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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
the former will leave the film before the toluene, and since toluene is a nonsolvent for VinYlite, rough films having Poor adhesion will be obtained. MISCELLANEOUS
The nitroparaffins may be used advantageously with a large number of other coating materials. Cellulose triacetate, for example, is exceedingly resistant to attack by practically all solvents except the chlorinated hydrocarbons which have the disadvantages of being relatively toxic and corrosive. The nitroparaffins are latent solvents for cellulose triacetate and permit the formulation of solvent mixtures containing only small amounts of chlorinated hydrocarbons. Mixtures containing as little as 10 per cent of tetrachloroethane are excellent solvents for cellulose triacetate. The nitroparaffins are also valuable in reducing the gelling tendencies of alcoholic zein solutions. They are perhaps the most powerful solvents for the synthetic rubber known as Hycar OR, and they have been found to be useful in cements made with this material. Certain nitroparaffin derivatives are also valuable antigelling agents while others are heat senwell as from sitizers for cements made from Hycar OR natural rubber (4). Table VI is a list of the types of compounds soluble and insoluble in the nitroparaffins. This table indicates that the usefulness of the nitroparaffins as solvents lies in many different fields.
=
James
Vol. 35, No. 10
LITERATURE CITED
The following literature haa been cited for its direct bearing 011 this paper. No attempt has been made to present a complete bibliography or to list all of the patents on the uses mmtioned. (1) Bogin, Charles, Paint, Oil Chsm. Rev., 104, No. 18, 19. 20, 21 (1942). (2) Bogin, Charles (to Commercial Solvents Corp.), U. 9. Patent 2,150,096 (March 7, 1939). (3) Bogin,Charles, and Wampner, H.L., IND.ENQ.CKEM., 31, 1091 (1942). (4) Campbell, A. W., Ibid., 33, 809 (1941). (5) Dijck, W. J. D. van (to Shell Development Co.), U. 9. Patent 2,023,375 (Dec. 3, 1935). (6) Gabriel, C. L., Chem.Industries, 45, 664 (1939). (7) H w , H.B., Hodge, E. B., and Vanderbilt, B. M., IND. ENQ. CHEM., 28, 339 (1936). (8) Kirkpatrick, S.D.,C h m . & Met. Eng., 49, 129 (1942). (9) Lippincott, 9. B. (to Commercial Solvents Corp.), U. 8. Patent 2,233,620 (March 4, 1941). (10) Lippincott, S. B., and Hass, H.B., IND.ENQ.CHEM.,31, 118 (1939). (11) Machle, Willard, Scott, E. W., and Treon, Joseph, J . Ind. H y l . ToziCol., 22, 315 (1940). (12) IW., 24, 5 (1942). (13) McKittrick, D. S., Irvine, R. J., and Bergsteinsson, I.. IND. ENO.CREM.,ANAL.ED.,10, 630 (1938). (14) Paski, A. J . van (to Shell Development Co.), U. S. Patent 2,019,772 (Nov. 5, 1935). (16) Senkus, Murray, J . Am. Chem. Soo., 63, 2635 (1941). (16) Vanderbilt, B. M., and Hass, H. B., IND.ENCI.CKEM..32, 34 (1940).
G.Park and T. R. DonIan
S t A N D A R D A L C O H O L COMPANY, NEW YORK, N. Y.
The scope of this paper includes the saturated alcohols commercially and economically available to the protective coating and chemical industries. Since considerable information had been published on these products before the war, the present paper is confined to more recent developments. Also included in the discussion are the relative positions of the various alcohols with respect to the war effort. Some attempts are likewise made at predictions regarding their postwar status.
ETHYL rtlcohol is now being produced commercially M by three different processes-one old and two relatively new. The oldest source is the crude wood alcohol produced during the destructive distillation of wood in the manufacture of charcoal. Approximately 6 million gallons of methyl alcohol are obtained by this means. The output cannot be increased, however, since methyl alcohol thus made should be considered a by-product of charcoal which, in turn, is limited by the availability of proper hardwood and suitable labor to cut and collect the lumber. The value of the by-products obtained in the distillation of pyroligneous acid-namely, acetic acid, acetone, and methyl alcohol-becomes an asset to the operation if the price of and
demand for charcoal justify the lumbering operation. In the event, however, that there is insufficient demand for charcoal, the cost of the solvents must pay for both the lumber and for the expense of their own distillation. At present as in the past, the two main outlets for wood alcohol are in automotive antifreeze blends and ethyl alcohol denaturants. The crude alcohol contains a number of.impurities which impart a strong odor to the material and thus make it specially suitable for these purposes. An additional distillation is required t o render it satisfactory for other uses. Wood-distillation methyl alcohol is in heavy demand a t the present time, but its production cannot be greatly increased. The postwar position of this material will depend entirely 011 its ability to compete in cost of production with the synthetic product. As the manufacturing limitations of wood alcohol did not permit production to keep pace with demand, the manufacture of synthetic methyl alcohol, first prepared in this country in 1923, has steadily increased in volume. The two outstanding processes for producing synthetic methyl alcohol are a t present limited by difficulties in obtaining critically needed material. As an instance, the process in which carbon monoxide is partially reduced by hydrogen requires a pressure of 200 atmospheres at 450' C. with a zinc oxide-chromic oxide catalyst. Since high pressure equipment is practically unobtainable, this process cannot easily be expanded at this time. The second method, the catalytic oxidation of methane, requires 100 atmospheres pressure at
October, 1943
INDUSTRIAL AND ENGINEERING CHEMISTRY
260° C. The methane is paased through copper tubes in a ratio of 9 parts methane to 1of oxygen.
The chemical and physical properties of methyl alcohol make it an important product in industry. It finds extensive use as an industrial solvent for such products as wood stains, soaps, artificial leather, gums, celluloid cementa, motor fuels, paint and varnish removers, shellac solutions, spirit varnishes, alcohol lamps, etc. In normal times the largest use, as previously mentioned, is in automobile antifreere blends. Maximum antifreeze protection per gallon of the thrw watersoluble alcohols is given by methyl, and therefore it is probably the most economical to use. Data recently secured, however, tend to indicate that methyl alcohol loses sufficient volume in evaporation to reduce significantly its antifreeze protection. The second major use for methyl alcohol is in the denaturing of ethyl alcohol. Both wood alcohol and a small amount of synthetic methyl alcohol are used for this purpose. It serves as a highly satisfactory denaturant owing to the difficulty in its separation from ethyl alcohol and the relative ease with which it can be detected. Large quantities of synthetic methyl alcohol are used &cl the raw material in many chemical processes; the most important is the prepsration of formaldehyde by mild oxidation of the alcohol. In recent years formaldehyde has become extremely impor tant as a constituent of various synthetic resins, plastics, and explosive intermediates such aa pentaerythritol. Heavy demands for explosives and other military requirements have resulted in a scarcity of methyl alcohol. Increseed activity in certain plastics such as the methacrylates is also a contributing factor in the reduced availability. Since synthetic methyl alcohol and ammonia are produced in the same type of equipment, increased production of methyl alcohol during the war period must necessarily be balanced by the military and agricultural requirements for ammonia. If the combined demand for these two products is in excess of the available supply, the least important aivilian uses must be curtailed or replacement by less critical materials must be made. In the postwar period, however, the demand for methyl alcohol through its chemical derivatives may be expected to increase. There wil1,be sufficient excess ammonia equipment in the country, and synthetic methyl alcohol should be readily available and in a favorable economic position. The basic cost for methyl alcohol should be figured in terms of ammonia since the value of the former can be calculated directly in ammonia displacement. ETHYL ALCOHOL
Ethyl is the oldest of the alcohols. It is derived largely fromthe fermentation of sugar, cellulose, and related materia,la. Before the war practically-all fermentation alcohol produced in this country was made from blackstrap molasses, but wartime difficulties in transporting molasses have increased and most of the ethyl alcohol today is being produced from grain. More recently, however, the fermentation of specially milled flour has been undertaken. The fermented liquor, containing about 10 per cent crude alcohol, is concentrated by fractionation. The heads cut contains aldehydes and the tails a certain proportion of fusel oils. During the process of fermentation carbon dioxide is produced in quantities about equivalent to the weight of alcohol. This is recovered and merchandised as dry ice. The tails from molasses fermentation have been proceased to produce cattle feed. The synthesis of ethyl alcohol by hydrating ethylene is an increasingly important method for producing this valuable
1031
product. I n the process ethylene is absorbed by sulfuric acid a t slightly elevated temperatures; the ethyl hydrogen sulfate so formed is passed into water and is heated to hydrolyze the ester to ethyl alcohol. The product is characterized by its freedom from higher alcohols. In normal times many industrial usea for ethyl alcohol are found. Production expanded enormously from the milliongallon output of the year 1907. A large part of this increase was due to the introduction of the closed car which permitted winter driving. The resulting antifreeze market consumed during one period almost 50 per cent of the total ethyl alcohol production. With ita replacement in this field by methyl alcohol, ethylene glycol, and isopropyl-methyl alcohol blends, however, the volume of ethyl alcohol used today is only 25 per cent of the quantity produced; the balance goes into industry for other purposes. The largest prewar consumption of ethyl alcohol was in the cellulose industry. Here it was used to dehydrate nitrocotton and prepare acetic anhydride, a starting component in the manufacture of cellulose acetate. Other large uses were in the preparation of shellac, lacquer, varnish, solvents, ethyl acetate, and toilet goods. The introduction of anhydrous ethyl alcohol greatly extended its uses owing to increaaed solveut power. It may be said that hardly an industry is without the need of ethyl alcohol during some phase of operation. The greater part of the present gallonage goes into butadiene for synthetic rubber. Large quantities are also consumed in the preparation of smokeless powder and other military requirements, including medicinals. To meet this increased demand, the entire beverage industry of the United States is now utili5ing its facilities to produce ethyl alcohol. After the war this industry will naturally return to its former business, and the production of ethyl alcohol will immediately be more than halved. In 1939, 25 per cent of our ethyl alcohol w m made synthetically. These facilities have been greatly expanded during the war so that at least 50 per cent of the country’s normal production can be obtained from synthetic plants. Any discussion of the postwar synthetic rubber situation a t the preeent time would be pure speculation. It is possible, however, that fairly large quantities of ethyl alcohol might be used to produce butadiene a t that time. If new developments do not absorb the increased production, the demand will be largely drawn from the source having the lowest production cost. As approximately 2.5 gallons of blackstrap molasses or 0.4 bushel of grain is needed to produce a gallon of alcohol, the extent to which fermentation alcohol can compete with synthetic will depend entirely upon the postwar agriculture prices. R-PROPYL AND ISOPROPYL ALCOHOLS
*PROPYL.Originally obtained from fusel oil, this material is a constituentsf the higher alcohol fraction in the production of synthetic methanol. The biggest market for the small amounts available is in ita oxidation to propionic acid. ISOPROPYL. Prepared in substantially the same manner as synthetic ethyl alcohol, isopropyl alcohol became available commercially in 1920; production figures have steadily increased. One of the largest present uses is the production of acetone and ketene by catalysis. Acetone can be made in this manner a t a lower cost and probably in a purer form than that obtained by fermentation; the result is an increased demand for this product. Another large market for isopropyl alcohol is in antifreere compositions. In combination with methyl alcohol it produced a particularly satisfactory anti-
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INDUSTRIAL AND ENGINEERING CHEMISTRY
freeze blend with properties not porn& by either alcohol alone. As B result of war restrictions on the use of ethyl alcohol, isopropyl alcohol is now being employed as a satisfactory substitute in the toilet goods and cosmetic field. At present virtually all rubbing alcohol is made from isopropyl alcohol. Many other preparations such as after-shave lotions, toilet waters, etc., contain isopropyl alcohol. Certain types of perfume are now being blended with isopropyl alcohol as the carrying agent. The anhydrous grade displays solvency for certain essential oils in excess of that exhibited by the corresponding grade of ethyl alcohol. Since there has been a gradual improvement in the quality of isopropyl alcohol due to better manufacturing technique, perfumers are adjusting their blends to accommodate the new odor and improved solubility. It is believed that after thc war many users will not return to ethyl alcohol. Isopropyl alcohol is contributing to the war effort in such uses as fuselage cleaners, de-icing fluids, plywood impregnee ing solutions, shackle lubricants, shock absorber fluids, vitamin crystallization, lacquer thinners, e t c Increasingly large amounts are also being consumed in preparing isopropyl acetate, a nitrocellulose solvent finding wider uses within the past few years. BUML ALCOHOLS
ISOBUTYL.Before the war isobutyl alcohol was obtained in large quantities as a by-product in the preparation of synthetic methyl alcohol. It exhihit.s typicsl reactions of the primary alcohols, except that the presence of a branched chain next to the carbinol group makes rearrangement unusually easy. Au example is the reaction between isobutyl alcohol and hydrobromic acid to produce terkbutyl bromide rather than the is0 compound. The commercul value of isobutyl alcohol is about halfway between normal and secondary butyl alcohol. Its use, therefore, has been limited largely to the production of the corresponding acetate, a satisfactory nitrocellulose solvent. Isobutyl alcohol has found some use &sa lacquer cosolvent and ass constituent of brake fluids combined with castor oil. It is understood, however, that major producers are now using it in specisl war work which may find a definite position in industry after the war. SW-BUTYL.This alcohol is becoming increasingly available due to improved manufacturing facilities. It is produced in substantially the same manner as ethyl and isopropyl slcohols-i. e., by hydrating the corresponding olefin. At present its two most important uses are in the preparation of 8%butyl acetate, an excellent intermediahvaporating nitrocellulose solvent, and methyl ethyl ketone obtained by dehydrogenation of the alcohol. Methyl ethyl ketone is a valuable solvent for vinyl resins, nitrocotton. and synthetic rubber. In the anhydrous state it presents solvent properties equal to that of acetone. Its evaporation rate, however, is definitely slower than acetone, a fact responsible for its high initial blush resistance in lacquer formulations. After the war the demand for this material should continue to increase, as special resins and synthetic rubbers, upon which its use is somewhat dependent, will continue to expand. Its superior nitrocotton solvency has been demonstrated. In this capacity it should replace ethyl and isopropyl acetates in many cases. terkBuTYL. This alcohol is readily obtained from the hydration of isobutylene. In the pure state, however, it freeaes a t 25' C., a property rendering its commercial use somewhat limited. It is employed as an alkylating agent in the prepare tion of such compounds as lerl-butylphenol.
Vol. 3s. No. 10
AMYL ALCOHOL
Originally amyl alcohols, both normal arid iso, were obtained as by-products in the fermentation of grain. Little is apparently being produced a t this time, probably owing to changes in manufiletiiring teohnique. The only addition51 amyl alcohol, other than that produced by chlorination, is see-amyl alcohol. This milterial, prepared before the war by hydration of amylene, was used to make methyl n-propyl ketone, a dewaxing solvent. sec-Amyl acetate, derived from the alcohol, has found use in the lacquer trade. Amylene, the raw material from which see-amyl alcohol was made, now possesses a greater war value than thnt of the alcohol itself. The production of the alcohol, therefore, bas dropped to almost nothing. CONCLUSION
During the past twenty yearv the alcoliul and solvent buai13888 has grown from infancy to maturity, hut it found its place more in the protective coating field than in other industries. The war, however, has increased the outlets for these alcohols, so thnt today virtually all of the msjor chemical industries are consumers of one or more of the alcohols or their derivatives. While the release of the greater part of these new developments is now restricted because of rnilitary necemity, we may generalize to the extent of saying that aside from the protective coating industry itself, these alcohols, either as solvents or intermediates, will play a leading part in the postwar development of textiles, resins, rubber, and chemical intermediates, and, due to reduced cost, will contrihute greatly to a better postwar standnrd of living.
Courtur. du
Pmr
Company
Equipment for Mekin9 Fwmldehyde from Mdhyl Alcohol
and Air
