (3)felt that there was a definite genetic relationship between the hydrocarbons and the accompanying acids and felt at first that the acids were man-made but later found the higher acids from crude oil and refinery products appeared identical. Pilat and Reymann (28) also examined acids from crude oil and concluded that they were essentially the same as those obtained during refining of'the same crude oil. Numerous reports and patents on acids produced when oil is deliberately oxidized by blowing air through it show that a mixture of hydroxy, unsaturated, and other types of acids quite different from naphthenic acids is obtained along with ordinary carboxylic acids. It therefore seems unlikely that traces of oxygen present during refinery operations mould lead only to naphthenic acids. There is, however, still much uncertainty in regard to the amount of acids obtained from crude oil and from refinery products from an equal volume of the same crude. Possibly some of the higher acids may be pyrolyzed to yield lower acids, although this seems rather unlikely during straight-run refinery operations since decarboxylation seems to be more likely. Ridgway and coworkers ($8)isolated acids from both crude and distilled Texas oil and reported no essential difference in their nature. A puzzling feature in regard to the naphthenic acids is the very high concentration of cyclopentyl acids compared with naturally occurring cyclopentane derivatives. Brooks (7, 8) has discussed this problem as have Stevens and Spalding ($9). It is possible that the cyclohexyl acids which were originally expected to predominate are rearranged during prolonged contact underground a t moderately high temperatures with catalytically active surfaces. -4series of studies of acids produced by certain high pressure gas wells has been carried out under the sponsorship of the Corrosion Committee of the Natural Gasoline Association of America. Among these studies the individual acids present in the water phase produced in the Katy field near Houston have been carefully identified (16) and the ratios of lower to higher acids produced have been determined for a number of wells from different fields (27). I n all cases acids with two to more than seven carbons are definitely produced as such by these gas wells. Unfortunately the expense involved in isolating a sufficiently large amount of gas-well acids to permit isolation and identification of naphthenic acids from either the water phase or the hydrocarbon phase produced by these condensate Tells was too great to carry out this interesting study.
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If petroleum is derived from vegetable or animal products, the nitrogen compounds are presumably derived from proteins, alkaloids, or other nitrogenous compounds The specific origin of the most plentiful of the higher bases studied by Bailey's group-2,4dimeth~~l-6-(2,2,6-trimethylcyclohexyl)pyridine-presentsan interesting problem. The 2,2,6-trimethylcyclohexyl substituent could obviously be considered as a carotenoid derivative, but no natural compound containing the combination of pyridine nucleus with this carotenoid test is known. Since 2,2,6-trimethylcyclohexanecarboxylic acid is also one of the main naphthenic acids found in California petroleum, it is wondered whether the acid is derived from the base or the base from the acid. It is planned to continue studies of these two compounds, which are easily isolated even from relatively small volumes of acids or bases boiling in the proper range, in the hope that they may ultimately contribute to knowledge of the origin, not only of petroleum bases but of naphthenic acids also. High pressure gas wells yield small amounts of basic compounds along with the lower acids. When water phase samples are alkalized and distilled to obtain concentrated solutions of salts of the acids, the first 10 to 20% of the water distilled is found to react alkaline to phenolphthalein, but the total alkalinity to litmus of the distillate obtained from a gallon of such water amounts to only about 0.1 mg. equivalent of bases. When the hydrocarbon phase material from a Seabreeze field \vel1 was studied it mas found that approximately 2 grams of base hydrochlorides were ohtained from 56 barrels of hydrocarbon phase. Since the gas-well products should be low boiling, it was felt that these probably would be found to consist of the lower aliphatic amines, but a careful study showed that no measurable amount of basic material was obtained with boiling point below 200' C. Qualitative behavior, odor, etc., seemed to indicate that the bases consist of a mixture of quinolines or isoquinolinrs They are being studied a t present by another worker in this laboratory. A host of interesting studies remain to be carried out in this field and the recent rapid development of highly efficient sepaiation methods which permit separations based on strength of acids. distribution between solvents, and surface activity effects makes it possible to supplement distillation Kith one or more of these methods which do not depend primarily on boiling point or molecular weight. These will make possible the isolation and semiquantitative separation of individual compounds of scientifir interest and may be useful in future geochemical studies.
