Esterification - Industrial & Engineering Chemistry (ACS Publications)

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September 1950

INDUSTRIAL A N D ENGINEERING CHEMISTRY

trioxide-alumina 01 vniiadium pentoxide-alumina catalyst at 1OOO' F, The yield based on the starting furan is approximately 10% of the theoretical. Sodium catalyzes the direct amidation of pyridine with anhydrous ammonia at 250" t~ 260" C. in an inert solvent system. Both %amino-, and 2,g-diaminopyridine may be prepared in this manner (9). Frank and Seven (17)have studied the Chichibabin synthesis for making substituted pyridines through condensation of ketones, aldehydes or u and @ unsaturated carbonyl compounds with ammonia.

LITERATURE CITED (1) Babcock. D. F. (to E. I. du Pont de Nemours &z Co.), U. 8. Patent 2,461,191 (Feb. 8, 1949). (2) Bishop, R. B. (to Socony Vacuum Oil Co.), U. S. Patent 2,487,300(Nov. 8,1949). (3) Bishop, R. B., and Denton, W. I. (to Socony Vacuum Oil Co.), U. S. Patent 2,478,452 (Aug. 9, 1949). (4) Zbid., 2,487,298 (Nov. 8, 1949). (8) Zbid., 2,487,299. (6) Buckley, G. D., and Ray, N. H. (to Imperial Chemical Industries Ltd.), British Patent 622,965 (May 10, 1949). (7) Buckley, G. D., and Ray, N. H., U. 8. Patent 2,479,205 (Aug. 16,1940). (8) Ciba Ltd., British Patent, 624,101 (May 27, 1949). (9) Cilag Ltd., Swiss Patent 239,755 (Mar. 1, 1946). (10) Cosby, J. N. (to Allied Chemical and Dye Corp.), U. 9. Patent 2,481,826 (Sept. 13, 1949). (11) Cosby, J. N., and Erchak, M., Jr. (to Allied Chemical and Dye Corp.), U. 8.Patent 2,499,055 (Feb. 28, 1960). (12) Denton, W. I. (to Socony Vacuum Oil Co.), U. S. Patent 2,496,661 (Feb. 7, 1950). (13) Denton, W. I., and Bishop, R. B. (to Socony Vacuum Oil Co.), U. S. Patent 2,478,464 (Aug. 9, 1949). (14) Zbid., 2,496,659 (Feb. 7, 1960). (15) Zbid., 2,496,660, (16) Erchak, M., Jr. (to Allied Chem Patent 2,486,934 (Nov. (17) Frank, R. L., and Seven, R. P., J . Am. Chem. SOC (1949). (18) Frejaeques, J. L. M. (to Campagnie de Products Chimiques et

Electro-Metallurgiques Alasis Froges et Carmargue), U. 8. Patent 2,498,538 (Feb. 21, 1960). (19) Gresham, W. F. (to E. I. du Pont de Nemours & Co.), British Patent 628,659 (Sept. 1,1949). (20) Gresham, W. F., Brooks, R. E., and Bruner, W. M. (to E. I. du Pont de Nemours & Co.), U. S. Patent 2,501,509 (March 21, 1950).

