INDUSTRIAL AND ENGINEERING CHEMISTRY
the esterification rate diminished noticeably a t acid number 50 and leveled off a t 15. From Table VI it will be seen that, with only 5% excess, a relatively lorn acid number was reached, a!though an excess of a t least 10% was necessary to accomplish this in a reasonable time. Although no such systematic studies were carried out with pentaerythritol, it has been observed that, when 5 and 10% eycesses of this poly01 were used under similar conditions, changes in esterification rate \\-ere essentially comparable t o those obtained with glycerol. Color, viscosity, and drying time of the finished glycerol esters varied little over the range from 0 t o 20% eycess. Eight-hour and overnight drying times were run (8 to 15 hours). I t is felt that the information here presented is adequate to establish conditions for esterifying tall oil under laboratory conditions and should be useful in establishing plant proccdures. ACKNOWLEDGMENT
Vol. 42, No. 8
(1) Atlas Pov.-er Co., “Esterification of Tall Oil with Sorbitol,” Industrial Chemicals Dept. Bulletin, November 1946.
( 2 ) Bailey, A. E., “Industrial Oil and F a t Products,” p. 674, X c w York, Interscience Publishers, 1945. ( 3 ) Burrell, H a r r y , ISD.ENG.CHEW,37,86-9 (1945). (4) Burrell, H a r r y . Oil & Soav. 21, 206-11 (1944). ( 5 ) Burrell, H a r r y , and VanderValk, C. J.’,Paint, Oil, Chem. Rev., 107, S o . 2 5 , 3 3 (Dee. 14,1944). (6) Feuge, R. O., Kraemer, E. 9., and Bailey, A. E., Oil &: Soap, 22, 202 (1945). (7) Gardiier, H . A,, and Sward, G . G., “Physical and Chemical Examination of Paints, Varnishes, Lacquers, and Colors,” 10th ed., p. 155, 1946. (8) Heyden Chemical Corp.. “Pentek Resins,” 1948. (9) Konen, J. C . , Clocker, E. T., and Cox, R. P., Oil & Soap, 22, 57-60 (1945). (10) Kiorthnestern P a i n t & Tarnish Production Club, Ob’icial Digest, 286, 845 (November 1948). (11) Rooney, J. F., “Utilization of Tall Oil in Germany,” F I A T Final
This work mas done under the sponsorship of the Union Bag permission to publish these data is &- Paper Corporation, gratefully acknowledged.
RECEIVED RIas 26, 1949. Presented before the Division of Paint, Varnish, and Plastics Cheinistry at the 116th Meeting of the ~ I E R I C A NCHEVICAL SOCIETY, San Francisco, Calif.
HYDROTROPIC SOLUBILITIES Solubilities in Aqueous Sodium
m-, and p-Xylenesulfonate Solutions
HAROLD SIMMONS BOOTH1 AND HOWARD E. EVERSON2 Western Reserve Uniuersity, Cleveland 6, Ohio
A study was made of the solubility of six selected solutes in seteral concentrations of aqueous sodium o-xylenesulfonate, sodium rn-xylenesulfonate, and sodium p-xylenesulfonate solutions at 25.0’ and 60.0’ C. with the object of determining which of these salts was most effective as a hydrotropic solvent for the solutes used. The results indicate that, in general, comparable concentrations of aqueous solutions of the three isomeric salts are very similar in solvent action for the solutes studied. However, sodium rn-xylenesulfonate is preferred for use at lower temperatures as it is more soluble in water than either sodium 0- or sodium p-xylenesulfonate.
S PRES’IOUS articles the authors presented results of solubility determinations of a rather extended list of solutes in comrnercial aqueous 40% sodium xylenesulfonate solutions a t 25.0’ C. (1) and also made a comparison of aqueous solutions of several other sodium arylsulfonate salts as hydrotropic solvents for a selected list of ten solutes ( 2 ) . These latter determinations weie made a t several salt concentrations and a t 25’ and 60’ C. The object of the present study is t o make a comparison of the relative effect of aqueous solutions of the sodium salts of the monosulfonation products of 0-,m-, and p-xylene on the solubilities of six solutes selected from the list of ten solutes used in the second phase of the problem. The solutes chosen for this study ere: acetophenone, aniline, benmldehyde, o-cresol, cyclohexanol, and ethyl acetate. All the solutes used were either C.P. or highest grade commercial samples purchased expressly for this study, and are from the same stock as the inaterials used for the determinations made previously ( 2 ) . The sodium o-xylenesulfonate and sodium m-xylenesulfonate mere furnished by the Wyandotte Chemicals Corporation of Kyandotte, hlich., in the form of aqueous solutions. The sodium p-xylenesulfonate was prepared by neutralizing an aqueous solution of p-xylenesulfonic acid with aqueous 50y0 sodium hydroxide solution prepared from reagent grade sodium hydroxide pellets. An external indicator was used 1 ?
