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Water‐Catalyzed Dehalogenation Reactions of the Isomer of CBr 4 and Its Reaction Products and a Comparison to Analogous Reactions of the Isomers of Di‐ and Trihalomethanes
Author(s) -
Zhao Cunyuan,
Lin Xufeng,
Kwok Wai Ming,
Guan Xiangguo,
Du Yong,
Wang Dongqi,
Hung Kam Fa,
Phillips David Lee
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200400695
Subject(s) - chemistry , photodissociation , photochemistry , catalysis , reaction mechanism , chemical reaction , formaldehyde , halogenation , reaction intermediate , ultraviolet , acetonitrile , inorganic chemistry , organic chemistry , physics , quantum mechanics
A combined experimental and theoretical study of the UV photolysis of a typical tetrahalomethane, CBr 4 , in water and acetonitrile/water was performed. Ultraviolet photolysis of low concentrations of CBr 4 in water mostly leads to the production of four HBr leaving groups and CO 2 . Picosecond time‐resolved resonance Raman (Ps‐TR 3 ) experiments and ab initio calculations indicate that water‐catalyzed OH insertion/HBr elimination of the isomer of CBr 4 and subsequent reactions of its products lead to the formation of these products. The UV photolyses of di‐, tri‐, and tetrahalomethanes at low concentrations in water‐solvated environments are compared to one another. This comparison enables a general reaction scheme to be deduced that can account for the different products produced by UV photolysis of low concentrations of di‐, tri‐, and tetrahalomethanes in water. The fate of the (halo)formaldehyde intermediate in the chemical reaction mechanism is the key to determining how many strong acid leaving groups are produced and which carbon atom final product is likely formed by UV photolysis of a polyhalomethane at low concentrations in a water‐solvated environment.