Arylstearic Acids from Oleic Acid

pounds. Schulze and Buell (10) called attention to the possible economies to be obtained by desulfurization of gasolines to which tetraethyllead is to...
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110 406

104 390

100 396

AC AC l3d A0 Ce Bd Sulfur content, %: Total 0.433 0.20 0.44 0.084 0.20 0.42 Disu 1fide 0.013 0.004 0.013 0.001 0.004 0.013 Sulfide 0.025 0.006 0.025 0.004 0.006 0,025 Residual (thiophene) 0.395 0.190 0.395 0.079 0.190 0 . 3 9 5 Octane No. with following Der gal.: - cc. of tetraethyllead 0 69.7 69.0 69.0 68.0 68.0 68.0 0.5 71.5 72.0 71.0f 72.5 71.0 70.0f 1 .o 73.5 74.5 73.0 75.5 73.5 72.0 2.0 75.5 76.5 75.0 77.5 75.5 74.5 Lead susceptibility 0.63 0.79 0.61 1.02 0.80 0.69 a 98 per cent sulfuric acid treating at 20° F. b Naphtha cracked from mixed California residuum. c Gasoline as produced. d N-Amyldisulfide, propyl sulfide, and dimethyl thiophene added t o equal total sulfur content and amounts of the different types of sulfur compounds in gasoline from 10.5pound treat. e Same as d exoept to duplicate 21.0-pound treat.

results show that pure olefins have poor lead susceptibility, aromatic compounds as typified by toluene are considerably better, and paraffin hydrocarbons have a high lead susceptibility. These data, combined with those shown in Figure 3, indicate that although aromatics have a higher lead susceptibility than olefins when substantially sulfur-free, they are more sensitive to the detrimental effects of sulfur compounds. Schulze and Buell (10) called attention to the possible economies to be obtained by desulfurization of gasolines to which tetraethyllead is to be added. More recently, Ridgway (9) evaluated caustic washing gasolines as a means of removing mercaptans and thereby increasing lead susceptibility. Typical results of the effect of acid treatment on the knock rating and lead susceptibility of cracked gasoline are given in Table VI1 and shown in Figure 5 . Although increasing acid treatment lowered the knock rating, the de-

VOL. 31, NO. 7

sulfurization accomplished by the treatment increased the lead susceptibility so that high knock rating values were obtained with less tetraethyllead. When high knock ratings are required, increase in the amount of acid applied in refining cracked gasoline is an economical means of saving tetraethyllead. Also of interest in Table VI1 is the addition of pure sulfur compounds to the more severely treated gasolines to duplicate the sulfur content of the less severely treated stocks. When the sulfur compounds were, added back, no detectable effect on knock rating was found, but the lead susceptibility of the higher sulfur content stocks was duplicated. ,

Aclmowlkdgment The courtesy of L. E. Hebl, T. B. Rendel, F. 1,. Garton, and the Shell Petroleum Corpora-

tion in furnishing advance coties of the new Ethyl blending c h k t for use in ihis investigation is gratefully acknowledged.

Literature Cited Birch and Stansfield, IND.ENG.CHEM.,28, 665 (1936). Born, Natl. Petroleum News, 25, No. 14, 23 (1933). Campbell, Signaigo, Lovell, and Boyd, IKD. ENG. CHEM.,27, 593 (1935). Hebl, Rendel, and Garton, IND.ENG.CHEM.,25, 187 (1933). Hebl, Rendel, and Garton, Petroleum Div., Am. Chem. Soo., Sept., 1938. Kobayashi and Kajimoto, J . SOC. Chem. Ind. (Japan), 39, suppl. binding, 307 (1936). Ibid., 39, suppl. binding, 354 (1936). Kobayashi et al., Brennstoff-Chem., 17,73 (1936) ; J . SOC.Chem. Ind. (Japan), 38, suppl. binding, 654 (1935). Ridgway, Oil Gas J.,36, No. 46, 53 (1938). Schulze and Buell, Natl. Petroleum News, 27,No.41,25 (1935). Wirth, Kanhofer, and Murphy, Oil Gas J . , 32, No. 8,13 (1933). PRESENTED before the Division of Petroleum Chemistry at the 96th Meeting of the American Chemioal Society, Milwaukee, Wis.

Arylstearic Acids from Oleic Acid A. J. STIRTON AND R. F. PETERSON Industrial Farm Products Research Division, Bureau of Chemistry and Soils, Washington, D. C.