LITERATURE CITED (1) Baumgarten, H. E., and Gleason, D, C., J. Org. Chem., 16, 1658 (1951). (2) Bratton, A. C., and Bailey, J. R., J. Am. Chem. Soc., 59, 175 (1937). (3) Braun, J. von, Ann., 490, 100 (1931). ( 4 ) Ibid., p. 108. (5) Braun, J. von, Keller, W,, and Weissbaoh, K., Ibid., 490, 179 (1931). ( 6 ) Braun, J. von, Mannes, L., and Reuter, M., Ber., 6 6 , 1499 (1933). (7) Brooks, B. T., J. Inst. Pelroleuin Technol., 20, 182 (1934). (E) Brooks, B. T., Science, 111, 648 (1950). (9) Buchmann, E. R., and Sargent, H., J . Org. Chem., 7, 148 (1948). (10) Campbell, S. E., private communication. ENG.CHEW,32, 503 (1940). (11) Goheen, G. E., IND. (12) Goodman, H. H., Ph.D. thesis. University of Texas, Austin, Tex., 1951. (13) Hackman, J. T., and Wibaut. J. P., Rec. trav. chim., 62, 229 (1943). (14) Hancock, K., and Locht,e, H. L., J . Am. Chem. Soc., 61, 2448 (1939). (15) Harkness, R. W., and Bruun, J. H., IXD.EXG.CHEM.,32, 499 (1940). (16) Loohte, H. L., Burnam, C. W., and Meyer, H. W.H., Petroleum Engr., 21, 225 (August 1949). (17) Lochte, H. L., Meyer, H. W.H., and Wheeler, E., Rpt. to Corrosion Comm. of Natural Gas. Assoc. Am., June 1950.
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PETROLEUM-COMPOSITION (18) Lmhte, H. L., Thomas, D., and Truitt, P., J.Am. Chem. Soc., 66, 550 (1944). (19) Mabery, C. F., Ibid.,41,1690 (1919). (20) Mabery, C. E”., and Wesson, L. G., Ihid., 42,1014 (1920). (21) Mapstone, G . E., Preprint A17, 2nd Oil Shale and Cannel Coal Conf., Glasgow, July 1950. (22) Meinschein, W. G., Ph.D. thesis, University of Texas, Austin, Tex., 1951. (23) Mukherji, Debi, Science and Culture, 13,296 (1948). (24) Nenitzescu, C. D., Iaaoescu, D. A., and Volrap, T. A., Ber., 71B,2055 (1938). (25) Ney, W. O., Crouch, W. W., Rannefeld, C. E., and Lochte, H. L., J . Am. Chem. SOC.,65,770 (1943). (26) Parker, Ivy, private communication. (27) Perrin, T. S., and Bailey, J. R., J . Am. Chem. Soc., 55, 4136 (1933). (28) Pilat, S., and Reymann, I., Ann., 499,76 (1932). (29) Poth, E. J., Armstrong, W. D., Cogburn, C. C., andBailey, J. R., IND. ENQ.CHEM.,20,83 (1928). (30) Prelog, V., and Geyer, U., Helv. Chim. Acta, 29,1587 (1946). (31) Quebedeaux, W., Wash, G., Ney, W., Crouch, W. W., and Lochte, H. L., J.Am. Chem. SOC.,65,767 (1943). (32) Ridgway, C. M., Ayers, G. W., and Henderson, L. M., Oil Gas J.,38,114,118, 121 (1940). (33) Rusicka, L., Seidel, C. F., Schinz, H., and Pfeiffer, M., Helv. Chim. Acta, 25,188 (1942).
