m-Aminophenylarsonic Acid as a Reagent for the Extraction Preconcentration of Phenol

The azocoupling reaction of phenol with the diazonium salt of m-aminophenylarsonic acid was used for the determination of phenol in water at a level of maximum permissible concentrations. The resulting compound is stable in a wide pH range, which made it possible to develop a procedure for the determination of phenol with the preconcentration of the azo compound by extraction to isobutanol at pH 2 and subsequent back extraction to the aqueous phase at pH 10. The high concentration coefficient of phenol (65) provides for determination of phenol down to 0.9 g/L.     

Regioselective Monoacetylation of Methyl Pyranosides of Pentoses and 6‐Deoxyhexoses by Acetic Anhydride in the Presence of MoCl5

Convenient regioselective syntheses of 3‐acetates of methyl pyranosides of α‐L‐rhamnose, α‐ and β‐L‐arabinose, α‐D‐fucose, α‐D‐lyxose, and β‐D‐ribose with good yields have been attained using MoCl₅ as catalyst. Methyl β‐L‐rhamnopyranoside under this conditions gave 2‐acetate.     

Synthesis of methyl ethers of methyl 2-acetamido-2-deoxy-α-D-glucopyranoside

A convenient method is proposed for the synthesis of all the individual methyl ethers of methyl 2-acetamido-2-deoxy-α-D-glucopyranoside based on the partial methylation of 2-acetamido-2-deoxy-α-D-glucopyranoside with dimethyl sulfate in an alkaline medium followed by preparative liquid column chromatography on silica gel of the resulting mixture of methyl ethers.     

The effect of the counterion composition on the chain restriction in the cationic polymerization of isobutylene

The effects of the nature of halogens in the initiatingtert-butyl halide-aluminum-containing Lewis acid system on the number average molecular weightM _n and the structure of end groups of polyisobutylene macromolecules obtained in the cationic polymerization of isobutylene in hexane at -78 °C were studied. An increase inM _n is observed in the transition from chlorine to bromine and iodine, accompanied by a decrease in the fraction of end C=C groups and an increase in the relative content of C-Hal groups (Hal = Cl, Br, and I). When atoms of different halogens are present in the counterion, more bulky atoms preferentially participate in the formation of the end groups. The results are interpreted within the framework of the principle of hard and soft acids and bases.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1184–1187, May, 1996.     

m-Aminophenylarsonic Acid as an Analytical Form for the Photometric Determination of Phenol in Water

The azocoupling reaction of diazonium salts of o- and m-aminophenylarsonic acids with phenol was studied. On the basis of quantum-chemical calculations of the reagents, conformation analysis of resulting azo compounds, and experimental data, it was found that the meta isomer of aminophenylarsonic acid is of practical interest as an analytical reagent for the determination of phenol. The advantage of the proposed reagent is a high stability of the diazonium salt. A procedure was developed for the spectrophotometric determination of phenol in water at a level of 0.06 g/mL. The error in the determination is no higher than 5.5%.     

Photometric Determination of Octadecylamine with Methyl Orange

The reaction of octadecylamine with Methyl Orange in water at pH 2.5–4.0 was studied. Linear relationships were revealed between the decrease in the absorbance of an aqueous solution of Methyl Orange and the concentration of octadecylamine. Optimal conditions of the reaction were found. It was demonstrated that 50- to 200-fold amounts of lower aliphatic and aromatic amines and salts of lower quaternary ammonium bases do not interfere with the determination. Procedures were developed for the photometric determination of 0.083–1.0 g/mL and 0.74–10 g/mL octadecylamine.     

Action of the transferase activity of phospholipase D on rat liver mitochondria

The action of phospholipase D on rat liver mitochondria in the presence of methanol, glycerol, and ethanolamine has been studied. The phospholipid compositions of the modified and native mitochondria have been determined. Incubation of the mitochondria with phospholipase D led to a considerable decrease in the activities of cytochrome c oxidase and NADH-cytochrome reductase.Institute of Marine Biology, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Far Eastern State University, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 364–369, May–June, 1982.     

K-absorption spectrum of aging Al-Zn alloys

The K-absorption spectra of aging Al-Zn alloys experience a systematic shift of the main edge during natural aging toward the short wavelength side. This is apparently due to filling of the 4S–4P shells of the zinc atoms by electrons at the expense of the aluminum atoms. Additions of Mg and Sn lead to a more intense redistribution of the outer electrons. The early zone stage of aging of Al alloys exhibits an electronic character.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 7, pp. 18–22, July, 1971.In conclusion the authors wish to thank Prof. A. E. Bryukhanov and docent V. I. Kotlyat for constant interst shown in the study and valuable comments made while discussing the results.