ECENT interest in the utilization of phenylstearic acid, particularly as an addition agent to lubricants, has . suggested the preparation of new arylstearic acids from oleic acid and an aromatic compound, according to the Friedel and Crafts reaction. The present investigation deals with p-tolylstearic, p-chlorophenylstearic, p-bromophenylstearic, p-methoxyphenylstearic, p-phenoxyphenylstearic, and p-xenylstearic acids. The esters, ethyl tolylstearate and methyl phenoxyphenylstearate have also been prepared in a similar manner from ethyl and methyl oleate, respectively. These compounds have been submitted to the National Bureau of Standards to be tested as addition agents to lubricants. Other possible uses, a study of which is either in progress or planned, include their conversion to soaps, wetting agents, and waxes. Preliminary experiments and tests (surface tension, wetting efficiency, and solubility of calcium

salts) indicate that the sulfonation products have desirable properties as penetrants. Phenylstearic acid was made by Nicolet and de Milt (11) from benzene and oleic acid in the presence of aluminum chloride. Apparently this acid had been prepared earlier by Marcusson (9) by the same means in the course of an investigation of the polymerization of fatty oils by air and by chemicals. Since 1927, numerous references t o this acid have appeared. These include a study of the rate of phenylation of oleic acid (14) and the conclusion that phenylstearic acid prepared by the Friedel and Crafts reaction is a mixture of approximately equal portions of 9- and 10-phenyloctadecanoic acids ( 5 ) . The properties of lubricating greases made from soaps of the acid (S), patent claims for improvements in compounded lubricating oils (4, 10, l 7 ) , and improvements in the method of preparing phenylstearic acid

JULY, 1939


Preparationb Phenylstearic acid rTolvlstearic acid

Grams Crude before Vacuum Distn. 23 1 240 233 225 218 269 245








Yield on 2nd Vacuum Fractionationc

Neutralization Equivalent 7

B. P., O C. 220-30 (1 mm.) 232-8 ( 0 . 5 mm.) 235-6 ( 0 . 4 mm.) 240-5 ( 0 . 5 mm.) 241-50' ( 0 . 2 mm.) 250-65 ( 0 . 5 mm.) 246-8 ( U . 5 mm.)

Grams 97 101 128 71 68 93 96

% of theory 38 38 47 25 22 29 35

Found 364.7 380.8 392.9 399.1 439.3 481.0 396.0

Theory 360.3 374.3 388.4 394.8 439.2 452.4 390.3

Saponification Equivalent Ethyl tolylstearate Methyl phenoxyphenylstearate 5


163 198

212-22 (1 mm.) 253-66 (1 mm.)

76 103

37 44

Found 400.8 457.0

Theory 402.4 466.4

A mole ratio of aromatic compound to oleic acid (or alkyl oleate) as high as 7 : l is desirable.

Low ratios result i n decreased yield. Conditions for preparing the acids: 100 grams (0.75 mole) of aluminum chloride added in portions a t room temperature during 15 minutes t o a solution

of 200 grams (0.709 mole) oleic acid i n a n excess of the aromatic compound: t h e temperature was slowly raised t o 80' C. and held there for 6 hours; mechani-

cal a g i b t i o n was continuous. Conditions for esters: 71 grams 0.535 mole) of aluminum chloride and 0.5 mole of the ester were used: otherwise the conditions were t h e same except t h a t t h e reaction product was hydrchysed in water rather than in dilute hydrochloric acid. The yields represent a C T h e yield was not increased b y adding a solution of oleic acid t o a suspension of aluminum chloride i n t h e aromatic compound. particular fraction after two vacuum distillations: considerably higher yields of a product of technical quality can be obtained. A dark and very viscous oil remains as the residue from the initial vacuum distillation: this material is probably a polymerization product from a reaction between oleic acid and aluminum chloride (8, 9,18), and i t may possess valuable qualities as a n addition agent t o lubricants (4).

