Jean Timrnermans University of Brussels Brussels, Belgium Translated bv Raloh E. Oesoer University of Cincinnati Cincinnati, Ohio
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Frederic Swam (1866-1940)
Frederic Swarts devoted his entire professioual career to the University of Ghent, where he was a student under his father who had been the collaborator with and eventually the successor t,o -4ugust Kekule.' Frederic Swarts exemplified tenacity of effort and work, having acquired the degrees of Docteur ell Sciences and later Docteur en MBdecine. He ascended one by one all of the steps in an academic and university career, and eventually became the President du Comit6 National Belge de Chimie and Prbsident du Comite Scientifique de 171nstitutInternational de ChimieSolvay. He was competent in both organic and physical chemistry, and will always he renowned as the real creator of t,he chemistry of organic fluorine compounds. Before Swarts had entered this field, Beilstein described a mere dozen such compounds in his Handbuch; eventually Swarts added 40 more, including the parent "Freon" in 1907. The preparation of fluorinated organic derivatives for many years had been acknowledged to be most difficult. Hydrofluoric acid does not atstack the hydrocarbons; in addition it is difficult to handle because of its attack on glass. The use of elemental fluorine, which had been isolated in useful amounts by Moissan, required platinum equipment. Consequently, an indirect method had to be devised to overcome these difficulties. It was necessary to start with a chlorinated or iodinated derivative and then to introduce the fluorine by substitution. For this purpose Swarts prepared a wide variety of previously unknown compounds containing halogens, and used them as starting materials for the preparation of the corresponding fluorine compounds. At first he used a mixture of bromine and antimony trifluoride, later he employed antimony fluochloride, and finally mercury(1) fluoride. I n aromatic compounds, the fluorination of a side chain goes more readily. Swarts isolated trifluotoluic acid which on oxidation yielded trifluoroacetic acid. Eventually he succeeded in preparing fluorobromo-chloro-methane (CHFBrCI),an asymmetric compound. Unfortunately, the antipodes racemize too rapidly to permit the isolation of the optically active forms. 'See GILLIS,J.,
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JOURNAL, S 38,
121 (1961).
Frederic Swartr
Being thus provided with a considerable stock of original materials, he hegan to study the most characteristic properties from the physical chemical standpoint. He showed that fluorine behaves like the other halogens but sometimes uniquely. For example, the acidifying function is much stronger in the fluorinated derivatives than in the corresponding chlorine or bromine organic compounds. With the aid of strychnine, he made the first resolution of a molecule containing two carbon atoms, namely, fluorochlorobromo-acetic acid. The C-F bond was found to he especially strong. Molecules containing it associate very little, have low surface tension, and very low boiling points. For example, trifluoroacetyl fluoride boils a t -5Q°C, whereas acetyl fluoride boils a t +20.5'C. In 1919, Swarts began to study the heats of combustion of fluorinated compounds and verified the high heat of formation of such compounds. For example, the heat of formation of carbon tetrafluoride is 200 kcal/mol, double that of carbon dioxide. The many years of dealing with these compounds had gradually affected his respiratory system, and a t the close of his career he found it imperative to spend the winters in a warmer climate than that of Belgium. However, the occupation of Belgium by the Germans in the spring of 1940 prevented Swarts from taking his usual trip and he died during the following winter.
Volume 38, Number 8, August 1961 / 423
