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Tuesday, November 24, 2020 | History

4 edition of Ambident anions found in the catalog.

Ambident anions

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  • 8 Currently reading

Published by Consultants Bureau in New York .
Written in English

    Subjects:
  • Anions.

  • Edition Notes

    Includes bibliographical references and index.

    StatementO.A. Reutov, I.P. Beletskaya, and A.L. Kurts ; translated from Russian ; translation edited by J.P. Michael.
    ContributionsBelet͡s︡kai͡a︡, I. P., Kurts, A. L.
    Classifications
    LC ClassificationsQD561 .R442 1983
    The Physical Object
    Paginationxiii, 338 p. :
    Number of Pages338
    ID Numbers
    Open LibraryOL3168079M
    ISBN 100306109751
    LC Control Number83010137

    COVID Resources. Reliable information about the coronavirus (COVID) is available from the World Health Organization (current situation, international travel).Numerous and frequently-updated resource results are available from this ’s WebJunction has pulled together information and resources to assist library staff as they consider how to handle coronavirus. Book Chapter. Benin, V. “The Ambident Ethyl N-Nitrosocarbamate Anion: Experimental and Computational Studies of Alkylation and Thermal Stability”, J. Am. Chem Nechev, L. “a-Amidoalkylation of Ambident Nucleophiles by Means of N-Benzoylbenzaldimine.


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Ambident anions by Reutov, O. A. Download PDF EPUB FB2

Buy the Paperback Book Ambident Anions by O. Reutov atCanada's largest bookstore. Free shipping and pickup in store on eligible orders. The importance of ambident reactivity in synthetic and mecha­ nistic organic chemistry cannot be overemphasized. It is therefore all the more frustrating that the breadth and diffuseness of the.

The present volume is an attempt to meet these needs, at least as far as ambident anions are concerned. As a reference work combining under one cover an account of the factors underlying ambident behavior, a survey of the chemistry of the most important ambident anions (with especial emphasis on enolates), and a comprehensive compilation of.

ISBN: OCLC Number: Description: xiii, pages: illustrations ; 26 cm: Responsibility: O.A. Reutov, I.P. Beletskaya, and A.L. A nucleophile is a chemical species that donates an electron pair to form a chemical bond in relation to a molecules or ions with a free pair of electrons or at least one pi bond can act as nucleophiles.

Because nucleophiles donate electrons, they are by definition Lewis bases. Nucleophilic describes the affinity of a nucleophile to the positively charged atomic nuclei of atoms. The kinetics of the reactions of the ambident 2- and 4-pyridone anions with benzhydrylium ions (diarylcarbenium ions) and structurally related Michael acceptors have been studied in DMSO, CH3CN, and water.

No significant changes of the rate constants were found when the counterion was varied (Li+, K+, NBu4+) or the solvent was changed from DMSO to CH3CN, whereas a large decrease of Cited by: Controlling the regioselectivity of ambident nucleophiles toward alkylating agents is a fundamental problem in heterocyclic chemistry.

Unsubstituted triazoles are particularly challenging, often requiring inefficient stepwise protection–deprotection strategies and prefunctionalization protocols. Herein we report on the alkylation of archetypal ambident 1,2,4-triazole, 1,2,3-triazole, and.

Reactions of Ambident Anions and Cations Little is known about the regioselectivity in reactions of ambident cations, and acceptorsubstituted derivatives were studied only recently. Electron-releasing groups give rise to a higher positive charge at C-1, electron-withdrawing groups to a higher one at C - 3.

2-Nitrotrifluoromethylbenzene- and 2-nitrobenzene-sulphenate anions, generated by the base-catalysed hydrolysis of the corresponding disulphide or sulphenate ester, undergo S-methylation with methyl iodide but predominantly O-methylation with the ‘harder’ methylating agents, methyl fluorosulphonate and dimethyl nate ions react similarly with methyl fluorosulphonate.

Alkylation of nickel(II) corrole ambident anions. Grigg, A. Johnson and G. Shelton Abstract. The first page of this article is displayed as the abstract. About. Cited by For reproduction of material from all other RSC journals and books. A study of the factors influencing the site of alkylation of the ambident anion of mono-N-substituted amides, where competition is between oxygen and nitrogen, has been undertaken.

With the alkali metal and tetraalkylammonium salts of formanilide anions, the alkylation product is invariably the corresponding N -alkylformanilide.

Reactivity of ambident anions. Communication 2. Influence of the nature of the alkylating agent on the ratio of o- and c-isomers in the ethylation of alkali enolates of acetoacetic ester.

Kurts 1. Book: Basic Principles of Organic Chemistry (Roberts and Caserio) at least where kinetic control is dominant; namely, the freer (less associated) the ambident anions is from its cation, the more likely is the electrophile to attack the atom of the anion with the highest negative charge.

Thus \(\ce{O}\)-alkylation of the sodium enolate of 2. The crystal structure revealed a dimer with an eight membered ring formed by two ambident anions bridging the iodine atoms of two cations by N and S coordination.

The favored dimerization of [(C 6 F 5) 2 I][SCN] and [(C 6 F 5) 2 I][CN] in the gas phase is supported by ab initio computations. A study was conducted to investigate ambident reactivity of the cyanate anion. The study showed that the cyanate anion is an ambident nucleophile, which may react with electrophiles either at the.

HSAB concept is an initialism for "hard and soft (Lewis) acids and bases".Also known as the Pearson acid-base concept, HSAB is widely used in chemistry for explaining stability of compounds, reaction mechanisms and pathways.

It assigns the terms 'hard' or 'soft', and 'acid' or 'base' to chemical species. 'Hard' applies to species which are small, have high charge states (the charge criterion. A chemical species or molecule that possesses two alternative reactive sites, either of which can bond in a reaction; examples include cyanate ions, thiosulfate ions, oxime anions, and enolate ions.

The term is most commonly applied to conjugated nucleophiles, for example the enolate ion (which may react with electrophiles either at the -carbon atom or at oxygen) or -pyridones, and also to the vicinally ambident cyanide ion, cyanate ion, thiocyanate ion, sulfinate ion, nitrite ion, and unsymmetrical hydrazines.

Ambident electrophiles are exemplified by carboxylic esters RC(O)OCR3 which. The ambident anion is usually coordinated to some extent with cation (ion pair) so that the atom of highest e- density (hard atom) is screened, thus hindering rxn at hard site. Solvent ability to solvate cations disrupts ion pair formation.

The alkali metal salts of indole behave as typical ambident anions in their reactions with methyl iodide. Indolylmagnesium halides reveal their ambident character only in HMPT which breaks up the. This paper is a survey of the best conditions for alkylation at either site of ambident anions.

Emphasis is on the choice of experimental conditions; however, the influence of the leaving group and of the alkylating agent on the site of alkylation is also briefly discussed.

Solvent Influence on the Reactivity of Ambident Anions. Solvent Effects on Mechanisms and Stereochemistry of Organic Reactions. Influence of Micellar and Solvophobic Interactions on Reaction Rates and Mechanisms.

Liquid Crystals as Reaction Media. Solvent Cage Effects. External Pressure and Solvent Effects on Reaction Rates. Solvent Isotope Effects. Therefore, an ambident nucleophile can be thought of as an anionic nucleophile in which the negative charge of the ion is delocalized over two different atoms by resonance effects.

Commonly, enolate ions exhibit this quality. An illustration of such a resonance structure of an ambident nucleophile is. B Ambident Nature of Enolate Ions in Aldol Addition. The two possible valence-bond structures of the enolate anion, \(7a\) and \(7b\), show that the anion should act as an ambident nucleophile - a nucleophile with nucleophilic properties associated with both carbon and oxygen.

The addition step in the aldol reaction therefore may be expected to take place in either of two ways: The anion. An ambident nucleophile is an anionic nucleophile in which the negative charge is delocalized over two unlike atoms. You can reuse this answer Creative Commons License.

The most common type of elimination involves 1,2-elimination where the. The reactivities of ambident enolate and phenoxide ions in alkylation reactions are examined.

It is shown that the mode of C- and O-alkylation of an ambident anion is determined by the structures of the alkyl group and the group eliminated from the alkylating agent, the nature of the solvent, and the type of counter influence of each of these factors on the dual reactivity of the.

Abstract. The deprotonation of 3-aryl-substituted alkyl propargyl ethers with n-butyllithium provides an ambident anion that reacts with carbonyl compounds to provide mixtures of γ-substituted products with alkoxyallene substructure and of α-substituted propargyl ratio of the two product types strongly depends on the solvent: in diethyl ether the γ-substituted products.

Alkylation of Enolate Anions (Enolates are Ambident Nucleophiles) O +LDA O Li O Si(CH3)3 O CH3I CH3 (CH3)3SiCl "O"-alkylation "C"-alkylation +LiCl +LiI These are [S N2] reactions As the HOMO indicates, enolates are ambident nucleophiles, being reactive a both C α and oxygen.

Consistent with the largest lobe of the HOMO being on C α. The Ambident Character of Enolate Anions. Since the negative charge of an enolate anion is delocalized over the alpha-carbon and the oxygen, as shown earlier, electrophiles may bond to either atom.

Reactants having two or more reactive sites are called ambident, so this term is properly applied to enolate anions. Related Books SoS C-1 Building Blocks in Organic Synthesis SoS Multicomponent Reactions Ambident Anions Consultants Bureau; New York: p 7a Welton T.

Chem. Rev.7b Wasserscheid P. Keim W. Angew. Chem. Int. Alkylation of 5-substituted benzimidazole anions with a variety of primary alkyl halides in both protic and aprotic solvents showed only small regioselectivity, with a slight preference for reaction at N1 for 5-nitro and N3 for 5-methoxy systems.

With 4-substituted benzimidazole anions, alkylation gave more divergent results with the N1 to N3 regioselectivity varying between and O-Alkylation of Ambident Anion By Marc Halpern, the leading expert in industrial phase-transfer catalysis. As we deal with COVID there is a lot of talk about.

Related Books SoS C-1 Building Blocks in Organic Synthesis SoS Multicomponent Reactions SoS Cross Coupling and Heck-Type Reactions SoS Asymmetric Organocatalysis SoS Water in Organic Synthesis Ambident Anions Plenum; New York: 10a de la Hoz A.

An ambident nucleophile is one that can attack from two or more places, resulting in two or more products. For example, the thiocyanate ion (SCN −) may attack from either the S or the N.

For this reason, the S N 2 reaction of an alkyl halide with SCN − often leads to a mixture of RSCN (an alkyl thiocyanate) and RNCS (an alkyl. The neutral molecules or ions (or atoms or group of atoms) which are directly attached to the central metal ion or atom through co-ordinate bonds in the complex ion are called ligand or ligands.

Read more about ligands and its types for IIT JEE at cyclopentadienyl anion, deuterium exchange, displacement reactions, ElcB elimination and,electronic effects in, enolate anions,formation, in carbonation, in Danens reaction, in decarboxylation, in Favorskii reaction, in halogenation of ketones, in Kolbe-Schmidt reaction, Ambident Enolate Anions.

Alkylation of Enolate Anions. Practice Problems. Carboxylic Acids. Nomenclature of Carboxylic Acids. Natural Products. Related Derivatives. Physical Properties. Acidity. Preparation of Carboxylic Acids. Reactions of Carboxylic Acids. Salt. Regioselective Phosphorylation of Ambident Anions and Electrophilic Reaction of Carbanion of Allyl-Phosphonate.

Phosphorus, Sulfur, and Silicon and the. Ambident Nucleophiles Thiocyanate Ion, Cyanide Ion and Nitrite Ion (and the Nitronium Cation) Enolate lons Allyl Anions Aromatic Electrophilic Substitution Electrophilicity Trigonal Electrophiles Tetrahedral Electrophiles Hard and Soft Electrophiles - Explore Ramona Rad's board "Anion gap" on Pinterest.

See more ideas about Nursing study, Nursing notes, Anion gap.8 pins. Ambident definition is - capable of initiating a reaction from two or more sites. How to use ambident in a sentence. Aprotic solvents have dipoles due to their polar bonds but they do not have H atoms that can be donated into an H-bond.

The anions which are the O- and N- of sodium saccharin are not solvated therefore are “naked†and the reaction is not inhibited and preceded .Anions are atoms or radicals (groups of atoms), that have gained they now have more electrons than protons, anions have a negative charge.

For example, chloride ions Cl- bromide Br- iodide I. These are monovalent anions, meaning they have a valency (combining capacity) with only one ion of rly there are bivalent anions, etc.α-addition α-effect α-elimination 'A' value abstraction acceptor number \(\text{AN}\) acid acidity function activated complex activation energy addend addition reaction additivity principle adduct agostic allylic substitution reaction alternant ambident amphiphilic amphiprotic (solvent) amphoteric anionotropic rearrangement annelation.