( 7 ) have been reported. A mixCertain analogs of phenylstearic acid have pressure. The results are rebeen prepared to be tested as addition corded in Table I. The prodture of olive oil and the triglycucts are clear viscous oils which eride of phenylstearic acid has agents to lubricants. Other possible uses could not be made to crystalbeen suggested as a lubricant (12). The Friedel and Crafts which are being given consideration inliae. reaction has also been used in clude their conversion to soaps, wetting the preparation of xylylstearic agents, and waxes. The alkyl oleates beReactions i n an Inert acid (14)i a-napht'hylstearic acid have similarly to aleic acid in the Friedel Solvent ( I S ) , and phenylstearyl alcohol and Crafts reaction with an aromatic Carbon disulfide, (15). H y d r o c a r p i c a n d u n compound* The Preparations tetrachloroethane, nitrobenzene, decylenic acids or their esters can be arylated in the same type the generality of the reaction of oleic acid petroleum ether, and o-dichloroof reaction (2). or an oleate with aromatic substances. benzene were tried as solvents. In every case in which a higher Only in the case of the last two olefinic acid enters into this type was the preparation successful. ' of Friedel and Crafts reaction, the product is a TTlSCOUS oil which cannot be made to crystallize ( 2 , 11, 13, 14, 15). Structure of Arylstearic Acids The arylstearic acids of the present investigation. were no Tolylstearic, chlorophenylstearic, bromophenylstearic, pheexception. Apparently they consist of a mixture of the two noxyphenylstearic, and xenylstearic acids were oxidized by possible isomers : aqueous potassium permanganate a t 100" C. The degradaCHa(CHz)&H(CHg)sCOOH tion products identified were terephthalic, p-chlorobenzoic, I p-bromobenzoic, p-phenoxybenzoic, and p-phenylbenzoic Ar acids, respectively. Terephthalic acid was converted to the CH@Hz)&H=CH (CH&COOH crystalline dimethyl ester (melting a t 140" C.), and the others were identified by the method of mixed melting points. X o aliphatic degradation product was isolated in the perCHs(CHz)sCH(CHz)+2OOH manganate oxidation which would indicate the position of the I ' aryl radical in the chain. Methoxyphenylstearic acid was Ar catalytically oxidized by oxygen with a manganese dioxide catalyst, but only p-anisic acid was isolated (identified by the Reactions Using an Excess of the Aromatic method of mixed melting points). No proof of the position Reactant of the aryl radical in the chain can therefore be offered, but Reactions in which an excess of the aromatic reactant conpresumably these arylstearic acids are mixtures of about equal stituted the solvent were the most successful. This method proportions of 9- and 10-aryloctadecanoic acids (6). The was applied to the preparation of p-tolylstearic, p-chloroisolation of the aromatic acids demonstrated the presence of phenylstearic, p-bromophenylstearic, p-methoxyphenylpara-oriented arylstearic acids. stearic, p-phenoxyphenylstearic, and xylylstearic acids, as well as to ethyl tolylstearate and methyl phenoxyphenylPhysical Properties and Analysis stearate. The methods of Nicolet and de Milt ( 1 1 ) and of The purified arylstearic acids and esters were analyzed, Schmidt (14) were compared, and it was concluded the former and the molecular refractivity was determined (Table 111). was to be preferred when the purpose was to use an oleic acid p-Chlorophenylstearic and p-bromophenylstearic acids were of commerce (U. S. P. grade) and to isolate the product by analyzed for chlorine and bromine, respectively: fractional distillation under reduced pressure. The nonvolatile oily residue obtained after the usual steps Found, per cent C1: 8.90, 8.87; calculated for CZ4H3~O2C1, of hydrolysis, separation, and removal of solvent by steam per cent C1 = 8.98. distillation was dried over anhydrous calcium sulfate and subFound, per cent Br: 17.85, 17.89, 17.96; calculated for jected to fractional distillation under about 1-2 min. of mercury C24H3Q02Br, per cent Br = 18.20.



VOL. 31, NO. 7

TABLE 11. REACTIONS IN AN INERT SOLVENT" Aoid p-Methoxyphenylsteariob p-XenylstearioG, d

Yield on Final Fractionation

Mo!e Ratio Aromatic/Oleic 'Acid

Grams of Solvent 300 petroleum ether 600 o-dichlorobenzene

1.059 2.000

B. P., O C. 240-6 (2 mm.) 277-90 (1.5mm.)

Neutralization Equivalent


% of theory

40 36

14 12




395.0 441.4

390.3 436.4

200 erams oleic acid. 100 grams AlCls. mechanical agitation. AlCly added during 1 h o u r a t 10" C then temperatire kept a t 10-20' for 1.5 hours, 25' for 3 hours. AlCh added during 30 minutes a t 3 3 C then temperature kept at 80' for 3 hours. d May be prepared without the use of solvknt i n a crude yield of 28 per cent (one vacuum distillation).


. .

i, 0

TABLE 111. ANALYSIS AND MOLECULAR REFRACTIVITY Compound p-Tolylstearic acid Xvlvlstearic acid &Chlorophenylstearic acid p-Bromophenylstearic acid pMethoxyphenylstearic acjd p-Phenoxyphenylstearic acid Xenylstearic aoid thy1 to1 lstearate Methyl p~enoxyphenylstearate


Equivalent by

B. P., O C. Titration 232-8 (1 mm.) 380.W 214-6 (0.2mm.) 390.2" 217-23 0 2 mm.) 394.2" 241-50 {0:2 mm.) 439.30 240-6 (2 mm.) 395.Oa 265-7 (1 mm.) 460.5" 277-90 (1-1.5 mm.) 441.4" 403,O b 220-2 (1 mm.) 252-65 (1 mm.) 461.6b



