Toshio Kinugasa

High-pressure high-resolution nuclear magnetic resonance. Effect of increased pressure on the proton chemical shift of biphenyl

Abstract The proton NMR measurement of biphenyl-3,3′,5,5′- d 4 has been carried out in hexane up to 2000 kg CM −2 using a 100-MHz high-resolution spectrometer. An anomalous feature of pressure dependence of the ortho proton chemical shift is interpreted in terms of the decrease in the dihedral angle between the rings under increased pressure.

Solid Complex Formation of Oxalic Acid with a-Amino Acids

SOIid complex formation of oxal ie acid with several a-ami no acids was studied by usi ng an X-ray diffractometer, a R i ltfrared spectrometer and a differential thermobalance a Ralyser.Oxalic acid forms enly o ne ki nd of complex with dlnt-ala nine, dl-nerleucine or dl-leucine i n a molar ratio of 1:1, while it ferms two kinds of complexes with glyei qe, dl-a-ami Robutylic aeid, dl-val i ne. dl-norvaline o r dl-isoleuci ne i n molar ratios of 1:1 a nd 1:2. lt was presurned that the formation of the cemplexes was promoted by proten-transfer from the carboxyl group in oxalic aeid to the ca rboxyl ion of amino aeid i n t he case of 1:1 complex and by the intermolecular hydrogeR bond between two hydregen atoms of t h e carboxyl groups i R oxalic acid a nd t he carboxyl ions ef t wo molecules of ami no acid i lt t he case of 1:2 complex.The difference i n com plex formatioA amoRg a-ami nO acids is suppostxl to resu l t from the steric request of a-ami no acid, although it can hardly be explai ned enly by the size of the alkyi group at a-position.

Infrared spectroscopic study of the interaction between 2,6-diarylphenols and alkyl cyanides

The O–H stretching absorptions of 2,6-diarylphenols are composed of two symmetrical bands (intramolecular OH ⋯π and intermolecular OH ⋯ N interactions) in the presence of alkyl cyanides in carbon tetrachloride solution.The equilibrium constants K for the competitive interactions were determined. The equilibrium study suggested that the K values depend on the dihedral angle between the phenol ring and the 2,6-aryl groups. Comparison of log K with ν0(OH)(the frequency of the OH ⋯ N band at infinite dilution in CCl4) revealed a linear relation. Furthermore it was found that the frequency shifts caused by the concentration of cyanide can be explained by the Kirkwood-Bauer-Magat relationship.

Equilibrium study of biphenyl-2-ol by infrared spectroscopy

Biphenyl-2-ol is composed of cis- and trans-isomers in CCl4 solution. The percentage of trans-isomer is estimated by comparison of i.r. intensities for solutions in basic solvents; the proportion of cis-isomer is obtained by comparison with 2,6-diphenylphenol.