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(34) Schenck, L., and Bailey, J. R., J. Am. Chem. Soc., 62, 1967 (1940). (35) Zhid., 63,1365 (1941). (36) Schutze, H., Shive, W., and Loohte, H. L., IND.ENG.CHEM., ANAL.ED.,12,262 (1940). (37) Shive, W., Horeczy, J., Wash, G., and Lochte, H. L., J . Am. Chem. SOC., 64,385 (1942). (38) Shive, W., Roberts, 9. M., Mahan, R. I., and Bailey, J. R., Zhid., 64,909 (1942). (39) Stevens, P. G., and Spalding, S. C., Ibid., 71,1687 (1949). (40) Tanaka1 y . and ~ Kuwatai T., J. Faculty EnO. TokW Imp. Uni8.1 17,293 (1928). (41) Tchitchibabine, A. E., Chimie & industrie, Spec. No., 306-18 (1932). (42) Thorne, H. M., Murphy, W., Stanfield, K., Ball, J. S., and Horne, J. W., Preprint B24, 2nd Oil Shale and Cannel Coal Conf., Glasgow, July 1960. (43) Wash, G., Ph.D. thesis, University of Texas, Austin, Tex., 1941. (44) Willie, H., Brennstofl Chem., 23, 271 (1942). RECEIVED for review June 25, 1951. ACCEPTED July 28, 1952. Presented in part a8 part of the Symposium on Composition of Petroleum and Its Hydrocarbon Derivatives before the Division of Petroleum Chemistry at the 119th Meeting of the AMERICAN CHEMICAL SOCIETY, Cleveland, Ohio, April 1951.
Distribution of Nitrogen in Petroleum According to Basicity F. P. RICHTER, P. D. CAESAR, S. L. MEISEL, AND R. D. OFFENHAUER Socony-Vacuum Laboratories Research and Development Department, Paulsboro, N. J.
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and coworkers (16). These T h e deleterious effect of nitrogen in catalytic cracking workers concluded that “in operations and the increasing usage of stocks high in gen compounds in crude crude oil t h e nitrogen comnitrogen content for this purpose have accentuated the oils has long been of inpounds are in the main not need for fundamental information concerning the nature terest from the standpoint of of these compounds in petroleum. The existence of basic basic, but in distillates bases its possible relation to the appear along with nonbasic nitrogen compounds in virgin crudes has been proved by o r i g i n of petroleum. Renitrogen compounds of unextraction with 5% aqueous hydrochloric acid. Moreover, c e n t l y t h e nitrogen comknown structure.” This conperchloic acid titration of a number of crude petroleums pounds in various petroleum clusion was based on their from widely different sources and of the distillate fractions stocks have received renewed of three crude oils has shown that a constant 0.30 f 0.05 failure to extract basic nitroattention because of the ingen compounds with 16% sulratio of basic to total nitrogen holds true generally in hibitory effect of nitrogen in crude oils and virgin stocks and does not vary with profuric acid from a sample repcatalytic cracking processes longed heating at 600” F. This work indicates that the resenting t h e crude oil from (14,25). Another source of the iMcKittrick district of types and the relative proportion of types of nitrogen interest has been the demonCalifornia. Sachanen (18) compounds in various crudes are essentially the same, stration of the presence of although the relative amounts vary considerably. This stated that the nitrogen bases pyrrolic nitrogen in certain is indicative of a common mechanism of formation for in distillates appear to result distillate fuel oils and its posfrom the decomposition of the various crude petroleums. sible effect on the stability of some neutral complex nitrothese materials (19). gen compounds a t distillation A survey of the nitrogen content of 153 crude petroleums was temperatures. The nitrogen bases-reported b y Bailey and his published recently by Ball and coworkers (6) and Lochte (13) students (4, IS) have frequently been considered to be formed in has reviewed the knowledge of petroleum bases up to 1951. this manner. Bailey (4) stated categorically that nothing is known of the structure of the nitrogen compounds in crude, undistilled petroDEFINITION OF BASIC NITROGEN leum. A review of the literature has revealed that except for the work of Bailey and his students (4, 18) relatively little has As a first approach to the understanding of the nature of the been reported in this field. Although one of the most important nitrogen compounds in petroleum it would seem justifiable t o properties of nitrogen compounds is their relative basicity, no have some classification according to basicity, By the term tangible progress has been reported in the study of the nitrogen “basicity” is meant the relative availability of the electrons on compounds in petroleum in this respect since the paper by Poth the nitrogen atom. This is a most important property because
HE nature of the nitro-
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November 1952
INDUSTRIAL AND ENGINEERING CHEMISTRY
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