ISSN:0165-0513    

DOI:10.1002/recl.19530720402

出版商:WILEY‐VCH Verlag    

年代:1953

数据来源: WILEY

摘要:

AbstractThe method previously describedThis is the second of a series of communications on the influence of substituents on the reactivity of aromatic compounds. For the first communication cf:F. L. J. Sixma, J. Chem. Phys.19, 1209 (1951).for calculating the influence of the electric field of a substituent (inductive effect) on the energy content of the intermediate complex of substitution reactions in the benzene nucleus, proceeding from the known values of dipole moments, bond lengths and valency angles, is further elaborated.The theory is tested on the experimental results for electrophilic substitution reactions. The agreement between calculated and experimental values for the percentage meta‐substitution is very satisfactory for those substituents which show little or no resonance interaction (E‐effect) with the pentadienate cat

ISSN:0165-0513    

DOI:10.1002/recl.19530720403

出版商:WILEY‐VCH Verlag    

年代:1953

数据来源: WILEY

摘要:

AbstractA synthesis of the 5‐chloro‐derivative of 2,4‐dihydroxypyridine is described. In addition to this compound, 5‐chloro‐2‐ethoxy‐4‐hydroxypyridine, 5‐chloro‐4‐ethoxy‐2‐hydroxypyridine, and 5‐chloro‐2,4‐diethoxypyridine were prepared.The reactivity of 5‐chloro‐2,4‐dihydroxypyridine towards bromine and aqueous solutions of hydrobromic an

ISSN:0165-0513    

DOI:10.1002/recl.19530720404

出版商:WILEY‐VCH Verlag    

年代:1953

数据来源: WILEY

摘要:

Abstract3,5‐Dibromopyridine‐N‐oxide, when heated with a mixture of fuming nitric acid and sulphuric acid, just like 3‐bromo‐ and 3‐ethoxypyridine‐N‐oxide, yields the 4‐nitro‐derivative. In 3,5‐diethoxypyridine‐N‐oxide, however, the nitro‐group enters the 2‐position.3,5‐Dibromo‐4‐nitropyridine‐N‐oxide and 3,5‐diethoxy‐2‐nitropyridine

ISSN:0165-0513    

DOI:10.1002/recl.19530720405

出版商:WILEY‐VCH Verlag    

年代:1953

数据来源: WILEY

摘要:

AbstractThe polarographic behaviour of β,γ‐benzotropolone, tropolone, β‐methyltropolone, and β‐methyltropolone methyl ether is described. Certain correlations between these compounds and the naturally occurring tropolones, colchicine and colchiceine, are pointed out. An explanation is offered for discrepancies between the present results for tropolone and data given byJamesandSpeakman10) for this

ISSN:0165-0513    

DOI:10.1002/recl.19530720406

出版商:WILEY‐VCH Verlag    

年代:1953

数据来源: WILEY

摘要:

AbstractLa difficulté d'obtenir des sulfones par oxydation de thiophènes a deux causes: la stabilité du groupement électronique dans L'anneau “aromatique” de thiophène et L'abaissement de cette stabilité par suite de L'oxydation du soufre. Ce mémoire étudie L'influence de substituants sur la possibilité de préparer

ISSN:0165-0513    

DOI:10.1002/recl.19530720407

出版商:WILEY‐VCH Verlag    

年代:1953

数据来源: WILEY

摘要:

AbstractThe retardation method1) described previously has been applied to a number of polyalkylbenzenes. The reactivities of the alpha methylenic *) groups towards hydrogen abstraction by trichloromethyl radicals were compared with those of monoalkylbenzenes.Compounds having two alkyl groups in adjacent positions ‐ with the exception of methylated benzenes ‐ were found to be far less reactive than expected on the basis of additivity. In these cases, scale drawings as well as model considerations show that coplanarity of the three remaining valencies at the alpha methylenic carbon atom is markedly interfered with by steric repulsions. With other isomers, reactivity appeared to be nearly additive.The results are interpreted in terms of steric hindrance of resonance: geometrical arguments are put forward to show that this hindrance occurs not only in the final state — i.e. in the benzyl‐type radical formed upon hydrogen abstraction ‐ but also in the transition state.The extremely low reactivity found for the anthracene‐maleic anhydride addition product is attributed to the fact that the bridge prevents formation of a pla

ISSN:0165-0513    

DOI:10.1002/recl.19530720408

出版商:WILEY‐VCH Verlag    

年代:1953

数据来源: WILEY

摘要:

AbstractThe relative reactivities towards trichloromethyl radicals were determined for a number of tetralin, indan and dihydroanthracene homologues, using the retardation method described previously1)2).As in the case of alkylbenzenes2), several of the hydrocarbons showed marked decreases in reactivity compared with the additive values. The effects are again attributed to steric interference with the most favourable transition state configuration. They were found to become increasingly important in the order (1‐methylindan, hexahydrofluorene), 1,4,7‐trimethylindan, (cumene, 1‐methyltetralin, 9,10‐dimethyl‐9,10‐dihydroanthracene), 9,10‐diisopropyl‐9,10‐dihydroanthracene, (o‐cymene, hexaethylbenzene, 1,2,4,5‐tetraisopropylbenzene).The magnitudes of the effects are discussed on the basis of the calculated distances between the centres of the interfering groups in the absence of steric repulsion. This leads to an estimate of the effective methyl radius of about 1.5 Å at angles of approach of about 80°,i.e.a value considerably smaller than the Van d

ISSN:0165-0513    

DOI:10.1002/recl.19530720409

出版商:WILEY‐VCH Verlag    

年代:1953

数据来源: WILEY

摘要:

AbstractA method described byPfeilandSchroth1) for the quantitative determination of formaldehyde appeared to be applicable in the presence of phenols and phenol alcohols.

ISSN:0165-0513    

DOI:10.1002/recl.19530720410

出版商:WILEY‐VCH Verlag    

年代:1953

数据来源: WILEY

摘要:

AbstractNew synthetic anticoagulants were obtained in the series of 1‐alkoxy‐2,2‐bis‐(4‐hydroxy‐coumarinyl‐3)ethanes (III). In the rabbit the most active members of this group are as active as dicoumarol (I), while they equal ethyl biscoumacetate (II) with respect to resorption and rapid elimination. Clinical investigations ar

ISSN:0165-0513    

DOI:10.1002/recl.19530720411

出版商:WILEY‐VCH Verlag    

年代:1953

数据来源: WILEY