It is known that upon heating or UV irradiation perfluoroiodoalkanes R/sub F/I split hexaalkyldistannanes R/sub 3/SnSnR/sub 3/, giving trialkylstannyl iodides and trialkylperfluoroalklstannanes R/sub F/SnR/sub 3/. The authors showed with reference to trimethylstannylphenylacetylenes that upon IV irradiation perfluoroiodoalkanes react with trialkylstannylacetylenes to give primarily perfluoroalkylacetylenes. Yields of target products reach 50%
The calculation indicate that the polarity of the C=C bond in vinylidenephosphonic acid is reversed on complete ionization, which corresponds to the observed change in the disposition of the carbon-atom signals in the /sup 13/C NMR spectra for the acid and tetraanion. When vinylphosphonic acid and other ..cap alpha..,..beta..-unsaturated monophosphonic acids are ionized completely (in the formation of the dianions and monoanions), the /sup 13/C NMR spectra show the C/sub ..cap alpha../ signal shifting to the weak-field side and C/sub ..beta../ to the strong one, but there is no change in the mutual disposition of the signals, while the calculations indicate that there is no change in the polarity of the C=C bond.
We have investigated the conductivity of pentaphenyl derivatives of phosphorus, arsenic, and antimony in acetone, DMF, nitromethane, THF, and propyl bromide. The choice of solvents was determined by solubility conditions, the existence of as great as possible ranges of values of dielectric constant and viscosity, and also the participation of the solvent in specific interactions. The fairly wide range of concentrations used (0.01-0.0001 M) enabled us to trace changes in the structure of the carriers of the charges and determine the possibility of dissociation or association. In the organic solvents investigated pentaphenyl derivatives of phosphorus, arsenic, and antimony behave as weakly dissociated electrolytes. The conductivity falls appreciably as we pass from phosphorus derivatives to arsenic and antimony derivatives.
The reactions of (acetoxyimino)(diethoxyphosphinyl)acetic amides and esters with diazomethane are found to go with the insertion of a methylene group in the C-P bond. They open the way to the preparation of various 3-(diethoxyphosphinyl)propionic derivatives with a nitrogen function in the 2 position and also of phosphonomethylated heterocycles. A full analysis is performed of data obtained from the NMR, IR, and electron-impact mass spectra of the reactants and products. Chemical shifts. spin-spin coupling constants, multiplet structures, molecular-ion peaks, and vibrational states are tabulated.
In the synthesis of the peptidyl-polymer corresponding to the sequence (57-100) of the ..beta.. chain of human hemoglobin on Teflon with radiationally grafted polystyrene a comparative study was made of different methods of fragment condensation. It was shown that the most effective methods are azide condensation and condensation with the use of complex F.
The electronic and three-dimensional structures of products of the reaction of the metaphosphate ion with a number of nucleophilic molecules: NH/sub 3/, H/sub 2/O, H/sub 2/S, were investigated by semiempirical MNDO methods. It was found that as a result of addition of the nucleophilic molecules to the PO/sub 3//sup -/ ion, thermodynamically stable adducts with a quasitetrahedral structure, capable of dissociating with the elimination of H/sup +/, are formed.
The ortho-palladization of R(+)-N-isopropyl-..cap alpha..-(2-naphthyl)ethylamine was realized under the conditions of the Cope-Friedrich reaction at an elevated temperature (64/sup 0/C) compared with the normal temperature for the palladization of tertiary amines. It was established that the ortho-palladization of ..cap alpha..-(2-naphthyl)ethylamines unsymmetrically substituted at the nitrogen atom is highly stereoselective and results in the fixation of the coordinated nitrogen atom of these ligands in only one of the two possible absolute configurations. On the basis of a comparative analysis of the chiral-optical and NMR characteristics of the obtained and of the previously investigated ortho-palladized compounds it was concluded that the nitrogen atom of the metallated ligand has the S/sup N/-configuration, determined by the R/sup C/-configuration of the adjacent asymmetric carbon center
1,3-Dipolar cycloaddition of diazomethane to the triple bond of trialkylsilyl-, trialkylgermyl-, and trialkylstannylalkoxyacetylenes proceeds regioselectivity and is a convenient method for synthesis of the previously not described 3(5)-element-substituted 4-alkoxypyrazoles. When heated in methanol in the presence of an acid, 3(5)-silyl(germyl)-4-alkoxypyrazoles are slowly hydrolyzed with cleavage of the element-carbon bond.
In this work the desulfonation of amino sulfonic acids was studied by the determination of the kinetics of homogeneous isotopic exchange in radioactive sulfuric acid labeled with the isotope /sup 35/S, either containing HB(HSO/sub 4/)/sub 4/, or not containing it. The radioactive sulfuric acid was taken in an amount of 20 moles per mole of the amino sulfonic acid. Preliminary experiments showed that under these conditions neither the formation of disulfonic acids, nor the accumulation of desulfonated products occurs.
The constants for the extraction of thorium by solutions of alkylaromatic ..cap alpha..-hydroxy acids in heptanol occur in the order log K/sub ex/ (hydroxydiphenylacetic acid) > log K/sub ex/ (phenoxyacetic acid) > log K/sub ex/ (hydroxyphenylacetic acid). For the example of extraction equilibria involving the participation of thorium carboxylate complexes an extraction efficiency parameter is introduced which enables the efficiency of extraction to be predicted on the basis of information on the formation constants of the neutral complexes and the dissociation constants of the extractant acids in the aqueous phase.
A method is proposed for the preparation of 2-amino-4,6-di-tert-butylphenol. N-(3,5-Di-tert-butyl-2-hydroxyphenyl)salicylaldimine is readily mercurated with the formation of a mercury-containing free radical. Pd(II), Co(II), and VO(II) salicylaldiminates based on 2-amino-4,6-di-tert-butylphenol are capable of one-electron oxidation with the formation of metal-containing phenoxyl radicals. Analysis of the ESR spectra showed that the appearance of the metallocycle leads to a sharp increase in the stability of the radical system.
This paper records the process of the interconversion of enantiomeric tetrahedral structures by the dynamic-NMR method for inner-complex compounds with a chelate entity of NiN/sub 2/X/sub 2/ (X = S, Se), namely systematic series of bis(4-(iminomethyl)pyrazole-5-thiolato(selenolato) )nickels. The values of the activation barriers to interconversion are determined by the steric structure of the substituents on the coordinated nitrogen tom and increase with rise in the steric hindrance in the planar form of the complexes, which indicates that the reaction goes by the diagonal-twist mechanism.
This paper presents results on the effects of the fusion of a pyrazole ring containing prochiral isopropyl and benzyl groups at N/sup 1/ and c/sup 3/ to the MN/sub 2/X/sub 2/ metallocycle, variation in the nture of the central metal atom, of the donor atom X (O, S, or Se), and of the substituents R/sup 1/, R/sup 2/, and R/sup 3/ on the spectral characteristics and kinetic and activation parameters for enantiomerizaiton in the Zn(II), Cd(II), Hg(II), and Pb(II) bischelates (III) prepared using imines of 1,3-disubstituted 4-formy1-5-hydroxy-, 4-formy1-5-tthio-, and 4-formy1-5-selenopyrazoles.
