Abstract. The reactions of benzene derivatives C,H,X (X = H, CI, CH, and CF,) with hydrazine and ozone in the dark (a source of O H radicals) have been studied in a flow reactor at ambient temperature. (Substituted) phenols were formed, but these were relatively unimportant compared to N-heterocyclic compounds (condensation products of cis-butenedial and analogues with hydrazine) and other (degradation) products. Benzene and (trifluoromethy1)benzene follow a similar path as toluene, also with oxidative ring opening as major reactions.
Abstract. The possible pathways for the formation of (chloro)phenol, following the addition of O( 'P) to (chloro)benzene, have been examined using deuterated substrates: C6D6 (also in admixture with C,H,) and p-deuterochlorobenzene. Whereas with 0 -C6H6 adduct biradicals, loss of H' to give phenoxy radicals predominates, only one-third of the 0 -C,D, intermediates undergo the corresponding reaction. Phenoxy radicals lead to phenol by transfer of an H(D) atom from cyclohexadienyl-type radicals, formed from H' (D') and substrate. Analogously, in reactions of p-deuterochlorobenzene, loss of H is a major reaction after addition of an oxygen atom to a meta position, whereas loss of D (to givep-chlorophenol) occurs only with 35% of the corresponding O( 'P) adduct biradicals. The isotopic composition of phenol formed from p-DC,H4CI (via p-DC,H,O'; generated by @so substitution) revealed that H transfer to phenoxy radicals primarily gives the keto tautomers as major products. Isomerization of (chloro)-benzene-O( 'P) adduct biradicals to the corresponding phenols also appears to involve mainly, keto tautomers. The reaction of O( 'P) with p-deuterochlorobenzene showed a slight change in the o/m/p distribution; this can be explained by the absence of a net secondary H/D kinetic isotope effect for O(3P) addition to the para site and a normal secondary isotope effect for meta addition.
1991atmospheric chemistry, space chemistry atmospheric chemistry, space chemistry V 0340
-296Gas-Phase Reactions of Benzene and Derivatives Triggered by Hydrazine/ Ozone; Hydroxylation vs. Degradation.-The H2N-NH2/O3 system is examined with regard to hydrazine (and derivatives) being high-energy fuels, used as rocket propellants, and atmospheric consequences therefrom. Moreover, the hydrazine/O3 system is a good source of hydroxyl radicals according to the first reaction step: H2N-NH2 + O3 → H2N-NH· + OH· + O2. Benzene derivatives Ph-X (X: -H, -Me, -CF3, -Cl) are used as substrates (in the dark, flow reactor, ambient temp.). Phenols are formed, but are relatively unimportant compared to N-heterocyclic and other degradation products. -(SOL, V. M.; MULDER, P.; LOUW, R.; Recl. Trav. Chim. Pays-Bas 109 (1990) 12, 577-582; Cent. Chem. Environ., Gorlaeus Lab., Leiden Univ., Leiden, Neth.; EN)
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