- Solvent Effect on Kinatics and Reaction Mechanisms. The Formation of Sulphonium and Selenonium Salts
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Second-order rate constants and activation parameters for the methylation of methyl phenyl sulphide and methyl phenyl selenide by dimethyl sulphate have been measured in 14 aprotic solvent covering a wide range of dielectric constants.The same reactivity order is observed with both substrates in the various solvents.The analysis of the medium effects on the reactivity was performed by the Koppel-Palm multi-parameter approach.The results indicate that the polarization and electrophilicity of the solvents are responsible for the rates of both reactions.The higher reactivity of methyl phenyl selenide has been ascribed to the higher polarizability and softness of the selenium atom in comparison with the sulphur atom.
- Maccarone, Emanuele,Perrini, Giancarlo
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- Method for producing 2-(substituted aryl) propionaldehyde
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A 2-(substituted aryl)propionaldehyde of the formula, STR1 (wherein Ar denotes STR2 is produced in high yield by reacting a methyl (substituted aryl) ketone of the formula STR3 with phenyldimethylsulfonium methylsulfate of the formula, STR4 in the presence of alkali metal hydroxide to obtain a reaction mixture containing 2-(substituted aryl)1,2-epoxypropane of the formula, STR5 and thioanisole, and subjecting the reaction mixture to contact with anhydrous MgCl2. The propionaldehyde compound is also produced in high yield by contacting the epoxypropane compound with anhydrous MgCl2 in the presence of a soft nucleophile such as a sulfide, a thiol and a phosphine.
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