204
INDUSTRIAL AND ENGINEERING CHEMISTRY
cium and magnesium naturally occurring in the juice is utilized in the formation of the insoluble aconitate with the result that the amount of aconitate precipitated is in excess of that to be expected from neutralization of the free acids of the juices. The average was almost 43% of the total aconitic acid present. Therefore, i t is necessary to add only a maximum of calcium chloride equivalent to 607, of the total aconitic acid contained in the juices. The use of calcium chloride and lime might be expected to cut down materially the amount of magnesium in the precipitated aconetate; however, in duplicate runs made in 1942 for comparison of the lime alone with the lime and calcium chloride treatments, the magnesium was not eliminated from the aconitate by use of calcium chloride, but 13 to 147, of the aconitic acid in the precipitated aconitate was in combination with magnesium. I n the sugar manufacturing process when juices are treated by lime only or by lime and calcium chloride, the aconitic acid content is not significantly changed until the sirup is heated. The removal of the aconitate from the sirup removes solids by both methods. I n the sirups made from juices treated with lime and calcium chloride, a slightly greater increase in purity is obtained than when lime only is used. This is attributed to the replacement of the aconitate radical, whose combining weight is 58, by
voi. 38, N ~ 2.
the chloride radical, whose combining weight is 35.5. As an example, potassium aconitate in the juices would be changed to potassium chloride and calcium aconitate, the latter being removed by precipitation. The remaining potassium chloride has a lower equivalent weight than the potassium aconitate originally present. LITERATURE CITED
(1) Ambler, J. A, 'Purer, J., and Keenan, G. L.,J . A m . Chem. Soc., 67, 1 (1945). (2) Buchner, Ann., 28, 243 (1838). (3) Guinochet, E., Compt. rend., 94, 455 (1882). (4) McCalip, M.A , and Seibert, A. H., IND. ENG.CHEM.,33, 637 (1941); Sugar Bull. 19, No. 17, 84 (1941). (5) Parsons, H. B., Am. C'hem. J.,4, 39 (1882). (6) Prinsen-Geeiligs, H. C., Arch. Suikerind., 41, 720 (1933). (7) Ventre, E. K., Sugar J . , 3,No. 7, 23 (1940). (8) Ventre, E. K., Ambler, J. A., Byall, Sam, and Henry, H. C., U.S. Patent 2,359,537 (Oct. 3, 1944). (9) Ventre, E. K., and Paine, H. S.,Ibid., 2,280,085 (April 21, 1942). (LO) Wiley, H. W., and Xaxwell, IT., A m . Chem. J . , 12, 216 (1890). PRESENTED on the program of the Division of Sugar Chemistry and Technology of the 1945 Meeting-in-Print, AMERXCAN CHauIcilL SOCIETY.Cocitribution 168 of the Agricultural Chemical Reeearch Division, U. 8. Department of Agriculture.
Yeasts from Wood Sugar Stillage E. F. IQURTH Oregon Forest Products Laboratory and Oregon State College, Corvallis, Oreg, Three strains of yeasts, Torula utilis No. 3, iMycotorula lipolytica (P-13), and Hansenula suaveolens Y-838, were grown on still waste liquor from the production of wood sugar alcohol. -411 three were found to utilize a large proportion of the unfermentable sugars and acids in the liquor, which indicates that these yeasts have possibilities for a practical utilization of such still waste liquors. The yield of dry Torula yeast may exceed 50% of the weight of sugar consumed, which indicates that components other than sugars are assimilated for yeast growth. Air diffusion was found to be an important factor in the rate of yeast growth and consumption of sugar. With proper aeration the assimilable sugar is consumed by Torula in 18 hours.
T
HE wood-sugar alcohol plant a t Springfield, Oreg., will have approximately one-half million gallons of still waste liquors for disposal each day. This dark colored liquor contains the unfermentable sugars (pentoses) , organic acids and salts, and miscellaneous other products resulting from the hydrolysis of Douglas fir wood. The primary hydrolysis products from wood are lignin, wood sugars, and acetic and formic acids. Secondary products, such as levulinic acid from the hexoses and furfural from the pentoses, are produced by further decomposition of the sugars during hydrolysis of the hemicelluloses and cellulose. Normally, softwoods give sugar mixtures that include glucose, galactose, mannose, arabinose, and xylose. The first three sugars are decomposed with brewer's yeast, Saccharomyces cerevisae, to alcohol and carbon dioxide, whereas the pentoses are unaffected and remain in the spent beers. Distillation of the alcohol from the beers gives a liquor which is still high in biochemical oxygen demand. It is desirable to find a use for this still waste liquor and simultaneously decrease its stream pollution load. For this purpose the feasibility of manufacturing feeding yeast by growing
species capable of utilizing the residual pentoses was investigated by the Oregon Forest Products Laboratory in cooperation with the U.S. Forest Products Laboratory and the Willamette Valley Wood Chemical Company. Torula utilis is of particular importance in Europe for the manufacture of fodder yeast and protein feeding stuffs. Its high nutritional value has been established ( I , 3, 6). Yields of dry yeast of 35 to 50% on wood sugar have been reported (4, 7 , fO), and Lechner (5)has obtained a yield of 46-4974 on xylose. I t s abilitj to utilize arabinose is reported to be negligible ( 6 ) . The feasibility of growing fodder yeast on the still waste liquor raises several important questions. Among them are the yield of yeast that may be expected, the extent to which the materials in the still waste liquor are assimilable, and the time required for their utilization by yeast. The fermentation of the fermentable sugars to alcohol is complete within 24 hours. Therefore, the utilization of the unfermentable sugars in a similar period IS desirable from the standpoint of plant operation. The still waste liquors used in this work were prepared from Douglas fir hydrolyzates fermented R ith brewer's yeast in the pilot plant of the U.S. Forest Products Laboratory. I n the pilot plant, wood waste, including some bark, was first subjected to hydrolysis a t 150' to 185' C. with concentrations of 0.5 to 1.0% of sulfuric acid. The hot wood sugar solutions were neutralized with lime to a pH of approximately 5.0 under 35 pounds steam pressure and passed through a filter press to remove the calcium sulfate sludge. After cooling and the addition of urea and NaHzPOl as nutrients, the wood sugar wort was adjusted to a pH of approximately 5.8 and fermented with a strain of Saccharomyces cerevisae. Fermentation of roughly 5% wood sugai worts was complete within 24 hours with 80 to 837, utilieation oi the reducing sugar present. The yeast was recovered by centrifuging and re-used for the fermentation of the next batch of wood hydrolyzate.
February, 1946
INDUSTRIAL AND ENGINEERING CHEMISTRY
TABLEI. ANALYSISOF LIQUORBEFORE
was added to give a 1% suspension of yeast by volume (1 ml.
AND AFTER
GROWTH Total solids, % Reducing sugar (xylose) % Reducing sugar after hyhrolysis with HISOL, % Volatile acid (acetlc), % Volatile and nonvolatile acid (acetic), % Ash. % Rkaiaue upon combustion Residue converted t o sulfate Total carbon, % 5-Day B.O.D. PH
205
TORULA yeast precipitate to 100 ml. of solution). The flasks, containing
Still Waste Liquor 3.2 0.81 0.97 0.24 0.78
Torula Spent Liquors 2.40 0.20 0.34 0.10 0.31 t o 0.6
the yeast-inoculated and uninoculated arabinose and xylose solutions, were placed in a shaker in a room maintained a t 30" C. The experimental data in Table I1 demonstrated t h a t Torula utilis No. 3 is able to consume both arabinose and xylose.
