an
I=/E (= IUnit Processes Review
Esterification by Marvin 1. Peterson and John W. Way, E . I . du Pont de Nemours & Co., Gibbstown, N . J., and James J. Carberry, E. I . d u Pont de Nemours & Co., Wilmington, Del.
Firmly based fundamental information aids development of new operational procedures and use of esterification to prepare tailor-made products
CATALYSIS
continues to be a major activity in the development of esterification technology. Catalysts which promote selective esterifications and those which function without causing secondary reactions or degrading other sensitive groups are necessary in some applications. Organotin compounds have been developed as effective catalysts which do not cause appreciable dehydration of secondary alcohols in esterifications and transesterifications. Tin soaps are selective for the formation of monoesters from glucosides and fatty acids. A variety of compounds of titanium have been developed as catalysts. Ammonium halides specifically promote the formation of monoesters from ethylene oxide and carboxylic acids. Additional techniques for removing water from esterification mixtures to overcome unfavorable equilibria have been developed. In a continuous esterification process, water of reaction is removed by a cationic ion-exchange unit. Processes involving extractive and azeotropic distillation have been engineered. When solubilities of the hydroxyl compound and of the acid or acid derivative differ widely, the selection of a suitable mutual solvent is difficult. Cyclic amides and dimethylformamide are good solvents for the esterification of sucrose and other saccharides by carboxylic acid derivatives. A considerable volume of literature continues to appear on the modification of oils, fats, and carbohydrates by esterification to yield products with tailormade properties. Thus, polyesters prepared by the esterification of mixtures of fatty acids, short-chain dibasic acids, and glycerol have a much greater and more variable viscosity than do naturally occurring oils and fats. Sucrose acetate isobutyrate, prepared by the esterification of sucrose with acetic and isobutyric anhydride, has been developed for use in lacquers and similar protective coatings. Contributions have been made toward elucidating the mechanism in the vaporphase catalytic synthesic of vinyl acetate.
b Dimethylformamide and cyclic amides are excellent for esterification of saccharides and other polyhydroxy compounds with anhydrides or acid chlorides
b Both allyl acetate and diacetylbenzene have been oxidized and esterified simultaneously b In alcoholysis of dimethyl terephthalate with ethylene glycol, a sieve plate column was used for cowntercurrent contacting of glycol vapor with methyl ester Adsorption of acetylene on the catalyst system and the kinetics of the reaction have been investigated. Esterification Processes Esterification of Acids. Esterification and air-oxidation have been carried on simultaneously in the preparation of glycerol triesters by passing oxygen into a liquid phase mixture of allyl acetate, a monocarboxylic acid, and cobalt(I1) bromide catalyst. At atmospheric pressure and 100' C., triacetin was formed very rapidly from allyl acetate and acetic acid (29A). Esterification and oxidation were simultaneous also in preparing alkyl esters of terephthalic acid by the oxidation of alcoholic solutions of p diacetylbenzene with alkaline hypochlorite solutions ( 3 9 A ) . If an acrylic acid is esterified with a primary or secondary alcohol boiling above 135" C. in the presence of an inert solvent, such as toluene, the side reactions normally accompanying the esterification are substantially reduced. Water is removed from the reaction mixture as an azeotrope ( 7 3 4 . I n the continuous esterification of esters with boiling points below 100' C., water of reaction is removed by a cationic ion-exchange unit, the incompletely reacted effluent being recycled to the reactor. This is particularly advantageous for the esterification of boric acid with methyl alcohol (76A).
