A carbon-carbon bond formation using an endoperoxide of N-methoxy-carbonylpyrrole and a convenient synthesis of 4-alkylindoles

A convenient synthesis of 4-alkylindoles was attained by utilizing the result of a stannous chloride-effected reaction of endoperoxide of N-methoxycarbonylpyrrole with carbon nucleophiles.     

Photoelectric pulse interval distribution of gaussian-lorentzian light

The time interval distribution of two successive photoelectric pulses depends not only upon the spectral linewidth but also on the correlation factor. The distribution is derived in the case of gaussian-lorentzian light under the condition of a markovian process and is also applied to the analysis of the counting loss of a circuit with dead time, from which information on the spectral linewidth is obtained. The theoretical counting loss is compared with the experimental one.     

Evidence of coupled rotational tunnel states of methyl groups of hexamethylbenzene by nuclear magnetic resonance

Two tunneling frequencies were identified for methyl groups in hexamethylbenzene from 4.2 up to 30.9 K by means of the N.M.R. field cycling method. The frequencies were 9.6 ±- 0.4 MHz (A) and 7.9 ±- 0.4 MHz (B) at 4.2 K. The frequency A was almost independent of the temperature whereas the frequency B decreased as the temperature increased, the decrease being a linear function of T³. These facts indicate that the six methyl groups in hexamethylbenzene molecule are not independent but are coupled to one another rather strongly.     

Ionic liquid salt bridge based on tributyl(2-methoxyethyl)phosphonium bis(pentafluoroethanesulfonyl)amide for stable liquid junction potentials in highly diluted aqueous electrolyte solutions

A moderately hydrophobic ionic liquid, tributyl(2-methoxyethyl)phosphonium bis(pentafluoroethanesulfonyl)amide ([TBMOEP⁺][C₂C₂N⁻]), shows a very stable liquid junction potential upon contact with an aqueous solution whose ionic strength is as low as 1 μmol dm⁻³. The stability with the maximum excursion of the potential within ±0.5 mV for 30 min is very promising for accurate determination of pH and other single ion activities potentiometrically.     

Synthesis of the ABC ring system of Jiadifenin via Pd-catalyzed cyclizations

An efficient route toward the central ABC system of jiadifenin has been developed using two key Pd-catalyzed cyclizations. A protic solvent-activated Mizoroki-Heck reaction was used to construct the C(9) quaternary carbon and the A ring. A cascading Tsuji-Trost cyclization/lactonization sequence was employed to establish the BC ring system and the C(5,6) stereochemistry.     

Development of quality assessment method for optically active food flavor chemicals

A quality assessment method for commercially available, optically active flavor compounds, namely, menthol, menthyl acetate, borneol, perillaldehyde, and 1,8-cineol, was developed. A gas chromatograph equipped with a flame ionization detector and a DB-5ms capillary column was used for the chemical purity test. A GC/MS with a beta-DEX cyclodextrin column was used for the optical purity test, by which the enantiomeric separation of each flavor compound was achieved. Enantiomeric excess was calculated as an expression of optical purity. Of the 25 standard samples subjected to the chemical purity test, six were found to have lower purity than the data provided by the manufacturers. When the same samples were subjected to the optical purity test, 11 were found to have lower purity than that indicated on the reagent labels. These results suggest that there is a need to conduct an optical purity test, in addition to a chemical purity test, for the quality assessment of flavor standards.     

Intermolecular vibrational spectra of C3v CXY3 Molecular Liquids, CHCl3, CHBr3, CFBr3, and CBrCl3

We report the quality anisotropic intermolecular vibrational spectra within the frequency range 0.5-800 cm(-1) of four C(3v) CXY(3) molecular liquids, CHCl(3), CHBr(3), CFBr(3), and CBrCl(3), by means of femtosecond optical-heterodyne-detected Raman-induced Kerr effect spectroscopy. The results show that the first moment of the intermolecular vibrational spectrum is proportional to the square root of the value of the surface tension divided by the liquid density. This implies that the intermolecular vibrational spectrum reflects the bulk properties of the liquids. To understand the molecular-level aspects of the intermolecular vibrational spectra of the liquids, the spectra are compared with the molecular properties such as molecular weight, rotational constants, and bimolecular interaction energy. Overall, the first moment of the spectrum moderately correlates to the inverse square roots of both the molecular weight and the fast rotational constant. Therefore, the molecular properties are responsible for the intermolecular vibrational spectrum. Plots of the first moment of the intermolecular vibrational spectrum vs the square root of the value of the simple bimolecular interaction energy divided by the molecular surface area and the molecular weight show a linear correlation in the case of the oblate symmetric top molecular liquids, CHCl(3), CHBr(3), and CFBr(3). However, CBrCl(3), which is a prolate symmetric top molecular liquid, does not show the same correlation for the oblate molecular liquids.