0.65 1.03 1.42 16,400 5.0
0.36 to 0.47 0.58 t o 0.68 0.94 t o 1.04 9600 7 . 5 to8.0
YEAST. The foreign matter deposited with the yeast made the standard centrifuge and turbidity procedures not applicable. For routine qualitative tests, cell counts were made under a microscope with a Bausch & Lomb hemacytometer cell. A determination of the relation between cell counts and dry weight of yeast, showed that there may be a 33'34 variation from the average value of the tests. The procedure adopted for separating the foreign matter from the yeast to give a quantitative estimate of the dry weight of yeast present follows :
I n the preliminary yeast work done a t the Forest Products Laboratory, the alcohol was stripped from the beers by distilling off 20% of their volume in a 45-gallon batch copper still. This amount of water was then returned to the still residues to bring them to the same volume as the original beers. The reducing sugar content of these liquors varied from 0.6 to 1.5% with a normal reducing sugar content of 0.8%. Other analytical data showed p H of 5.5 to 5.7, 2.3 to 2.5% dissolved solids, 0.5 to 0.7% ash, 0.201, volatile acid calculated as acetic, and 0.45% volatile and nonvolatile acid calculated as acetic. Boiling with 2.50% sulfuric acid for 1 hour gave a 20 to 27% increase in reducing sugar. Analysis of the sulfated ash residue showed calcium 26.0%, potassium 17.0%, iron 2.9%, magnesium 2.4%, and phosphorus 0.16%. Only traces of nitrogen were found in the liquor with a Kjeldahl determination. Inasmuch as i t was desirable to carry out the yeast studies on liquors representative of alcohol plant operating conditions, much of the quantitative work was performed on a still waste liquor produced in the pilot-plant distillation unit of The Vulcan Copper & Supply Company. The analytical data obtained are included in Table I. All of the still waste liquors were black and gave an amorphous deposit upon standing. Torula utilis No. 3, Mycotorula lipolytica (P-13), and Hansenula suaveolens Y-838 have been reported as good consumers of pentose sugars (7,11). Cultures of these yeasts were obtained and grown without difficulty on the still waste liquors. A phenomenon observed with all three is that they are able t o remove acidic components in addition t o approximately three fourths of the unfermentable sugar present. The unconsumed reducing material appears to be incompletely hydrolyzed substances that have reducing properties and are calculated as reducing sugar. The utilization of the acids in the liquor produces a change from an initial pH of 5.0 t o a final pH of 7.5 t o 8.0. The growth of the yeasts in the liquor is accompanied with deposition of mineral matter, chiefly calcium carbonate, and a n amorphous ligninlike material. The comparative performance of these three yeasts, together with vitamin and amino acid assays, was continued as a separate study.
ANALYTICAL METHODS
Pipet 10 ml. of the yeast suspension into a 15-ml. tared centrifuge tube. Centrifuge out the yeast and wash the precipitate in the tube with 10 ml. of 0.35% hydrochloric acid (1 ml. concentrated hydrochloric acid in 100 ml. of water). Disperse the yeast uniformly in the acid solution with a heavy platinum wire. Centrifuge out the yeast and repeat the washing immediately with a 1%solution of sodium carbonate. Dry the tube with the washed yeast in a vacuum oven at 65" C. for 3 hours. Cool in a desiccator, and weigh the tube and dried yeast on the analytical balance. The washings produced no apparent harmful effects. Torula yeast washed with 0.35% hydrochloric acid and 1 to 2% sodium carbonate solutions (pH 10.7) showed no loss in the number of yeast cells through autolysis and, when added t o aerated sugar solutions, resumed normal growth. The weight per hundred million Torula cells from glucose solutions averaged 1.67 mg.; from neutral still waste liquor clarified with lead acetate, 1.62 mg.; and from still waste liquor (acid- and alkali-washed yeast), 1.54mg.
TABLE11. UTILIZATION OF ARABINOSE AND XYLOSEBY Torula utilis No. 3
Medium Arabinose solution Yeast-inoculated Uninoculated Xylose solution Yeast-inoculated Uninoculated Still waste liquor diluted with equal vol. of water Yeast-inoculated Uninoculated
No. of Tests
Hours of Incubation
Reducing Sugar, %
6
0 24 48 48
0.96 0.63 0.16 0.96
0 24 48 48
0.49 0.25 0.16 0.49
1
1 1
UTILIZATION OF ARABINOSE AND XYLOSE BY Torula utilis NO. 3
A yeast suitable for the complete utilization of the pentoses in still waste liquors obtained from wood hydrolyzates should consume arabinose and xylose. The capacity of Torula utilis No. 3 to utilize these sugars was tested on still waste liquors with added amounts of arabinose and xylose. The arabinose media were prepared by diluting 50 ml. of still waste liquor with 50 ml. of an approximately 1% solution of &arabinose (levorotatory). Similarly, the xylose media were prepared with 50 ml. of still waste liquor and 50 ml. of an approximately 1.0% solution of I-xylose (dextrorotatory). X'utrients added were 0.1% of urea and 0.05% of KH2P04. The initial p H of the media was 5.6. Transfer of the yeast was made from a stock slant culture to a sterile glucose-malt sprouts medium. After 48 hours the yeast was centrifuged from this medium and added t o sterile shake flasks containing the prepared sugar solutions. Sufficient yeast
REDUCING SUGAR. The micro sugar method of Schaffer and Somogyi (9)was found excellent for this purpose. The procedure was standardized against C.P. xylose, and all reducing sugar values are calculated for this sugar. VOLATILE ACID. The volatile acid content was determined by distilling a 100-ml. sample of the liquor acidified with 2 ml. of concentrated sulfuric acid. Distillation was made until the volume in the distilling flask was reduced to 20 ml. when carbondioxide-free water was added from a separatory funnel. When 100 ml. of distillate were obtained, the distillation was stopped. Aliquots of the volatile acid distillate were titrated with standard 0.1 N sodium hydroxide to phenolphthalein. NONVOLATILE ACID. The nonvolatile acid content was determined by extracting with ether, in a liquid-liquid continuous extractor for 24 hours, a 100-ml. sample acidified with 2 ml. of
206
INDUSTRIAL AND ENG INEERING CHEMISTRY TaBLE
111. EFECTO F
Time, Hours 16 19 24 24 72
Aerator @-porosity fritted-glass tubes Cloth or EC-porosity fritted-glass disks 4-mm. glass tubing Shaker flasks TABLE
TEmp.,
C.
28
28 32
AERATION
Final Reducing Sugar, 70 0.30 0.20 0.20-0.22 0.40-0.49 0.30
Iv. EFFECTO F
SIZE O F INOCULUM Yeast Reducing Increase, Sugar Million Content, Cells/Cc. 70
The growth of Torula yeast o n the liquor removed roughly one fourth of the dissolved solid matter, three fourths of t,hc reducing sugar, 60% of the volatile acid, 36 to 60% of the volatile and nonvolatile acids, 26 to 347, of the tot,al carbon, and roughly 40y0 of the biochemical oxygen demand. The yield of oven-dry yeast groivn under laboratory conditions was 0.30 to 0.33Y0. Wit,h a daily product,ion of 500,000 gallons of still n-astcs, this would indicate about 12,500 pounds of dry yeast per day. EFFECT OF VARIABLES
Initial Concn., Alillion Cells/Cc.
