The Acid-catalyzed Hydrolysis of CF3-deactivated Diazoalkanes

The acid-catalyzed hydrolysis of CF₃CHN₂ ( 1 ) follows an A2 mechanism of preequilibrium protonation and rate-determining solvolysis of the intermediate diazonium ion 4 ; this was demonstrated by: (a) the inverse kinetic isotope effect; (b) H-D exchange; (c) the unimportance of general acid catalysis; (d) strong rate acceleration by added nucleophiles. The activation parameters have been determined in two solvent systems. In contrast to 1 the secondary diazocompound CF₃? CN₂? CH₃ ( 2 ) follows the normal A-S_E2 mechanism of rate-determining proton transfer.     

S-Alkylation en série hétérocyclique par catalyse par transfert de phase: thioalkyl-2-thiazoles,thioalkyl-2-Δ-4-thiazolines et thioalkyl-2-benzothiazoles

S-Alkylation in heterocyclic serie by phase transfer catalysis: 2-alkylthiothiazoles, 2-alkylthio-Δ-4-thiazolines and 2-alkylthiobenzothiazoles Some Δ-4-thiazoline-, thiazolidine-, and benzothiazoline-2-thiones have been S-alkylated by phase transfer catalysis; yields averaged 80 to 90%. With halogenated heterocyclic compounds of poor reactivity, the main reaction consisted in a dequaternization of the catalyst by the thiones acting as nucleophiles.     

Temperature and density dependence of the structure of liquid lithium from an improved pseudopotential theory

Leribaux, H.R., and Lemarchand, J.L., 1978. Temperature and density dependence of the structure of liquid lithium from an improved pseudopotential theory. Fluid Phase Equilibria, 2: 79–90.The structure of liquid lithium and alloys has recently been measured more accurately near their melting point. We present for liquid lithium a modification of a previous pseudopotential for liquid metals, obtained by including explicitly the Xα exchange energy in the electron pseudopotential. The structure factor S(q), obtained from this model potential via the effective pair potential, and calculated by our solution of the Percus—Yevick equation, is found to have the right oscillations compared with the experimental structure factor, the first peak also having the right magnitude. A Percus—Yevick hard-sphere structure factor is also obtained via thermodynamic perturbation and is found to be surprisingly good even for lithium, except for the high-q oscillations. We present computed structures and radial distributions for several higher temperatures involved typically in the liquid lithium alloys, up to the highest temperatures at which saturated density is measured. Our model potential predicts also the correct cohesive energy for liquid lithium and liquid lithium—magnesium.     

The preparation of synthons on route to terpenoids of marine origin

An approach to versatile intermediates by Claisen rearrangements followed by chemical purification gave a stable γδ-unsaturated acid useful for title mentioned compounds.     

Vinylboron compounds

Summary A general method for synthesizing unsaturated boron compounds was developed.     

Editorial

Stability analysis is suggested as a preliminary step in isothermal flash calculations, and a number of numerical methods for stability analysis based on Gibbs' tangent plane criterion are described. These methods, which are applicable for both single phase and multiphase systems, are developed mainly for Equation of State calculations using a single model for all fluid phases. Special adaptions ensuring convergence in critical regions are discussed.     

Synthèse de dérivés imidazopyridiniques et pyridinotriaziniques

Propargylpyridiniums 2-substituted by hydroxylamine or hydrazine moieties cyclize by heating to imidazopyridiniums whereas derivatives substituted by methylhydrazine or N,N' -dimethylhydrazine lead to pyridino-as-triaziniums. These differences are discussed.