Acid-catalyzed ortho-alkylation of anilines with styrenes: an improved route to chiral anilines with bulky substituents

[reaction: see text] Reaction of para-substituted anilines with styrene derivatives at elevated temperatures, when catalyzed by CF3SO3H, results in highly chemoselective ortho-alkylation of the aniline. When R = H, dialkylation can be achieved by varying the ratio of styrene to aniline. Several different substituted anilines and styrenes were examined, and good yields (42-87%) were obtained, except in the case where electron-withdrawing substituents are present on the styrene.     

Floc strength characterization technique. An insight into silica aggregation

This paper tests an approach to the estimation of relative particle bond strength based on the nondimensional floc and aggregation factors. The strength of flocs formed by aggregating nanosized silica particles with the addition of potassium chloride (KCl) or cationic surfactants, alkyltrimethylammonium bromide (mixture of CTAB, DTAB, and MTAB) was analyzed. The bonding force of the flocs formed in surfactant compared to that formed in the KCl system was estimated using the new dimensional analysis approach. This force ratio was then compared to that obtained by atomic force microscopy.     

Which sites react first? Functional site distribution and kinetics on solid supports investigated using confocal Raman and fluorescence microscopy

Fluorescence microscopy is a powerful technique for analyzing beads with very low loadings of fluorophores; however, the method is flawed when looking at more highly loaded beads as a result of severe problems with absorption. To probe distributions at higher loading levels, Raman spectroscopy avoids many of these issues. These studies show that there is a uniform distribution of reactive sites throughout the beads but that the spatial distribution of reacted sites depends on the polymer type, with a fine balance between reaction and diffusion rate.     

Longitudinal impact of cylindrical shells

The transient response due to longitudinal impact of three aluminum cylindrical shells of different thickness-to-radius ratios is studied both analytically and experimentally. The analyses were obtained from method of characteristics' solutions of two sets of equations: one which includes the transverse shear, radial inertia and rotary inertial effects; and the other set is from a modified membrane theory. Experimentally, longitudinal and circumferential strains are monitored along the length of each of the shells; the velocity of the impacter ring is also measured. The experimental results of this study indicate that the wavefront, after traveling three diameters from the impacted end, propagates at essentially the plate velocity, in agreement with the theory. In addition, the longitudinal and circumferential strains calculated from the two theories are in good agreement with the experimental results.     

Identification of urinary acylcarnitines using gas chromatography-mass spectrometry: preliminary clinical applications.

Many disorders of organic acid metabolism are associated with abnormalities in the levels of acylcarnitines excreted in urine. Profiling of urinary acylcarnitines allows diagnosis and characterisation of many acidurias and acidemias, monitoring dietary treatment of such patients, and elucidation of the metabolism of some exogenous acidic compounds. Urine (ca. 0.5 ml) was subjected to a simple work-up by ion-exchange chromatography, and the isolated acylcarnitines were derivatized by cyclization in 35 min to give volatile lactones that are compatible with gas chromatography-mass spectrometry using electron or chemical ionization. The feasibility of this new and affordable procedure has been confirmed by identifying urinary acylcarnitines in cases of medium-chain acyl-coenzyme A dehydrogenase deficiency, propionic acidemia and isovaleric acidemia.