Synthesis trichloromethane

The reaction of a carboxylic acid with N,Af -carbonyldiimidazolellH33 (abbreviated as CDI), forming an imidazolide as the first step followed by alcoholysis or phenolysis of the imidazolide (second step), constitutes a synthesis of esters that differs from most other methods by virtue of its particularly mild reaction conditions.t41,[5] It may be conducted in two separate steps with isolation of the carboxylic acid imidazolide, but more frequently the synthesis is carried out as a one-pot reaction without isolation of the intermediate. Equimolar amounts of carboxylic acid, alcohol, and CDI are allowed to react in anhydrous tetrahydrofuran, benzene, trichloromethane, dichloromethane, dimethylformamide, or nitromethane to give the ester in high yield. The solvents should be anhydrous because of the moisture sensitivity of CDI (see Chapter 2). Even such unusual solvent as supercritical carbon dioxide at a pressure of 3000 psi and a temperature of 36-68 °C has been used for esterification with azolides.[6]... 

Nevertheless, new examples have also been reported of allenyl sulfoxides [101] and especially allenyl trichloromethyl sulfoxides [39, Y+-X = S(0)CC13] [102]. There have been many trials to use these sigmatropic rearrangements for the synthesis of diallenes (compare 40 — 42), e.g. the reaction of the diols 43 with trichloromethane-sulfenyl chloride 44 to the diallenes 45 (Scheme 7.7) [103]. 

Chloroform (trichloromethane, CHClj). Chloroform was first used as an anaesthetic in 1847 and its narcotic effects on the central nervous are well documented (ref. 4la). It has important applications as an intermediate in the chemical synthesis of a large number of industrial chemicals chlorofluorocarbons, dyes, drugs and pesticides. Its powerful solvent properties and low boiling point (6l°C) have made it a favorite for extractive and purification operations in preparing antibiotics, alkaloids, flavors and vitamins. 

Treatment of a phenol with chloroform (trichloromethane) in the presence of hydroxide ion results in the synthesis of a 2-hydroxybenzalde-hyde through C-formylation. Dichlorocarbene, CCl2, is generated by the action of base on chloroform and this highly reactive electrophile then attacks the phenoxide. The mechanism of the Reimer-Tiemann reaction, is given in Scheme 4.12. 

Trichloromethyl trimethylsilane (trimethylsilyl trichloromethane) [5936-98-1] M 191.6, m 130-132 , b 146-156 /749mm. It distils at atmospheric pressure without decomposition and readily subhmes at 70 /10mm. It has one peak in the m NMR spectrum (CH2CI2) 8 0.38. [Speier J Am Chem Soc 73 824 1951, Hergott Simchen Synthesis 626 1980, Beilstein 4 IV 3892.]... 

Folpet is synthetised from phthalimide with trichloromethane sulfenyl chloride under conditions similar to those of captan synthesis, but the yield of the process and the purity of the product are somewhat lower than is the case with captan, the yield being 85% and the purity of technical folpet 90% (Pfeifer and Kov, 1972). 

Modern carbene chemistry started, however, in a rather unusual way when Hine (1950) conducted a kinetic study of the alkaline hydrolysis of trichloromethane (chloroform). He proposed a two-step a-elimination involving CCI2 as an intermediate. The result of this mechanistic study was unusual because it opened a new field of synthetic organic chemistry, whereas, in general, such studies improve our understanding of fields already known from synthetic work. Mine s dichlorocarbene was subsequently applied to a cyclopropane synthesis by Doering and Hoffmann (1954, see later in this section). 

Chloroform Trichloromethane, CHCI3. Chloroform is a clear, colorless, volatile, nonflammable liquid with characteristic pungent smell. It is toxic and carcinogenic. Derived by chlorination of methane. Formerly used as an anesthetic, it is now used mainly as a solvent and in organic synthesis to manufacture fluorocarbon plastics and insecticides. 

The industrial synthesis of dichloromethane by thermal chlorination also leads to trichloromethane and tetrachloromethane. An optimal yield of this product is obtained by a large excess of methane and/or methyl chloride relative to chlorine. 

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