Seth Elsheimer

Dechlorination comparison of mono-substituted PCBs with Mg/Pd in different solvent systems

It is widely recognized that polychlorinated biphenyls (PCBs) are a dangerous environmental pollutant. Even though the use and production of PCBs have been restricted, heavy industrial use has made them a wide-spread environmental issue today. Dehalogenation using zero-valent metals has been a promising avenue of research for the remediation of chlorinated compounds and other contaminants that are present in the environment. However, zero-valent metals by themselves have shown little capability of dechlorinating polychlorinated biphenyls (PCBs). Mechanically alloying the metal with a catalyst, such as palladium, creates a bimetallic system capable of dechlorinating PCBs very rapidly to biphenyl. This study primarily aims to evaluate the effects of solvent specificity on the kinetics of mono-substituted PCBs, in an attempt to determine the mechanism of degradation. Rate constants and final byproducts were determined for the contaminant systems in both water and methanol, and significant differences in the relative rates of reaction were observed between the two solvents.

Mechanisms for the alkaline hydrolysis of dibromodifluoromethane-alkene adducts to α,β-unsaturated carboxylates

Abstract Alternative mechanisms for the title reactions are probed. The previously-reported pathway involving double dehydrobromination to a difluorodiene is operative in at least one case, but this route is specifically excluded for systems that cannot dehydrobrominate to dienes yet still yield carboxylates upon alkaline hydrolysis. Although S N 2, S N 1, S RN 1, and monoelimination–addition processes appear formally possible, an S N 2′ mechanism is implicated by studies on model compounds.

Electrochemical fluorination of some industrially important organic compounds

Organo-fluorine compounds are industrially important. Their method of preparation depends on the selection of flourinating agents. Electrochemical fluorination is a widely used induatrial method for obtaining fluoro-organic compounds. electrofluorination, the Philips method or Cave process, and Simons process. the advantages, cell design, difference in different electrochemical methods and the mechanism in each method are reviewed in detail. The electrochemical synthesis of some induatrially important fluoro-organic compounds, especially amines, nitrogen-containing carboxylic acids, benzene, substituted benzene, heterocyclic compounds, simple carboxylic acids, organo-sulfur compounds and cyclic amino acids ethers, is discussed at length.

The thermal rearrangement of CIS,CIS-1-fluoro-2-methyl-3-vinylcylopropane. The kinetic effect of a single fluorine substituent.

Abstract It was demonstrated through a kinetic study of the thermal rearrangement of cis , cis -1-fluoro-2-methyl-3-vinylcyclopropane to cis -3-fluoro-1,4-hexadiene that a single fluorine substituent lowers that activation barrier for rearrangement by about 2 kcal/mole as compared to 6.4 kcal/mole for geminal difluoro substitution.