Showing papers in "ChemInform in 1976"
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TL;DR: The formation of ozonides (1,2,4-trioxolanes) from alkenes and ozone can be described as a succession of three [2+3] cycloadditions or cycloreversions involving primary ozone oxides and aldehyde or ketone oxides as decisive intermediates as discussed by the authors.
Abstract: The formation of ozonides (1,2,4-trioxolanes) from alkenes and ozone can be described as a succession of three [2+3] cycloadditions or cycloreversions involving primary ozonides (1,2,3-trioxolanes) and aldehyde or ketone oxides as decisive intermediates, all of which have finite lifetimes. There is no warranted experimental basis for assuming an alternative mechanism.
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TL;DR: In this article, a pit model was developed on the assumption that the metal ions hydrolyze inside the pits and that the corrosion products are transported by diffusion, and the main reason for passivity breakdown at the initial stages of pit growth was found to be the localized acidification due to metal ion hydrolysis.
Abstract: A pit model was developed on the assumption that the metal ions hydrolyze inside the pits and that the corrosion products are transported by diffusion. Concentrations of Me2+, , and H+ ions, as a function of pit depth and current density, for Zn, Fe, Ni, Co, Al, and Cr were calculated. The main reason for passivity breakdown at the initial stages of pit growth, was found to be the localized acidification due to metal ions hydrolysis. Assuming a criticalpH value for pit initiation, the following experimental facts could be explained: (i) the effect of the external pH on the pitting potential of Fe and stainless steel; (ii) the effect of sodium borate concentration on the pitting potential of Zn; (iii) the effect of weak acid salts on the pitting potential of Al; (iv) the oscillations of the electrode potential of stainless steel and nickel in solutions of ions; (v) the existence of a pitting inhibition potential ; and (vi) the existence of a pitting protection potential. Through analysis of the transport processes inside a pit it was also concluded that the pitting potential of a metal should change with the Cl− ion concentration according to the equation being the slope of the curve at room temperature.
92 citations
TL;DR: In this article, the cell reactions between lithium and several transition metal oxides and sulfides have been found to produce ternary phases and not the formation of lithium oxide or sulfide as previously proposed.
Abstract: The cell reactions between lithium and several transition metal oxides and sulfides have been found to produce ternary phases and not the formation of lithium oxide or sulfide as previously proposed. These reactions, at 25°C, take place with essential retention of the crystalline lattice, thus facilitating secondary cathodic behavior. It is found that cell reversibility is optimized when no chemical bonds are broken during discharge, that is, where ternary phases are formed by an intercalation reaction and where a broad range of nonstoichiometry exists as in the system . Where some chemical bonds are broken as for and partial or difficult reversibility is found, but when all the bonds are broken as for example in , the cell only exhibits primary characteristics.
TL;DR: The flight response of both sexes of Dendroctonus brevicomis to the mixture of myrcene, racemic frontalin, and (1R,5S,7R)-(+)-exo-brevicomin was significantly greater than the response to the same mixtures in which the antipodes were substituted as discussed by the authors.
Abstract: The flight response of both sexes of Dendroctonus brevicomis to the mixture of myrcene, racemic frontalin, and (1R,5S,7R)-(+)-exo-brevicomin and to the mixture of myrcene, (1S,5R)-(-)-frontalin and racemic exo-brevicomin was significantly greater than the response to the same mixtures in which the antipodes were substituted. The flight response to these two mixtures was also greater than the response to the ternary mixture of myrcene, racemic frontalin, and racemic exo-brevicomin (MFE). The walking response of both sexes to the mixture of myrcene, racemic frontalin, and (+)-exo-brevicomin was not different from the response to MFE. Substitution of the antipode lowered the response when compared to that of MFE. When evaporated with ponderosa pine turpentine, (-)-frontalin was active in the field while its antipode was not.
TL;DR: In this article, the energies of planar vs. tetrahedral geometries of tetracoordinate organic molecules have been surveyed by ab ini- tio molecular orbital calculations and electropositive substituents, especially lithium, are particularly effective in stabilizing the planar arrangements selectively.
Abstract: The energies of planar vs. tetrahedral geometries of tetracoordinate organic molecules have been surveyed by ab ini- tio molecular orbital calculations. Because of their 7~ acceptor and u donor character, electropositive substituents, especially lithium, are particularly effective in stabilizing the planar arrangements selectively. Multiple substitution by such metals and by three-membered rings provides further stabilization, and 1,l-dilithiocyclopropane (XVII) and 3,3-dilithiocyclopropene (XVIII), inter alia, are actually calculated (RHF/STO-3G theory) to be more stable planar than tetrahedral.
TL;DR: In this paper, the reaction of 1,2-Diphenylathan with N-chelatisierten Butyllithium reagenzien werden zwei Komplexe, Stilben-bis-[1ithium-N,N,N′,N ′-tetramethylathylendiamin] and Stilb-bis]-lithium n,N, N′, N", N"-pentamethyldiathylentriamin], dargestellt and isoliert.
Abstract: Durch Reaktion von 1,2-Diphenylathan mit N-chelatisierten Butyllithiumreagenzien werden zwei Komplexe, Stilben-bis-[1ithium-N ,N,N′,N ′-tetramethylathylendiamin] und Stilben-bis-[lithium-N,N,N′,N",N"-pentamethyldiathylentriamin], dargestellt und isoliert.
TL;DR: In this article, the authors highlight the use of acetylenic esters in the synthesis of different heterocycles, primarily involving nucleophilic additions, and discuss the reaction of amines with acetylenecarboxylate.
Abstract: Publisher Summary This chapter highlights the use of acetylenic esters in the synthesis of different heterocycles, primarily involving nucleophilic additions. The chapter discusses the reaction of amines with acetylenic esters. The primary amines react with dimethyl acetylenedicarboxylate (DMAD), giving rise chiefly to the enamine fumarates. The preferential formation of the fumarates in these additions can be understood in terms of their relative stabilities, as compared to the corresponding maleates, due to internal hydrogen bonding. The enamine adducts formed in the reaction of aromatic amines with DMAD have been found to undergo cyclization leading to heterocyclic compounds, and the mode of these reactions is influenced by the reaction conditions, the catalyst employed, and also the nature of the functional groups present in the starting amine.