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Fluorine's First One Hundred Years
| Article
# : |
10407 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
12 / 1986 |
3,938 Words |
| Author
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Harold Goldwhite
Harold Goldwhite is professor of chemistry at California
State University, Los Angeles. |
On June 28, 1886, the august French Academy of Sciences heard the news chemists had been hoping for since the beginning of the nineteenth century. Henri Moissan, a 34-year old French chemist, had finally isolated the element fluorine. This was the "fluoric radical" that Antoine-Laurent Lavoisier, the "father" of modern chemistry, had predicted in 1789 when he produced the first precise definition of a chemical element and the first table of substances that he considered elements. The idea that a new element may be contained in substances as familiar as the mineral fluorspar (calcium fluoride) posed a challenge to the chemists of the early nineteenth century, and numerous attempts to isolate fluorine from its compounds were undertaken.
The celebrated English chemists Sir Humphry Davy and Michael Faraday were among the first to try the method that eventually proved successful--that is, electrolysis, which is the passage of an electric current through a conducting solution of an appropriate fluorine compound. Their experiments were carried out in the early part of the nineteenth century but were not successful. During the succeeding decades, many others tried variants of the electrolytic method and also failed. The extreme corrosiveness and toxicity of the fumes of hydrogen fluoride, the most widely used solvent for these electrolytic experiments, gave the pursuit of fluorine a reputation for danger--and a number of martyrs.
The Irish chemists George J. and Thomas Knox, after three unavailing years of research on fluorine, required a long convalescence. The Belgian chemist Paulin Louyet was less fortunate; he died from complications arising initially from inhalation of hydrogen fluoride vapors. But the search continued. Edmond Fremy, one of Henri Moissan's teachers, made a major advance in 1850 when he showed how water-free hydrogen fluoride could be prepared.
Moissan had trained initially as a pharmacist, and his earliest researches were in the realm of organic chemistry, the chemistry of plants in particular. However, he turned his attention to inorganic chemistry, the chemistry of the mineral world, soon after he received his doctorate in 1880, and this remained his principal field of work for the rest of his career. He started work on fluorine chemistry in 1884 and made rapid progress, isolating novel fluorine compounds containing phosphorus and arsenic. With these he hoped to become successful in the isolation of fluorine itself, but the new compounds did not give conducting solutions either alone or mixed with hydrogen fluoride. He then tried the effects of adding potassium flouride to his solutions, and this
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