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(21) Gresham, W. F., and Sohweitser, C. E. (to E. I. du Pont de Nemours & Co.), U. 8.Patent 2,485,236 (Oct. 18, 1949). (22) Gumbolt, A., and Feichtinger, H.,2. Naturforoch, 4b, 123 (1949). (23) Hoog, H., and Engel, W. F. (to N. V. deBataafsohe Petioleurn 'Maatachappi), Dutch Patent 62,562 (March 15. 1949). (Za) Hughes, E. C., and Veatch, F. [to Standard Oil Co. (Ohio)]. U. 9. Patent 2,490,813 (Deo. 13, 1949). (25) Johnson, 0. H. (to Merck and Co.), U. 6 . Patent 2,481,697 (Sept. 13,1949). (26) Larson, A. T. (to E. I. du Pont de Nemours & Co.), U. S. Patent 2,497,310 (Feb. 14, 1950). (27) Long, M. W., Jr. (to Dow Chemical Co.), U. 8.Patent 2,497,553. (Feb. 14,1950). (28) Lutz, R. E., Amacker, T., King, 3. M.,and Shearer, X. A., J . Org. C h m . , 15,181 (1950). (29) Mahan, J. E. (to Phillips Petroleum Co.), U. S. Patent 2,500,256 (March 14,1950). (30) Marisic, M. M., Denton, W. I., and Bishop, R. B. (to Socony Vacuum Oil Co.), U. S. Patent 2,463,466 (March 1, 1949). (31) Merrill, D. R., and Perry, W. A. (to Rohm and Haas Co.), U. 5. Patent 2,478,875 (Aug. 9, 1949). (32) Niederhauser, W. D. (to Rohm and Haas Co.), U. 3. Patent 2,493,637 (Jan. 3, 1950). (33) Reynolds, P. W., Bremner, J. A. M.: and Imperial Chemical Industries, Ltd., British Patent 632,219 (Nov. 18, 1949). (34) Robinson, C. N., Sr,, and Olin, J. F. (to Sharples Chemicals), U. 8.Patent 2,477,943 (Aug. 2, 1949). (35) Slocombe. R. J., Hardy, E. E. (to Moneanto Chemical Co.), U. S. Patent 2,480,088 (Aug. 23, 1949). (36) Ylocombe, R. J., Hardy, E. E., and Saunders, J. H. (to Moneanto Chemical Co.), U. 8. Patent 2,480,089 (Aug. 23, 1949). (37) Staple, E., and Wagner, E. C., J. Org. Chem., 14, 659 (1949). (38) Sweet, R. 8. (to Heyden Chemioal Corp.), U. S. Patent 2,490,385 (Dec. 6, 1949). (39) Teter, J. W. (to Sinclair Refining Go.), U. S. Patent 2,479,879 (Aug. 23,1949). (40) Thomas, A., Ann. Chim., (12) 4,258 (1949). (41) Tyerman, W. (to Imperial Chemical Industries Ltd.), British Patent 631,672 (Nov. 8, 1949). (42) Zbid., 631,673. (43) Zbid., 631,674. (44) Zbid., 631,675. (45) Wegler, R., and Pieper, G., Chem. Ber., 8 3 , l (1960). (46) Whitman, E. M. (to E. I. du Pont de Nemoura & Co.), U. S. Patent 2,501,556 (March 21, 1950). (47) Widiger, A. H. (to Dow Chemical Co.), U. 8. Patent 2,476,170, (July 12,1949). (48) Winnek, P. S. (tu .\nier.ican Cyanamid Co.), Can. Patent 486,742 (1949). R E C C I VJune ~ D 16, 1930

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E.

ESTERIFICATION

PO3 EAST 33RD ST., BALTIMORE 18, MD.

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HE making of esters goes on apace but little is publishcd either about theory or practice. Enormous quantities of a number of staple esters are turned out, ethyl and butyl acetates, about 60 million pounds each pcr year, dibutyl and dioctyl phthalates, together about the same amount, and cellulose esters in still larger quantities. GENERAL A thorough study has been made of the hydrolysis of tallow and of coconut oil by water a t 453" and 483 O F. Known amounts of fat, fatty acid, and glycerol were heated in a special autoclave, with stirring, until equilibrium was reached. Samples from both layers were analyzed. The results were the same a t both temperatures. The extent of the hydrolysis depends on the percentage of glycerol in the aqueous phase, which shows that glycerol must be removed in order to complete the reaction. The results indicate that the hydrolysis is stepwise. At 500" F. the

rniwd acids from tallow dissolve about 12% of water and those from coconut oil about 24%. All proportions of tallow and water form a single phase at 610"F. (74). Saponification methods have been reviewed (69). The hydrolysis of ethyl acetate has been investigated from the standpoint of ion-dipole theory. The reaction is strictly secondorder and conforms to theory in respect to the effect of ion strength on the rate (84). The rate of esterification of adipic acid by decamethylene glycol was measured at four temperatures, 138' to 180' C . The reaction is of the second order. It is only 3.6 times as fast a t 180" m a t 138" C., showing a low temperature coefficient. The rates with decamethylene glycol are 2.5 times as fast as with ethylene glycol a t comparable temperatures (86). Polyesters from adipic acid and ethylene glycol havc been fractionated into high and low molecular weight groups by the stepwise addition of petroleum ether (87).

I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY

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Vol. 42, No. 9

Aldehydes and ketones may be transesterified by enol esters in the presence of an acid catalyst (81,86). The diacetate, CHz:CHCH(OAc)l, results from the gradual addition of acrolein to acetic anhydride containing sulfuric acid (96). I t is customary to heat mixtures in order to effect esterification but subtilin, dispersed in an alcohol, is esterified a t 0" C. in the presence of hydrogen chloride (15). A more extreme case is the preparation of esters of nitroacetic acid, NOnCH~COOH. The dipotassium salt, KOzN:CHCOOK, is mixed with an alcohol and sulfuric acid a t -50" C. or below, to produce the ester, OzNCHzCOOR. At this low temperature the yield of ester is 60% while a t 0" C. i t is only 12%. Nitroacetic acid is too unstable to be handled in the usual way (34). Penicillin, which is unstable under the usual conditions of esterification, is treated with diazo compounds (68). When a trialkyl phosphite is treated with an acid chloride the result is a peculiar dialkyl ester of phosphoric arid (31).

P(OR)a

+ R'COCI +R'COPO(OR)z + RCI

Esters are produced by seqeral methods which are quite different from those usually thought of as esterification. Acetylene is pumped into an autoclave containing formaldehyde, acetic acid, and a little sulfuric acid. At 130"to 140"C. the products are the acetates of the glycols, H&(CHzOH)z and HC(CH20H)s (78). l-Chloro-1,1,2,2-tetrafluoroethanereacts with sodium ethylate to form an ether. FzHCCFzCI

+ NaOEt +FzHCCAOEt + NaCI

Treatment of this with concentrated sulfuric acid replaces two fluorine a t o m by oxygen, giving ethyl difluoroacetate. Other a-difluoro ethers react similarly (110). Cyclohexanone is added slowly to a strongly cooled mixture of sulfuric acid, 30% hydrogen peroxide, Proctor & Gamble Continuous Hydrolysis and Soap Making Unit and ethyl alcohol. The cyclohexanone is oxidized and opened up to give ethyl ehydroxycaproate (6.6). Methanol is gassed over pellets of 10% copper and 90% silicon, The reaction velocities of methyl, ethyl, propyl, and butyl alcoat 300' C. to produce tetramethyl silicate (8). hols with butyryl chloride decrease as the molecular weight increases, except for the propyl (91). The transesterification of ethyl acetate by butyl alcohol is of the first order. The forward SPEEDING U P ESTERIFICATION and backward rates are practically equal (3%). In nonpolar Diglycolic acid is sufficiently strong to serve as its own esterifisolvents the rate of acid-catalyzed alcoholysis is proportional to cation catalyst (13). The same is true of mono-, di-, and trithe ester and catalyst concentrations and independent of that of chloroacetic acids. Benzene as an entrainer for the water helps the alcohol. Secondary alcohols react much more slowly (14). (49). The reaction of carbon monoxide with an alcohol to make a A mixture of oleic acid and cholesterol in benzene was divided formic ester is catalyzed by a sodium alcoholate and is of the first into two parts, one of which was kept in the dark aDd the other in order with reference to the carbon monoxide. The reaction prosunlight for 150 days. The one in the light showed 6.3% estericeeds to an equilibrium. At 40' C. the equilibrium constants are fication compared to 6.1 for the other, thereby showing no appre4 for tert-butyl alcohol, 6 for the normal and secondary, 8 for ciable advantage (25). isobutyl alcohol, and 11 for propyl alcohol (18). Furfuryl alcohol, which is sensitive to strong acids, can be The formation of monoethyl sulfatc from sulfuric acid and alcoesterified by refluxing with acetic acid in the presence of fused hol is explained by the assumption of oxonium complexes. The calcium chloride (46). pAminosalicylic acid dissolved in ethyl initial reaction is 500 times as fast with a 3.5 to 1 ratio of sulfuric alcohol is treated with boron fluoride etherate and kept a t room acid t o ethyl alcohol as with the reverse proportions (10%). temperature for several days to prepare the ester (94). ChloroEsters derived from the isomeric enol forms of aldehydes, sulfonic acid is recommended as an esterification catalyst (SO). RCH:CHOH, have been known for many years but only recently Phosphorus pentoxide is added to a mixture of acetic acid and a have they attracted much interest. Along with them the correphenol, or naphthol, and the mixture heated to make the acetate sponding esters from ketones have come in. Actually, the well( 2 ) . Hydrogen chloride is used with hexahydrobenzyl alcohol known and important vinyl acetate, H,C:CIIOAc, belongs to and tetrahydrobenzoic acid (6). this class but it is made by the addition of acetic acid to acetylene The addition of a small amount of copper to ptoluenesulfonio and not by the acetylation of acetaldehyde. Ketene is absorbed acid as a catalyst is recommended (34). Sulfuric acid is useful in in acetone and the esterification effected a t 65' to 70" C. in the making triallyl borate (92). presence of a strong acid (46,60,109). Terephthalic acid is converted to the monobutyl ester by heating to 250" C. with butyl alcohol without a catalyst. The dibutyl CHIC( :CHz)OH CHzCO +CHaC( :CHe)OCOCH3

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September 1950

INDUSTRIAL A N D E N G I N E E R I N G C H E M I S T R Y

ester is obtained under the same conditions in the presence of :I mixture of lead and zinc oxides, or of zinc or lead borate (89). A phenolsulfonic acid-formaldehyde resin has been used SUPcewfully aa an esterification catalyst (70). The esterification of glycol by higher mixed fatty acids is completed in 3 hours by passing carbon dioxide into the heated mixture (101). Under the same coditions glycerol gives diglycerides (69,60). Trichloroethylene is recommended as a water entrainer (66).

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formed from methacrylic anhydride in the presence of pyridine (103). Ferric chloride catalyzes the reaction of acid anhydrides with certain alcohols (106). Esterification of ethyl alcohol with acetic-propionic anhydride gives 64% ethyl acet,at