The formation of azeotropes often poses separation problems in esterification processes. Two patents ( 7 4 2OA) disclose continuous processes involving extractive and azeotropic distillation, respectively. Relative volatility changes are engineered in the former case, while the latter involves flashing of reactor effluent, followed by distillation in the presence of pentane which forms a low boiling azeotrope with the alcohol. The ester and water are removed a t the bottom of the column. Diesterification of methyl glucoside with fatty acids was accomplished by fusion in the presence of a litharge catalyst at 180' to 190' C. Equimolar quantities of methyl glucoside and acid with a lead or sodium soap catalyst gave products predominantly diester and unreacted methyl glucoside. Tin soaps, however, gave high yields of monoesters from equimolar quantities of reactants (234. Organotin compounds which contain at least one carbon-tin bond are very effective catalysts for esterifications and transesterifications of various types. Butylstannonic acid (C4H9SnOrH) and dibutyltin oxide are equal or superior to p-toluenesulfonic acid and do not appreciably dehydrate secondary alcohols (24A). Amino acids containing sensitive protective groups have been esterified without their loss in the presence of halides, sulfuryl chloride, phosphorus pentachloride, arsenic trichloride, silicon VOL. 52, NO. 9
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Machine wrapping of chicken i s demonstrated on semiautomatic packaging unit. Heat-sealable, controlled shrinkage polyester film has enough rigidity and dimensional stability for commercial packaging devices and conforms to surfaces
tetrachloride. phosphorus tribromide, and thionyl chloride ( 4 7 A ) . A variety of titanium compounds have been used as esterification catalysts. Titanium sulfate incorporated in a porous absorptive material has been used for esterifications at reflux temperature in which water is continuously removed (8A). Relatively nonvolatile esters of polyesters have been prepared using catalytic quantities of titanium dichloride diacetate (7A). Hydroxy, alkoxy. acyloxy, aminoalkoxy, and halogen derivatives of titanium also have been proposed as esterification catalysts (5OA, 57A). I n the reactions of carboxylic acids with alkylene oxides. such as ethylene oxide, an ammonium halide catalyst specifically promoted monoester formation while suppressing the formation of polyesters ( 3 2 A ) . Polyesters prepared by esterifying mixtures of fatty acids, short-chain dibasic acids, and glycerol are much more viscous than naturally occurring edible oils and fats. Viscosity can be controlled by varying the ratio of fatty acid to dibasic acid. The polyester properties suggest potential uses as coating materials for the food industry (79A). Sucrose acetate isobutyrate, developed for use in lacquers, hot melts, and similar
808
protective coatings, is produced by the controlled esterification of sucrose with acetic and isobutyric anhydrides. Its electrical properties are equivalent to or better than those of many widely used plasticizers. It also has good thermal properties and hydrolytic stability ( 75A). Polycarbonate polyester plastics will be used as film bases for photographic products by the Ansco Division, General Aniline and Film Corp. The principal use will be in applications where a high degree of dimensional stability is required. Interesterification. Hydrolysis and alcoholysis of esters occur by mechanistically similar reactions. In alcoholwater mixtures, methanolysis and ethanolysis of phenyl acetate occurred faster than hydrolysis. The relative rates of attack on an ester by hydroxide ion, methoxide ion, and ethoxide ion were calculated to be in the ratio 1 to 1.59 to 4.17 (5A). This order of nucleophilicities does not parallel relative basicities. Aminolysis of ethyl formate and phenyl acetate supports the probability that OH tetrahedral
INDUSTRIAL AND ENGINEERING CHEMISTRY
complexes,
R-C-OR”
1
AR
where A is oxygen or nitrogen, are general for bimolecular nucleophilic substitution a t carbonyl carbon as in interesrerification (72A, 27A). Monoglycerides of fatTy acids can be prepared in a continuous system with nearly- stoichiometric ratios of glycerol and fats or oils (6A). The highly variable induction period often encountered in this alkali-catalyzed reaction is overcome by recycling a portion of the monoglyceride product. The anhydrous components are premixed, preheated, and then reacted as a thin film continuously passed over a heated surface. Rapid quenching. neutralization, filtration, and stripping yields monoglycerides in high yield and conversion. Thorough mixing of reagents, enhancement of heat transfer during reaction, and rapid quenching all improve yield and conversion. Basic physical and chemical principles are exploited in a continuous