摘要:

AbstractA general study on the β‐cis‐elimination mechanism was made, concentrating on the steric requirements of the reaction and the influence of substituents in the alkyl (especially the β‐position) and in the acid moieties. Kinetic data on cycloalkyl esters ‐ mainly substituted cyclohexyl acetates ‐ show that a planar transition state, if not essential, is highly preferred. Polar substituent effects (β‐alkyl, ‐chloro, ‐acetoxy and ‐acetyl) in the alkyl moiety, being relatively small as such, are found to be coupled with those of other structural variations, especially in the case of β‐acetyl derivatives.Mechanistic implications are discussed in detail, leading to a transition state description comparable with that of solvolytic elimination reactions: a range of structures – in this case of a strongly concerted character – intermediate between carbonium ion

ISSN:0165-0513    

DOI:10.1002/recl.19720910102

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe practical possibilities of a tubular reactor are evaluated, aiming at the isolation of unreacted, relatively stable compounds from mixtures with more reactive contaminants. The system approaches ideal ‘tube flow’ behaviour closely enough to make the method useful on a preparative sc

ISSN:0165-0513    

DOI:10.1002/recl.19720910103

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractSulfonation of anthracene‐9‐d with sulfur trioxide‐dioxane in dioxane as solvent at 40° leads to 31 ± 2% α‐, 8 ± 2% β‐ and 61 ± 2%meso‐substitution. The substitution at themeso‐position proceeds with a maximal substrate kinetic isotope effect of hydrogen ‐kH/kD= 6.8 with 5.6 and 8.6 as limiting values ‐ indicating that the proton removal from the σ‐complex is rate‐limiting.From the data for anthracene‐9‐d it was calculated that the sulfonation of C14H10leads to 21 ± 3% 1‐, 6

ISSN:0165-0513    

DOI:10.1002/recl.19720910104

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe isomer distribution in the sulfonation of toluene with sulfur trioxide in nitromethane at ‐ 25.0° and 25.0° has been determined aso: m: p= 13.6: 0.8: 85.4, and 12.2: 1.4: 86.4, respectively. These isomer distributions are overall data for the primary and secondary sulfonation. As indicated by flow system experiments, the degree ofortho‐substitution is greater for the primary sulfonation than for the secondary sulfonation.The degree ofortho‐substitution for the sulfonation of toluene in nitromethane as solvent is virtually the same for the protic reagents ClSO3H, FSO3H, H2S2O7, C6H5S2O6H and CH3S2O6H,viz.6.0

ISSN:0165-0513    

DOI:10.1002/recl.19720910105

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractTwo general methods are given for the synthesis of mono‐sulfonyl‐substituted methylenephosphoranes,(1). (i) Methylenetriphenylphosphorane can be substituted by using sulfonyl fluorides to give 1. A similar reaction with sulfonyl chlorides, however, fails mostly, (ii) The synthesis of sulfonylmethyltriphenylphosphonium bromides (5) from bromomethyl sulfones and triphenylphosphine, due toSpezialeandRatts, was improved. The bromides5were readily transformed to1by base.As an extension of (i), the reaction of benzylidenetriphenylphosphoranes with sulfonyl halides has been studied. Contrary to previous reports it was found that the product from ethoxycarbonylmethylenetriphenylphosphorane and tosyl chloride is α‐ethoxycarbonyl‐p‐tolylthiomethylenetriphenylphosphorane, instead of the corresponding tosyl compound. Method (i), however, does not apply to ethoxycarbonylmethylenetriphenylphosph

ISSN:0165-0513    

DOI:10.1002/recl.19720910106

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractBy means of ESR techniques a systematic study has been made of radicals prepared by reaction of aromatic nitro and nitroso compounds with pentacyanocobaltate(II). Assignments of hyperfine coupling constants have been confirmed by deuterium substitution. The structure of the radicals, aryl pentacyanocobalt nitroxides, has been confirmed by experiments with nitro, corresponding nitroso and dinitro compounds and experiments with varying cobalt‐substrate ratio. Substituent effects on the nitrogen hyperfine interactions have been expressed in terms of aHammettrelationship aN= −1.46 σ ± 13.79. A qualitative ligand‐field model is given to get a better understanding of the delocalization of the unpaired electron over the transition metal ion and the aromatic

