摘要:

AbstractValues of ϵ′ and ϵ″ were determined for glycerol triacetate, tripropionate, and tributyrate in the frequency ranges 120 Hz to 100 kHz and 100 MHz to 9 GHz. The temperature‐dependence of the static dielectric constant indicates that the conformation of the molecules changes with the temperature. This conclusion is corroborated by the fact that for the triacetate and the tripropionate the distribution of relaxation times becomes broader with increasing temp

ISSN:0165-0513    

DOI:10.1002/recl.19710901002

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractHomogeneous and heterogeneous peptides have been synthesized from pyrimidinyl‐ and purinyl‐amino acids la, b, c. Investigation of the oligopeptide derived from 1a (poly‐1a) showed no secondary structure as a result of base‐base interaction: however, the polymer was found to complex weakly with poly‐adenylic acid. Poly‐1a also exhibited a stimulation of phenylalanine incorporation in thein vitrosynthesis of poly‐

ISSN:0165-0513    

DOI:10.1002/recl.19710901003

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractThe partial rate factors for the nitration of sevenprimaryalkylbenzenes have been determined. The activation entropy of theortho‐substitution in neopentylbenzene is 2.9±1.7 e.u. smaller than that of thepara‐substitution. The steric hindrance of the nitration in theortho‐positions has been discussed by reference to the conformations of the initial states and the transition states. The increase of the steric hindrance is compensated by the increase of the polarizability of the alkyl

ISSN:0165-0513    

DOI:10.1002/recl.19710901004

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractThe isomer distributions for the nitration of sixsecondaryalkylbenzenes and the partial rate factors of three of these compounds have been determined. The steric hindrance of the nitration in theortho‐position of isopropylbenzene is mainly of an enthalpic nature. The increase of this hindrance in the series of isopropylbenzene,s‐butylbenzene, (1‐ethylpropyl)benzene is of an entropic nature and can be explained from the conformational analysis of the initial states and the transition states. The steric hindrance in theortho‐positions of (2‐methyl‐1‐ isopropylpropyl)benzene and (1‐t‐butyl‐2.2‐dimethylpropyl)

ISSN:0165-0513    

DOI:10.1002/recl.19710901005

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19710901006

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractReaction of cobaltocene with hydrogen halides HX (X = Cl, Br, I) in ethereal solution yields the ionic complexes [Cp2Co]+2[CoX4]2−in high yields. If triphenylphosphine is present in the reaction mixtures, the cobalticenium halides [Cp2Co]X are formed as the main products. Reaction of cobaltocene with hydrogen fluoride gives [Cp2Co][HF2]. The mechanisms of these reactions are discusse

ISSN:0165-0513    

DOI:10.1002/recl.19710901007

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractIt has long been recognized that the vinylic hydrogens of cyclopropene have an acidity comparable to that of the hydrogens of acetylene1, but it is only in isolated cases that this property has been turned to advantage in the synthesis of substituted cyclopropene derivatives2‐7. In this communication we report the preparation of the cycloprop‐1‐enyl anion and its reaction with cyclopropene and alkyl h

ISSN:0165-0513    

DOI:10.1002/recl.19710901008

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractThe synthetic route to heterohelicenes has been simplified significantly by a judicious choice of starting materials and the use of appropriate intermediates.

ISSN:0165-0513    

DOI:10.1002/recl.19710901009

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19710901010

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractDiaryloxymethyl halides and divinyloxymethyl halides, formates, trichloro‐acetates, monochloroacetates, and acetates have been synthesized from corresponding vinyl orthoformate

ISSN:0165-0513    

DOI:10.1002/recl.19710901011

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY