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Diazonium compound
Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group R-N2+ X− where R can be any organic residue such alkyl or aryl and X is an inorganic or organic anion such as a halogen. Diazonium salts, especially those where R is an aryl group, are important intermediates in the organic synthesis of azo dyes.〔Chemistry of the Diazonium and Diazo Groups: Part 1. S. Patai, Ed. 1978 Wiley-Blackwell. ISBN 0-471-99492-8. Chemistry of the Diazonium and Diazo Groups: Part 2. S. Patai, Ed. 1978 Wiley-Blackwell. ISBN 0-471-99493-6.〕 == Preparation == The process of forming diazonium compounds is called "diazotation", "diazoniation", or "diazotization". The reaction was first reported by Peter Griess in 1858, who subsequently discovered several reactions of this new class of compounds. The most important method for the preparation of diazonium salts is treatment of aromatic amines such as aniline with nitrous acid. Usually the nitrous acid is generated in situ (in the same flask) from sodium nitrite and mineral acid. In aqueous solution diazonium salts are unstable at temperatures above +5 °C; the -N+≡N group tends to be lost as N2 (nitrogen gas). One can isolate diazonium compounds as tetrafluoroborate salts, which are stable at room temperature. Often, diazonium compounds are not isolated and once prepared, used immediately in further reactions. This approach is illustrated in the preparation of an arylsulfonyl compound: :500px It is often preferred that the diazonium salt remain in solutions, but they do tend to supersaturate. Operators have been killed and injured by an unexpected crystallization of the salt followed by its detonation.〔(【引用サイトリンク】title=UK CRHF Incident Report - Supersaturated Diazonium salt causes Fatality )〕
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