Thermal decomposition of cyclic organic peroxides in pure solvents and binary solvent mixtures

Abstract

The thermal decomposition reaction of acetone cyclic triperoxide, acetone cyclic diperoxide, 4-heptanone cyclic diperoxide, and pinacolone cyclic diperoxide ca. 0.02 M was studied in pure solvents (acetone and 1-propanol) and in binary mixtures of acetone/1-propanol at 150 • C. The kinetics of each system was explored by gas chromatography (GC) at different solvent compositions. The reactions showed a behavior accordingly with a pseudo-first-order kinetic law up to at least 90% peroxide decomposition. The main organic products derived from these thermolysis reactions were detected by GC analysis. Among them, the corresponding ketones, methane, ethane, and propane were the main identified products. The rates of decomposition of pinacolone diperoxide in the pure solvents were practically independent of the solvent characteristics, so it was of no interest to analyze its kinetic behavior in binary solvent mixtures. In acetone/1-propanol mixtures, the solvation effect on the cyclic peroxides derived from 4-heptanone and acetone molecules was slightly dominated by specific interactions between 1-propanol and a diradical-activated complex initially formed. This species was preferentially solvated by 1-propanol instead of acetone. Specific interactions between the O atoms from the peroxidic bond and the H from the OH in 1-propanol can be taken into account. C

Mono, Di and Trifunctional Cyclic Organic Peroxides: The Effect of Substituents and Ring Size on their Thermolysis in 1,4-dioxan

“…substituents of the tetraoxacyclohexane ring in 7 clearly stabilizes the molecule, probably because it is confined in a compact solvent cage where the recyclization reaction is highly probable. Similar kinetic results have been obtained in previous works while studying the thermal decomposition in benzene, [15] toluene, [16] acetone, and propan-1-ol, [17] which demonstrates that 7 decomposes at the lowest rates in comparison with those cyclic peroxides with voluminous substituents (e.g., n-propyl, tertbutyl, and phenyl) (Table 4).…”

“…Diperoxide 6 has shown a very high reactivity not only in 1,4dioxan (Table 1) but in aprotic non-polar (toluene), [16] aprotic mildly polar (acetone), and protic solvents (propan-1-ol) (Table 4), [17] probably because of the presence of the bulky tert-butyl groups which causes a particular substituent effect on the rate constant values assigned to the O-O bond linkage. The thermal stability of 6 in solution appears close to that observed for voluminous trioxanes 1-3 rather than diperoxides 7 and 8 with similar van der Waals volumes (Fig.…”

Effect of ionic liquid on the thermal decomposition of cyclic organic peroxides

“…Regarding the kinetic and thermodynamic studies on the thermal decomposition of DEKTP and PDP in solution of solvents with different physicochemical properties Cañizo, 2006;Iglesias et al, 2010), the decomposition reactions obey a pseudofirst order kinetic law up to more than three half-lives for both peroxides, showing that there are no contributions from second order processes. Moreover, it was found that these cyclic peroxides thermally decomposed in solution by the homolytic cleavage of one of the O-O bonds generating a biradical intermediate (Scheme 2) which, in later stages, can be decompose following different routes Cañizo, 2006).…”

Thermal decomposition reaction in ethanol solution of deuterated acetone cyclic diperoxide and acetone diperoxide. Secondary inverse isotopic effect

“…1). 9,[12][13][14][15][16] It is very improbable that the biradical-activated complex would be solvated to the same extent as the starting material since differences in the electronic configuration, and therefore polarizability, should exist. The differential solvation of starting material and biradical--activated complex should lead to a difference in the reaction rate and subsequently in the activation parameter (e.g., energy of activation).…”