

Thermal decomposition 
T 
rate of reaction 
A= constant 
E= activation energy 
R= gas constant 
Oo 
T= K 
In K = In A- E_ 
RT 
Calculation showed that at 55°C the rate of decomposition of 
bidrin became appreciable. Infra-red analyses showed the presence of 
trimethylphosphate, N,N-dimethylacetoacetamide, dimethylamine salt of 
H3P04, polyphosphate, and a compound formed by condensation of two or 
more crotonamide residues. Thus, thermal decomposition of bidrin 
initially produced orthophosphoric acid and its methyl esters. A 
pyrophosphate esterified with methyl groups also seemed to be present. 
Technical bidrin contains measurable amounts of strong acid, 
mainly dimethyl phosphoric acid, and water. On storage, the water 
gradually hydrolyzes the di-ester to produce further acids. When the 
concentration of acid reaches a sufficient level, a self sustaining 
trans-esterification reaction between phosphoric acids and insecticide 
can be initiated (193). 
Studies with azodrin indicated stability of the crotonamide 
group and a mechanism for decomposition different than that for 
bidrin (193). 
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