摘要:

The addition reaction of mercapto‐ethanol to cyclohexanone has been measured at 27.0° in solvant Ethanol‐Water “50/50”. The influence of initial thiol and hydronium ion concentrations on the rate of addition and on the equilibrium constant has been especially examined.The reaction obeys general acid catalysis and general base catalysis; the thiol plays a dual role, acting both as a nucleophile and a general base. A mechanism is proposed for this

ISSN:0165-0513    

DOI:10.1002/recl.19720910902

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractA study is reported on thecis‐transisomerization rates and equilibria of the ions Co(NH3)4(H2O)23+, Co(NH3)4(OH)(H2O)2+and Co(NH3)4(OH)2+in acidic and ammoniacal solutions. The relative reaction rates follow the pattern shown by the analogous ethylenediamine complexes, whereas the absolute rates for the ammine complexes studied are a 100 times large

ISSN:0165-0513    

DOI:10.1002/recl.19720910903

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractA full report is given of our investigations into the synthesis of a series of linear peralkylpolygermanes, both by reacting organohalogenogermanes with alkali metals and by coupling of organohalogenogermanes with trialkylgermyl alkali metal compounds2–4. The latter type of reaction always gives in addition to the asymmetric compound R3GeGeR3′, varying amounts of the symmetrical products R6Ge2and R6′Ge2. Evidence is presented that these side‐products are formed by a nucleophilic cleavage of the GeGe bond of the primary asymmetrical coupling products, rather than by a halogen‐metal exchan

ISSN:0165-0513    

DOI:10.1002/recl.19720910904

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractChlorotris (triphenylphosphine) iridium (I) andtrans‐carbonylchlorobis (triphenylphosphine) iridium (I) have been treated with hydrogen peroxide to yield catalysts for homogeneous hydrogenation. Evidence is presented that the activation involves selective oxidation of one triphenylphosphine ligand.Hydrogenation of terminal orcis‐substituted olefinic double bonds, catalyzed by both complexes, is accompanied by extensive isomerization. The kinetics of the hydrogenations are rather complex and remained unexplained. Deuteration experiments revealed some details of the mechanism of hydrogen addition and excha

ISSN:0165-0513    

DOI:10.1002/recl.19720910905

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe reduction of naphthalene and alkylnaphthalenes with lithium in liquid ammonia has been studied. With excess of alkali metal and in the absence of a proton donor the reaction yields tetralins. The reduction of 1, 4‐dideuteronaphthalene shows that the first proton addition at an α‐position is irreversible and that the amide‐catalyzed isomerization of the initially formed 1, 4‐ into the 1, 2‐dihydronaphthalene is mainly a one step process. This isomerization is the rate‐determining step in the reduction to tetralin. Reduction of 1‐alkyl‐ and 1, 4‐dialkyl‐naphthalenes occurs mainly in the unsubstituted ring. With 2‐alkyl‐naphthalenes the selectivity of ring reduction depends on the alkyl group; in 2‐methylnaphthalene the substituted ring is about twice as reactive as the unsubstituted ring whereas the reverse is tru

ISSN:0165-0513    

DOI:10.1002/recl.19720910906

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe rate constants of reactions between 4, 4′‐di‐isocyanato‐diphenylmethane (MDI) and alcohols inN, N‐dimethylformamide (DMF) have been determined by an UV‐spectroscopic method. On the basis of the kinetics observed and the values of the activation parameters ΔS≠and ΔH≠, a proposal is made for a mechanism with a four‐centre transition state. The rate constants for the reaction of several alcohols with MDI in DMF are correlated with the extended Taft equation:(Ecs= corrected steric substituent constant a

ISSN:0165-0513    

DOI:10.1002/recl.19720910907

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractBenzophenone and 4, 4′‐dimethylbenzophenone are added photochemically to 1‐methoxy‐1‐propyne. Besides methyl 3, 3‐diarylacrylates I, the alkylidenecycloheptatrienes IIEand IIZa

ISSN:0165-0513    

DOI:10.1002/recl.19720910908

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractCatalytic hydrogenation of the 9(11)‐double bond of 3, 14α, 17α‐trihydroxy‐19‐nor‐1, 3, 5(10), 9(11)‐pregnatetraen‐20‐one (1a) furnished a mixture of the 9α‐ and 9β‐stereoisomers.In the case of the 14α, 17α‐ethylidenedioxy‐derivatives4aand4bthe 9β‐isomers were obtained almost exclusively.Reduction of 14α, 17α‐ethylidenedioxy‐3‐methoxy‐1, 3, 5(10), 9(11)‐pregnatetraen‐20‐one(4b)with sodium in liquid ammonia gave the steroisomeric 9α‐compounds(5b).The stereochemistry

ISSN:0165-0513    

DOI:10.1002/recl.19720910909

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe bimolecular rate constants for reaction of the enantiomers of isopropyl methylphosphonofluoridate, isopropylp‐nitrophenyl methylphosphonate and isopropylS‐2‐dimethylaminoethyl methylphosphonothioate with α‐cyclodextrin have been calculated from the dissociation constants (Kdiss) of the prereaction 1:1 inclusion complexes and the maximal rate constants (k2max) for the ensuing nucleophilic reactions. These data are compared with the corresponding rate constants for the inhibition of acetylcholinesterase.It is concluded that the stereospecificity exhibited by α‐cyclodextrin in its reaction with enantiomeric organophosphorus compounds is reflected mainly in the nucleophil

ISSN:0165-0513    

DOI:10.1002/recl.19720910910

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractPerylene, naphthacene, anthracene and some substituted anthracenes are oxidized to the dipositive ions by SbF5(neat or in SO2CIF). In FSO3H‐SbF5dication formation takes only place with the easily oxidizable arenes perylene and naphthacene. The dication of anthracene has also been obtained by bromide abstraction from 9, 10‐dibromo‐9, 10‐dihydroanthracene. The PMR spectra of the dications are reported. Like in the dianions, the sum of the charge‐induced shifts varies considerably from one arene to

ISSN:0165-0513    

DOI:10.1002/recl.19720910911

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY