Iodobenzene reaction with chlorine

Depending on the reaction conditions, halogenation of thieno[2,3-Z>]pyridine (20) can lead to a variety of products resulting from substitution, addition, and oxidation reactions. 2,3-Dibromo-thieno[2,3-/)]pyridine is produced by the reaction of compound (20) with bromine in an aqueous carbon tetrachloride system and the 2,3-dichloro-2,3-dihydro derivative is formed from the same starting material upon treatment with chlorine in chloroform/water or with iodobenzene dichloride in aqueous acetonitrile (70JHC81, 71JHC931). 

Diaryliodonium compounds can be prepared by acid-catalyzed condensation of iodoso aryls with another aryl molecule (equation 129). Another method is the use of iodine trichloride in reaction with organometalUc compounds (equations 130 and 131). RICI2 may be prepared by direct chlorination of RI (R = CF3CH2, CHF2(CF2)sCH2) and these materials can be used to chlorinate iodobenzene to give the less hydrolytically stable compound PhICl2. ... 

Chlorination of alkynes. The reaction of iodobenzene dichloride with alkynes (CHCI3, reflux, azobisisobutyronitrile initiation) results in anri-addition to give E-dichloroalkenes (equation I). Use of chlorine (ionic or radical) leads to complex mixtures. ... 

Historically, (dichloroiodo)benzene, PhICh, was the first reported organic compound of polyvalent iodine. It was prepared by Willgerodt in 1886 by the reaction of iodobenzene with ICI3 or, preferably, with chlorine... 

C6H5C1, is produced commercially in the liquid phase by passing chlorine gas into benzene in the presence of molybdenum chloride at 30—50°C and atmospheric pressure. This continuous process yields a 14 1 ratio of chlorobenzene to dichlorobenzene [106-46-7], C6H4C12. The reaction ofiodine with benzene takes place only in the presence of oxidizing agents such as nitric acid. Iodobenzene [591-50-4], C6H5I, is thus produced from reaction of benzene,... 

The addition of chlorine and bromine or the epoxidation of 4,7-dihydro-l,3-dioxepins 46 has already been described in CHEC-II(1996). Treatment of 46c with iodobenzene diacetate and A-aminosuccinimide in MeCN yielded a mixture of exo- and OT -A-amino-substituted aziridinodioxepanes 22c (Scheme 1) <2005AXC705> (cf. Section 13.11.3.2). The diastereomeric mixture was easily separated by column purification of the crude reaction product. 

The evolution of the mass spectra of the ion-molecule reaction products of m/z 77 ions with ammonia as a function of the nature of the precursor halobenzene is also of interest. The m/z 94 m/z 93 branching ratio measured as 22 78 for the chlorinated precursor becomes 30 70 for the brominated precursor and 49 51 for the iodinated precursor. Moreover, this ratio is still significantly modified (60 40) if ionized iodobenzene is prepared by charge exchange with methylene chloride in the Cl source. The degree of fragmentation of the m/z 94 ions thus appears extremely dependent on the distribution energies of the precursor m/z 77 ions, but the occurrence of isomeric species of the phenyl cation cannot also be ruled out completely. 

Lower yields were obtained in acetonitrile or nitromethane the reaction of trimethylcyclo-propene with molecular chlorine under various conditions also resulted in ring opening, although addition of iodobenzene dichloride gave a 1,2-dichlorocyclopropane. 

From a study of the kinetics of bromination of cycloalkenes, it was concluded that bromination of cyclohexene and cyclopentene proceeds via a cyclic bromonium ion whereas bromination of cyclo-octene proceeds via an a-bromocarbenium ion. Chlorination of conjugated dienes with iodobenzene dichloride gave mixtures of 1,2- and 1,4-dichlorides via radical reactions, e.g. a mixture of cis- and trans-3,4- and -3,8-dichlorocyclo-octenes was obtained from cyclo-octa-1,3-diene. ... 

Full details (see Vol. 1, p. 185) of the Japanese work on the preparation of trifluoromethylarenes from trifluoroiodomethane and iodoarenes in the presence of copper powder and a dipolar aprotic solvent have become available, and it appears that the best solvent in some cases is pyridine. This method (but with DMF as solvent) has also been used to prepare the compounds PhR [R = Me03C (CF3)3, CF3 0 (CF2)2, or perfluoro-2-tetra-hydrofurfuryl] in good yields from iodobenzene and the corresponding polyfluoroiodo-compounds. Perfluoroalkyl-copper compounds are very probably involved in such reactions, and the reactions of preformed n-perfluoroheptylcopper in dimethyl sulphoxide with the aromatic carbon-hydrogen bonds of benzene, toluene, p-xylene, nitrobenzene, and chlorobenzene also lead to (perfluoroalkyl)arenes (some replacement of chlorine occurs in the case of chlorobenzene). Homolytic substitution by perfluoro-heptyl radicals, perhaps within the co-ordination sphere of the copper atom,... 

Several procedures exist for the synthesis of a-chloro thioethers and sulfoxides. The solid iodobenzene dichloiide [phenyliodine(III) dichloride] reagent is a convenient source of positive chlorine, and the lipophilic iodobenzene by-product can be recycled. Colonna and cowoikers have reported reactions of sulfoxides with iodobenzene dichloride and investigated the stereochemistry of a-chloro sulfoxides obtained und various conditions. ... 

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