THERMALLY INDUCED DECOMPOSITIONS

During the vacuum fractional distillation of bulked residues (7.2 t containing 30-40% of the bis(hydroxyethyl) derivative, and up to 900 ppm of iron) at 210-225°C/445-55 mbar in a mild steel still, a runaway decomposition set in and accelerated to explosion. Laboratory work on the material charged showed that exothermic decomposition on the large scale would be expected to set in around 210-230°C, and that the induction time at 215°C of 12-19 h fell to 6-9 h in presence of mild steel. Quantitative work in sealed tubes showed a maximum rate of pressure rise of 45 bar/s, to a maximum developed pressure of 200 bar. The thermally induced decomposition produced primary amine, hydrogen chloride, ethylene, methane, carbon monoxide and carbon dioxide. 

Part of the high yield of formaldehyde may arise from the thermal-induced decomposition of hydrogen peroxide which is known (25) to occur in anhydrous methanol. 

TG-IR has also been used to examine the thermally induced decomposition products of polyvinyl chloride (PVC), polyacrylamide, tetrafluoroethylene-propylene, styrene-... 

The results described above clearly reflect the diversity of the possible reactions of acyclic disilenes. The 1,2-aryl migrations in tetraaryldisilenes have not been mentioned as they have already been reviewed in depth6. The same is true for the thermally induced decomposition of the disilene 35 to furnish the silylene molecule Tbt(Mes)Si , the unusual chemistry of which is reviewed elsewhere in this series129. 

In addition to the chemical activation non-equilibrium systems, the thermally induced decomposition of hydrocarbons and hydrocarbon radicals has also been widely encountered. The earliest hydrocarbon reactions to be studied were the thermal unimolecular decompositions of alkanes10 and alkyl radicals11 in which mirror removal techniques were used to demonstrate the actual presence of the radicals. These thermal reaction systems tend to be complex and, despite continued investigation, 12-13 many are not fully understood. 

Thermally Induced Decomposition of Arenediazonium Tetrafluoroborates (Thermal Balz-Schiemann Reaction)... 

Table 10. Synthesis of Fluoroarenes from Anilines via Thermally Induced Decomposition of Complex Diazonium Fluoride Salts ...

Thermally Induced Decomposition of Pure Ammonia Borane... 

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