Time, Hours
174 217 364
24 24 24
2 07 291 160
0 49 0 49
0.47
7.4 7.5 7.6
242 331
24 24
230 200
0 47 0.49
7.9 7.9
100
22 22 22
219 179 191
0 20 0.24 0.32
7.9 7.5 7.2
186 211
Vol. 38, No. 2
PH
concentrated sulfuric acid. The increase in extracted acid beyond the 24-hour period was negligible. The ether was evaporated, and aliquots of the acid solution were titrated with standard 0.1 N sodium hydroxide t o phenolphthalein. TOTAL SOLIDS.Samples (25 ml.) in glass beakers were evaporated to dryness in a vacuum oven a t 65" C. ASH. Samples (25 mi.) evaporated t o dryness in a platinum dish were ashed over a Meeker burner. Weighings were made of the residue as such and when further ignited with sulfuric acid. Increase in ash weight, when converted t o sulfates, was over 507G. TOTAL CARBON.The total carbon content was determined by wet combustion with iodic acid in concentrated sulfuric acid, using the micro procedure of Christensen, Rong, and Facer ( 2 ) . In the early part of the investigation several small a n d large sca.le runs wit,h Torula utilis No. 3 were made on still waste liquors using continuous feed and batch processes. Minimum reducing sugar content of the spent Torula liquors vias invariably about 0.2%. No iiicrease in yeast gron.th v a s observed with reducing sugar content below 0.27& and rapid autolysis of the yeast occurred when the runs mere continued beyond this point. The consumpt,ion of the reducing sugar in the still v.-ast,e liquors ranged from 75 to 900/0, depending upon the initial sugar concentration; a liquor with a high initial sugar content, indicating unfermented hexoses present, showed a high percentage of sugar consumed, whereas a liquor with a lon- initial reducing sugar content shoa-ed lomer percentages of sugar utilized. These trial tests left unanswered the effect' of aeration, temperature, nutrients, hydrogen ion conccnt,ration, and size of yeast inoculum on the yield and rate of yeast growih. Thc effect of t'hese factors was studied on the liquor prepared in the pilot,-plant dist,illation unit of The S'ulcan Copper & Supply Company under proposed alcohol plant distillation conditions. Table I gives analytical data obtained 011 this liquor before and after yeast gron%h. This liquor had 3.27; dissolved solids, of which 25.3y0 is total reducing sugar, 24.5y0 total acids calculated as acetic, 7.59;1,volatile acid calculated as acetic, and 20.3% ash residue upon combustion. When the nonvolatile acid is calculated as levulinic (32.670) the sum of the above constituents accounts for 85.7% of the solid matter. Acid hydrolysis of the liquor increased the reducing sugar content 20y0, Tvhich indicates t h a t 6.2y0unhydrolyzed carbohydrate was present. The liquor could be decolorized with neutral lead acet#atet o a light yellow color with no loss in reducing sugar.
The effect of various fact,ors on the time and yield of yeast groivth were studied in a series of runs made, ab tar as practical, under the same conditions except for the factor under concideration. These runs were repeated until the results mere consistent,. The runs were generally made with 200 ml. of medium in 400-ml. glass bottles in a constant temperature chamber. The recorded temperature was that of the medium. The inoculum was obtained by centrifugation of an aliquot of the immediately preceding run. Aseptic technique was not followed alter the first propagation on still waste liquor. No interfering contamination developed during several weeks of successivc transfers for 103 runs. No growth of organisms or decrease in sugar content occurred in the liquor, stored in its wooden shipping barrel, during the course of t'he investigat'ion. NUTRIENTS.Ammonium sulfate and urea were tried a s sources of nitrogen. Monobasic potassium phosphate and diammonium hydrogen phosphate in concentrations of 0.059; were used as sources of phosphorus. S o variation in yeast yield or rate of growth was observed betlvvecn t,lie two or v-ith conccntrations exceeding 0.05yG. The final pH of the Torula liquor is independent of t8henitrogen nutrient. Concentrations of urea in excess of 0.