Halogen-substituted compounds

The transformation of 1,2,4-thiadiazoles bearing a reactive substituent such as amino or halogen group in the 5-position is the most useful method for the synthesis of 5-substituted 1,2,4-thiadiazole derivatives. The latter compounds can be reacted with nucleophiles to afford a wide range of derivatives this is not the case for 3-halogen-substituted compounds. 

The isothermal compressibilities (in GPa 1) of solvents calculated from Eq. (3.8) plotted against the experimental values. Dots ( ) pertain to hydrocarbons upright triangles (A) to hydroxy compounds, circles ( O) to oxy-compounds, squares ( Q ) to halogen substituted compounds, and downward pointing triangles (V) to nitriles and amines... 

To determine the contribution of solvent to the proton shifts of halogen-substituted compounds, the shifts of haloformic protons (CHC13, CHBr3 and CHI3) have been measured in 24 -electron donor solvents1. The effect of hydrogen bonding on the proton shift... 

Among benzene derivatives, halogen-substituted compounds have been extensively studied and in the structure-reactivity studies " carried out on the reaction of OH and SO with the ortho and meta isomers of dichloro and dibromobenzenes and mono-bromotoluenes, the formation of substituted hydroxycyclohexadienyl radical was observed to be the major reaction channel. The bimolecular rate constants obtained for the reaction of OH with substituted halobenzenes are in the range (1.7 to 9.3) x 10 dm mol s. The rate constants obtained are found to follow the Hammett relationship for the reaction of OH with substituted halobenzenes and the p was found to be -0.5, indicating that OH radicals react by addition to the benzene ting. 

Sai i jSbi is equal to the cohesive pressure since the atomic vblume Vm is proportional to b, and additivity of atomic volumes is assumed, they found Tb=k2(Sai yi2JVa=k42Va. For additivity of b.p. for halogen substituted compounds, must be the same for each halogen. For tetrahalogen... 

R-S-CO-Ar 1680-1665 5.88-6.01 vs m Orrto-halogen-substituted compounds absorb at higher frequencies... 

Halogen-Substituted Compounds. Elving and co-workers [22, 83] investigated the reduction of meso- and racemic dibromo-succinic acids at a mercury cathode. At all pH values the meso acid gave only fumaric acid, i,e., trans-elimination of bromine occurred. Racemic dibromosuccinic acid gives various products depending on the pH fumaric acid alone is also formed in strongly acidic and alkaline solutions, i.e., cis-elimination of bromine occurs, but at pH values between 0.4 and 6.9 a mixture of fumaric acid and maleic acid is formed, and the latter is the main product at pH 4 (70% yield). 

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