Properties of the amino group in N-(aminophenyl)pyridinium perchlorates

The pyridinium ring as a substituent in aniline is an electron acceptor, the effect of which is comparable to the effect of NO₂ and N(CH₃)₂ groups. Correlation of the reactivities with the basicities of the amino groups is not observed in the investigated reactions of N-(aminophenyl)pyridinium perchlorates with some electrophilic reagents, inasmuch as steric factors apparently play a greater role.     

Contribution a l'électrochimie des thiols et disulfures : Partie I. Cystéine et cystine

A study of the electrochemical characteristics of cysteine and cystine was carried out by d.c., a.c. and differential pulse polarography. Up to three waves were observed depending on the concentration and pH. The waves of the two amino acids could be separated in a borate buffer of pH 9.2. Differential pulse polarography made it possible to determine as little 0.12 mg of cysteine and 0.24 mg of cystine per litre.     

Die Pentafluoro-orthoselen- und -orthotellurgruppe,eine 19F-Kernresonanzuntersuchung

A ¹⁹F-NMR Study of the (Pentafluoro)orthoselenium and -tellurium Group In ¹⁹F-nmr the (pentafluoro)orthoselenium and (pentafluoro)orthotellurium groups show characteristic AB₄ spectra. Chemical shifts give information about the different bondings. The axial fluori ne atom is often more influenced, a certain trans effect may be discussed. The values of is otopic splittings, coming from ⁷⁷Se agree with these observations, isotopic splittings from ¹²³Te und ¹²⁵Te are much less important. Comparison is done with selected compounds containing a (pentafluoro)orthosulphur group.     

Hydrolysis of furan and 5-nitrofuran penicillins by penicillinase Bacillus licheniformis

The enzymatic hydrolysis of various furan and 5-nitrofuran penicillins by penicillinaseBacillus licheniformis 749/c was investigated. The effect of various side-chain structural groupings on the rate of inactivation of these compounds was studied. The introduction of bulky substituents in the ortho or positions to the amide group and lengthening the side chain or increasing its degree of unsaturation sharply decrease the catalytic action of penicillinase and, consequently, the rate of cleavage of the-lactam ring of the antibiotic. The majority of the furan and 5-nitrofuran penicillins surpass benzylpenicillin in resistance to the enzyme but are inferior to methicillin and oxacillin.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 295–298, March, 1971     

Reaction of onium salts with nucleophilic reagents

Russian Chemical Bulletin -