Dipolar Aprotic Media Research Articles

1,4-Diamino-and 1,4-dibutylamino-anthraquinones: reduction and/or deprotonation-initiated elimination of the butyl groups in dipolar aprotic media

The standard redox potentials of the one- and two-electron reductions of the title compounds have been determined. The deprotonated form of the dibutylamino compound underwent a base-initiated elimination of the butyl groups and the basicity of the radical anion resulting from one-electron reduction was sufficient to provoke the same type of cleavage through an initial father–son reaction. A multi-step mechanism is proposed for the elimination on the basis of the identification of intermediates.

ChemInform Abstract: 77Se NMR. Application of JSe‐Se to the Analysis of Dialkyl Polyselenides.

AbstractElemental selenium is partially reduced via either disproportionation or reaction with sodium methanolate and hydrazine in dipolar aprotic media.

Complex formation between S −6 and organic polysulphides in dimethylacetamide

In a dipolar aprotic medium (dimethylacetamide), organic sulphides or polysulphides RS x R (R = alkyl or phenyl group, x = 1, 2, 3) are not reduced into thiolate ions by S 3 − or S 2− 8, electrogenerated from sulphur, but give complexes RS x R, S 2− 6 by shifting the equilibrium between S 3 − and S 2− 6 ions. Complexes stability constants, visible spectra and rates of formation are given. A mechanism for the complex formation is proposed form the kinetic studies.

ChemInform Abstract: Initial State and Transition State Solvent Effects: Reactions in Protic and Dipolar Aprotic Media (51 Literaturangaben).

Chemischer InformationsdienstVolume 13, Issue 7 Reviews ChemInform Abstract: Initial State and Transition State Solvent Effects: Reactions in Protic and Dipolar Aprotic Media (51 Literaturangaben). E. BUNCEL, E. BUNCELSearch for more papers by this authorE. A. SYMONS, E. A. SYMONSSearch for more papers by this author E. BUNCEL, E. BUNCELSearch for more papers by this authorE. A. SYMONS, E. A. SYMONSSearch for more papers by this author First published: February 16, 1982 https://doi.org/10.1002/chin.198207330AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume13, Issue7February 16, 1982 RelatedInformation

Synthetic Applications of Dealkoxycarbonylations of Malonate Esters, β-Keto Esters, α-Cyano Esters and Related Compounds in Dipolar Aprotic Media - Part I

Synthetic Applications of Dealkoxycarbonylations of Malonate Esters, β-Keto Esters, α-Cyano Esters and Related Compounds in Dipolar Aprotic Media - Part I

Catalytic mechanisms of acyl transfer reactions in dipolar aprotic media. 2. Electrophilic activation of the carbonyl group by quaternary alkylammonium and imidazolium functions

Catalytic mechanisms of acyl transfer reactions in dipolar aprotic media. 2. Electrophilic activation of the carbonyl group by quaternary alkylammonium and imidazolium functions

Deficiencies of the ferricinium-ferrocene redox couple for estimating transfer energies of single ions

The difference between the partial molal entropies of ferrocene and ferricinium\((\bar S_{{\text{Fc}}}^{\text{0}} - \bar S_{{\text{Fc}}^{\text{ + }} }^{\text{0}} )\) has been determined in nine solvents from the temperature dependence of the formal potential of the ferricinium-ferrocene redox couple using a nonisothermal electrochemical cell arrangement in order to probe possible structural reasons for the limitations of the ‘ferrocene assumption’ for estimating the transfer thermodynamics of single ions between different solvents. In contrast to the uniformly small positive values of\((\bar S_{{\text{Fc}}}^{\text{0}} - \bar S_{{\text{Fc}}^{\text{ + }} }^{\text{0}} )\) predicted by the Born model, the experimental quantities varied widely from small or even negative values in hydrogen-bonded solvents (−5 to 3 e.u.) to substantially larger values (11–14 e.u.) in dipolar aprotic media. These variations appear to arise chiefly from additional solvent ordering in the vicinity of the ferricinium cation compared to the ferrocene molecule which is enhanced in the aprotic solvents. The variations in\((\bar S_{{\text{Fc}}}^{\text{0}} - \bar S_{{\text{Fc}}^{\text{ + }} }^{\text{0}} )\) between water and a number of nonaqueous solvents provide a predominate contribution to the differences between the free energies of single ion transfer calculated using the ferrocene and alternative extrathermodynamic assumptions.

Catalytic mechanisms of acyl transfer reactions in dipolar aprotic media. 1. Desolvated carboxylate ion as acyl acceptor

Catalytic mechanisms of acyl transfer reactions in dipolar aprotic media. 1. Desolvated carboxylate ion as acyl acceptor

Initial state and transition state solvent effects: Reactions in protic and dipolar aprotic media

Interpretation of the variation in reaction rates brought about by solvent changes has traditionally utilized relationships based on absolute rate theory. Thus the Laidler-Eyring equation satisfactorily correlates rate data for the Menschutkin reaction in a number of binary solvents. However solvent parameters such as the dielectric constant are limited as measures of solvent influence since correlation is attempted with a quantity (ΔG ≠ or ΔG o) which represents a difference of two states and these may be affected differentially by the solvent change. Direct information about the nature of solvent involvement requires dissection of the solvent effects into initial and transition state (final state) contributions. This dissection is possible using the thermodynamic transfer function appoach [1–5]. In this presentation we utilize the relationship δ Δ T tr = δΔG R tr + δΔG ≠ for the free energy of transfer of the transition state (δΔG T tr) on solvent change, from the experimentally determined free energies of transfer of the reactants (δΔG R tr) and the kinetic activation parameters (δΔG ≠, and correspondingly for the equilibrium process δΔG tr = δG P tr − δG R tr, to discuss solvent effects on various rate and equilibrium processes. The discussion emphasizes dipolar aprotic solvents such as dimethyl sulfoxide for which dramatic medium effects have been observed in a number of systems. Specific reactions considered include solvent effects on S N2 and S NAr processes; the competing σ-complex formation and proton abstraction in nitroaromatics-base interactions; and the hydroxide ion catalyzed isotopic exchange of D 2. Some future directions in this area are indicated, as for example synergistic and antagonistic effects as probes of changing transition states.

Alkyl effects on equilibrium acidities of carbon acids in protic and dipolar aprotic media and the gas phase

Alkyl effects on equilibrium acidities of carbon acids in protic and dipolar aprotic media and the gas phase

Solvolysis in dipolar aprotic media. I. Production of water-extractable bromide vs. olefin distribution in the course of the solvolysis of 2-bromo-2-methylpentane in dimethylformamide

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSolvolysis in dipolar aprotic media. I. Production of water-extractable bromide vs. olefin distribution in the course of the solvolysis of 2-bromo-2-methylpentane in dimethylformamideMarc Anteunis and Hendrik L. PeetersCite this: J. Org. Chem. 1975, 40, 3, 307–311Publication Date (Print):February 1, 1975Publication History Published online1 May 2002Published inissue 1 February 1975https://doi.org/10.1021/jo00891a009RIGHTS & PERMISSIONSArticle Views126Altmetric-Citations10LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (643 KB) Get e-Alerts Get e-Alerts

Solvolysis in dipolar aprotic media. II. Initial rates of bromide ion production from tertiary alkyl bromides in dimethylformamide, measured in situ. Proposal of a solvolysis scheme for 2-bromo-2-methylpentane

Solvolysis in dipolar aprotic media. II. Initial rates of bromide ion production from tertiary alkyl bromides in dimethylformamide, measured in situ. Proposal of a solvolysis scheme for 2-bromo-2-methylpentane

Chemistry of the podocarpaceae—XVI : Heterolytic fragmentation of 6α-bromo-7-oxototarol

Treatment of 6α-bromo-7-oxototaryl acetate (II, R = OAc) with NaHCo 3/DMSO gives 6α-bromo-7-oxototarol (II, R = OH, 5%), Δ 5-dehydro-7-oxototaryl acetate (III, R = OAc, 45%), Δ 5- dehydro-7-oxototarol (III, R = OH, 15%), and by fission of the dA/B ring junction, 7-oxo-5,10-secototara- 5,8,10(20),11,13-penataen-13-ol (IV, R = H, 5%). The yield of the secoditerpenoid is improved markedly (80%) when 6α-bromo-7-oxatotarol rather than its acetate is the substrate. The action of NaHCO 3/DMSO on other 6Δ-bromo-7-oxo-diterpenoids is examine and formation of the secoditerpenoid shown to be by a fragmentation reaction which is explicable in terms of the structure and stereochemistry of the parent and the nature of the dipolar aprotic medium.