Deceased. Present addless, Unireisity of Cincinnati, Cincinnati 2 1 Ohlo
to determine the neutral point of the solution. Tlic xylcncsulfonic acid was purchased from the Eastman Kodak Company, Rochester, N. 1‘. The analyses and characteristics of the stock hydrotropic solutions are given in Table I. The appropriate concentrations of salt solutions for the solubility measurements were made from the stock solutions by dilution with distilled n-ater or by evaporation where necessary.
ANALYSES AND CHARACTERISTICS O F %POCK AQUEOUS SOLUTIOSS O F SoDIVlLr X Y L E N E S C L F O N A T X S Sodium o-Xylenesulfonate 19.40 0.24
0.005 8 26 1.072
Sodium m-Xylenesulfonate 39,oo 0.79 0,002
7.71 I , 189
Sodium p-Xylenesulfonate 15.32 0.29 C.058
I n this study the authors are interested in the sodium salts of the monosulfonation products of the xylenes, and the follotving discussion is given to show what can be expected as products of direct sulfonation of the xylenes. There are a total of six possible isomers of sodium xglenesulfonate which can be formed from the three xylrnes. There is only
INDUSTRIAL AND ENGINEERING CHEMISTRY
one isomer of p-xylenesulfonic acid. There are two isomers of 0xylenesulfonic acid with the sulfonic acid group in either the 3 or 4 position on the ring. Three isomers are possible for m-xylenesulfonic acid, with the sulfonic acid group in the 2,4, or 5 position on the ring. Jacobsen ( 3 ) reported the preparation of p-xylenesulfonic acid by the method of reacting p-xylene with fuming sulfuric acid. He also prepared the sodium salt ( 4 ) and this was verified later by Moody and Nicholson (8).
the two phases becomes very nearly equal, thereby making separation next t o impossible. Another factor is the ease with which these materials form colloidal solutions. RESULTS
The results of the solubility determinations are shown in Table
I1 and are expressed in milliliters of solute dissolved in 100 ml. of solvent. No attempt was made to determine the solubility when
IN WATERA N D IN AQUEOUS SODIUM o , m-, TABLE 11. SOLUB~LITIES 7
Solute Acetophenone Aniline Benzaldehyde o-Cresol Cyclohexanol Ethyl acetate
Temp., 'C. 25 60 25 60 25 60
25 60 25 60 25 60
HzO 0.54 0.80 3.80 4.90 0.40 0.96 2.20 3.08 3.40 3.38 8.80 7.40
Sodium o-Xylenesulfonate, % 5.0 10.0 20.0 1.38 3.71 0.80 4.47 1.68 1.01 32.3 7.83 4.40 32.1 9.34 5.85 1.26 3.58 0.88 4.66 1.90 1.50 70.4 214 9.40 42.9 281 7.10 17.5 210 5.18 15.9 200 4.57 15.44 10.45 9.25 15.15 10.02 8.22
-Solubility,M1. Solute/100 M1. Solvent Sodium m-Xylenesulfonate, % 5.0 10.0 20.0 25.0 40 .O 0.70 1.29 3.92 30.5 ... 5.00 29.4 1.05 1.49 4.25 6.77 28.1 51.8 >400 > 400 29.5 55.1 5.17 8.52 1.25 3.83 24.8 0.80 ... ... 4.97 28.1 1.85 1.37 55.2 >400 2.50 7.30 291 > 400 35.5 6.40 > 400 196 ... 19.5 5.02 197 >400 ... 5.00 17.8 16.7 40.5 ... 9.19 10,83 40.3 15.9 10.05 8.27
Lauer ( 5 )sulfonated o-xylene with sulfuric acid containing 10% sulfur trioxide and obtained no o-xylene-3-sulfonic acid but only o-xylene-4-sulfonic acid. hloody ( 7 ) succeeded in preparing the o-xylene-3-sulfonic acid by indirect means. He then showed that the 3 isomer rearranges to the o-xylene-4-sulfonic acid on heating to 115'to 120' C. In studies by Moody (6) and also by Pollak (IO)it was shown that it is possible to get m-xylene-2-sulfonic acid and m-xylene-4sulfonic acid by direct sulfonation and that if the former is heated a t 100' C. it will rearrange to the m-xylene-4sulfonic acid. Further, in ordinary sulfonation of m-xylene it is shown that the product is practically entirely the stable m-xylene-4sulfonic acid. The third isomer, m-xylene-5-sulfonic acid, was prepared by hloschner (9) but was not obtained by direct sulfonation. EXPERIMENTAL PROCEDURE