ester exchange reaction between dimethyl terephthalate and glycol (254). A sieve plate column is employed to achieve countercurrent contacting of glycol vapor with a liquid solution of the methyl ester and glycol. Product methyl alcohol is thus stripped simultaneously, with 99.570 conversion of the methyl ester. The equilibrium constants of the ester interchange reaction of dimethyl terephthalate and ethylene glycol (zinc acetate catalyst) depend only slightly on the temperature and composiLion of the reaction mixture. The small values of the equilibrium constant relative to the removal of methyl ester groups are in line with the difficulty of achieving complete glycolysis of dimethyl terephthalate before polycondensation starts (74A). Alcoholysis of lower alkyl benzyl phthalates with higher molecular weight alcohols produced the unsymmetrical higher alkyl benzyl phthalates smoothly (40.4) The benzyl group was not displaced, even if the displacing alcohol had a boiling point higher than that of benzyl alcohol. The higher alkyl benzyl phthalates are not readily prepared by other simple conventional methods. In the reactions of diols with diethb-l carbonate, the nature and yields of the reaction products depend upon reaction conditions and diol structures. In the 1,3-propanediols, branching a t carbon atoms 1, 2 > or 3 favors the formation of cyclic esters but suppresses their tendencies to polymerize. When a large amount (5 to 10 mole yo)of dry sodium methoxide catalyst was used in the transesterification of neopentylene glycol with diethyl carbonate, cyclic carbonate yields were high. If the quantity of catalyst were decreased tenfold, a polymeric carbonate was produced (47A). When an alkaline catalyst is used in the reaction of glycerol with dialkyl carbonate, the I
a n v d Unit Processes Review yield of monomeric glycerol carbonate is tenfold greater than that obtained when the reaction is run under nonalkaline conditions ( 4 4 ) . Ester interchange occurred rapidly
between lithium aluminum alkoxides of the type (R0)dAlLi and ethyl acetate. When ethyl acetate was added to the reaction mixture from the reduction of 3-butyl-3-propyloctanoic acid with
Sucrose acetate isobutyrate (SAIB),developed b y Eastman for use in lacquers, hoi melts, and similar protective coatings, i s a high-molecular weight, clear, semisolid material at room temperature with a viscosityof about 100,000 cp. Solubility i s indicated by greatly reduced viscosity (about 700 cp.) of 90 to 10 solution of SAIB in ethyl alcohol, the form in which the product will be marketed
lithium aluminum hydride, extensive transesterification occurred and a mixture of the alcohol from the reduction and its acetate ester was obtained (45A). In the interesterification of methyl oleate, triolein, and soybean oil with various catalysts, neither cis-trans isomerization of double bonds nor conjugation of double bonds occurred. Polymerization occurred only when esterification was carried out above 150’ C. (28A). The reaction of aliphatic esters with sulfuric acid to form the carboxylic acid and alkylsulfuric acid is reversible, and concentration equilibrium constants can be calculated ( 3 A ) . The effectiveness of magnesium metal catalyst in the formation of poly(ethy1ene terephthalates) from a glycol and a diester of terephthalic acid is greatly increased by adding a small amount of free iodine. The magnesium can be activated by the iodine prior to introducing it into the reaction mixture, or the magnesium and iodine can be added directly to the reaction mixture ( 7 8 A ) . Cyclic amides, such as formylmorpholine, acetylmorpholine, and acetylpiperidine, were good solvents for the esterification of sucrose with methyl laurate and potassium carbonate catalyst. The shorter the reaction time used, the more sucrose diester was formed. However, if the diester were heated for 4 to 8 hours under reduced pressure, it was largely converted to monoester (3OA). Esters from Carboxylic Acid Derivatives. In preparing esters from nitriles through imino-ether hydrochlorides, hydrochloride formation was slow, and ester yields were low. However, when dry hydrogen bromide or iodide was passed into a solution of a nitrile and an equivalent of alcohol at -15’ C., the corresponding imino-ether hydro bromide or hydrogen iodide was formed quantitatively in a few minutes. Treatment of the imino-ether salt with cold water produced the ester (37A). Aromatic esters of polyhydric alcohols may be prepared by reacting an aromatic carboxylic amide and a polyhydric alcohol in the presence of a basic catalyst, such as magnesium oxide, at reflux temperature. Benzamide and ethylene glycol yielded ethylene glycol monobenzoate, and terephthalamide and ethylene glycol reacted similarly ( Z Z A ). The formation of cyclic 1,2-carbonates in the preparation of bis(ch1oroformates) of 1,2-diols by the reaction of a diol with phosgene is minimized by the addition of about 0.01 mole of a tert-amine per mole of phosgene ( 4 4 4 . The acetylation of carbohydrates with acetic anhydride in pyridine solutions sometimes presents difficulties because higher oligo- and polysaccharides are VOL. 52, NO. 9
