From Carboxylic Acid Hydrazides and Phosphorous Halides

From Carboxylic Acid Hydrazides and Phosphorous Halides 

The reaction of arylcarboxylic acid hydrazides with phosphorus pentachloride is the classical method of synthesis of hydrazidoyl chlorides I 

This reaction can be conducted either without a solvent or using inert organic solvents, such as chloroform, carbon tetrachloride or methylene chloride, and the yields are quite good. Sometimes, the polarity of the solvents has some influence on the course of the reaction. For example, in the reaction of 2,4,6-trimethoxybenzoic acid-2,4,6-trinitrophenylhydrazide with phosphorus pentachloride in benzene, chlorination of one of the aryl groups occurs, whereas in methylene chloride the desired 2,4,6-trimethoxy-benz-2,4,6-trinitrophenylhydrazidoyl chloride is obtained in good yield ( ). 

6-Trimethoxybenz 2,4,6-trinitrophenylhydrazidoyl chloride ( ). To a suspension of 4g (0.00915 moles) of 2,4,6-trimethoxybenz-2,4,6-trinitro-phenylhydrazide in 100 ml of methylene chloride is added 2.5 g (0.012 mole) of phosphorus pentachloride in 40 ml of methylene chloride over a period of 40 min with ice-cooling and stirring. After stirring for an additional 15 min, the reaction mixture is added to 300 ml of methanol, and, after standing for 13 hours, and crystallization from acetone, 2.75 g (66%) of 

In the reaction of j8-benzoylphenylhydrazone with phosphorus penta-chloride Huisgen et al. added phenol to the reaction mixture in order to generate the hydrazidoyl chloride from the phosphorus-containing intermediate CeHsC Cl)=N—N(POC 2)CeH5. Recently, Stille and coworkers synthesized the bis-hydrazidoyl chloride III by this method 

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A. From Carboxylic Acid Hydrazides and Phosphorous Halides... 

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