ISSN:0165-0513    

DOI:10.1002/recl.19720910107

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractPhotoaddition of aromatic ketones to 1‐alkynyl ethers R ′O ‐ C  C ‐ R generally affords,viaC3O‐cycloaddition (oxete derivatives) alkyl 3,3‐diarylacrylates: Ar2C = CR ‐ COOR′in good yields (R = H,CH3,C2H5;R′ = CH3,C2H5).Analogously from acetone and 1‐methoxy‐1‐propyne, methyl 2,3‐dimethyl‐2‐butenoate (CH3)2C = C(CH3)COOCH3was obtained, together with RH‐adduct III and an isomerised analogue IV.In two cases some 1,3,5‐triethoxybenzene, resulting from trimerisation

ISSN:0165-0513    

DOI:10.1002/recl.19720910108

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe synthesis of cobalticenium (triphenylphosphine)trihalogenocobaltates(II), [Cp2‐Co][Co(PPh3)X3] (X = Cl,Br,I), which were first found as by‐products in the reaction of cobaltocene with triphenylphosphonium halides, is reported. The nature of the green complexes was derived from analytical and spectroscopic data and confirmed by X‐ray analysis of the iodo complex. Oxidation of solutions of the iodo complex by oxygen gives the compound [Cp2Co][Co(OPPh3)I3].[Cp2Co][Co(PPh3)I3] is cubic (a = 18.272 Å), space group Pa3, with eight formula units in the cell. The structure consists of discrete ions [Ph3PCoI3]−and [CpCoCp]+, both lying on a threefold axis. The apparent threefold symmetry of the cobalticenium cations is due to disorder of the π‐cyclopentadienyl ligands about the threefold axes. The substituents of P and Co in the [Ph3PCoI3]−anion are in staggered configuration; the metal atom is approximately tetrahedrally surrounded by 3 I (at 2.557 Å) and 1 P (at 2.368 Å), the latter distance being larger than in other phosphinec

ISSN:0165-0513    

DOI:10.1002/recl.19720910109

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractA number of complexes of the general formula M(CH30H)2+6(Anion)−2is reported, the anions being ClO−4, BF−4, NO−3. The cations are Mg, Mn, Co, Ni Zn and Cd, which are completely solvated by methanol in these complexes.The compounds are prepared by reaction of the metal hydrates with trimethyl orthoformate. Information about the structure of the complexes was obtained from chemical analyses, infrared spectra, ligand‐field spectra, X‐ray powder diagrams and NMR measurements.Three other compounds of the formula M(CH3OH)3SO4are reported, with the cations Ni

ISSN:0165-0513    

DOI:10.1002/recl.19720910110

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractA number of compounds of the general formula M(NIPA)n(anion)mis reported, in which M = Mg,Ca,Sr,Ba,Al,Cr,Fe and In; NIPA = nonamethylimidodiphosphoramide { = [(CH3)2N]2P(O)N(CH3)P(O)[N(CH3)2]2}, n = 1‐3, m = 2,3 and the anions are BF−4, Cl−, Br−, I−, NO−3and NCS−.The compounds are characterized by chemical analyses and physical measurements.With the aid of infrared and ligand‐field spectra in combination with X‐ray powder patterns octahedrally coordinated metal ions are found in all compounds.The ligand is shown, by means of infrared spectroscopy, to coordinateviathe oxygen lone pair electrons to the metal ions investigated.Metal‐ligand stretching frequencies are observed in the 700 − 450 cm−1region for the trivalent metal compounds. The absence of these bands in the spectra of the bivalent metal complexes is explained in terms of the high ionic character of the metal‐ligan

ISSN:0165-0513    

DOI:10.1002/recl.19720910111

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY