Abstract
Gas phase slow combustion of (chloro)benzene in O2/N2 mixtures, and induced by addends such as tert butylhydroperoxide, cyclohexane, or methanol, leads to (chloro)-phenol as the only important aromatic product. Using C6H6/C6D6 mixtures, formation of phenol/perdeuterophenol was studied between 520–1080 K. The temperature dependence of this product ratio was found to obey the Arrhenius expression for the intermolecular isotope effect log kH/kD = −0.14 ± 0.03 + (1240 ± 80)/2.303RT (R in cal/mol K). Essentially the same result was obtained for the intramolecular isotope effect, measuring the change in isomer distribution for the chlorophenols formed from p-deuterio-chlorobenzene versus those for chlorobenzene. These results are in accordance with H(D)-abstraction by ·OH, via a linear transition state, as the first and (relative) rate determining step. Whereas above 1000 K, at reduced pressure, the intramolecular isotope effect continues to prevail, C6H6/C6D6 do not show differences in rate of formation of C6H5OH/C6D5OH. Under these conditions, the only effective reaction of arene to phenol appears to be set in by addition of O(3P).
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