(s570 s h o m d no beneficial results in rc;jpcct to yeast yield or rate of sugar consumpt,ion, whereas conccntral ions of urca in excess of 0.2y0 retarded cell multiplication and rate of sugar consumption. AERATIOS. This was found to be the most' important factor affecting t,he rate of yeast groTyth and sugar consumption. The fineness of the air diffusion appears more important than the volume of air (Table 111). In shake flasks, t8heconsumption of sugar may be incompkte after 72 hours. Aeration through 4-mm. glass tubing may require 36 t o 48 hours. With temperatures of 30" Lo 34" C. and air diffusion by means of cloth bags or gas dispersion disks made of extracoarse-porosity fritted glass, the sugar x i s reduced to the minimum 0.270 under 24 hours; q-hercas with gas dispersion tubes of coarse-porosity fritted glass (Corning No. 39533, C porosity) the time was reduced to approximately 18 hours. &$eration studies on small amounts of liquor in glass bottles tell lit'tle concerning the optimum conditions or the quantity of air required in yeast manufacture. Aeration of the still waste liquor is accompanicd by profuse foaming. Peterson, Snell, and Frazier found i t was necessary t,o use liberal quant,ities of Vegifat as a foam breaker on wholc wood sugar solutions ( 7 ) . Among those tried in the present work m r e oleic acid, corn oil, cottonseed oil, soybean oil, castor oil, and sulfonated castor oil (Turkey-red oil). The latter appeared most satisfactory; no foam difficulties occurred with yeast concentrations up to 400,000,000 cells per cc. With higher yeast concent,rations foaming was more noticeable. ISITIAL pH. Sansur (8j mentioned that for the optimum growth of Torula utilis the pH must be 7.0 to 8.0, whereas Peterson, Snell, and Frazier ( 7 ) found that, the production of yeast from whole wood hydrolyzate occurred eficiently when the initial p W was adjusted between 4.5 and 5.5. Inasmuch a s t'he still waste liquor had a pH of 5.0, runs were made villi the pI-1 adjusted between 5.0 and 6.5 with ammonia. The addition of ammonia t o the liquor invariably formed an amorphous precipitate. No beneficial resultx were obtained by raising the initial pH of the liquor wit,h ammonia. Good yeasts growth occurred a t a n initial pH of 4.5.
INDUSTRIAL AND ENGINEERING CHEMISTRY
February, 1946
TABLE V. EFFECTOF TEMPERATURE Temp., No. of C. Runs 25 28 32 34
3
6 4 11
30
3
Time Hours 24 23 22 22
Fina Yeast Yield, Reducing Sugar % Content, % ' Cloth Aerators . . . . . .. 0.30-0.33 0.33 0.30-0.31
0.30-0.47 0.23-0.32 0.20 0.18-0.20
C-Porosity Fritted-Glass Tubes 18 0.31 0.20-0.21
Fina pH
7.4 7.5 7.4 7.4-7.9
7.8
SIZE OF INOCULUM. Studies made of the optimum yeast inoculum (Table IV) indicated that initial yeast concentrations of approximately 100,000,000 yeast cells per cc. were desirable. The experimental data further indicate that yeast concentrations considerably in excess of 100,000,000 cells per cc. did not increase the rate of sugar consumption. DILUTION WITH WATER. The dilution of the still waste liquor with water speeded the removal of the sugar but had no apparent effect on the yield of yeast. The unconsumed residual reducing sugar content of 0.2 per cent was decreaqed proportionately with the amount of dilution. TEMPERATURE. Studies were made between 25" and 34" C. The rate of sugar consumption increased with increase in temperature (Table V). ACKNOWLEDGMENT
Grateful acknowledgment is made to L. J. Wickerham, Northern Regional Research Laboratory, for supplying the transfer of
207
Hansenula suaveolens; to E. E. Harris, Forest Products Laboratory, for supplying the still waste liquor and the transfer of Torula utilis No. 3 and Mycotorula lipotytica (P-13); and t o W. H. Peterson, University of Wisconsin, for counsel. Acknowledgment is gratefully made to F. G. Kachelhoffer, Engineering Experiment Station, Oregon State College for the B.O.D. determinations; to I. w. Davies, Oregon State College, for data on composition of the ash; t o Mary Neal and Janet Bubl, Forest Products Laboratory, for the sugar analyses in Table 11; and t o Willamette Valley Wood Chemical Company for interest and support. LITERATURE CITED
Biinger, H., e t a l . , Landw. Vers.-Sta., 121, 193 (1934). Christensen, B. E., Wong, R., and Facer, J. F., IWD.ENG. CHEM., ANAL.ED.,12, 364 (1940). Colonial Food Yeast Ltd., "Food Yeast: A tenture in Practical Nutrition", 1944. Fink, H., Lechner, R., and Heinisch, E., Biochem. Z., 278, 23 (1935).
