Formaldehyde
Formaldehyde, HCHO, is the simplest member of the class of organic compounds known as aldehydes. At room temperature formaldehyde is an extremely reactive colorless gas with a suffocating odor. It is commonly sold as an aqueous solution (formalin) or in solid polymeric forms (paraformaldehyde and trioxane). Formaldehyde is used in the manufacture of dyes, in the production of synthetic resins, and in embalming and as a preservative for biological specimens.
Formaldehyde was first intentionally produced by August Hofmann, a German chemist (1818-1892), in 1867. Justus von Liebig had researched aldehydes earlier but had never succeeded in producing formaldehyde. Alexander Mikhailovich Butlerov (1828-1886) had hydrolyzed methylene acetate while trying to form methyl glycol and produced formaldehyde gas. He had noted that the product of the reaction behaved as an aldehydes. Hofmann, in 1867, exposed a mix of methyl alcohol vapors and air over a hot platinum spiral to form stable formaldehyde. Formaldehyde today is produced either from methanol, as Hofmann did, or by oxidizing hydrocarbons.
Hofmann, who had studied chemistry with Liebig in Germany, went to England in 1945 to supervise the Royal College of Chemistry. Although Hofmann was an excellent lecturer, teacher, and practical chemist, he was awkward in the laboratory. As a consequence he was especially concerned with hiring assistants who possessed good laboratory techniques.
Hofmann's doctoral dissertation focused on coal tar and its derivatives. He and some of his students, including William Perkin (1838-1907), Johann Peter Griess (1829-1899), continued this research in later years, studying benzene and alkyl amines. Hofmann discovered quaternary ammonia salts, investigated isocyanates, from which formaldehyde was produced. Hofmann and his students began Britain' s synthetic dye industry, when Perkin developed aniline purple while trying to create quinine. They all profited from the development of synthetic dyes. Hofmann personally discovered fuschine (1862) and aniline blue (1863), both important dyes that replaced natural dyes.
Formaldehyde forms a colorless gas with an irritating odor. It is commonly used for embalming, preserving biology specimens, and disinfecting, and is also used in the production of urea resins, organic dyes, and Bakelite. Fumigating candles are made of solid formaldehyde. It is most often used in the form of formalin, formaldehyde gas dissolved in water.
Due to health concerns, in 1992 the Occupational Safety and Health Administration (OSHA) lowered the legal exposure limits for formaldehyde from 1.0 parts per million to 0.75 parts per million. Nonetheless, the U.S. formaldehyde market remains strong with production anticipated to reach 12 billion pounds annually by the end of the century.
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