Edwin C. Friedrich

A Convenient Synthesis of Ethylidine Iodide

Abstract Ethylidine iodide has recently become of considerable importance for use as a synthetic reagent. This is due to the discovery by Furukawa and coworkers1 that ethylidine iodide can be used, via reaction with diethylzinc, for addition of ethylidine groups onto the double bonds of olefins to yield the corresponding methyl substituted cyclopropanes.2

Quaternary ammonium bromide catalyzd chloride for bromide redistributions between carbon of alkyl halides and tin of tri-n-butyltin halides

Abstract Quaternary ammonium bromides have been found to strongly catalyze reversible chloride for bromide substitution reactions by tri-n-butyltin chloride on benzyl bromide and n-octyl bromide. However, they have only a small effect upon the rate of the corresponding reaction with benzhydryl bromide. It is suggested that the catalytic effect involves initial coordination of bromide ion with tri-n-butyltin chloride to form a nucleophilic anionic complex containing pentavalent tin which is reactive for backside displacements at carbon of sterically unhindered alkyl halides. No catalytic effects could be demonstrated, however, for ligands such as pyridine or N , N -dimethylformamide which could potentially form zwitterionic complexes with tri-n-butyltin chloride.

Halogen redistribution reactions between alkyl halides and trimethylsilyl iodide

Abstract Trimethylsilyl iodide has been found to react rapidly at 50°C with 1-fluorooctane, 2-fluorooctane and benzyl fluoride to produce the corresponding octyl or benzyl iodides and trimethylsilyl fluoride. Also, it reacts rapidly and cleanly with t-butyl chloride or bromide to form t-butyl iodide. However, it does not react readily with the 1-octyl, 2-octyl, benzyl or allyl chlorides or bromides. We have discovered that tetra-n-butylammonium iodide catalyzes the reactions of primary alkyl chlorides or bromides with trimethylsilyl iodide, and molecular iodine catalyzes the reactions of secondary and tertiary alkyl chlorides and bromides. However, tetra-n-butylammonium iodide slows down the reactions of secondary and tertiary alkyl chlorides and bromides. Mechanistic pathways are suggested for each of the various types of halogen redistribution processes encountered.

Chloride for bromide substitutions on carbon utilizing tri-n-butyltin chloride

Abstract A new halogen for halogen substitution reaction on carbon utilizing tri-n-butylin halides is reported. The substitutions proceed to equilibrium positons rather than to completion. Mechanistic investigations indicate, at least for benzhydryl and secondary benzyl type bromides, that the substitutions using tri-n-butylin chloride proceed via rate determining organotin halide assisted alkyl halide ionization for both the forward and reverse reactons.

Metal-halogen bonding studies with group IV A trialkylmetal halides

Abstract Halogen redistribution reactions have been found to take place between benzyl bromide or benzyl iodide and the Group IVA silicon, germanium, tin, and lead containing triakylmetal chlorides. However, for the reactions of the Si, Ge and Sn compounds, a quaternary ammonium halide catalyst was necessary to enable the equilibria to be established at reasonably rapid rates. The equilibrium constants at 50°C have been measured for each at these halogen redistributions. They have been found to increase gradually on going down in Group IV A from silicon to lead, being considerably less than unity in the case of silicon and somewhat greater than unity in the case of lead for both the R 3 MCl + BzBr and R 3 MCl + BzI reactions. The Δ G ° values for these equilibria have been calculated, and it is suggested that their differences may be explained in terms of the relative importance of p π d π contributions to the halogen—metal bonding in the various Group IV A trialkylmetal halide systems.

Convenient one-step syntheses of tri-n-butyltin bromide or iodide and di-n-butyltin dibromide or diiodide from the corresponding organotin chlorides

Abstract Tri-n-butyltin bromide or iodide and di-n-butyltin dibromide or diiodide may be conveniently prepared from the corresponding organotin chlorides by tetra-n-butylammonium halide-catalyzed halogen redistribution reactions with suitable alkyl bromides or iodides. However, similar transformations are not feasible for trimethylhalosilanes.