摘要:

AbstractThe most stable conformations of some protonatedtertiarycarboxylic acids in HF‐BF3and HF‐SbF5have been shown to be those which have one OH protonsynand the otherantito the alkyl groups. In HF solutions, the intramolecular interconversions between the two degenerate conformations is much faster with tertiary than with secondary or primary carboxylic acids; with the tertiary acids it is likely to proceedviathetrans‐transrather than the cis‐cis con‐former as an intermediate. The conformational equilibration of protonated pivalic acid is much faster in HF solution than in FSO3H‐SbF5‐SO

ISSN:0165-0513    

DOI:10.1002/recl.19730921002

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractHydride transfer from isoalkanes to methylated benzyl cations in strong proton acids and proton exchange between isoalkanes and strong proton acids have comparable velocities. The rate of proton exchange between isobutane and several strong proton acids has been studied by PMR line broadening and the following parameters were obtained: (with HSO3F) ΔH≠= 5.5 kcal/mole., ΔS≠= ‐35 cal/mole.°K; (with CF3SO3H) ΔH≠= 4.3 kcal/mole., ΔS≠= ‐43 cal/mole.°K.Using 2‐2H‐isobutane and tritiated HSO3F, labelled hexamethylbenzene was preparedviahydride transfer to pentamethylbenzyl cations at various temperatures. The analyses for deuterium and tritium were combined with the known rates of proton exchange to get an estimate for the rate of hydride transfer and the corresponding activation parameters: ΔH≠= 1 kcal/mol

ISSN:0165-0513    

DOI:10.1002/recl.19730921003

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

Abstract2‐Alkynyl alkanedithioates R1R2CHC(S)‐S‐CH(R3)CCR4(R1‐R4=H or alkyl) rearrange at 130‐140° in the presence of catalytic amounts of C2H5N(i‐C3H7)2to 1,3‐dithiole derivatives (5) possiblyviaallenyl alkanedithioates R1R2CHC(S)SC(R4)CCHR3although these intermediates have not been isolated. Traces of acids can cause dimerisation

ISSN:0165-0513    

DOI:10.1002/recl.19730921004

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe interaction of the sulfonyl group with an adjacent unsaturated centre has been studied by IR spectroscopy. The sulfur‐oxygen stretching frequencies of thiophene dioxides are compared with those of the open‐chain counterparts. The observed differences indicate a small contribution of “ketonic” type of resonance to the ground state of thiophene dioxides. The same result is obtained using the internal relationship between SO stretching frequencies and hydrogen bonding abilities.Qualitatively, these experimental results are in good agreement with the characteristics of the SO2moiety, as obtained from HMO calcu

ISSN:0165-0513    

DOI:10.1002/recl.19730921005

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19730921006

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractReaction models were derived by analogue simulation, to describe the course of the reaction in the hydrogenolysis of tetralin and indan up to high conversion levels.The side chain cracking ofn‐butylbenzene results mainly in styrene, ethyl‐benzene and toluene;n‐propylbenzene preferentially forms styrene and ethyl‐benzene, while l‐methylindan undergoes demethylation and α ring‐opening almost exclusively at the methyl substituted C‐atom.Mechanisms proceedingviabenzylic radicals, are proposed for the side

ISSN:0165-0513    

DOI:10.1002/recl.19730921007

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractIt is demonstrated that the course of the reaction of tris(dimethylamino)phosphine with aromatic bromides is strongly dependent on the nature of the solvent. The reaction in DMF or THF gave rise to the formation of radicals, which could be measured directly or by the method of spin‐trapping, using 2‐methyl‐2‐nitrosopropane as a sc

ISSN:0165-0513    

DOI:10.1002/recl.19730921008

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe electron paramagnetic resonance (EPR) spectra of the ions CrOF5=, MoOF5=, WOF5=, MoOCl5=, MoOBr5=, WOCl5=and WOBr5=, all incorporated into a single crystal of a suitably chosen host lattice, are presented.An attempt is made to correlate the EPR parameters to bonding orbital coefficients by using theAbragamandPryce method.The analysis of the ligand hyperfine tensor components in bonding coefficients gives satisfactory results for the oxyfluorides with an increase in orbital delocalisation going from chromium to molybdenum.The existing methods of correlating g‐ and A‐tensor to molecular orbital coefficients are reviewed critically and shown to be highly dependent on an arbitrary choice of a charge distribution over the comp

ISSN:0165-0513    

DOI:10.1002/recl.19730921009

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

Abstract1‐Metallocyclopropene is instantaneously and nearly quantitatively formed on addition of cyclopropene to an at least equimolar amount of alkali amide in liquid ammonia. Alkylation yields mono‐ and dialkylated cyclopropenes. On standing, 1‐metallocyclopropene slowly converts into a mixture of 1‐metallo‐,2‐cyclopropylcyclopropene, 1,2‐dicyclopropylcyclopropene and cyclopropylidenecyclopropane, in a yield that greatly depends on the reaction conditions. A detailed kinetic study has made it possible to select optimum reaction conditions for the formation of each of these products.A route has been developed for the synthesis of monoalkylated and 1,2‐dialkylated cyclopropenes, either with identical or with differe

ISSN:0165-0513    

DOI:10.1002/recl.19730921010

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe crystal and molecular structure of a cyclopropane containing marine steroid, 23‐demethylgorgosterol, and its absolute configuration have been determined on the p‐iodobenzoate derivative. The compound crystallizes in the space group P21212,1with cell dimensions a = 14.076, b = 39.15 and c = 5.987 Å. There are four formula units (C36H51O2I) per unit cell. The structure was determined and refined using 1872 counter data. The final R‐value is 7.4%. The structure determination confirms the presence of a cyclopropane ring in the side chain. An explanation is given for the two additonal highfield protons observed in the NMR sp

ISSN:0165-0513    

DOI:10.1002/recl.19730921011

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY