Dimethyl carbonate synthesis and other oxidative reactions using alkyl nitrites

The oxidative reactions using the alkyl nitrites (RONO) as an oxidant have been developed by Ube Industries, Ltd. In the alkyl nitrite reactions, substrates such as CO andyor unsaturated- andyor carbonyl-compounds are oxidized over the palladium catalysts in no direct contact with molecular oxygen. The dimethyl carbonate (DMC), dialkyl oxalates and other useful chemicals are synthesized efficiently under moderate conditions by the alkyl nitrite reactions.     

A new oxidation system using nitrite oxidants

The oxidative reactions using alkyl nitrites (RONO) as oxidant have been developed by Ube Industries, Ltd. The substrates such as CO and/or unsaturated-and/or carbonyl-compounds are oxidized by RONO over the palladium catalyst with no contact of molecular oxygen. Dialkyl carbonates, dialkyl oxalates and other useful chemicals are synthesized efficiently under moderate conditions by this alkyl nitrite technology.     

Effects of ultraviolet irradiation during growth of ZnSe epilayers by atmospheric pressure metalorganic vapor-phase epitaxy using dimethyl zinc and H2Se

This work has investigated the effects of ultraviolet irradiation on the epitaxial growth process of undoped ZnSe by atmospheric-pressure metalorganic vapor phase epitaxy. Dimethyl zinc and H₂Se at a [VI]/[II] mole ratio of 20 were the source gases used for growth onto (100)-just oriented semi-insulating GaAs substrates. Hydrogen was used as the carrier gas. A 500 W Hg-Xe lamp irradiated the substrate at 300 nm wavelength during growth. Growth temperature was varied from 210 to 450°C. Epilayers grown in the presence of irradiation experienced a prominent decrease in growth rate, which occurred even at high temperatures. Through a combination of surface and vapor-phase reactions, UV irradiation also affected the photoluminescence properties, crystalline quality, and surface morphology of the epilayers.     

Dielectric study on the flow alignment in 4-n-pentyl-4'-cyanobiphenyl

Dielectric permittivity and loss are measured under steady shear flow as functions of temperature, shear rate, electric field frequency, and electric field strength in the nematic (N) and the isotropic (I) phases of 4-n-pentyl-4'-cyanobiphenyl. In the N phase, the dielectric permittivity in the quiescent state is largely modified if the steady shear flow is applied. These behaviors are discussed based on the Leslie-Ericksen theory [Q. J. Mech. Appl. Math. 19, 357 (1966); Arch. Ration. Mech. Anal. 4, 231 (1960)], showing that the dielectric properties under the shear flow are consistently interpreted in terms of the flow alignment of the director, a unit vector specifying the orientation of the liquid crystals. It is also suggested that the behaviors of dielectric permittivities are similar to those of the viscosities.     

Effect of solvent on the reactivity of functional groups in polycondensation reactions

The effect of solvent on solution or interfacial polycondensations was investigated in terms of selectivity and control of functional groups such as amine or hydroxyl groups toward polycondensation reactions. Solution polycondensation of a mixture of resorcinol (RL) and m-xylyenediamine (m-XD) with isophthaloyl chloride was affected by solvents to such extent as to change the course of the polycondensation reaction, and hexamethylenephosphoramide (HMPA) caused the formation of amide-rich polymer, while tetrahydrofuran (THF) was a solvent favoring formation of a polyamide ester with a regular structure. Polycondensation of 3,3′-dihydroxybenzidine (DHB) with isophthaloyl chloride yielded exclusively a linear polyamide in HMPA solution, while with aldehyde as a solvent polyester was obtained owing to the preservation of the amine group. Thus, it was found that the course of polycondensation reactions of monomers having different functional groups could be controlled by selection of a suitable solvent.     

Synthetic studies of potential antimetabolites. XIII. Synthesis of 7-amino-3-β-d-ribofuranosyl-3H-imidazo[4,5-b] pyridine (1-deazaadenosine) and related nucleosides

7-Amino-3-β-D-ribofuranosyl-3H-imidazo[4,5-b]pyridine (III, 1-deazaadenosine) was synthesized in 32% yield from the diacetyl derivative prepared from 7-aminoimidazo[4,5-b ]pyridine (1-deazaadenine) and 1,2,3,5-tetra-O-acetyl-β-D-ribose by the fusion method. A synthesis of 7-amino-4-b?-D-ribofuranosyl-4H-imidazo[4,5-b]pyridine (IV) was also achieved.     

Optical Computed Tomography Based on Extraction of Quasi-Straight forward Propagating Photons Using Sum-Frequency Generation Technique

Aiming at the realization of optical computed tomography (optical CT), a compact system comprised of two cw-lasers and a detector was proposed for the extraction of quasi-straightforward propagating photons from scattered light transmitting through a scattering medium. The extraction ability of the system based on the sum-frequency generation technique was investigated using a standard scattering medium of Intralipid-10% aqueous solution and was found to be 78 dB in dynamic range. The optical CT image of absorbers placed in the scattering medium was successfully obtained with high contrast using the proposed system.     

Optical Computed Tomography Imaging of Absorbers in a Highly Scattering Medium by Detection of Photons Preserving Initial Polarization

A method utilizing light polarization was applied to take the projection data of absorbers in a highly scattering medium. The floor level of the projection data due to diffused light was significantly suppressed by detection of photons which preserved initial polarization. An optical computed tomgraphy image was reconstructed from the projection data taken by this method and exhibited higher spatial resolution than the image reconstructed from the projection data by conventional method.