INDUSTRIAL A N D ENGINEERING CHEMISTRY
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has been little change. I n this connection we should mention the work of Dennis and his pupils. The use of the slow combustion method for the determination of paraffins has almost entirely replaced the explosion method. It is well known that the ordinary method that is now practiced does not differentiate either the olefins present in the illuminants or the various members of the paraffin series which are ordinarily known as methane and ethane. Burrell’s work on the liquefaction and subsequent fractional distillation of the gases a t low temperature has
Vol. 18, No. 9
furnished the basis of a method that i t is hoped may result in commercial development. Tropsch, in Fischer’s laboratory, has devised a n apparatus in which it is said that a determination can be made in a day and it is hoped that future work will make it possible to reduce this time still further. I n view of the great technical advances of recent years and with the more wholesome public relations that now exist, the gas industry looks forward to the future as holding a greater promise than the past.
Paint and Varnish-Yesterday, Today, and Tomorrow’ By Maximilian Toch 443
FOURTHAvE., NEW YORK,N. Y.
T
HE earliest records in existence are those of the Egyptians, who forty-five hundred years ago used about seven pigments and mixed them with lime and water for decorative purposes. With the exception of two, these were natural earth pigments-ocher, whiting, hematite, charcoal, and lampblack. There are some evidences that the Egyptians used powdered minerals, such as malachite, and the only artificial color that they applied was a material called fritts, which was powdered porcelain or glassware that had been colored with cobalt oxide. A thousand or fifteen hundred years later, when interior decoration was practiced, the Persians and the Egyptians used white of egg and boiled parchment as adherents for pigments. I n the ruins of Pompeii there are remnants of two paint shops, showing practically the same colors, excepting a red known now as Pompeian red, which was supposed to be a natural cinnabar. Oils
I n 1399, the Brothers Van Eyck published the information that decorative paint could be applied with a drying oil. It is conceded that this drying oil was linseed oil and for five hundred years practically no other oil was used on a large scale. To be sure, poppy oil was used in portrait painting, but its drying qualities are different than those of linseed oil, and today we are able to identify portraits that were painted with poppy oil because the crackle is much smaller than that of other drying oils. Up to 1900 or practically five hundred years after the invention of the Van Eycks, other oils, notably China wood oil, began to come into the paint and varnish industry, and last year some fifteen million gallons were used in a raw state, which would indicate that between thirty and fortyfive million gallons of paint and varnish were made of this very remarkable oil. The Chinese have been using this oil for centuries, never in its raw state, but always gently cooking i t until it became thick; but in America methods were discovered for producing waterproof paints and varnishes that had never been known before. I n addition t o this oil, large quantities of three varieties of fish oil are used. Soy bean oil has come to be constant, particularly for baking japans. Perilla oil is of great value for certain enamels, and corn oil, rape seed, and sunflower seed oil are regarded as drying or semidrying oils and can be used as substitutes. I n fact, the great demand for oil paints during the war, and the dearth of linseed and China wood oils brought out the fact that there are many drying oils which have a practical value. 1
Received June 4, 1926.
Pigments
For ages the only white pigment was white lead. Within the last seventy-five years zinc oxide has run a close second, and within the last twenty years lithopone, which is a barium sulfate-zinc sulfide double precipitate, has been used in such large quantities that the combined use of zinc oxide and lithopone is considerably greater than that of white lead. White lead, however, has its place and is a most excellent pigment, but for interior flat paints and for enamel paints zinc and lithopone are superior. Recently we have had titanium oxide precipitated with barium sulfate, which has even greater hiding power than white lead, but cannot as yet be used alone as an exterior paint. Antimony oxide is another new white pigment, but it is used abroad to a greater extent than in this country. Cadmium separated in the purification of zinc is now precipitated as sulfide, together with barium sulfate, making a cadmium lithopone that is permanent to light and heat and reasonable in price. The same progress is true of the organic lake colors. We have permanent reds now ten times stronger and infinitely lower in price than quicksilver vermilion. No one knows when an oil paint has become absolutely dry, because by the time it has thoroughly dried it probably has perished. This is because the catalytic action continues and i t is the cause of the decomposition of most paints. Lacquers
Five years ago hardly any ‘one thought of using a nitrocellulose lacquer composed either of scrap movie film or condemned large-caliber rifle powder, or directly nitrated cotton, but since that time, it is no exaggeration to state, millions of gallons of automobile lacquers have been used. The one great advantage of lacquer is that when it is dry it is completely dry and no further oxidation or catalytic action takes place. Lacquer, however, must today be applied by means of a spray under heavy air pressure, but the results obtained are marvelous for gloss, water resistance, and wear. But tomorrow there will be thousands and thousands of various sized cans on the market containing lacquer which can be brushed on, which will dry in half a n hour, and which will give infinitely greater satisfaction than any of the old-time enamels. These will not be pure nitrocellulose, nor will they be the amyl and butyl solvents usually used for spray purposes. The chemist has already found large varieties of solvents heretofore unused and hardly known, and scores of combinations of various resins are mixed perfectly with nitrocellulose solutions. As a first step the householder
September, 1926
Iil‘DCSTRIAL A X D ELVGINEERIAVGCHEMISTRY
will become accustomed to use these to lacquer or enamel household furniture, as the active operation will be complete within a half hour. Thus has the paint and varnish industry emerged, after
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five hundred years of stagnation, into a whirlwind of discoveries and inventions, and it is not within the knowledge of any man to say what will be next in the line of useful paint and varnish materials.
