The Decomposition of 2,2-Bis(tert-Butylperoxy)-butane under High Pressure

The thermal decomposition of the bifunctional peroxide 2,2-bis(tertbuty1 peroxy)butane was investigated in a flow reactor at temperatures of 135 to 212°C and pressures of up to 2000 bar. The concentration of the peroxide in isododecane was varied between 1 and 22% by weight. The rate of decomposition measured was used to determine the energy of activation (E_A = 151.1 ± 3 kJ/mol) and the activation volume (Δv” = 22.3 mL/mol). Up to a peroxide concentration of 5% by weight, the decomposition takes place according to a firat-order rate equation. Above this concentration, induced decomposition takes effect. Gas chromatographic analysis showed that the liquid decomposition products consisted mainly of acetone and tert-butyl alcohol apart from methyl ethyl ketone, propionic acid methyl ester, acetic acid ethyl ester, tert-butyl methyl ether, and oligomers of the solvent. The gaseous decomposition products consisted of methane and carbon dioxide as well as small quantities of ethane, propane, and ethylene. A theoretical explanation of the mechanism of decomposition is postulated which explains the spectrum of these components and its changes as a function of the peroxide concentration, the residence time, the temperature, and the pressure.