The methods used for the solubility determinations were precisely those employed in the second phase of this problem (3)namely, addition of measured quantities of solute t o a measured quantity of solvent contained in a closed vessel in a constant temperature water bath. Successive additions of solute were made until the first permanent appearance of a second phase in the solution. All solvent and solute volume measurements except those of o-cresol were made a t 25.0 * 0.1 O C. The volumes of o-cresol were measured a t 31.0 * 0.5" C., as the freezing point of this material is but slightly below this value, Constant temperature was maintained by the use of mercury bulb-type thermoregulators immersed in the constant temperature water baths. Mercury bulb thermometers calibrated against a Bureau of Standards thermometer were used to check the temperatures throughout the solubility determinations. As was pointed out in the earlier studies, the solubility of a liquid solute can be determined within 0.1 ml. of solute for a given volume of solvent. However, this degree of accuracy is not attained for o-cresol and cyclohexanol in some of the intermediate concentrations of hydrotropic salts. In these cases it becomes difficult to observe the appearance of a second phase when solute is added to solvent. One factor involved is that the density of
Sodium p-Xylenesulfonate, % 5.0 10.0 15.0 0.80 1.04 2.19 1.07 1.57 2.70 13.2 4.30 6.26 5.35 14.6 8.09 1.10 0.60 2.00 1.73 1.50 2.62 22.9 4.90 177 4.90 28.8 179 89.6 19.0 5.02 17 . O 4.57 74.2 11.05 8.54 13.40 10.34 13.07 8.27
it was found t o be greater than 400 ml. of solute per 100 ml. of solvent. The maximum concentration of hydrotropic salt used for the determinations was governed by the solubility of the salt in water a t 25.0' C. except that the maximum concentration of sodium m-xylenesulfonate used was 40.0%. Aqueous sodium m-xylenesulfonate solutions are very similar in solvent power t o the commercial sodium xylenesulfonate solutions studied previously (2). The aqueous solutions of sodium o-xylenesulfonate and sodium p-xylenesulfonate exhibit fair solubilizing action on the materials studied. However, they are limited in this action a t the lower temperature, for the highest concentrations obtainable of these salts in water is much less than that which is possible for sodium m-xylenesulfonate. Undoubtedly, comparable results among the ortho, para, and meta salts could be obtained at higher temperatures, for in that case higher concentrations of the former two salts could be used. ACKNOWLEDGMENT
The authors wish to express their gratitude to Thomas H. Vaughn, vice president in charge of research and development, Wyandotte Chemicals Corporation, and t o H. Earl Tremain of the same organization for suggestions and encouragement during the course of these investigations. LITERATURE CITED
(1) Booth, H. S., and Everson, H. E., IND. ENG.CHEM.,40, 1491 (1948). (2) Ibid., 41, 2627 (1949). (3) Jacobsen, O., Ber., 10, 1009 (1877). (4) Ibid., 11, 22 (1878). (5) Lauer, K., J.prakt. Chem., 138,81 (1933). (6) Moody, G. T., Chem. News, 58,21 (1888). (7) Ibid., 67, 34 (1892). (8) Moody, G . T., and Nicholson, T. G., J. Chem. SOC.,57, 978 (1890). (9) Moschner, J., Ber., 34, 1258 (1901). (10) Pollak, J., and Meissner, F., Monatsh., 50, 237 (1928).
RECEIVED January 16, 1950.