On the decomposition of diazo-acetic ester catalysed by protons and deutons

Gross, Ph.; Steiner, H.; Krauss, F.

doi:10.1039/tf9363200877

Cited by 32 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, the addition of a strong nucleophile dramatically increased the rate. The authors thus concluded that these observations are pieces of evidence for an A2 bimolecular process, which is also in agreement with the preferred decomposition pathway of other deactivated diazoalkanes (i.e., diazoacetate, k H / k D = 0.34) [ 145 – 146 ]. Extending the investigations to diazo compound 217b led to a different conclusion as a “normal” isotope effect of k H / k D = 1.67 was obtained in this case.…”

Section: Reviewsupporting

confidence: 71%

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

Fernandes¹,

Panossian²,

Michelet³

et al. 2021

Beilstein J. Org. Chem.

View full text Add to dashboard Cite

“The extraordinary instability of such an “ion” accounts for many of the peculiarities of organic reactions” – Franck C. Whitmore (1932). This statement from Whitmore came in a period where carbocations began to be considered as intermediates in reactions. Ninety years later, pointing at the strong knowledge acquired from the contributions of famous organic chemists, carbocations are very well known reaction intermediates. Among them, destabilized carbocations – carbocations substituted with electron-withdrawing groups – are, however, still predestined to be transient species and sometimes considered as exotic ones. Among them, the CF3-substituted carbocations, frequently suggested to be involved in synthetic transformations but rarely considered as affordable intermediates for synthetic purposes, have long been investigated. This review highlights recent and past reports focusing on their study and potential in modern synthetic transformations.

show abstract

Section: Reviewsupporting

confidence: 71%

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

Fernandes¹,

Panossian²,

Michelet³

et al. 2021

Beilstein J. Org. Chem.

View full text Add to dashboard Cite

show abstract

“…Its temperature dependence is given in Eq. (55). There is a slight decrease in energy, indicating that a hydrogen bond in the cyclic complex is stronger than a hydrogen bond between A and the solvent.…”

Section: Discussionmentioning

confidence: 97%

Dynamic NMR Study of the Interference between Cyclic Proton Exchange, Selfassociation and Hindered Rotation of Diphenylformamidine in Tetrahydrofuran

Meschede

Gerritzen

Limbach

1988

Ber Bunsenges Phys Chem

View full text Add to dashboard Cite

Chcriiicd KineticsThc 90 M H z ' H N M R spectra of '5N,'sN'-dipentadeutcrophenylformamidine (DPFA), a nitrogen analogue of formic acid, dissolved in tetrahydrofuran-d8 (THF) have been measured as a function of concentration, deuterium fraction in the 'H-I5N sites, and of temperature. The spectra show characteristic changes, from which thermodynamic and kinetic information on hindered rotation, hydrogen bond association and proton exchange of DPFA in THF are obtained by NMR lineshape analysis. DPFA forms two conformers A and B in THF, to which s-trans and s-cis structures have been assigned. At low concentrations both DPFA conformers are located in a hydrogen bond to the solvent molecules. However, as a result of the different structure, only A is able to selfassociate to any observable extent. This effect leads to concentration dependent A/B populations. Higher selfassociates or mixed AB associates are not observed. Whereas B is not able to exchange protons, A is subject to a very fast proton transfer. By measuring proton lifetimes as a function of concentration and of the deuterium fraction in the labile proton sites, it was established that two protons are transferred in every exchange process. Thermodynamic data of the association process obtained by the analysis of the chemical shifts, of the A/B populations and the proton lifetimes as a function of concentration agreed very well. These results are evidence that A forms only selfassociated hydrogen bonded dimers with a cyclic structure in which the double proton transfer takes place. The observation of a kinetic HH/HD isotope effect of 20 at 178 K establishes this transfer as the rate limiting step of the overall proton exchange. Rate constants of the double proton transfer in the cyclic dimer were obtained as a function of temperature from which an activation energy of about 19 kJ mol-' was obtained. In addition, the rates of interconversion between the two conformers were determined as a function of temperature. Details of the reaction mechanism and differences to the related carboxylic acids are discussed. Thus, it is shown that dynamic NMR spectroscopy can be a useful tool for elucidating elementary steps of complex reaction networks.

show abstract

“…Effect of deuterium concentration on the rate of some catalyzed reactions. Curve a, decomposition of diazoacetic ester (78); curve b, acid-catalyzed hydrolysis of acetal (171); curve c, inversion of sucrose (81); curve d, acid-catalyzed hydrolysis of methyl acetate (165); curve e, base-catalyzed decomposition of diacetone alcohol (165); curve f, acid-catalyzed mutarotation of glucose (86); curve g, acetate ion-catalyzed mutarotation of glucose (86); curve h, base-catalyzed decomposition of nitramide (125). Other reactions which have been studied are: the acid-catalyzed hydrolysis of ethyl formate (165), the acidcatalyzed hydrolysis of ethyl orthoformate (30), the bromination of acetone (184), and the alcoholic fermentation of glucose and sucrose (180).…”

Section: Ionic Reactions In Deuterium-containing Solventsmentioning

confidence: 99%

The Deuterium Isotope Effect

Wiberg¹

1955

Chem. Rev.

708

303

View full text Add to dashboard Cite

On the decomposition of diazo-acetic ester catalysed by protons and deutons

Cited by 32 publications

References 0 publications

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

Dynamic NMR Study of the Interference between Cyclic Proton Exchange, Selfassociation and Hindered Rotation of Diphenylformamidine in Tetrahydrofuran

The Deuterium Isotope Effect

Contact Info

Product

Resources

About

On the decomposition of diazo-acetic ester catalysed by protons and deutons

Cited by 32 publications

References 0 publications

CF3-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

CF3-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

Dynamic NMR Study of the Interference between Cyclic Proton Exchange, Selfassociation and Hindered Rotation of Diphenylformamidine in Tetrahydrofuran

The Deuterium Isotope Effect

Contact Info

Product

Resources

About

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry