Pyrolysis of model compounds of the flame retardant poly(N‐dimethylphosphonomethyl acrylamide)

Abstract

AbstractAn investigation of the thermal decomposition of N‐dimethylphosphonomethyl amides has shown that the major volatile products for decomposition above 300°C are methanol, the methyl ester of the carboxylic acid, the nitrile, the carboxylic acid, the N‐methyl amide, and the N,N‐dimethyl amide. Also, benzoic acid was the only volatile product detected in the decomposition of α‐benzamidomethylphosphonic acid. A mass balance for the decomposition of N‐dimethylphosphonomethyl benzamide at 420°C showed methanol and methyl benzoate to be the major volatile products. Methanol and benzonitrile formation increased with an increase in temperature at a faster rate than the other volatile products. The reaction of amides and phosphonates was further studied using sealed tubes in a furnace. Reaction of N‐methylbenzamide with dimethyl methylphosphonate at 307°C in a sealed tube produced methyl benzoate and N,N‐dimethylbenzamide. N,N‐dimethylbenzamide and dimethylmethylphosphonate were also shown to produce methyl benzoate at 310°C. After a 5‐min period more methyl benzoate was produced in the N,N‐dimethylbenzamide reaction than in the N‐methylbenzamide reaction. Also, addition of ethanol to the N,N‐dimethylbenzamide/dimethyl methylphosphonate reaction resulted in less ethyl benzoate methyl benzoate after heating at 310°C.