Ultraviolet photolysis of urine for suppression of color quenching prior to liquid scintillation counting of tritium

In order to reduce the color quenching in the measurement of tritium in urine by liquid scintillation counting , UV irradiation was applied to decompose the organic substances in the sample. Urine was decolorized under UV irradiation in the presence of hydrogen peroxide. As a result, color quenching was considerably suppressed and higher counting efficiency of tritium was obtained. This UV treatment made it possible to increase the urine content in the sample from 2 to 40% (v/v) without significant decrease of counting efficiency. Either higher sensitivity or shorter analysis time was achieved in the tritium measurement by the augmentation of urine content. When the measurement time was 30 min, the detection limit of tritium defined as 3s was 0.03 Bq/ml. At the expense of some sensitivity (set at a detection limit of 0.3 Bq/ml), the measurement time was shortened to 0.5 min. These results will make a great improvement to routine tritium monitoring as well as to emergency monitoring in mass tritium exposure.      

Synthesis and Reactivity of Six‐Membered Oxa‐Nickelacycles: A Ring‐Opening Reaction of Cyclopropyl Ketones

Cyclopropanecarboxaldehyde ( 1 a ), cyclopropyl methyl ketone ( 1 b ), and cyclopropyl phenyl ketone ( 1 c ) were reacted with [Ni(cod)₂] (cod=1,5‐cyclooctadiene) and PBu₃ at 100 °C to give η²‐enonenickel complexes ( 2 a – c ). In the presence of PCy₃ (Cy=cyclohexyl), 1 a and 1 b reacted with [Ni(cod)₂] to give the corresponding μ‐η²:η¹‐enonenickel complexes ( 3 a , 3 b ). However, the reaction of 1 c under the same reaction conditions gave a mixture of 3 c and cyclopentane derivatives ( 4 c , 4 c′ ), that is, a [3+2] cycloaddition product of 1 c with (E)‐1‐phenylbut‐2‐en‐1‐one, an isomer of 1 c . In the presence of a catalytic amount of [Ni(cod)₂] and PCy₃, [3+2] homo‐cycloaddition proceeded to give a mixture of 4 c (76 %) and 4 c′ (17 %). At room temperature, a possible intermediate, 6 c , was observed and isolated by reprecipitation at ?20 °C. In the presence of 1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene (IPr), both 1 a and 1 c rapidly underwent oxidative addition to nickel(0) to give the corresponding six‐membered oxa‐nickelacycles ( 6 ai , 6 ci ). On the other hand, 1 b reacted with nickel(0) to give the corresponding μ‐η²:η¹‐enonenickel complex ( 3 bi ). The molecular structures of 6 ai and 6 ci were confirmed by X‐ray crystallography. The molecular structure of 6 ai shows a dimeric η¹‐nickelenolate structure. However, the molecular structure of 6 ci shows a monomeric η¹‐nickelenolate structure, and the nickel(II) 14‐electron center is regarded as having “an unusual T‐shaped planar” coordination geometry. The insertion of enones into monomeric η¹‐nickelenolate complexes 6 c and 6 ci occurred at room temperature to generate η³‐oxa‐allylnickel complexes ( 8 , 9 ), whereas insertion into dimeric η¹‐nickelenolate complex 6 ai did not take place. The diastereoselectivity of the insertion of an enone into 6 c having PCy₃ as a ligand differs from that into 6 ci having IPr as a ligand. In addition, the stereochemistry of η³‐oxa‐allylnickel complexes having IPr as a ligand is retained during reductive elimination to yield the corresponding [3+2] cycloaddition product, which is consistent with the diastereoselectivity observed in Ni⁰/IPr‐catalyzed [3+2] cycloaddition reactions of cyclopropyl ketones with enones. In contrast, reductive elimination from the η³‐oxa‐allylnickel having PCy₃ as a ligand proceeds with inversion of stereochemistry. This is probably due to rapid isomerization between syn and anti isomers prior to reductive elimination.     

Synthesis of CF2H‐Containing Oxime Ethers Derivatives from ClCF2H,tert‐Butyl Nitrile and Indoles

Summaryof main observation and conclusion A new and intriguing methodology to access various O-difluoromethylation oxime compounds from CICF2H,TBN and indoles is developed under mild reaction conditions.This strategy can suppress N-difluoromethylation of indoles successfully,in which there are two different active species(:CF2and·NO)while indoles are unprotected,featuringsimple operation and radical involvement.     

Synthesis of thiophene/phenylene co‐oligomers. II [1]. Block and alternating co‐oligomers

We report the synthesis of block and alternating thiophene/phenylene co‐oligomers that is based either on the Suzuki coupling reaction or on the Grignard reaction. These reaction schemes enable us to obtain the target compounds at reasonably high yields. The resulting materials have been fully characterized through the solid‐state ¹³C nmr and Fourier‐transform ir as well as the ¹H nmr. Of these, the solid‐state ¹³C nmr and ir are particularly useful in characterizing the materials of higher molecular weight, since those materials are difficult to dissolve in organic solvents.     

Raman spectra of K2CuF4

The crystal structure of K₂CuF₄ has been studied by means of Raman scattering. The structure is found to belong to the space group D_4h⁵ rather than D_4h¹⁷ of K₂NiF₄ between 2 and 800 K because of the distortion arising from the “orbital ordering effect”.