The Evolution of Synthetic Medicinal Chemicals’ By H. V. Arny COLUMRU I ~X I X
ERSITY
COLLEGE OF P 7 1 i R M 4 C Y N E \ \ ’ I ‘ O R K .
HEN the writer entered the retail drug business in 1884, about the only prescribed medicinal substance that could be called a synthetic organic chemical was chloral hydrate. It is true that phenol was being made synthetically, and so was salicylic acid, but these substances had been introduced into medicine from quasi-natural sources, whereas chloral hydrate was marketed from the Liebreich pharmacy as a novel hypnotic, even though chloral itself had been described by Liebig thirty-six years earlier.’.* Synthetic medicinal chemicals may therefore be considered as creations of the half-century during which the A b r E R I C A N CHEMICAL SOCIETYhas existed, and the entire remarkable progress made in this field of synthetic chemicals may be included in the recollections of many of us who are still interested in this field. Upon the shelves of the drug store just mentioned were also two other bottles which excited the interest of the pharmaceutical apprentice. One was labeled “croton chloral hydrate” (now known as butyl chloral hydrate),2 which enjoyed for a while some vogue as a hypnotic, coming into use on the wave of popularity of chloral hydrate; the other was labeled “propylamine” (now known as trimethylamine), which was employed by a former owner of the pharmacy as the chief ingredient of a rheumatism remedy which he marketed. The first of the synthetic organic medicaments which came into use during the writer’s experience was iodol. Antipyrine followed shortly and behind it came acetanilide masquerading under the copyrighted name of “antifebrin,” and in their train a horde of substitutes, some of distinct merit and others fraudulent imitations. This is true of almost all the pioneers in the groups of organic synthetics enumerated below. The followers of the typical chemicals were either honestly conceived irnprovcments over the original product or were merely the inferior outputs of competing houses. A study of the groups of synthetic chemicals which will be discussed in this paper shows the interesting fact that the six years 1884 to 1890 were not only the beginning years of what we now call synthetic organics, but were also the years when most of our present-day groups of organic synthetics had their beginnings. This can best be shown by a n enumeration of the groups with the date of introduction of the type chemical heading the list.
W
Aseptol (18%) and other phenol derivatives Beta-naphthol (1884) and other naphthol derivatives Iodol (1886) and other iodoform substitutes Antipyrine (1885) and other synthetic antipyretics Salol (1886) and other salicylic compounds Sulfonal (1888) and other synthetic hypnotics Methylene blue (1890) and other antiseptic dyestuffs Eucaine (1894) and other alkaloidal synthetics Guaiacol carbonate (1902) and other creosote derivatives 1
Received June 2, 1926.
* Numbers in text refer t o bibliography
a t end of article
N Y
Arsphenamine (1909) and other arseno- and metallo-organics Epinephrine and other glandular chemicals Hexamethylenetetramine and other miscellaneous chemicals
Phenol Derivatives Phenol3 has been known as a valuable antiseptic for over fifty years, while phenolsulfonates were employed as watersoluble antiseptics as far back as 1870.4 The first product. however, marketed as under a coined name was asept01,~ a solution of o-phenolsulfonic acid. This was followed in 1889 by soziodo1,e which was marketed as metallic salts of iodo-p-phenolsulfonic acid; and in 1893 aluminum pphenolsulfonate under the name s o ~ o l . ~The accidental discovery in 1906 of the purgative action of phenolphthaleinS has transferred its main value from a n indicator to the field of medicine, and of late years phenolsulfonephthaleing has become the standard diagnostic reagent for determining the efficiency of kidney functionation. Naphthol Derivatives I n 1884 beta-naphthol10 was recommended as a skin and intestinal antiseptic, and for several years following there was considerable controversy as to the relative value of it and its rivals, such as alpha-naphthol and the so-called hydro-naphthol. Beta-naphthol has enjoyed continued esteem in dermatological practice, but its popularity as an intestinal antiseptic has been lessened because of its peppery taste. Derivatives such as benxo-naphthol, or beta-naphtho1 benzoate,” betol, or beta-naphthol salicylate,12 and asaprol, or calcium beta-naphthol m o n o ~ u l f o n a t e ~ have ~ some vogue because of their mild taste. Iodoform Substitutes Iodoform14 has been used as a n antiseptic since 1868, and the only drawback to its use is its persistent odor. The first odorless substitute appeared in 1885 under the name of i0d0l.l~ This substance is tetra-iodopyrol and enjoyed much popularity until the appearance in 1890 of a r i ~ t o l , ’ ~ or dithymol diiodide, the lavish advertising of which caused it to become the foremost iodoform substitute. Synthetic Antipyretics With the introduction of antipyrine or phenyldimethyl paraxolon in 1889’ the era of synthetic organic chemicals might be said to have fairly begun. The three groups just discussed are either chemicals discovered in routine research with medical uses later discovered or modifications of such chemicals designed to remove their objectionable features. Antipyrine, however, was a new product, the medical uses of which were published almost simultaneously with its discovery, and since Knorr’s remarkable success investigators the world over have been attempting the synthesis of chemicals with their medical uses directly in mind. Rivals of this immensely successful antipyretic sprang up in large numbers. Some, like antifebrin or acetanilide,lg
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