Toxic gases, 10 Yield point

Some of the important factors to consider in the development of alternative physical blowing agents are solubility, permeability, boiling point, vapor pressure, flammability, toxicity, VOC, ODP, GWP, availability, and cost. Similarly, the key important factors to be considered in the selection of CBAs for a given polymer are decomposition temperature, gas yield, rate of gas release, environmentally acceptable decomposition products, toxicity, and dispersability in the polymer matrix. 

Diazomethane methylation is a good way of making methyl esters from carboxylic acids on a small scale because yields are excellent and the only by-product is nitrogen. However, there is a drawback diazomethane has a boiling point of-24°C, and it is a toxic and highly explosive gas. It therefore has to be used in solution, usually in ether the solution must be dilute, because concentrated solutions of diazomethane are also explosive. It is usually produced by reaction of N-methyl-N-nitrosourea or N-methyl-N-nitrosotoluenesulfonamide with base, and distilled out of that reaction mixture as an azeotrope with ether, straight into a solution of the carboxylic acid. 

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