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Unit Processes Review
insoluble. Acetylation in a water-pyridine mixture is usually incomplete, and large amounts of pyridine are required. If the saccharides are acetylated in dimethylformamide solutions in the presence of pyridine, 85 to 95% yields of fully acetylated product are possible (424. A method whereby solid esters are continuously produced from fatty acid halides and alcohols has been patented ( 3 6 A ) . The mass is mechanically agitated during the initial stage of reaction, while product gases act as a fluidizing force at later stages. The solid ester is thus produced in a finely divided state. Steric factors play a role in the preparation of esters from 2,G-disubstituted sodium phenylates and methacrylyl chloride. I n an aqueous sodium hydroxide solution with the standard SchottenBaumann technique, a low ester yield is obtained. However, in methanolic sodium hydroxide, the esters are prepared without difficulty (4611). Long-chain tert-butyl peresters were prepared in nearly quantitative yields in high purity by acylating pure tertbutyl hydroperoxide with acyl chlorides in ether-pyridine solutions ( 4 3 A ) . The Schotten-Baumann method is inconvenient for preparing peresters of longchain fatty acids because emulsions are formed which are difficult to break, and hydrolysis of acyl chlorides reduces the yield of esters. Miscellaneous Preparations. Butyrolactone is produced by reacting oxacyclobutane with carbon monoxide under pressure and at high temperature in the presence of a metal carbonyl catalyst (38.4). In the Reppe synthesis of acrylic esters from acetylene, carbon monoxide, and alcohols, the amount of catalyst can be reduced and the yields improved by the presence of a carboxylic acid and a heavy metal halide in addition to a carbonyl-forming metal catalyst. Copper and mercury halides are particularly effective activators, and the activating action of copper is sufficiently great that very small amounts have considerable effect in the presence of carboxylic acids
acetate deposited on various supports was studied ( 3 5 A ) . While carbon or zinc acetate alone did not chemisorb acetylene, the zinc acetate supported on carbon did. Adsorption decreased when large amounts of zinc acetate were deposited, indicating a piling up of salt upon the carrier, an effect noted by others for diverse catalyst systems. The kinetics of the reaction were studied also, and it was concluded that acetylene adsorption might be rate controlling in synthesis at 195’ C. The second kinetics study pertained to the reaction as catalyzed by zinc aluminate ( 2 1 A ) . Second-order kinetics prevailed, and rate studies as a function of catalyst pellet size suggest the absence of pore diffusion retardation of rate. Although the reaction of alkoxyacet).lenes with carboxylic acids usually produces the corresponding anhydrides in good yield, 1 -methoxyvinyl esters can be prepared in good yield from a wide variety of carboxylic acids by reacting the acid in methylene chloride solution with a large excess of niethoxyacetylene. Another procedure, particularly useful on a large scale, utilized the catalytic effect of mercury(I1) ions on additions to the acetylenic linkage. When methoxyacetylene and a carboxylic acid were reacted in methylene chloride solution in the presence of mercury(I1) ions, very small amounts of anhydrides were formed along with good yields of 1methoxyvinyl esters ( 4 9 A ) . Cationic exchange resins of the polystyrene-divinylbenzene sulfonic acid types containing as much as 5374 moisture catalyzed the formation of tert-alkyl formates from formic acid and alkenes (53A). Carboxylic acid esters were prepared by reacting thr acids in the liquid phase with carbon monoxide at an elevated temperature in the presence of a hydrogenation catalyst. Thus. lauric
acid reacted in the presence of copper chromite at 280’ C. to give a practically quantitative yield of lauryl laurate (17A).
Cellulose Esters I n a study of the sorption of acetylation catalysts on cellulose in glacial acetic acid, the sorption rates of zinc chloride, sulfuric acid, and perchloric acid were measured by nonaqueous titration. The apparent sorption heats obtained from Clapeyron’s equation were 4 . 3 >8.5, and 13.6 kcal. per mole for zinc chloride, sulfuric acid, and perchloric acid, respectively, indicating that zinc chloride was held to cellulose by van der Waals forces, sulfuric acid by hydrogen bonding, and perchloric acid by both hydrogen bonding and chemical bonds
(W.
The addition of rV,iL--dimethylsuccinamic acid to a cellulose acetylation mixture produces a cellulose acetate with improved dyeing properties and the same solubili?,- and melting properties as cellulose acetate. If the methyl groups are replaced by larger alkyl or aryl groups, the cellulose esters have a greater solubility in organic solvents and a loi\rer melting point (3B). Trifluoroacetic anhydride is an effective catalyst for preparing partial cellulose acetates in which the fibrous structure of the original cotton is retained. I t acts as an impellant, and no additional catalyst is required ( 4 B ) . Partially acetylated cotton has superior heat and scorch resistance and excellent mildew and rot resistance, properties that should provide expanded markets. However, acetylation of cotton adversely affects tenacity, flex abrasion, and tear strength. Thus market research shows that only those markets which require heat and scorch resistance as primary qualities are coilsidered practical for partially acetylated cotton ( IB).
(24. In a patented variation on the Rrppe synthesis for preparation of acrylic acid esters (33A), a portion of the acetylene, carbon monoxide, and alcohol reactant stream is reacted over a nickel halide catalyst and then passed through the principal reactor where the reaction is completed in the presence of nickel carbonyl and an acid. Thus iniatition and maintenance of events in the principal reactor are promoted by the presence of products from the auxiliary reactor. Contributions have been made toward elucidating the mechanism in the catalytic synthesis of vinyl acetate. In one case acetylene adsorption upon zinc:
8 10
Good heat and scorch resistance of partially acetylated cotton make it a better choice for hot head press covers. After removal from press, partially acetylated cotton cover (bottom) used 16 days compares favorably with untreated cover (top), which shows wear after 4 days’ use
INDUSTRIAL AND ENGINEERING CHEMISTRY
a Esters
of
Inorganic Acids
Esters Containing Phosphorus. A new method of forming a type of imidoyl phosphates for synthesizing unsymmetrical diesters of phosphoric acid or pyrophosphates was described ( I C ) . When phosphoric acid monoesters are dissolved in a mixture of trichloroacetonitrile and pyridine, the imidoyl phosphates intermediates are not isolated. They combine with alcohols to give unsymmetrical diesters of phosphoric acid and with monoesters of phosphoric acid to give pyrophosphates. The samk reaction with unsubstituted orthophosphoric acid stops a t the monoester or the diester stage depending on the amount of base available to form the required phosphate anion. Esterification is the principal reaction in the trichloroacetonitrile method in the presence of nearly stoichiometric amounts of alcohols, whereas the well-known carbodiimide method yields pyrophosphates preferentially. In contrast to carbodiimides, trichloroacetonitrile reacts with neither dialkyl phosphates nor with carboxylic acids or water but only with the secondary anions of phosphoric acids. Esters Containing Nitrogen. The correlation of the rate of nitrating alcohols to nitrate esters in aqueous sulfuric acid with the acidity function CO is generally considered to be a criterion of the nitronium ion (NOz+) mechanism. However, this correlation was found to have serious weaknesses because of the fundamental variations in measuring the relationship between Co and sulfuric acid concentration over wide ranges (3C). Because the nitrous acid molecule is closely similar in size and structure to the nitric acid molecule, recent data on the degree of ionization of nitrous acid to nitrosonium ion (NO+) in aqueous perchloric acid and also aqueous sulfuric acid provide an acceptable proof of the nitronium ion mechanism for nitration in mixed acid solutions. Equilibria for the nitration of 2,4dinitrobenzyl alcohol or isopentyl alcohol with aqueous nitric-sulfuric acid mixtures were measured along with the rates of the various reactions involved. Nitrate and sulfate esters are formed. The rates measured for hydrolysis of isopentyl nitrate catalyzed by perchloric or sulfuric acid indicate that the transition state involves only the protonated nitrate ester and does not include a molecule of water (4‘). A kinetic study of the reaction of nitric acid and 2,4-dinitrobenzyl alcohol in acetic anhydride-acetic acid solvent indicates that dinitrogen pentoxide, not acetyl nitrate, is the active nitrating agent (3C). Other workers have shown
that dinitrogen pentoxide is formed in nitric acid-acetic anhydride-acetic acid mixtures only when nitric acid concentration is very high; under these conditions only traces of acetyl nitrate are formed. Evidence is also available that acetyl nitrate is not likely to be an intermediate in the formation of dinitrogen pentoxide. I n reaction mixtures containing 0 to 10% acetic anhydride, a maximum rate of formation of 2,4-dinitrobenzyl nitrate was found at about 7y0acetic anhydride, although at much higher acetic anhydride contents the reaction is immeasurably fast.
