Diazomethane reaction with, phosgene

A series of reactions with gases have been selected for the rapid quantification of many of the major products from the oxidation of polyolefins. Infrared spectroscopy is used to measure absorptions after gas treatments. The gases used and the groups quantified include phosgene to convert alcohols and hydroperoxides to chloroformates, diazomethane to convert acids and peracids to their respective methyl esters, sulfur tetrafluoride to convert acids to acid fluorides and nitric oxide to convert alcohols and hydroperoxides to nitrites and nitrates respectively. 

Sulphonic acids and their salts are analysed by GC after esterification with diazomethane or after chlorination with thionyl chloride or phosgene [119]. Reaction with thionyl chloride proceeds according to Scheme 5.14. A 0.5-g sample of sulphonic acid or its salt is placed into a round-bottomed flask fitted with a magnetic stirrer and a reflux condenser, 0.5 ml of dimethylformamide and 20 ml of thionyl chloride are added and the mixture is refluxed for several minutes up to 2 h (according to the character of the sample) until the evolution of gas from the reaction mixture ceases (detection with the aid of a bubbler filled with chlorobenzene). If a salt is chlorinated, solid chloride produced in the reaction mixture must be removed by dilution with dichloromethane and by careful filtration through a fine glass filter. Excess of thionyl chloride and solvent is evaporated carefully under decreased pressure. The residue is dissolved in a suitable solvent (CCU) and analysed by GC (silicone stationary phase, temperature 160°C). 

The reaction of phosgene with diazomethane in a molar ratio of 1 2 gives the previously unknown diazo compound, N2CHC(0)C1 [185] ... 

The initial stages comprise protection of (L)-(+)-cysteine with acetone, t-butoxy-carbonyl chloride (from t-butanol and phosgene) and diazomethane. The first key step was treatment with dimethyl azodicarboxylate, a new reaction, which Woodward found after several attempts (see next page). 

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