Methyl isocyanate decomposition products

Reaction of methylenephosphinophosphorane 83 with methyl isocyanate afforded zwitterionic compounds 84, 85 in a ratio 7 1 (Scheme 13) <1995TL2021>. However, the reaction is reversible. In nonpolar solvents the equilibrium is shifted to the cyclic products, while dissolving the latter in polar solvents leads to their decomposition to the starting reagents. If sulfur is added to the reaction mixture, compounds 84 and 85 disappear leaving oxidized compound 86 as the only product. Ethyl isocyanate reacts with compound 83 in a similar manner. 

In APCI mass spectra of carbamates, fragment ions are observed, which are most likely due to thermal decomposition in the heated nebulizer interface and snbseqnent ionization of the thermal decomposition products [11, 14, 20-23]. For example, base peaks were observed at m/z 163 for oxamyl, due to the loss of methyl isocyanate, at m/z 168 for propoxur, dne to the loss of propylene, and at m/z 157 for aldicarb, due to the loss of HjS. The APCI mass spectra of aldicaib and two of its metabolites, aldicarb sulfoxide and aldicarb snlfone, showed significant fragmentation. Major fragments for aldicarb were dne to the loss of carbamic acid (to m/z 116) and due to charge retention at [CH3-S-C(CH3)2]. For aldicarb sulfoxide and aldicarb sulfone, the loss of carbamic acid resnlted in the base peaks of the spectra (at m/z 132 and 148, respectively). 

Substituents of the imino group and the pyridine ring exert an essential influence on the decomposition of the product (see Table V). 2- and 4-Monoalkylpyridine A-ethoxycarbonylimines also yield only diazepines, but the corresponding A-acetylimines156 furnish considerable amounts of N-N bond cleavage products (pyridine and methyl isocyanate). Irradiation of 3,... 

This intermediate (or its ethyl homologue), produced dining the preparation of phosphoryl dichloride isocyanate from interaction of phosphorus pentachloride and methyl (or ethyl) carbamate, is unstable. Its decomposition to the required product may be violent or explosive unless moderated by presence of a halogenated solvent. 

N,N DIPROP YL-4-TRIFLUORO-METHYL-2,6-DINITROANILINE (1582-09-8) Ci3HjsF3N304 Combustible solid (flash point >185 F/>85°C oc Fire rating 1). May react violently with barium, potassium, sodium. Incompatible with organic anhydrides, acrylates, alcohols, aldehydes, alkylene oxides, substituted allyls, cellulose nitrate, cresols, caprolactam solution, epichlorohydrin, ethylene dichloride, isocyanates, ketones, glycols, nitrates, phenols, vinyl acetate. Exothermic decomposition with maleic anhydride. May increase the explosive sensitivity of nitromethane. Reacts with nitroalkanes, forming explosive products. As a dinitroaniline derivative, the extremes of heat (do not store above 90°F/32°C), mechanical shock, and fnction might be... 

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