Bibiliography
Esterification Processes (1A) Badische Anilin- und Soda-Fabrik A.-G., Brit. Patent 815,774 (July 1 , 1959). (2A) Ibid., 824,520 (Dec. 2, 1959). (3A) Bauman, R. A., Krems, I. .J., J . A m . Chem. Soc. 81, 1620 (1959). (4A) Bell, J. B., Jr., Currier, V. A., (to Jefferson Chemical Co.), U. S. Patent 2,915,529 (Dec. 1, 1959). (5A) Bender, M. L., Glasson, W. A . , J . Am. Chem. SOC.81, 1590 (1959). (6A) Birnbaum, H. (to Hachmeister, Inc.), IJ. S. Patent 2,875,221 (Feb. 24, 1959). (7A) Bond, G. R., Jr. (to Houdry Process Corp.), Jbzd., 2,910,489 (Oct. 27, 1959). (8A) Ibid., 2,928,853 (March 15, 1960). (9A) Bradley, D. J., Hollingworth, H. D. (to Distillers Co., Ltd.), Can. Patent 586,032 (Oct. 27, 1959). (10A) Britton, E. C., Livak, J. E. (to now Chemical Co.), U. S. Patent 2,917,535 (Dec. 15, 1959). (11A) Brokaw, G. Y . (to Eastman Kodak Co.), Zbid., 2,879,281 (March 24, 1959). (1ZA) Bunnett, J. F., David, G. T., J . Am. Chem. Soc. 82, 665 (1960). (13A) Carlyle, R. L. (to Dow Chemical Co.), U. S. Patent 2,917,538 (Dec. 15, 1959). (14A) Challa, G., Kec. trau. chtm. 79, 90 (1960). (15A) Chem. Eng. 66,No. 20,72 (1959). (16A) Chiras, S . ,J. ( t o O h Mathieson Chemical Corp.), Brit. Patent 806,769 (Dec. 31, 1958). (17A) Deutsche Hydrierwerke G.m.b.H., Brit. Patent 806,814(Dec. 31, 1958). (18A) Dickey, J. B., Stanin, ‘r. E. (to Eastman Kodak Co.), U. S. Patent 2,891,928(June 23, 1959). (19A) Feuge, R. O., Gros, A. ‘T., IND. ENG.CHEM.51, 1019 (1959). (20A) Fisher, G. J., MacLean, A. F. (to Celanese Corp. of 4merica), U. S. Patent 2,916,512(Dec. 8, 1959). (21A) Flid, R. M., Basova, R. V . , Nauk Doklady Vyssliez Slikoly, Khim. a Khim. Tekhnol. 1959, No. 1, 117. (22A) Gasson, E. J., Hadley, D. J. (to Distillers Co., Ltd.), U. S. Patent 2,914,553 (Nov. 24, 1959). (23A) Gibbons, J. P.. Swanson, C. .I., J . Am. Oil Chemzsts’Soc. 34, 553 (1959). (24A) Goodrich, B. F., Co., Brit. Patent 810,381 (March 18, 1959). (25A) Hurt, D. M., Pieper, A. H. (to E. I. du Pont de Nemours & Co.), U. S. Patent 2,905,707(Srpt. 22, 1959). (26A) James, F. L., Murphy, C. M., O’Rear, J . G., INII. ENG. CHF.M.51, 673 (1959).
