Aldehyde and ketone syntheses using methylthiomethyl p-tolyl sulfone

Methylthiomethyl p-tolyl sulfone (1) was conveniently alkylated to give mono- and dialkylated products (2 and 4). Reaction conditions for the trasformation of 2 and 4 into aldehydes (3) and ketones (5), respectively, were exploited.     

Tests of the homogeneous nucleation theory with molecular-dynamics simulations. I. Lennard-Jones molecules

Two kinds of the homogeneous nucleation theory exist at the present: the classical nucleation theory and the semiphenomenological model. To test them, we performed molecular-dynamics (MD) simulations of nucleation from vapor to liquid with 5000-20,000 Lennard-Jones-type molecules. Simulations were done for various values of supersaturation ratios (from 2 to 10) and temperatures (from 80 to 120 K). We compared the size distribution of clusters in MD simulations with those in the theoretical models because the number density of critical clusters governs the nucleation rate. We found that the semiphenomenological model achieves excellent agreements in size distributions of the clusters with all MD simulations we done. The classical theory underestimates the number density of the clusters in the temperature range of 80-100 K, but overestimates in 100-120 K. The semiphenomenological model also predicts well the nucleation rate in MD simulations, while the classical nucleation theory does not. Our results confirmed the validity of the semiphenomenological model for Lennard-Jones-type molecules.     

Pressure effect on adhesion

Zusammenfassung Unter der Voraussetzung von Verknüpfungen wird die Anfangsgeschwindigkeit der Adhäsion untersucht.Wenn Epoxyharz-Aminsysteme als Klebstoff gebraucht werden, ist die Beziehung zwischen Härtezeit und Anfangs-Bindefestigkeit theoretisch wie folgt gegeben:S(t)/S(t ₀ )=t+1. Dabei sindS(t) undS(t ₀) die Klebefestigkeit nach den Härtezeitent bzw.t ₀ ist ein Maß für das Ansteigen der Verknüpfungen, t=t–t₀.Die Beziehung zwischen Härtungsdruck und Verhältnis der Klebfestigkeiten lautet lnS(p)/S(p ₀ )=ln+·p. Wieder sind die Werte der FestigkeitenS aufp bzw.p ₀ auf die Drucke bezogen. und sind Konstanten.Die experimentellen Ergebnisse für das Kleben von Kupfer mit Epoxyharz-Aminsystemen bestätigen diese theoretischen Voraussagen.

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With 7 figures and 3 tables     

Photoelectron spectra of styrenes

The photoelectron spectra of styrene and its methyl derivatives were measured and interpreted. The vinyl group twisted by the steric hindrance of the α- or orthomethyl group was found to play an important role in the interpretation of the photoelectron spectra of these compounds. The dependence of the higher occupied π orbital energies of styrene upon the twist angle of the vinyl group was estimated from the experimental data.     

A two-phase reaction catalyzed by a protein — asymmetric oxidation of formaldehyde dithioacetals with aqueous sodium metaperiodate

We examined whether a protein could catalyze two-phase oxidation of formaldehyde dithioacetals with aqueous sodium metaperiodate and bovine serum albumin was found to be effective and give the corresponding S-oxides in optically active forms.     

Control of hole opening in single-wall carbon nanotubes and single-wall carbon nanohorns using oxygen

Due to the simplicity of the process, holes in the graphene walls of single-wall carbon nanotubes (SWNTs) and single-wall carbon nanohorns (SWNHs) have often been opened using O2 gas at high temperatures, even though this contaminates the nanotubes with carbonaceous dust (C-dust). To open holes with less C-dust contamination, we found that a slow temperature increase of 1 degrees C/min or less, in air, was effective. We also found that SWNHs having little C-dust could store a large quantity of materials inside the tubes. We infer that the local temperature increase due to the exothermic reaction of combustion may have been suppressed in the slow combustion process, which was effective in reducing the C-dust.