Inductive Effects on Molecular Ionization Potentials. V. Hydrogen Sulfide and Aliphatic Thioethers

Abstract

The ionization energies of thioethers, R 2S, have been correlated with the polar substituent constants and the inductive substituent constants. Good correlations are obtained which indicate that the effect of alkyl substituents on the S·atom is primarily an inductive one.we have shown recently that the ionization energies of alcohols [6] We now denonstrate that the ionization energies of thioethers, R 1S, are also linear functions of both 0* and 0 1 , The gas-phase expulsion of an electron from the non-bonding lone pair on the sulfur atom of a sulfide nolecule is in accord with the equation: and the ionization potential, E I, of course, corr-esponds approxiIrately to the energy of the highest occupied nolecular orbital [1,7,8]. The entire chemistry of thioethers, in fact, is dependent on the behavior of the 3p sulfur lone pair electrons. Electron-releasing alkyl groups bonded to the S-atom of an alkyl sulfide nolecule facilitates electron renoval, and thereby lowers the Er; the presence of electron-withdrawing groups should likewise cause an increase in the ionization energy [4]. The same effect manifests itself in a greater basicity, the greater is the electron density at the S-atom of the sulfide nolecule. This effect is similar to that recently denonstrated for alcohols [4]. It isinteresting that we are able to include hydrogen sulf'ide as the siJrplest thioether in the series. An excellent correlation is shown in Fig. 1 where the~values are plotted vs aI' '!he equation for the cor-re'latLon line is given by the following:Using the polar substituent constants,

Limited proteolysis of the coxsackievirus and adenovirus receptor (CAR) on HeLa cells exposed to trypsin

“…More than 30 years ago, Crowell and colleagues [5–7] reported that CVB3 binding to HeLa cells was unaffected by trypsin treatment. Experiments reported here reveal that the CAR is cleaved within 15 min following addition of trypsin to HeLa cells.…”

“…Experiments conducted before isolation of CAR found that the binding of CVB to HeLa cells is not altered by trypsin treatment [5–7], and in vitro experiments often use cultured cells exposed to virus only hours after subculture with trypsin. The experiments reported here reveal that CAR is not resistant to trypsin, and treatment of HeLa cells with trypsin alters the expression of this viral receptor.…”

Kinetics of the peroxydisulfate oxidation of sulfoxides in buffered solution. 2. The effect of initial sulfoxide concentration with diethyl and diphenyl sulfoxides

“…Mechanism e, somewhat modified since the time it was first proposed,3 is the mechanism that we currently favor, and involves the heterolytic autoionization of S2082" into sulfate and the zwitterionic sulfur tetroxide. The very first step probably gives an intimate ion pair, followed perhaps by subsequent equilibria involving solvated ionic species, but the subsequent equilibria, for the sake of simplicity, will not be shown: ~03-S-^0^-0 S03~S042-+ +0-SO3"" (slow) (12) and the rate -d[S20821/dz = fc2[R2SO] [SO40] = fci[S2082"] [R2S0]/([R2S0] 4 k^SOf']/^} (13) But since the rate in any given run is fc[S2082'], it follows that the observed rate constant is given by k = fc,[R2SO]/([R2SO] 4 k.x[S0421 /k2) (14) identical with eq 2 if b = fc_i[S042_]//c2.…”

Zone collector and transfer device for thin-layer chromatography

“…Because our general experimental approach (1-3) generate's a larg'e number 0 f TLC fractions of widely different radioactivity, an economi~al, convenient and rapid technique for collecting and transfering TLC zones to liquidscintillation vials was required. Many zone collectors have been described (4)(5)(6)(7)(8)(9)(10)(11), but were judged inadequate because of one or more of the following disadvant~ges: potential contamination by adsorbent from previous use adhering to the device, clogging of fritted glass filters, need for cleaning and drying prior to reuse, or need for a separate device for each sample. This report describes a device ~vhich is free of these disadvantages and is ~uitable for rapid collectiort and transfer of a series of zones.…”