n
v
d Unit Processes Review
(27A) Jencks, W. P., Carriuolo, J., J . Am. Chem. SOL.82, 675 (1960). (28A) Kaufmann, H. P., Grothues, B., Fette u. Seifen 61, 425 (1959). (29A) Keith, W. C. (to Sinclair Refining Co.), U. S. Patent 2,911,437 (Nov. 3, 1959). (30A) Komori, S., Okahara, M., Shinsugi, E., Technol. Refits. Osaka Univ. 8, 497 (1958). (31A) Konaka, R., Takahoshi, T., IND. ENC.CHEM.52, 125 (1960). (32A) Malkemus, J. D. (to Jefferson Chemical Co.), U. S. Patent 2,910,490 (Oct. 27, 1959). (33A) Mathews, H. H. (to Air Reduction Co.), 16id., 2,903,479(Sept. 8 , 1959). (34A) Mesnard, P., Bertucat, M., Bull. soc. chim. France 1959,p. 307. (35A) Mitsutani, A., Matsumoto, M., Nijfion Kagaku Zasshi 79, 948 (1958). (36A) Montross, C. F., Woodward, F. E. Wuerth, F. (to General Aniline and Film Corp.), U. S. Patent 2,920,088(Jan. 5, 1960). (37A) Morgan, D. J., Chem. €9Jnd. (London) 1959, p. 854. (38-4) Nienburg, H., Elschnig, G. ( t u Badische hnilin- & Soda-Fabrik A.-G.), Ger. Patent 1,066,572(April 7, 1960). (39.4) O’Neill, W. A. (to Imperial Chemical Industries, Ltd.), Can. Patent 586,808(Nov. 10, 1959). (40A) Raether, L. O., Gamrath, H. R . , J . Org. Chem. 24,1997 (1959). (41A) Sarel, S., Pohorgles, L. A., BeiiShoshan, R., Ibid., 24, 1873 (1959). (42A) Schlubach, H. H., Repenning, K . , An em. Chem. 71,193 (1959). (43Af Silbert, L. S., Swern, D., J . Am. Chem. Soc. 81. 2364 (1959). (44A) Spiegler; L. (to E. ’I. du Pont de Nemours & Co.1, U. S. Patent 2,873,291 (Feb. 10, 1959). (45A) Stopp, P. R., Rabjohn, N., J . Org. Chem. 24, 1798 (1959). (46A) Sumrell, G., Campbell, P. G., J . Am. Chem. SOC.81, 4310 (1959). (47A) Taschner, E., Wasielewski, C., Angew. Chem. 71,743 (1959). 148A) Ward, T. L.. Gros. A. T.. Feuec K. 0.; J . Am. Oil’Chemists’ Sic. 36; 667 (1959). (49A) Wasserman, H. H., Wharton, P. S., J . Am. Chem. Soc. 82, 661 (1960). (50.4) Werber, F. X . (to B. F. Goodrich Go.), Fr. Patent 1,165,428 (Oct. 24,
:.
1958).
(51A) Werber, F. X., Averill, S . : .Jr. (to B. F. Goodrich Co.), Ibid., 1,163,414 (Sept. 25, 1958). (52A) York, O., Jr. (to Hercules Powder Co.), U . S. Patent 2,906,737 (Sept. 29, 1959). (53A) Young, D. W., Park, E. M., J . 0 , : ~ . Chem. 23, 1772 (1958). (54A) Youngs, C. G., J . Am. Oil Chenrisis’ Soc. 36, 664 (1959). Cellulose Esters (1B) Anderson, E. V., Cooper, A. S.,Jr., IND.ENG.CHEM.51, 608 (1959). (2B) Kido, I., Suzuki, K., Yoshikawa, ’l’., Sen-i Gakkaishi 15, 857 (1959). (3B) Kiefer, J. E., Touey, G. P., Caldwell, J. R., IND.END.CHEM.51, 1481 (1959). (4B) Hamalainen, C., Textile Research J . 29, 821 (1959). Esters of Inorganic Acids (1C) Cramer, F. D., Weimann, G., Chev7. @ Znd. (London) 1960,p. 46. (2C) Bonner, T. G., J . Chem. Sod. 1959, w. 3908. (3C) Bonner, T. G., Frizel, D. E., Ibid., (4C) 1959, Zbid., p. 3894. p. 3902.
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