Bridges on the Chemical Highway J. N. TAYLOR Bureau of Foreign and Domestic Commerce, Washington, D. C.
CHEMISTRY'S contribution to everyday l i v i n g a t home, a t work, or a t play-is well known to all. Our food and dothing, the houses we live in and their furnishings, our transportation facilities, and even our amusements are in many cases dependent upon chemical processes. To just what extent chemical intermed i a t e s t h o s e bridges between primary and finished organic chemical-ter into our daily lives is not generally understood. As the term indicates, intermediates are materials part-way hetweeen orimarv and finished oroducts. Chemical intennedi. atcr, a9 the chemist claAfies them, include those of both cyclic and acyclic ongin. The cychc intermediates are generally coalderived, that is, from coal tar or coal gas., although some of them may he of petroleum origin, while the acyclic or noncyclic intermediates are obtained from petroleum and natural or waste gases, as well as thmugh wood distillation or fermentation processes. Phenol-arbolic a c i d a n d methanol-wood alcoholare, respectively. typical examples of cyclic and acyclic intermediates. The distinction between intermediates and finished products is at times arbitrary but when a product falls logically into more than one category, it is usually classified by the producer as an intermediate. I n many instances intermediates have end uses in themselves that place them in a finished product status as well as in the "halfway-house" category. Refined naphthalene is familiar to the housewife in the finished form as mothballs and to the chemist as an intermediate between black, sticky coal tar and brilliant, many-hued dyes. An outstanding example of this dual functioning is paradichlorobenzene, extensively used as an insecticide and deodorant and also employed as a stepping stone between benzene and certain dyes. On the other hand, dichlorodiphenyltrichloroethane,popularly known as DDT, is used exclusively as an insecticide and properly comes within the category of finished products. It has long been general industrial practice to consider cyclic intermediates as coal-tar intermediates regardless of origin. They are not found as such in coal tar but are prepared from coalderived or other cyclic crudes by treatment with chemicals such as sulfuric, nitric, hydrochloric, and acetic acids, soda ash and caustic soda, caustic potash, chlorine, bromine, ammonia, ethyl alcohol, and methanol. Intermediates so obtained are then converted by complex chemical processes into finished products such as dyes. medicinals, flavor and perfume materials, photographic chemicals, synthetic resins, tannine materials, rubber chemicals, insecticides, germicides, and other materials. These products in turn find application in industry, and are used by the textile. leather, rubber. paper, automobile, aircraft, radio, refrigeration, plastics, paint and varnish, food and beverage, drug and pharmaceutical, and 0th- grOUpS. The output of coal-tar intermediates in the United States has increased remarkably since World War I. In 1914 there were 7 establishments in the coal-tar chemical industry making coal-tar &tides, a limited number of intermediates, and a few finished products. Dye production was dependent almost entirely on German intermediates. A quarter of a century later-in 1939there were 49 establishments engaged primarily in the manufacture of coal-tar crudes and intermediates. Our war-born intermediates industry grew rapidly. Through intensive effortthe quantity and variety of intermediates production rose until in 1919 the output of coal-tar intermediates was reoorted a t 177.000.000 oounds. At the end of a decade (in 1G9), production reached 354,000.000 pounds, and in another 10 years (in 1939). 607.000,000 pounds. In subsequent years
(1940-3), domestic output grew a t a steady rate until in 1943 production totaled 1,534,000,000 pounds. The foregoing production figures are not strictly comparable, however, since current classification practice places certain products formerly classed as intermediates in specialized groups, such as synthetic rubber chemicals, flavor and perfume materials, and certain other miscellaneous chemicals in a general group characterized as photographic chemicals, plasticizers, syntans, and so an. The compmition of various groups arranged for statistical purposes has not changed appreciably in recent years, however, and data on intermediates have been fairly comparable beginning with 1936. Increases that have recently taken place in this branch of the synthetic organic chemical industry can now he portrayed definitely and are shown in the accompanying chart. Progress in this branch is measured not only in over-all increases in output but also in changes in indivjdual intermediates. Data showing increases in output of several individual items are shown in the accompanying tabulations~for1943 compared with 1937. Other intermediates showed gains while output of a number dropped. Among a host of cyclic intermediates, aniline and phenol are especially interesting in either wartime or peacetime. Both are made synthetically from benzene ( b e n d ) and hoth fan out into many end products having a variety of end uses. For security reasons, current statistics regarding their production cannot be published. But it can be stated that output has increased considerably, due to tbe many demands far manufactured g a d s into which they enter. Aniline is made by two processes, from nitrobenzene by reduction with iron filings or boring5 and from chlorohenzene by its reaction with ammonia. I t is a basic intermediate and large quantities are used in the manufacture of other intermediates which in turn are used in the preparation of a wide variety of products with a number of uses. For example, an acetic acid derivative of anilineacetanilideis converted into other intermediates such as p-aminoacetanilide or p-nitroaniline and these into certain dyes, or through the intermediary of acetanilide-sulfonal-chlorideinto the sulfa drugs. It may also be converted into P-phenyienediamine,used in dyeing furs and in making rubber antioxidants. Dimethylaniline and other aniline intermediate derivatives are employed in various ways in making dyes, medicinals, explosives, rubber chemicals, photographic developers, and the like. Aniline manufacture in the United States began in 1910. The annual output reached 2,000,000pounds in 1914 and in 1917, approximately 32,000,000; the 1939 output was 42,000,000 pounds. In 1940, domestic' production was over 55,000,000 pounds. While this ascensional trend was carried into the war years it is quite likely that the wartime peak will gradually diminish. The 1943 acetaniliderecord output (hoth technical and U. S. P. grades) of 13,823,000pounds dropped to 4,671,000 pounds in 1944, owing in part to the drop in sulfa drugs from 9,860,000 pounds in 1943 to 4,597,000pounds in 1944. Phenol likewise reacts to form a number of offspring. Much of the output goes into explosives. Another large consumer is the synthetic resin industry, phenolic resins going into a variety of molded, cast, and laminated plastics products. Salicylic acid and salicylates take large quantities, acetylsalicycylic acid production alone in 1940 amounting to 6,410,000pounds-enough to make 9,000,000,000aspirin tablets. Other medicinals, dyes, and o - h o t a m ~ h i cdevelooers consume considerable amounts. The (Conlznued on page 466)
460
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BRIDGES ON THE CHEMICAL HIGHWAY quantity of phenol used in making nylon is less than formerly because of the recently developed method employing benzene without phenol intermediation. UKITBD STATBS WODDCTIOY 01 CBRTMNI N D U S I ~ ~ ACOAL-TAR L* INTBXHeo1,ArEs
[I" Bou:drl Ilcn
.................... ................. ........................... ....................... ....
1937
I943t
Aeetanilide (technical). Bcnzidinc disulfonic acid.. Bcnzylchloride a-Dichlombenzmc.. 0-Dichlorobenaene . . . . . . . . . . . . . . . . . . . . . . . . . 1.4-~ihydroxy~nthreguiuion~ (Quinirarin)
5.5'-Dihydr?ry-7,7'~i~ulfon~c-2,2'-dinap~ ~ ~ ~ ( J ~ ~. .~. .d. .u. . r. .e. .a. .). . . . . . . . . . Naphfhalcne (refined). 2-Naphfhylarninc-4 &disuIfonlc acld.. l~~ephthylarnine-8:sulfffff (Periacid). Nifronaphthalenc . . . . . . . . . . . . . . . . . . . . . . . . . p-Nitrotoluene-o-sulfoniia c i d .............. Phthdi" anhydride.. . . . . . . . . . . . . . . . . . . . . . . Sulfanilic acid.. ...........................
...................... ....... ......
......
There are two sources of supply of phenol-natural and synthetic. The natural product is obtained from the fractional distillation of coal tar resulting from the manufacture of coke in by-product coke ovens and from the manufacture of coal gas. Two processes using benzene as the raw material are employed in the production of synthetic phenol. I n one, referred to as the caustic fusion process, benzene is converted to sodium benzene sulfanate which is treated with acid and the phenol distilled off. I n the other, benzene, together with hydrochloric acid and air, is passed through a catalyst to produce monochlorobenzene which by vapor or liquid phase hydrolysis yields phenol. Phenol stands near the head of the list of intermediates in quantity produced. Although for many years prior to World War I, the natural variety was made in the United States, its manufacture synthetically was not well established until 1917, when total phenol output was 64,147,000 pounds. This large production was due to its being in demand for the manufacture of explosives, picric acid, and ammonium picrate. At the time of the Armis-
.
(Continued from page 460)
tice, phenol (technical and U. S. P.) output had risen t o 106,800,000 pounds. The sudden drop in demand for military purposes resulted in surplus stocks and in a drop in price to 6 cents a pound. However, because of the increased demand for phenol in the manufacture of synthetic phenolic resins, accumulated stocks were soon exhausted. There are indications that the 1940 output of 98,000,000 oound-5 times that of a decade a m and 300 times the 1921 lowLhas now been passed and that th; close of the war wil! see huge surplus stocks. More information on this intermediate may be found in "Phenol-A Synopsis of Information:' published in the Inquiry Reference Service. Phthalic anhydride is another outstanding intermediate, a discussion of which appeared in Domestic Commerce for February, 1945. Phenomenal consumption requirements for its derivatives have created such a demand for it that the supply situation of naphthalene, from which it is derived, is critical. Each of the 500 or so coal-tar intermediates having industrial use has its own peculiar characteristics and has its own role to perform. Few are as versatile as aniline, phenol, and phthalic anhydride, but all are necessary bridges linking the crudes to finished products and thence to c o u s u ~ e r sgoods. ' Neither war demands nor former "normal" peacetime requirements are criteria of either near future or distant needs. With changing conditions brought about by VE-day and the heginuings of reconuersiou, the continuance,of intermediate production a t its present high rate of increase is hardly likely. The close of the war with Japan will bring cutbacks in production of intermediates for military purposes, but civilian markets will take up much of the slack. For a number of years to come, a large output will be necessary to supply civilian markets which have been suffering from a dearth of consumers' goods. The intermediates industry stands on the threshold of a new era. Research is constantlv addine new discoveries and new inventions, new uses for old prudurt, and hy-products. n'ith its expanded capabilitict and it. wwrplorrd poscihil~ies.thijindustry will be iucrea,in.dy wtivr in supplying those stcpping stones so necessary in making the finished goods of commerce.-Reprinted from Domcrlic Commerce (July, 1945).