%C 80.00,80.05 80.19,80.32 72.81,72.82 65.73,65.80 79.97,79.93 82.11,82.11 80.57,80.63 80.06,79.66





11.42,11.44 80.14 11.56,11.44 80.34 9.92,10.05 72.95 9.08, 9.14 65.57 10.91,10.91 76.86 9.66, 9.73 79.58 10.27,10.26 82.50 11.68,11.69 80.52 9.83, 9.84 79.76

%H 11.31 11.42 9.96

8.95 10.85 9.81 10.16 11.52 9.94

n"D" (Abbe)

Mol. Refractivity di0

1,4921 1.4QA3 1 ,4999 1.5067 1.4942 1.5203 1.5297 1 ,4828 1.5108

' Found


116.28 120.98 116.49 119.60 117.90 138.09 137.37 125.35 142.48

115.59 120.20 115.83 118.73 117.23 136.72 135.07 124.94 141.45

a Neutralization equivalent. b Saponification equivalent.

I n view of the proposed use of these arylstearic acids as addition agents to lubricants, their viscosity is an important physical property. The viscosities of the purest fractions available were measured with an Ubbdohde suspended-level viscometer (16). Kinematic viscosity index was calculated from the tables of Hersh, Fisher, and Fenske (6).

TABLE IV. VISCOSITY Compound Oleio acid Phenvlstearia aoid ~. Toiylstearia acid gylylstearic acid p-Chlorophenyletearic aoid p-Bromophenylstearic aoid ~Methoxyphenylstearicacid &Phenoxyph.enylstearic acid gXenylsteanc aoid t h 1 tolylstearate Met%yl phenoxyphenylstearate

-Kinematic At 100' F., centistokes

Visoosity--At 210' F., centistokes

21.73 150.0 219.5 323.8 265.0 294.0 241.4 421.5 799.0 21.15 42.75

4.94 13.47 16.48 20.06 18.70 19.32 17.11 23.80 33.40 4.14 6.19

Index 168.0

90.7 83.5 75.0 84.7 79.0 79.4 76.8 68.4 123.2 100.1

Derivatives Nicolet and de Milt (11) and Schlutius (18) were unsuccewful in forming crystalline derivatives of their rirylstearic acids. Harmon and Marvel prepared a crystalline p-bromophenacyl ester of phenylstearic acid (from the Friedel and Crafts reaction) with a melting point of 79-82' C., after fourteen recrystallizations. Selecting pchlorophenylstearic acid we obtained, with the reagents p-bromophenacyl bromide and p-phenylphenacyl bromide, products which we1e crystalline but melted below room temperature. With 8-benaylthiuronidm chloride (1) and pchlorophenylstearic acid, a solid derivative melting a t 129' C. was obtained. It was analyzed for nitrogen: Found, per cent N: 4.88,4.92, 4.88; calculated for CszHtsOzNa= 5.00.

CIS,per cent N

Acknowledgment The writers wish to acknowledge the advice and cooperation of Nathan L. Drake of the University of Maryland, and of P. H. Groggins of the Industrial Farm Products Research Division.

Literature Cited Donleavy, J. J., J . Am. Chem. SOC.,58, 1004 (1936). Fourneau, E., and Baranger, P. M., Bull. soc. chim., 49, 1161 (1931). Gilfoil, W. S., IND.ENG.CHEM.,22, 487 (1930). Gleason, A. H., U. S. Patent 2,106,247(1938). Harmon, J., and Marvel, C. S., J . Am. Chenz. Soo., 54, 2515 (1932). Hersh, R . F., Fisher, E. K., and Fenske, M. R.; IND. ENG. CHEM.,27, 1441 (1935). McKee, R. H., U. S. Patent 1,972,568(1934). Marcusson, J., Chem. Umschau Fette, &e, Wachae, Harze, 36, 53 (1929). Marcusson, J., 2.angew. Chem., 33, 234 (1920). Moran, R. C . , U. S. Patents 1,850,561(1932) and 2,043,836 (1936). Nicolet, B. H., and de Milt, C. M., J . Am. Chem. SOC.,49,1103 (1927). Roberti, G.,Piutti, P., and Dinelli, D., Ricerca sci., [2]7, 10 (1936). Schlutius, E., J. pralct. Chem., 142, 49 (1935). Schmidt, E . G., J . Am. Chem. Soc., 52,1172 (1930). Sisley, J. P., Chimie & Induatrie, Special No. 763 (April, 1934). Ubbelohde, L., IND.ENG.CHEM.,Anal. Ed., 9,85 (1937). Vobach, A. C.,U. S. Patents 2,081,075(1937) and 2,095,538 (1937). ZelinskiI, N. D.,and Lavrovski, K. P., Ber., 61,1054 (1928).

TAKDN in part from a thesis submitted by A. J. Stirton t o the Faculty of the Graduate School of the University of Maryland, i n partial fulfillment of the requirements for the degree of dootor of philosophy.