摘要:

AbstractThe experimental determination of the dipole moments of some derivatives of tetraphenylethene and tetraphenylbutatriene is described. The agreement between the experimental and theoretical values is demonstrated.

ISSN:0165-0513    

DOI:10.1002/recl.19610800102

出版商:WILEY‐VCH Verlag    

年代:1961

数据来源: WILEY

摘要:

AbstractThe isomer distribution for the homogeneous sulphonation of toluene at 25.0° in 82.3 ± 0.3 wt‐% aqueous sulphuric acid has been determined by the inverse isotope dilution method as 65.1%para. 2.9%metaand 32.0%ortho. Combining these data with the relative reactivity of toluene to benzene (kt/kb) = 66.1)1the partial rate factors were calculated as fpMe258; fmMe5.7 and foMe6

ISSN:0165-0513    

DOI:10.1002/recl.19610800103

出版商:WILEY‐VCH Verlag    

年代:1961

数据来源: WILEY

摘要:

AbstractIrradiation of ergosterol, lumisterol, tachysterol or previtamin D at room temperature for a long time brings about a considerable lowering of the extinction in the region 220‐300 mμ, whereas this phenomenon is not observed on irradiation of these compounds at 80°K in solid solution. From this it may be deduced that in the course of the photochemical reaction at room temperature ‐ besides the well‐known isomerisations – di‐ or poly‐merisations take place. A solution of tachysterol in liquid propane also shows the lowering of the extinction on irradiation. This indicates that the high viscosity of the medium rather than the low temperature is responsible for the non‐occurrence of lowering of the extinction in solid solution at 80°K.It is found that the photochemicalcis/transisomerisation of previtamin D into tachysterol is not ‐ or only partially ‐ inhibited by lowering the temperature to 80°K either in solid or in liquid solution. The conversion of tachysterol into previtamin D, on the other hand, did not occur on irradiation in liquid propane solution at 80° K. This is in agreement with theoretical considerations which were recently worked out in this laboratory for the mechanism of thecis/transisomerisation in the case of stilbene. These studies lead to the assumption that for the conversion of the photo‐excitedtrans‐isomer (in the singlet state) thermal energy is required to provide the (rather small) energy of activation. The excitedcis‐form may isomerise into thetrans‐form without

ISSN:0165-0513    

DOI:10.1002/recl.19610800104

出版商:WILEY‐VCH Verlag    

年代:1961

数据来源: WILEY

摘要:

Reductive acetylation has been investigated for the purpose of developing a suitable chemical method for the quantitative determination of quinone groupings in coal extracts. The reaction has been carried out successfully from an analytical point of view on a series of model quinones, either using zinc and acetic anhydride as the reagent, or copper and hydrogen sulphide, followed by acetic anhydride. However, the procedure with zinc failed to give satisfactory results when applied to a pyridine extract of vitrinite, on account of side reactions with nitrogenous groupings in the coal structure, and spurious hydrogenolysis of carbonoxygen bonds due to non‐aprotic conditions. These difficulties were avoided in the reduction with copper. Hence, it was possible to determine that the pyridine extract of a vitrinite having a carbon content of 84.3% contained 0.95% of quinone oxygen. This value represents barely 15% of the total oxygen present in the investigated extract. The sum of hydroxyl and quinone oxygen in the extract represents 60% of the total oxygen. The remainder is thought to be largely in the form of eth

ISSN:0165-0513    

DOI:10.1002/recl.19610800105

出版商:WILEY‐VCH Verlag    

年代:1961

数据来源: WILEY

摘要:

AbstractPregna‐5, 7‐dien‐3β‐ol‐20‐one was irradiated with ultraviolet light to obtain the corresponding 9β, 10α compound. Oppenauer oxidation, followed by isomerization of 9β, 10α‐pregna‐5, 7‐dien‐3α‐ol‐20‐one, yielded

ISSN:0165-0513    

DOI:10.1002/recl.19610800106

出版商:WILEY‐VCH Verlag    

年代:1961

数据来源: WILEY

摘要:

AbstractPyridine reacts directly with an alkylamine in toluene in the presence of powdered sodium or potassium. The yield of the 2‐alkylamino‐pyridine increases proportionally with the amounts of pyridine and sodium used. α‐Picoline and quinoline react in the same manner. Some derivatives of these heterocyclic bases have been prepared by reaction with primary alkyl‐ or aralkyl‐amines. Experiments with aromatic or secondary amines were unsuccessful. A mechanism has been proposed for this direct substitution in view of the experime

ISSN:0165-0513    

DOI:10.1002/recl.19610800107

出版商:WILEY‐VCH Verlag    

年代:1961

数据来源: WILEY

摘要:

AbstractA detailed picture is given of the mechanisms involved in the oxidation of acetophenones with oxygen to benzoic acids, at 150°, using manganese salts as catalysts and butyric acid as solvent.Kinetic studies indicate that the reaction is first‐order with respect to ketone and butyric acid, except at very high acid concentrations, and independent of the manganese concentrations as long as these exceed 0.008M.The results are most satisfactorily described by a mechanism involving enolization of the ketone as the rate‐determining step. The enol is then assumed to be oxidized by Mn+++to form the phenacyl radical, which adds on oxygen to form the phenacyl peroxy radical. This in turn readily reoxidizes Mn++to Mn+++; the phenacyl peroxy anion rearranges to form formaldehyde and the benzoate anion.Supporting evidence for this postulated scheme has been obtained from a study of some electron transfer reactions of side‐chain‐substituted acetophenones and of other compounds with manganic ions.When cobalt ions instead of manganese ions are used as the catalyst, the reaction becomes much slower and is first order in cobalt ion. The cause to which this difference is attributed is that now the re‐oxidation of cobaltous ion by the phenacyl peroxy radicals becomes rate‐determining, the oxidation potential of the cobalt ions being appreciably higher than that of the manganese ions.Electron‐withdrawing nuclear substituents were found to have a retarding effect, whereas electron‐supplying substituents had an accelerating effect, probably on account of their influence o

ISSN:0165-0513    

DOI:10.1002/recl.19610800108

出版商:WILEY‐VCH Verlag    

年代:1961

数据来源: WILEY

摘要:

AbstractThe reaction of gaseous sulphur trioxide with gaseous benzene has been studied at three different temperatures with different ratios of the reactants. The reactions are rapid. The number of products can be rather large and depends on the ratio of sulphur trioxide to benzene.At low ratios (up to 1.2) diphenylsulphone, benzene‐monosulphonic acid and benzene pyrosulphonic acid are formed, at higher ratios also more highly sulphonated products are obtained.The amount of sulphonic acid groups increases proportionally to this ratio. It is concluded that diphenylsulphone is formed via the intermediate product, benzenepyrosulphonic acid, because the presence of acetic acid reduced the amount of sulphone proportionally. The temperature – between 100 and 230° ‐ had no marked influence on the r

ISSN:0165-0513    

DOI:10.1002/recl.19610800109

出版商:WILEY‐VCH Verlag    

年代:1961

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19610800110

出版商:WILEY‐VCH Verlag    

年代:1961

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19610800111

出版商:WILEY‐VCH Verlag    

年代:1961

数据来源: WILEY