A new method for the hydroxymethylation of carbonyl compounds

Benzyl chloromethyl ether reacts with carbonyl compounds in the presence of SmI₂ to afford alcohols (I), which are subsequently subjected to hydrogenolysis to yield diols (II).     

Colloidal crystals of cationic spheres

Colloidal single crystals of cationic polymer spheres (198–250 nm in diameter) in deionized aqueous dispersions were formed for the first time. The spheres used were poly(styrene-co-methacryloyloxyphenyldimethylsulfonium) cations. These cations are unstable in deionized suspensions with mixed beds of cation-exchange and anion-exchange resins. This was clarified by reflection spectroscopy, pH, conductance and -potential measurements for 250 days after suspension preparation. Colloidal crystals formed over a period of 24 h for the deionized suspensions at sphere concentrations higher than 0.09 in volume fraction. The nearest-neighbor intersphere distances coincide satisfactorily with the calculated values using the diameter and the concentration of the spheres. Alloy crystals formed from binary mixtures of the cationic polymer spheres and the anionic silica spheres when the ratio of the volume fraction of cationic spheres against the sum of the both cationic and anionic spheres was smaller than 0.3.     

Rotational diffusion of tungstic acid colloids in microgravity as studied by aircraft experiments

 Rotational relaxation times (τ) of anisotropic tungstic acid colloids (3.24 μm in major axis) in aqueous suspension are measured in microgravity (0G), normal gravity (1G) and at 2G. The measurements at 0G and 2G are achieved by parabolic and circular flights, respectively. The limiting slopes of the relaxation curves in the plots of the transmitted light intensity against time are close to zero at 0G irrespective of the flow directions in the flow cell, whereas those at 1G and especially at 2G depend on the flow direction by the convection of the suspension and particle sedimentation. Experimental errors at the τ values at 0G are small compared with those at 1G and 2G, which is ascribed to the lack of movement of impurities in the suspension such as quite small air bubbles, which cannot be recognized with the naked eye, and the convection of the suspension in microgravity. More reliable rotational relaxation times are obtained in microgravity; however, the relaxation times themselves are quite insensitive to gravity. Theτ values observed are larger than those calculated from the particle size, which indicates the important contribution of the electrical double layers formed around the colloidal particles. Received: 22 February 2001 Accepted: 13 June 2001     

In vivo localization of radiolabeled monoclonal antibody to carcinoembryonic antigen (CEA) in a CEA-producing tumor--comparison with polyclonal antibody

To compare accumulation of the 125I-labeled antibodies (anti-carcinoembryonic antigen (CEA) monoclonal antibody and polyclonal antibody) to a CEA-producing tumor (SC-2-JCK), an in vivo localization study was performed in nude mice. The tumor-to-blood ratio at 120 hours after injection rose to 4.6 for the monoclonal antibody, but remained at 1.3 for the polyclonal antibody. However, no differences were noted between the antibodies up to 72 hours after injection. In autoradiograms, selective accumulation of the tracer was noted in the tumor for both antibodies. However, no superiority or inferiority of imaging for either of the antibodies could be definitely determined.     

An air-stable P-chiral phosphine ligand for highly enantioselective transition-metal-catalyzed reactions

A new P-chiral phosphine ligand, (R,R)-2,3-bis(tert-butylmethylphosphino)quinoxaline, has been prepared by the reaction of enantiomerically pure tert-butylmethylphosphine-borane with 2,3-dichloroquinoxaline. This ligand, in contrast to most of the previously reported P-chiral ligands, is an air-stable solid and exhibits excellent enantioselectivities in both Rh-catalyzed asymmetric hydrogenations and Rh- or Pd-catalyzed carbon-carbon bond-forming reactions.     

Biologically active constituents of Arnebia euchroma: structure of arnebinol, an ansa-type monoterpenylbenzenoid with inhibitory activity on prostaglandin biosynthesis.

Three phenolic compounds were isolated from the roots of Arnebia euchroma as inhibitors of in vitro prostaglandin biosynthesis. Two known compounds were identified as shikonofurans and des-O-methyllasiodiplodin. The other new compound was named arnebinol and its structure was elucidated as a novel ansa-type monoterpenylbenzenoid derivative.     

Synthesis and properties of new ferroelectric liquid crystalline compounds having a 1, 2-diphenylethane structure

Abstract

Chiral 1, 2-diphenylethane derivatives have been synthesized and found to form stable chiral Sc phases exhibiting ferroelectric properties. Comparison with diphenylacetylene derivatives revealed that flexibility of the bridging groups between two benzene nuclei strongly influences the stability of mesophases as well as transition temperatures.     

In situ observation of UF5 nanoparticle growth in a low-pressure mixed-flow reactor

5 nanoparticles equipped with an in situ size-monitoring system, a LPDMA (low-pressure differential mobility analyzer), was developed to experimentally investigate the nanoparticle growth mechanism. The concentration of photoproduced UF₅ molecules was controlled by changing three factors: (I) the concentration of the feed UF₆ gas, (II) the laser pulse energy of the irradiation, and (III) the repetition rate of the laser pulses. The dependence of the volumetric average diameter of the photoproduced particles on the UF₅ nascent concentration in all three cases was found to be very similar. The result strongly suggests that the reactor functions as a mixed-flow reactor under a complete mixing condition. The particle size measured by the LPDMA was found to be in the range of 6 to 11 nm, and it was approximately proportional to the power 0.3 of the initial concentration of photoproduced UF₅ molecules. Received: 11 May 1998/Accepted: 15 September 1998     

Poly(arylene thioether)s containing 9,9′‐spirobifluorene moieties in the main chain: Masked dithiol‐based synthesis and excellent optical properties

Poly(arylene thioether)s ( PTEs ) containing 9,9′‐spirobifluorene moieties were synthesized in high yields from 9,9′‐spirobifluorene‐2,2′‐bis(N,N‐dimethylcarbamothioate) 4 as the masked dithiol and various difluoroarenes as electrophilic monomers. All PTEs showed high thermal stability: The 10% weight loss temperature as evaluated by thermogravimetric analysis was over 470 °C under both nitrogen and air atmospheres. The glass transition temperature estimated by DSC was in the range 210–270 °C. The PTEs showed high solubility in ordinary organic solvents, such as CHCl₃, NMP, and THF. Most PTEs exhibited remarkably high refractive indices ranging from 1.69 to 1.73 at 587.6 nm, whereas no or little birefringence was observed for the PTEs . © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4192–4199, 2010