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Charge Transfer Complex Role in the Formation of Chlorobenzene in the γ‐Irradiated Carbon Tetrachloride‐Benzene System
Author(s) -
SifeEldeen KH. A.,
Ebraheem S.
Publication year - 2007
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.200700204
Subject(s) - chlorobenzene , chemistry , benzene , carbon tetrachloride , radiolysis , charge transfer complex , photochemistry , reaction rate constant , tetrachloride , carbon fibers , analytical chemistry (journal) , organic chemistry , kinetics , catalysis , aqueous solution , physics , materials science , quantum mechanics , composite number , tin , composite material
Abstract The formation of carbon tetrachloride‐benzene charge transfer complex was confirmed by UV and NMR spectrometric studies. A change in UV spectrum of benzene is observed upon addition of carbon tetrachloride. Whereas the appearance of new bands supports the formation of charge transfer complex. NMR study shows that, chemical shift of benzene pmr signal depends on the CCl 4 ‐C 6 H 6 molar ratio. This observation is another criterion for the formation of benzene‐carbon tetrachloride charge transfer complex. Job's Continuous Variation method indicates that a 2:1 CCl 4 ‐C 6 H 6 charge transfer complex (2:1 CTC) is formed. The association constants (K 2:1 ) of (2:1 CTC) was found to be 0.0197 M −2 . The maximum concentration of (2:1 CTC) was found to be in samples with 2:1 CCl 4 ‐C 6 H 6 molar ratio (33% benzene mole). On the other hand the maximum yield of chlorobenzene was obtained, also, upon radiolysis of CCl 4 ‐C 6 H 6 samples at a 2:1 molar ratio (33% benzene mole). Therefore, it could be concluded that (2:1 CTC) participates in the formation of chlorobenzene upon radiolysis of the benzene‐carbon tetrachloride system. This conclusion was supported by the dependence of the chlorobenzene yield of a γ‐irradiated carbon tetrachloride‐benzene system (2:1 molar ratio) on irradiation time according to a third order kinetic equation with a very good linearity (R 2 = 0.9977). Accordingly, the rate constant for the chlorobenzene formation under this condition was found to be ≈ 5.5 × 10 −7 L 2 .mol −2 .h −1 . We propose a radiation chemical mechanism in which the 2:1 CTC plays a role in the formation of chlorobenzene.