19121-63-2Relevant articles and documents
C-C and C-H Bond Splits of Laser-Excitated Aromatic Molecules. 1. Specific and Thermally Averaged Rate Constants
Brand, U.,Hippler, H.,Lindemann, L.,Troe, J.
, p. 6305 - 6316 (1990)
Toluene, m-,o-,and p-xylene, mesitylene, ethyl-, isopropyl-, and tert-butylbenzene were irradiated by nanosecond laser flashes at 193 nm.After fast internal conversion to the electronic ground state, the molecules dissociate by C-C or C-H bond splits.The
Kinetics of the reaction of the TEMPO radical with alkylarenes
Opeida,Matvienko,Bakurova,Voloshkin
, p. 900 - 904 (2007/10/03)
The kinetics of the reaction of the stable radical 2,2,6,6- tetramethylpiperidine-N-oxyl (TEMPO) with a series of alkylarenes containing primary and secondary benzyl C-H bonds was studied by ESR, and the reaction rate constants were determined. The scheme
Laser photolysis investigation of induced quenching in photoreduction of benzophenone by alkylbenzenes and anisoles
Oekada, Kafsuji,Yamaji, Minora,Smzuka, Haruo
, p. 861 - 866 (2007/10/03)
The quenching processes of triplet benzophenone (JBP) by alkylbenzenes (AB) and anisole derivatives (AD) in benzene (Bz) and a mixture of acetonitriie (ACT-,) and water (4 :1 v/V; have been studied on the basis of rate constants and efficiencies determined by nanosecond laser flash photolysis a; 355 n m at 295 K. It was found that (1) the deactivation of 3BPby ADs in ACN H2O (4 :1 v/v) was governed by electron transfer (ET) to produce the benzophenone anion (BP'~) and corresponding cation (AD' + ) radicals wiih efficiencies, atj 1 whereas no chemical species were formed in Bz; and 2) photoreduction of 3BPby ABs resulted in benzophenone ketyl radical (BPK) formation by benzylic hydrogen abstraction (HA) with efficiencies XHA 1 in 3z and ACN-H2O (4 :1 v/v). The residual efficiency (a: 1 -ET or ! -aH/1) was attributed to a birnolecular process with no photochemical product, which was named 'induced-quenching (IQf. The quenching rate constants (Jcq) of ;'BPby ADs and ABs were less than the diffusion limits of both Bz and AC1~H2O (4 :1 v/v). The net bimolecular rate constants for the ET, HA and IQ processes were estimated from the k values and efficiencies. The rate constants (%T and k,Q) of ET and IQ with AD versus the oxidation potential (￡) of AD followed Rchm-Weller behaviour while logarithmic rate constants {/CHA and ki(j) of HA and IQ by ABs increased linearly with a decrease in the Em of AB. It was suggested, for the deactivation mechanism of 3BPby ABs and ADs (RH), that ;1) the IQ process was intersystem crossing (ISC) enhanced by the partial charge transfer (CT) character of the triplet excipiexes, 3(BP"~- A-RHa + )a,e; (2) radical ion formation by ET might be accomplished in a polar solvent by further CT interaction in the excipiex; (3) the process of BPK formation was inferred to be H-atom transfer in the exciplex, where the more protic H-atom was readily mobile, rather than ET followed by proton transfer and (4) the loss of efficiencies of photochemicalproduct formation was derived not from back ET but from the IQ process, inherent to photoreactions, via triplet excipiexes. The deactivation processes of 3BPby RH are illustrated in Scheme 1. I ET BP'- + RH'(3BP' + RHJcoj -3(BPO- RHg,.-BPK 4 R' BP + RH Scheme 1.
