ISSN:0165-0513    

DOI:10.1002/recl.19630820902

出版商:WILEY‐VCH Verlag    

年代:1963

数据来源: WILEY

摘要:

Abstractα,β‐Unsaturated ketones are formed by reaction of aldehydes and ketones with phenylethyne under the influence of boron trifluoride. When using aromatic aldehydes 2,4,6‐triarylpyrylium tetrafluoroborates are formed as by‐products.trans‐2,3‐Diphenylindane‐1‐one is obtained from 1,2‐diphenylethyne

ISSN:0165-0513    

DOI:10.1002/recl.19630820903

出版商:WILEY‐VCH Verlag    

年代:1963

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19630820904

出版商:WILEY‐VCH Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractThe reaction of 1‐ethoxyvinyl esters and carboxylic acids has been investigated in non‐aqueous solvents. The kinetics in benzene follow the rate expressionV = k30· C1‐ethoxyvinyl ester · C2acidwhile in dioxan and sulpholane the following equation is obeyedV = (k30· C2acid + k4 · C3acid) · C1‐ethoxyvinyl esterThe rate constants in sulpholane are 20 to 30 times as large as those in dioxan, while the rate of reaction in benzene is approximately equal to that in sulpholane. The kinetic isotope effect, kH/kD, for the reaction of 1‐ethoxyvinyl acetate and either acetic acid orO‐deuteroacetic acid, amounts to 4.0 in benzene and to 3.6 in sulpholane as solvent. During this reaction no deuterium was incorporated into the vinyl ester molecule.Addition of tetrabutylammonium perchlorate to the solvent dioxan increases the rate constant of the reaction between 1‐ethoxyvinyl chloroacetate and chloroacetic acid in accordance with the equationk3= (k3)conc. salt = O (1 + b · Csalt)The value of the coefficient b amounts to 4 1/mole.From these results it was concluded, that in a number of pre‐equilibria a solvation complex is formed between a molecule of 1‐ethoxyvinyl ester and two, three or four molecules of carboxylic acid. These pre‐equilibria are followed by the rate determining step in which a proton is transferred to the substrate giving an ion pair as intermediate. The products are

ISSN:0165-0513    

DOI:10.1002/recl.19630820905

出版商:WILEY‐VCH Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractThe reaction between 1‐ethoxy‐1‐alkynes and carboxylic acids has been studied in non‐aqueous solvents. The first stage of this reaction, the formation of 1‐ethoxyvinyl esters, is described in this paper. The kinetics of the reaction in benzene follow the rate equationv = k03·C1‐alkynyl ether·C2acidwhereas in dioxan and sulpholane the equationv = (k03·C2acid+ k4·C3acid) C1‐alkynyl etheris obeyed. A considerable rate increase was observed on varying the solvent from dioxan to sulpholane, while the rate in benzene is approximately equal to that in sulpholane. From measurements on the reaction of ethoxyethyne and either normal orO‐deuteroacetic acid in benzene a kinetic isotope effect, kH/kD, of 3.1 was observed. In sulpholane as solvent kH/kDwas equal to 2.8. Infrared spectra of reaction mixtures of ethoxyethyne andO‐deuteroacetic acid showed that no incorporation of deuterium into ethoxyethyne occurred during reaction in benzene and sulpholane, whereas it did occur in dioxan. The effect of added tetrabutylammonium perchlorate on the rate of reaction of ethoxyethyne and chloroacetic acid in dioxan was also studied. The rates of a number of 1‐alkynyl ethers were correlated with a Taft‐equation.It was concluded that proton transfer occurs in the rate determining step in which an ion pair is formed. Before protonation the substrate is solvated by acid molecules in a

ISSN:0165-0513    

DOI:10.1002/recl.19630820906

出版商:WILEY‐VCH Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractA three step synthesis of the key intermediate (IV) for the total synthesis of 6‐aza‐19‐norsteroids is desc

ISSN:0165-0513    

DOI:10.1002/recl.19630820907

出版商:WILEY‐VCH Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractPropene‐1‐14C was partially oxidised with air to acrolein on a copper catalyst. The acrolein formed was degraded: equal amounts of radioactivity were found on carbon atoms 1 and 3, while essentially no radioactivity was found on the middle carbon atom (2). The “unreacted” propene was also degraded: a major part of the radioactivity was still on carbon atom 1, while a small part (10‐20%) was on carbon atom 3; no radioactivity was found on the middle carbon atom (2). These facts indicate that the oxidation of propene to acrolein on a copper catalyst takes place via a symmetrical intermediate.Partial isomerisation of unreacted propene also occurred when copper shavings were used as a catalyst. When D2O was present during the reaction, the unreacted propene was monodeuterated to only a very small ext

ISSN:0165-0513    

DOI:10.1002/recl.19630820908

出版商:WILEY‐VCH Verlag    

年代:1963

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19630820909

出版商:WILEY‐VCH Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractThe ratio of the overall rate constants for the sulphonation of toluene and benzene in aqueous sulphuric acid at 25° decreases from 110 to 25 on varying the acid concentration from 78 to 92 wt‐%. Similar trends are observed at 5° and 45°.The partial rate factors forortho‐, meta‐andpara‐substitution in the sulphonation of toluene with aqueous sulphuric acid all decrease strongly with increasing acid concentration. The partial rate factor forpara‐substitution is temperature independent, indicating a negligible difference in activation enthalpy between substitution at thepara‐position in toluene and at a single position in benzene. The corresponding difference in activation entropies is 7 ± 2 cal · deg−1· mole−1.The latter difference is ascribed to differences in solvation of the starting hydrocarbons or/and of the transition states. These differences in solvation may also be responsible for the small but apparent deviations from the Selectivity Relationship observed in the present study. It is suggested that the sulphonation of toluene and benzene in aqueous sulphuric acid proceeds via a Wheland

ISSN:0165-0513    

DOI:10.1002/recl.19630820910

出版商:WILEY‐VCH Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractThe acid dissociation constants of a number of substituted acetic acids were determined. Compounds were of the general type AC = X—BCH2COOH with A methyl, alkoxy, alkylthio or dimethylamino, X oxygen or sulphur, B oxygen, sulphur or nitrogen. The influence of the substituent AC(X)B upon the acidity is related to electronic (mesomeric and inductive) effects. In one instance complication by steric effects arises. The main results support the model, previously conceived for thiones with heteroatoms attached to the thiocarbonyl group: extensive mesomeric electron displacements together with appreciable contributions from inductive shifts, the latter especially noteworthy, where sulphur is concerned. In the molecules studied the thiocarbonyl group is more electron‐attracting than the carbonyl gr

ISSN:0165-0513    

DOI:10.1002/recl.19630820911

出版商:WILEY‐VCH Verlag    

年代:1963

数据来源: WILEY