Conversion of 2,5-dialkyl-1,3,4-oxadiazoles into 4-substituted 3,5-dialkyl-1,2, 4-triazoles

2, 5-Dialkyl-1, 3, 4-oxadiazoles react on heating with primary amines to form 4-substituted 3, 5-dialkyl-1, 2, 4-triazoles, which is a convenient method for synthesizing these almost unknown compounds.     

31P CIDNP in the reactions of phosphoranyl radicals

The polarisation of phosphorus nuclei (³¹P CIDNP) during the free radical reactions of triakyl and triaryl phosphites proceeding via intermediate phosphoranyl radicals is discussed.     

Research on aromatic heterocycles

Naphthofurazan is reduced in three stages. The anion radical formed in the first one-electron step is recorded by its ESR spectrum. The absence of a one-electron step in the reduction of naphthofuroxan and dihydro derivatives of sulfonaphthofurazan and sulfonaphthofuroxan should be associated with weakening of the aromatic properties of their molecules.     

Relaxation and exchange in a nuclear cooling agent: NMR and EPR in single crystal PrNi5

NMR of Pr and ESR of Gd in single crystals of PrNi₅ are observed to exhibit a dramatic increase of the resonance linewidth with temperature in the range 1.2K ? T ? 10K. The observations are interpreted, within the framework of a crystal field spin Hamiltonian model calculation, in terms of low frequency fluctuations of the Pr ions induced by Pr-Pr exchange coupling. A fitting procedure of the theory to the experimental data enabled us to extract the various Pr-Pr and Pr-Gd exchange parameters. The former yield independent information concerning the lowest temperature that can be achieved in nuclear cooling experiments.