1,8-bis(diphenylmethylium)naphthalenediyl dication as an organic oxidant: synthesis of benzidines via self-coupling of N,N-dialkylanilines

1,8-Bis(diphenylmethylium)naphthalenediyl dications promoted oxidative coupling of various N,N-dialkylanilines to afford the corresponding para-coupled bisanilines, benzidines, in good to excellent yield. The dications were readily prepared from a cyclic ether precursor, derived from 1,8-dibromonaphthalene, via deoxygenation with a silylating reagent in 1,1,1,3,3,3-hexafluoro-2-propanol under anhydrous conditions. [reaction: see text]     

Applicability of classical optical fiber theories to holey fibers

We discuss the applicability of well-established classical optical fiber theories to holey fibers. By appropriately defining the V parameter, we can easily estimate the fundamental properties of holey fibers, such as effective index, group-velocity dispersion, mode field diameter, beam divergence, and splice loss, through simple empirical expressions without the need for heavy numerical computations. We confirm the validity of the V parameter defined here by comparing the calculated results with the earlier experimental and numerical results.     

Lipase TL-mediated kinetic tesolution of 5-benzyloxy-1-tert-butyldimethylsilyloxy-2-pentanol at low temperature: concise asymmetric synthesis of both enantiomers of a piperazic acid derivative

Lipase TL-mediated kinetic resolution of (+/-)-5-benzyloxy-1-tert-butyldimethylsilyloxy-2-pentanol (5) at low temperature proceeded to give the corresponding (S)-alcohol 5 and (R)-acetate 6 in quantitative yields with high enantiomeric purity. The addition of bases such as pyridine, DMAP, 2,4- and 2,6-lutidines, or triethylamine considerably enhanced the rate of kinetic resolution. The alcohol (S)-5 and the acetate (R)-6 were converted to piperazic acid derivatives (R)- and (S)-3, respectively, via the intramolecular Mitsunobu reaction as a key step.     

Synthesis of conjugated enynes by assembly of three components, ketones, chloromethyl p-tolyl sulfoxide, and acetylenes, with the magnesium carbenoid 1,2-CC insertion as the key reaction

The reaction of 1-chlorovinyl p-tolyl sulfoxides, which were derived from ketones and chloromethyl p-tolyl sulfoxide, with lithium acetylides gave adducts in moderate to good yields. Treatment of the adducts with Grignard reagents resulted in the formation of magnesium carbenoids by the sulfoxide-magnesium exchange reaction. 1,2-Carbon-carbon insertion (1,2-CC insertion) reaction of the generated magnesium carbenoids took place to afford conjugated enynes in good to high yields. This procedure provides a good method for the synthesis of multi-substituted conjugated enynes.     

Gas by-products of CF3I under AC partial discharge

This paper presents the decomposition by-products of trifluro-iodo-methane and their relative proportions in the gas phase under the occurrence of partial discharge. The experiment was performed in the presence of water vapor from 250 to 400 ppm under a non-uniform electric field configuration. The experimental results reveal that the by-products of C₂F₆, C₂F₄, C₂F₅I with the amount of 1300, 200, and 55 (CH₃I) ppm, respectively, were produced for a cumulative charge of 161 mC. Other by-products, such as C₃F₈, CHF₃, C₃F₆ CH₃I were obtained at less than 30 ppm C₂F₆ was the dominant gas by-product of trifluro-iodo-methane suffering partial discharge.     

Size of support of initial heat distribution in the 1D heat equation

The size of support of initial heat distribution is determined by the heat flow observed either at any fixed time or at any fixed position     

Influences of hydrogen contents in precursor Si film to excimer laser crystallization

This paper presents for the first time experimental results which show a crucial role of the local Si-H bonding structures in Si precursors for crystallinity of polycrystalline silicon (p-Si), obtained by an excimer laser crystallization (ELC) process. This role was revealed in the distinct differences among (111) lattice plane spacings of p-Si according to deposition and dehydrogenation conditions of the precursors. It was also found that preablation behaviors, especially ebullition of the melt, are highly sensitive to the precursors. These results provide an important guide for the selection of the most adequate precursor in production, and also contribute an understanding of the mechanism of the ELC process.