Kinetics of the γ-radiation-induced polymerization of ethylene in liquid carbon dioxide

The γ-radiation-induced polymerization of ethylene with the use of liquid carbon dioxide as a solvent, was studied from the viewpoint of kinetics. The polymerization was carried out at conversions less than 10% under the pressure ranging from 100 to 400 kg./cm.², dose rates 1.3 × 10⁴?1.6 × 10⁵ rad/hr., and temperatures of 20–90°C. The concentration of carbon dioxide varied up to 84.1 mole-%. The polymerization rate and the polymer molecular weight were observed to increase with reaction time. This observation, however, becomes less pronounced with increasing concentration of carbon dioxide and with rising temperature. The exponents of the pressure and the dose rate were determined to be 2.3 and 0.85 for the rate, and 2.0 and ?0.20 for the molecular weight, respectively. From the kinetic considerations for these results, the effect of carbon dioxide on the initiation and termination reaction in the polymerization was evaluated.     

Synthesis of allenes via palladium-catalyzed hydrogen-transfer reactions: propargylic amines as an allenyl anion equivalent

Synthesis of allenes has been achieved by using palladium-catalyzed hydrogen-transfer reactions. Various propargylic amines, which were readily prepapred from iodobenzenes and propargylic amines by Sonogashira coupling reaction, underwent the hydrogen-transfer reaction in the presence of Pd2dba3.CHCl3/(C6F5)3P catalyst at 100 degrees C in dioxane for 24 h, giving the corresponding allenes in 43-99% yields. Various propargylic alcohols containing a propargylic aminomethyl group, synthesized by the addition of lithium acetylides of N,N-diisopropylprop-2-ynylamine to aldehydes and a ketone, also underwent the hydrogen-transfer reaction in the presence of Pd2dba3.CHCl3 catalyst and (C6F5)3P at 80 degrees C in dioxane, giving the corresponding allenes in 56-92% yields. In the current transformation, propargylic amines can be handled as an allenyl anion equivalent and introduced into various electrophiles to be transformed into allenes under palladium-catalyzed conditions.     

Synthesis of ene-allenes via palladium-catalyzed hydride-transfer reaction of propargylic amines under mild conditions

The palladium-catalyzed allene transformation reaction from propargylic amines proceeded in the presence of Pd₂(dba)₃·CHCl₃ (5 mol %) and (C₆F₅)₂PC₂H₄P(C₆F₅)₂ (10 mol %) in CHCl₃ at room temperature to give the corresponding allenes in good to high yields. Dicyclohexyl groups substituted on the nitrogen of propargylic amines were found to be effective for the current transformation and the conjugated ene-allenes 4 were synthesized from the corresponding propargylic amines 3 under mild conditions.     

Reaction of carbethoxycarbene with 2-phenyloxirane and 2-phenyloxetane

Thermal or photochemical decomposition of ethyl diazoacetate in 2-phenyloxirane gave a complex mixture, the analysis of which indicated that the reaction of carbethoxycarbene had proceeded according to the scheme summarized in Fig. 1. The reaction probably involves intermediate formation of an oxygen-ylide (IV), thus accounting for the observed oxygen-transfer and oxetane formation. Copper-catalysed thermal decomposition resulted in a more selective distribution of products, secondary reactions as well as the tar-formation being drastically reduced. The action of other carbenes such as dihalo-, phenyl- and diphenyl-carbene yielded less or no oxygen-transfer products and the formation of oxetane was not observed. In some cases, especially in the reaction of bis(benzene-sulphonyl)carbene, the major product was cyclic dimers of 2-phenyloxirane.

2-Phenyloxetane reacts more selectively with carbethoxycarbene to produce a mixture of cis and trans isomers of 2-carbethoxy-3-phenyltetrahydrofuran in 72–80% yield.     

2, 2'-bis(diphenylphosphino)-1, 1'-binaphthyl(binap) : A new atropisomeric bis(triaryl)phosphine. synthesis and its use in the rh(l)-catalyzed asymmetric hydrogenation of α-(acylamino)acrylic acids

Racemic 2, 2'-bis(diphenylphosphino)-l, 1'-binaphthyl has been synthesized from 2, 2'-dihydroxy-l, l'-binaphthyl in two steps and resolved into optically pure (R)-(+) and (S) (-) enantiomers by the use of (+)-di-μ-chlorobis[(S)-N,N-dimethyl-α-phenylethylamine-2C,N]dipalladium. This new axially dissymmetric bis(triaryl)phosphine serves as an excellent ligand for Rh(l)-catalyzed asymmetric hydrogenations of α-(acylamino) acrylic acids or esters. Factors controlling the enantioselectivity and mechanistic aspects are discussed on the basis of the ³¹P-NMR measurements     

Effect of hydrogen on the γ-radiation-induced polymerization of ethylene

The effects of hydrogen on the γ-radiation-induced polymerization of ethylene were studied from the viewpoint of polymer structure and kineties. All experiments were carried out at 30°C. In the polymerization of ethylene containing 21.6% hydrogen, the solid polymer was obtained as a main product, while no liquid product was found. There was no difference in hydrogen contents before and after the irradiation; and acetylene, ethane, butane, and butene-1 were found as gaseous products. The polymer yield increased almost proportionally with dose rate in the presence of 8.0% hydrogen; on the other hand the molecular weight was independent of dose rate. At hydrogen contents of 0–8%, the polymerization rate increased with reaction time and decreased with hydrogen content. The molecular weight also increased with the time, and the extent of the increment decreased with the time and hydrogen content. The number of moles of polymer chain increased proportionally with the reaction time and increased linearly with hydrgen concentration. These results were analyzed by using a graphical evaluation method for kinetics, and the effects of hydrogen on the each elementary step in the polymerization were discussed.     

The detachment of nylon particles from quartz plate by electro-osmotic flow

The direct application of electrokinetic phenomena to detergency was investigated. Experiments were carried out to remove particles from substrate by electro-osmosis. A model system which consisted of spherical nylon particles of 5m in mean diameter, a quartz plate, and wash liquid were used in analyzing the kinetic process of particle removal from substrate. When an electric field was applied to the system, electro-osmotic flow took place, and hence the particles were removed from the quartz surface. The -potentials of nylon particles and quartz plate were measured by electrophoresis. The rate constants of removal,, were obtained from the changes with time in the ratio of particle residue by applying the first-order reaction scheme. The value of increased with increasing electric field and with increasing concentration of surfactant. The total force of interaction between particle and plate was calculated on the basis of heterocoagulation theory of colloid stability.It was found from results thus obtained that the hydrodynamic force due to the electro-osmotic flow worked effectively as a mechanical force on the removal process and the adhesion force of particle to substrate reduced by adding surfactant.     

Multispectral image sensor attachable to low-cost microcomputers

Optical Review - Multi-spectral filter array composed of a wavy alternating dielectric multilayer was integrated on a CMOS image sensor of the Raspberry Pi HQ Camera. The filter array consists of...