Stereoselectivity in cycloaddition of phenylglyoxylonitrile oxide to 7-substituted norbornadienes and 8-substituted 2-azabicyclo[3.2.1]oct-3,6-dienes

The cycloaddition of phenylglyoxylonitrile oxide to the 7-substituted norbornadienes $\text{1}$a-c gives predominantly the endo isomers, but that to the 8-substituted 2-azabicyclo[3.2.1]oct-3,6-dienes $\text{2}$a,b the exo isomers.     

Rapid screening method for methamphetamine in urine by colour reaction in a Sep-Pak C18 cartridge

A simple screening method for methamphetamine in urine by colour reaction was developed. Methamphetamine, which is quantitatively retained in a Sep-Pak C18 cartridge, is (after a clean-up procedure) coloured by Simon's reagent (consisting of sodium nitroprusside solution, sodium carbonate solution and acetaldehyde gas). The detection limit was 0.5 microgram/ml using 5 ml of urine sample. The results of the screening method agreed with those of thin-layer chromatography and gas chromatography-mass spectrometry.     

Cloud point temperature of polyoxyethylene-type nonionic surfactants and their mixtures

The cloud point temperature, T(c), was investigated for aqueous solutions of poly(oxyethylene) alkyl ethers, C(n)E(m), and their mixtures. The experimental T(c)'s for single surfactant systems were analyzed according to the Flory-Huggins model for cloud point phenomenon, and the enthalpy and the entropy changes associated with the process of the separation of micellar solution into pure water and pure surfactant were estimated. It was found that the enthalpy-entropy compensation relationship holds for this process. The Flory-Huggins model was extended to the binary surfactant mixtures, and the expression of T(c) as a function of the composition was derived assuming the regular solution for mixed micelles. The experimental results of T(c) obtained for mixtures of C(n)E(m) were well reproduced by the model calculation. Discussion is given concerning the interaction parameters of different surfactant species in mixed micelles determined by this model calculation.     

Phosphorylation of disaccharides with inorganic cyclo-triphosphate in aqueous solution

The phosphorylation of disaccharides by inorganic cyclo-triphosphate (P(3m)) with a six-membered ring was examined in aqueous solution. In the phosphorylation of cellobiose, lactose, and alpha,alpha-trehalose with P(3m), beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranosyl 1-triphosphate, beta-D-galactopyranosyl-(1-->4)-beta-D-glucopyranosyl 1-triphosphate, and 3-O-triphospho-alpha-D-glucopyranosyl-(1-->1)-alpha-D-glucopyranoside were synthesized with maximum yields of 28%, 35%, and 20%, respectively. In the reactions of maltose and sucrose with P(3m), two phosphorylated products were obtained in yields of 42% and 58%, respectively. The main phosphorylated products were assigned to alpha-D-glucopyranosyl-(1-->4)-beta-D-glucopyranosyl 1-triphosphate and beta-D-fructofuranosyl-(2-->1)-2-O-triphospho-alpha-D-glucopyranoside by heteronuclear multiple bond correlation (HMBC) NMR. The phosphorylation mechanism of disaccharides with P(3m) is discussed.     

Estimation of water absorption state within ionized carboxylated polymer particles with high sensitive differential scanning calorimetry

Glass transition temperature (Tg) of submicron-sized, carboxylated polymer particles dispersed in aqueous media, which were prepared by emulsion copolymerization of styrene, iso-butyl methacrylate, or methyl methacrylate with methacrylic acid, was measured at alkali or acidic pH region with a power compensation-type high sensitive differential scanning calorimeter. The Tg of relatively hydrophilic polymer particles was obviously decreased by the neutralization of the carboxyl groups with KOH, whereas that of hydrophobic polymer particles was not changed though water was absorbed therein. These results indicate that water absorption state, which means not only the amount of water absorption but also the heterogeneity of the ionized carboxylated polymer particles, markedly depends on the hydrophilicity of their base polymers. This strongly supports the formation mechanism of multihollow particles by the stepwise alkali/acid or the alkali/cooling treatments of carboxylated polymer particles proposed by the authors.Part CCLXIX of the series, “Studies on Suspension and Emulsion.”     

Enantiospecific total synthesis of (-)-megaphone by a highly controlled consecutive 1,4- and 1,3-asymmetric induction

Enantiospecific total synthesis of (-)-megaphone (1) is reported. The key synthetic tactic is the use of (4$\text{S}$)-2$\text{Z}$-ethylidene-4-trityloxymethyl-butan-4-olide (6) to both establish the relative and absolute stereochemistry of the contiguous tertiary and quaternary carbon centers by a highly controlled 1,4- and 1,3-asymmetric induction and construct the 4-methoxy-6,6-dialkyl-cyclohexenone portion of 1.     

A novel method of preparing of glass capillary columns: Low-temperature plasma etching and polymerization

A novel method is described for the preparation of stable glass capillary columns (glass open tubular columns), including the etching and formation of a polymer film on the inner glass capillary surfaces. The approach used here is based on low-temperature plasma etching and polymerization. Under the influence of a field of radio frequency discharge, low pressure gases of fluoric compounds, introduced into the glass capillary tube, generate excited fluorine radicals which etch the inner surface. The plasma of organosilicone monomer in the glass capillary yields a uniform polymerized film on the inner surface. The resultant material functions as a good stationary phase for glass capillary gas chromatography (GC²). The inner surfaces treated with such a plasma, can be studied by means of a scanning electron microscope (SEM). The flexibility of this method permits the use of various stationary phases and surface modification.     

Sulfur-containing vinyl monomers. XII. Charge transfer complexes of thioethylene derivatives with π-electron acceptors

The absorption spectra of charge-transfer (CT) complexes of thioethylene derivatives with p-chloranil (CA), tetracyanoethylene (TCNE), and 7,7,8,8,-tetracyanoquinodimethane (TCNQ) were measured in methylene chloride. Since the CT bands of alkyl vinyl sulfides having bulky substituents such as isopropyl, cyclohexyl and tert-butyl were similar to that of methyl vinyl sulfide, the complexing site of these sulfides to acceptor was assumed to be the vinyl group rather than the sulfur atom. In the case of the TCNE complex of phenyl vinyl sulfide, however, a new second CT band at 378 nm was observed, and the first CT band was also close to that of ethyl phenyl sulfide, indicating that the TCNE formed a complex with this vinyl sulfide mainly at its phenyl group. To investigate further the conformation of the complex, CT spectra of bis-, tris- and tetrakis (phenylthio) ethylenes were measured. These compounds showed markedly different CT bands, and the changes in these CT bands with the number of the phenylthio substituents appears to be attributable to the change in complexing site with the acceptors used.     

The effect of spin-orbit coupling on fast neutral chemical reaction O(3P)+CH3-->CH3O

The effect of nonadiabatic transitions through the spin-orbit couplings has been investigated on the fast neutral reaction, O((3)P)+CH(3)-->CH(3)O. Adiabatic potential energies and the spin-orbit coupling terms have been evaluated for the four electronic states of CH(3)O ((2)E, (2)A(2), (4)E, and (4)A(2)) that correlate with the O((3)P)+CH(3) asymptote, as a function of CO distance and OCH angle under the C(3v) symmetry, by ab initio electronic structure calculations using multireference internally contracted single and double excitation configuration interaction method with the 6-311G(2df,2pd) basis sets. Multistate quantum reactive scattering calculations have been carried out with the use of thus obtained potential energies and spin-orbit coupling matrices, based on the generalized R-matrix propagation method. The calculated thermal rate constants show a slight positive dependence on temperature in a range between 50 and 2000 K, supporting the previous experimental results. It is shown that the spin-orbit coupled excited states give rise to reflections over the centrifugal barrier due to the quantum interference. Classical capture calculations yield larger rate constants due to the neglect of quantum reflections. It is concluded that the effect of nonadiabatic transitions is of minor importance on the overall reactivity in this reaction.     

Experimental and theoretical studies of small-angle electron scattering by the water molecule

The total (elastic plus inelastic) intensities of 51 keV electrons scattered by water molecules have been measured over a range of 1 ≦ K = (4π/λ) sin(θ/2) ≦ 12 Å^?1. A computer program, ELIC, has been written for calculating the total intensities of electrons scattered by free molecules. The intensities can be calculated with self-consistent field and configuration interaction wavefunctions. The theoretical intensities based on a CI wavefunction are in good agreement with the observed intensities.