ISSN:0165-0513    

DOI:10.1002/recl.19861051102

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractA combined13C and1H NMR study on borate esters of a series of polyhydroxycarboxylates is presented.13C substituent effects upon borate ester formation, as obtained from a set of model compounds, established that borate esters of thethreo‐3,4‐diol functions of gluconate, glucarate, idarate and probably also of gulonate are preferred. The conformations of the free polyhydroxycarboxylates and the corresponding borate esters were determined using vicinal proton coupling constants. Both in1H and13C NMR spectra, peak doubling, due to diastereomerism in borate diesters, is obser

ISSN:0165-0513    

DOI:10.1002/recl.19861051103

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe oxidation of the NADH‐model compounds 1‐R‐1,4‐dihydronicotinamide (R = benzyl, octyl or cetyl) and 1‐benzyl‐1,4‐dihydroquinoline‐3‐carboxamide by methylene blue proceeds via a direct hydride transfer mechanism. In the transition state of this reaction, a considerable fraction of positive charge is developed in the dihydronicotinamide ring. Effects of solvents and effects of NaLS micelles upon the reaction have been investigated. In organic solvents, the oxidation proceedsca.1.5–50 times more slowly than in water. Interestingly, the reaction rate in organic solvents increases with decreasing polarity of the solvents. In aqueous NaLS solution, the oxidation of the NADH models proceeds 9‐80 times more rapidly than in water. The kinetic data in micellar solution are analyzed in terms of the pseudophase model, taking into account partitioning of the reactants between micellar and aqueous pseudophase. It appears that the observed rate enhancements in micellar solution are completely due to an increase of the reactant concentrations in the micellar pseudophase. The second‐order rate constants for oxidation in the micellar pseudophase are 35‐150 times smaller than those in the aqueous phase. It is suggested that both a decrease of the micropolarity and a unfavourable orientation of the reactants contribute to the low values of the second‐order rate constants

ISSN:0165-0513    

DOI:10.1002/recl.19861051104

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19861051105

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe coupling reagent pivaloyl chloride reacts slowly with an internucleosidic H‐phosphonate function to afford the corresponding acylphosphonate derivativ

ISSN:0165-0513    

DOI:10.1002/recl.19861051106

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe synthesis and crystal structure of ((C2H5)4N) {Ni (C3S5)2} is described. Space group P21/n with a=7. 333(1)Å, b=25.734(3)Å, c=12.798(4)Å, β=104.95(2)° and Z=4. The structure consists of a one‐dimensional zig‐zag chain with alternating Ni‐Ni distances of 4.163Å and 4.243Å, respectively. The temperature dependence of the conductivity shows an unusual behaviour. The relationship ln(σ) ∞ T1/2is followed instead of the common semiconductor behaviour of ln(σ) ∞ l/T. The unexpectedly high value of the conductivity is related to the size of the counter cation in t

ISSN:0165-0513    

DOI:10.1002/recl.19861051107

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe reagent 2‐chloro‐5,6‐benzo‐1,3,2‐dioxaphosphin‐4‐one proved to be suitable for the preparation of an anomerically (α) pure hydrogenphosphonate as well as a phosphite‐triester. The former could be applied for the formation of an interglycosidic hydrogenpho

ISSN:0165-0513    

DOI:10.1002/recl.19861051108

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19861051101

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY