Benzin, Benzine, Benzene, Benzol, Benzole and Benzoline.
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Much confusion seems to exist between these terms, and the recent discussion in the " Chemist and Druggist " did not quite clear it up. For years I have collected data regarding these terms, haying made this a hobby, and I. give an abstract of the most important.
Michael Faraday discovered in 1825 a peculiar liquid, which was deposited by the condensation of ordinary coal gas, and the following account of the discovery is given by Professor Wilhelm Ostwald in his fourth lecture, delivered in the Department of Chemistry of Columbia University, New York City, in 1906 :— " Illuminating gas was just introduced in Berlin, but the gas was not sent through pipes in the streets as now, but was compressed in copper cylinders and brought from house to house, just as beer or any other liquid. This cylinder was connected with the user's pipe system, and the gas was used as long as it lasted. Now, the company that was making and distributing this gas was much annoyed by the fact that liquids separated out in the cylinder of compressed gas and decreased the lighting power. Some of this liquid was sent to Faraday that he might investigate, and, if possible, devise some means by which the trouble could be avoided. Faraday investigated this liquid. I cannot tell what he found, but would only like to mention that he, among other things, found benzole, and that this was an independent discovery of benzole, for it had also been discovered in quite another way."
Faraday gave this liquid the name " bicarburet of hydrogen," the old formula being CI, H„, which, of course, has since been changed to Co Ho. About the same time Eilhard Mitscherlich, Professor of Chemistry at the University of Berlin, obtained the same liquid by the distillation of a mixture of benzoic acid and lime. Mitscherlich proposed the name " benzine "—benzoin-like, on account of its aromatic odour. Faraday, however, objected to this name, especially the end syllable, " me" as being too similar to the distinctive name of the alkaloids. Faraday accordingly called this liquid " benzoic." The French, however, adhered to Mitscherlich's name, and even to-day call benzole " la benzine." Thus, Violette, in " Dictionnaire des Analyses Chimiques," 1851, Vol. I., p. 152, says : " Benzine voyez benzole "; p. 154, "benzole C12 Ho syn.: benzine, benzene, phenc." It is not unusual to find the English translation of a French article speaking of benzin, when the French original states " la benzine," which means benzole.
In Italy we also find confusion regarding these terms. Orosi, " Farmacologia Italiana," states, P. 1549, " Benzolabenzina, phew, idr. dm benzola C,, 113 H ; p. 161o, under petroleum distillates, " benzina, benzolina, nafta, etc., sp. gr. 0.720." There is one Continental Pharmacopeeia, the Portuguese, which even gives the official title " benzinam " to a benzole of sp. gr. o.85 and b. pt. 85 deg.
In Germany, Austria, and other countries there exists no confusion. Petroleum benzin is called " benzin." The official title in D.A.B. IV. is benzinum petrolei, and in Ph. Aust. III. is ther. petroli. Coal-tar benzine, on the other hand, is named benzol; official title, " benzolum," sp. gr. o.88o to o.89o, and b. pt. So deg. to 82 deg. The Erganzungsbuch III. (supplement to Germ. Pharmacop.), on p. 44, also gives as a synonym for benzolum the name " pyroleum benzinum," which is the official title for a rather impure benzole in the Swedish Pharmacopeia. In all Germanspeaking countries it is clearly understood that benzin means petroleum benzin, and benzol means coal-tar benzene. When we cross the Channel to Old England, there we find great confusion. We not alone have benzine, benzene, and fsenzol, but we also have found benzoline. In the first place we have the British Pharmacopteia " benzol." This is a mixture of homologous hydro-carbons obtained from the light coal-tar oil. It contains about 70 per cent. benzene,
Co Ho, and 20 per cent. to 3o per cent. toluene. C. CH:s This pharmacopwial benzol is. used as a solvent in thc preparation of eharta sinapis and also liquor caoutchouc; besides, the commercial benzol is the starting-point in The preparation of aniline dyes, etc. Among the English literature on the confusion of the terms benzine, benzol, and ben
zoline, I select the following : A. H. Allen, in the " Analyst;" 1879, No. 43, and in the " Chemist and Druggist," 188o, p. 38o; Proctor, " Pharmaceutical Testing," p. o; MacEwan, " Pharmaceutical Formulas," 1899, p. 299; Hurst, in " Garment Cleaning "; and McGowan, in his translation of Meyer's " History of Chemistry," p. 457—all show confusion of the terms.
From this chaos in Great Britain we cross the ocean, and in the new land, America, we get new ideas. Here there is no confusion between the petroleum and the coal-tar products, except in some old books. Mitscherlich's term " benzine " for benzole was discarded over here long ago. Benzine to-day, and for a long time in U.S., means always petroleum benzin, while benzoic is the name for the coal-tar product C5 Hs, and thus these two terms can be readily distinguished. The United States being the home of the American petroleum or crude oil, benzine is very cheap (about 15c_ per gal. = 228 fluid oz.), and is used extensively, particularly as a cleansing fluid. However, the American, as well as foreign, druggists sometimes get confused on the difference between benzin, naphtha, and gasoline. In a paper read before the American Pharmaceutical Association Iii 1905 I described a simple method of distinguishing these three similar hydrocarbons—namely, by their sp. gr. or I3aume hydrometer reading. Benzole C.P., crystallisable C, Ho. costs, on the other hand, 75c. per gal. It is used but little—in fact, is little known by the laity. Very few druggists indeed sell benzole. The much-confusing term " benzoline," I am glad to say, is not known or used in the United States. Formerly, and to some extent even now, the word in " petroleum benzin " was written " benzine," which name was, for instance, persistently used by the manufacturers, the Standard Oil Company, who have, however, now changed it. The brand formerly known as 62 deg. benzine is now called P. and V.M. naphtha (painters' and varnish-makers' naphtha). This change in name very likely was made to comply with the Pure Drugs Act, as the brand is not identical with U.S.P. benzin. The term benzole was also formerly written benzol. This is how the change occurred. The American Association for the advancement of Science, at its meeting in 1887, appointed a committee to consider the question of attaining uniformity in the spelling and pronunciation of chemical terms. The work required extensive correspondence and detailed discussion exhausting over four years, when in 1891 rules were adopted by the Association and recommended to chemists generally in the hope that they would cordially unite in the efforts to bring about uniformity in usage. The following rules pertain to benzin and benzole
1. The end syllable " me " should be used exclusively for alkaloids, In neutral bodies the final "c " should be dropped. " Benzine" should be "benzin."
2. Terminations in " ol " should be used exclusively for alcohols.
3. Terminations in " ole "; its use is limited to compounds which arc not alcohols—for instance, " benzole."
4. Among the list of words which should be avoided in
favour of the following synonyms, we find glycerin glycerol, henzol = benzene. For this reason the U.S. P. VIII. adopted the following nomenclature : benzinum = petroleum benzin: benzene or benzole. Co He.
Judging, however, frinn the correspondence in the " Chemist and Druggist," the confusion between the terms benzine, benzole, and benzoline in England is very great. Therefore ,yhy not use Faraday's term " benzoic " for the coal-tar product, and the term " benzine," or, still better, " benzin," for the petroleum distillate? Thereby all confusion would be avoided.----Oiro RACI3ENIIEIMER (in " The Chemist and Druggist ").