Lechner, R., Angew. Chem., 53, 163-7 (1940); Biochem. Z., 306, 218-23 (1940).
Lewis, J. C., Stubbs, J. J., and Noble, U'. M., Arch. Biochem., 4, 389 (1944).
Peterson, W. H., Snell, J. F., and Frazier, W. C., IND.ENQ. CHEM.,37, 30 (1945). Sansur, J. M., Rev. qzsim,furm. (Chile), 2, No. 23, 2-13 (1944). Schaffer, P. A., and Somogyi, M., J.Biol. Chem., 100,695 (1933). Scholler, H., Chem.-Zta., 60, 293 (1936). Wise, L. E., and Appfing, J. W., IND. ENG.CHEM.,ANAL.ED., 17,182 (1945). PRESENTED a t the Northwest Regional Meeting of the AarERICAx CHEMICAL SOCIETY a t Seattle, Wash., October, 1945.
Benzyl Benzoate from Benzyl. Chloride and Sodium Benzoate J
d
WALTER H. C. RUEGGEBERGI, ABRAM GINSBURG, AND RUSSELL K. FRANTZ Chemical Warfare Service Technical Command, Edgewood Arsenal, M d .
SA
RESULT of wartime restrictions on the availability of toluene and, hence, behzaldehyde, production processes for the manufacture of the miticide benzyl benzoate other than by the Claisen condensation of benzaldehyde (6,6) had to be investigated. Simultaneously, improved processes for production of benzyl chloride by chloromethylation of benzene and of benzoic acid through the aluminum-chloride-catalyzed reaction between benzene and phosgene were also studied in this laboratory (6). These developments led to two methods for carrying out the double decomposition between benzyl chloride and sodium benzoate to form benzyl benzoate. One of them depends upon the presence of water as reaction solvent for sodium benzoate, as first described by Gomberg and Buchler ( 3 ) ; the other relies on the catalytic activity of a small amount of tertiary amine in the absence of any reaction solvent other than that supplied by the reacting materials ( 1 ) . Although the results in Table I and Figures 1 and 2 on the aqueous double decomposition between benzyl chloride and sodium benzoate generally agree with those of Gomberg and Buch1 Present address, Carbide and Carbon Chemicals Corporation, South Charleston, W. Va.
ler (S), it should be noted that reaction times in excess of 6 hours tend to lower the yield of the ester. Also, Table I shows that 42% aqueous solut,ions of sodium benzoate may be employed in place of 22-27% solutions as used by Gomberg and Buchler without noticeably affecting the ester yield. Thus, much valuable reactor space is not surrendered to an inert solvent. The amine-catalyzed reaction on a slurry of dry sodium benzoate in benzyl chloride is interesting. Despite the fact that practically quantitative yields of aromatic acid esters may be obtained easily, this method has strangely remained out of the chemical literature since its first appearance as a German patent in 1912 ( 1 ) . Scelba ( 7 ) reports that dry sodium benzoate, heated with a slight excess of benzyl chloride at 170-175 O C. for 24 hours, pr0duces.a 70-75% yield of benzyl benzoate. According to the German patent (I), a small quantity of triethylamine lowers the reaction temperature required for this same reaction to about 130140" C., the reaction time to about one hour, and raises the ester yield to 95% or higher. Volwiler and Vliet (10) found that diethylamine possesses definite catalytic activity in the synthesis of benzyl salicylate and benzyl p-nitrobenzoate. Their data, as well as that presented
