Product instability nitration reactions

Reaction conditions which allowed for the large scale nitration of 5-Chloro-l,3-dimethy1-lH-pyrazole were developed which minimized the hazards generally associated with nitration reactions. Dilution with sulfuric acid decreased the risk of thermal instability. Using ordinary laboratory equipment, the experimental heat of reaction was determined to be -12,5 Kcal/mole. Likewise, the adiabatic temperature rise was found to be about 20°C, An exotherm was found to initiate at 100°C, The thermal stability and shock sensitivity of the product, 5-Chloro-l,3-dimethy1-4-nitro-lH-pyrazole, was investigated using simple tests. 

Phosphorus w) Compounds. Although the monomeric PO3 ion is severely electron-deficient, S.C.F. M.O. calculations have indicated a greater overlap population in both the a- and ir-systems for this species than in the isoelectronic nitrate ion. In view of this, it has been suggested that kinetic rather than thermodynamic reasons should be sought for the instability of PO3. The formation of monomeric methyl metaphosphate, Me0P02, reported in an earlier volume, has now been substantiated by identifying the methyl ester of p-diethyl-aminobenzenephosphonic acid as the product from the reaction with NN-diethyl-aniline at low temperatures. Substitution into the aromatic ring provided a measure of the electrophilicity of the monomer. 

Another method of preparing azobisindolizines is by reaction with tosyl or picryl azide.191-193 2-Methylindolizine is converted into the 3,3 -bisazo compound after 2 minutes. The product yields the radical ion 130 (detected by EPR) when treated with 1 mole of silver perchlorate.194,195 The redox characteristics of such compounds have been studied by Hiinig and co-workers.196,197 In view of the instability of aminoindolizines, they have not been used to prepare diazonium salts. 1-Nitrosoindolizines, however, yield diazonium nitrates in good yield when treated with dry nitric oxide.182,198 The products are stable both in... 

The major causes of instability of cellulose nitrate are due to the products of hydrolytic, thermal and photochemical reactions. Degradation of the polymer is autocatalytic, that is, the products of breakdown tend to catalyse a faster and more extensive degradation reaction than the primary processes, if allowed to remain in contact with degraded cellulose nitrate. 

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