Carbanions: Formation and Reactions Part 1. The C-C bonds of a molecule under construction constitute its scaffolding. Reactions which form new C-C bonds.

Slides:

Advertisements

Similar presentations

Based on McMurry’s Organic Chemistry, 7th edition

Advertisements

ORGANOHALIDES + Nucleophilic Reactions (SN1/2, E1/E2/E1cB)

The Wittig reaction involves phosphorus ylides as the nucleophilic carbon species. The Wittig and Related Reactions of Phosphorus Stabilized Carbon Nucleophiles.

Electrophilic Reaction on Nitrogen R = H: pKa 5,23pKa pKa 6.95.

10. Alkyl Halides Based on McMurry’s Organic Chemistry, 6 th edition.

Chapter 7 Organohalides Alkyl halide: a compound containing a halogen atom covalently bonded to an sp 3 hybridized carbon atom –given the symbol RX.

Alcohols, Carbonyls and REDOX The Carbonyl Group (Section 12.1) Oxidation/Reduction Reactions: Review (Section 12.2) Reduction of Carbonyls to Alcohols.

1 Nucleophilic reactions involving enolate anions Aldehydes, Ketons and other carbonyl compounds having H on α-C -> in equilibrium (in solution) -> Keto-Enol.

Chapter 13 Substitution Alpha to Carbonyl Groups Formation and Reactions of Enolate Anions and Enols Alkylation of Ketones and Esters: S N 2 Reaction with.

GRIGNARD REAGENTS ORGANOMETALLICS FROM DIVALENT METALS DIVALENT METALS.

Organometallic Compounds

Organometallic Compounds Chapter 15. Carbon Nucleophiles: Critical in making larger organic molecules. Review some of the ones that we have talked about….

Synthesis of Alcohols Reduction of Aldehydes and Ketones Common reducing agents and conditions: NaBH 4 ( sodium borohydride ) alcohol, ether, or H 2 O.

Compounds that contain _________________bond (______): Examples of M include ________(Grignard reagents), _____________. ____________ carbon: Reacts with.

Chapter 8: Ethers and Epoxides Diethyl ether in starting fluid.

1 Chapter 18 Chapter 18 Additions to the Carbonyl Groups Addition to the carbonyl group also occurs at the carbon of a carbonyl groups which is also electrophilic.

Organometallic Reagents Carbon-Metal Bonds. RX ++++ ––––RM –––– ++++ Nucleophilic carbon.

17.2 How Aldehydes and Ketones React (Part I) 1 ++ R = alkyl or aryl (C) Y = alkyl, aryl or H (class II) (No leaving group) -- Electron rich (Lewis.

Important Synthetic Technique: protecting groups. Using Silyl ethers to Protect Alcohols Protecting groups are used to temporarily deactivate a functional.

Α,β-Unsaturated Carbonyl Compounds. α,β-Unsaturated Carbonyl Compounds, reactions: 1.electrophilic addition deactivated 2.nucleophilic addition activated.

Alkynes. Structure sp hybridization Acidity of Terminal Alkynes Other strong bases that will ionize the terminal alkyne: Not KOH Stronger base Weaker.

Organometallic Reagents: Sources of Nucleophilic Carbon for Alcohol Synthesis 8-7 If the carbonyl carbon of an aldehyde or ketone could be attacked by.

Alkynes. Hydrocarbons with a carbon–carbon triple bond are alkynes. Noncyclic alkynes have the molecular formula C n H 2n-2. Acetylene (HC≡ CH) is the.

OrgChem- Chap20 1 Chapter 20 Enolates / Other Carbon Nucleophiles C-C bond formation is very important  larger, more complex organic molecule can be made.

© 2011 Pearson Education, Inc. 1 Organic Chemistry 6 th Edition Paula Yurkanis Bruice Chapter 6 The Reactions of Alkynes An Introduction to Multistep.

Chapter 14 Organometallic Compounds

C-C bond forming reactions Known C-C bond forming reactions (New C-C bond forming reactions in KJM3200) Organometallic coupling C-C bond forming reactions.

Reduction of Aldehydes and Ketones Reduction of Aldehydes and Ketones to Alcohols.

Chapter 14: Organometallics, structure and nomenclature.

Chapter 20 Introduction to Carbonyl Chemistry; Organometallic Reagents; Oxidation and Redction.

Introduction Structure of the Carbonyl Group

1 Chapter 13 Silicon reagents  General features  Two other highly important properties of silicon  Reactions of organosilanes  1,2 rearrangements (Brook.

GROUP 1 COMPOUNDS – SYNTHESIS AND STRUCTURE Lithium reagents generally exhibit lower reactivity. This arises from lithium forming bonds with a greater.

11.1 Organometallic Compounds (R-M) Organomagnesium & Organolithium compds 15.1 Lithium Diorganocopper (Gilman) Reagents 15.2 No t covered: Organopalladium.

Renee Y. Becker CHM 2210 Valencia Community College

Organometallic Compounds

Spring 2011Dr. Halligan CHM 236 Organometallic Compounds Chapter 11.

1 Introduction to Carbonyl Chemistry; Organometallic Reagents; Oxidation and Reduction Two broad classes of compounds contain the carbonyl group: Introduction.

Objective. Reactions of Haloalkanes with metals When a solution of an alkyl halide in dry ether is treated with magnesium, an alkyl magnesium halide is.

Properties of ,  -Unsaturated Aldehydes and Ketones 18-8 Conjugated unsaturated aldehydes and ketones are more stable than their unconjugated isomers.

Chapter 17 Aldehydes and Ketones II. Aldol Reactions

John E. McMurry Paul D. Adams University of Arkansas Chapter 10 Organohalides.

© 2016 Cengage Learning. All Rights Reserved. John E. McMurry Chapter 10 Organohalides.

Oxidation-Reduction & Organometallic

Carbanions | — C: – The conjugate bases of weak acids,

Chapter 14 Organometallic Compounds

Organometallic Compounds

CH 14 Delocalized Pi Systems

Chapter 10 Organohalides

Chapter 10 Organohalides

Chapter 10 Organohalides

Chapter 9 Alkynes: An Introduction to Organic Synthesis

Chapter 10 Organohalides.

Organic Halogen Compounds

CH 12-3: Grignard Reaction-I

Organometallic Compounds

Chapter 10 Organohalides

Anions Carey & Sundberg, Part A Chapter 7, ”Carbanions and Other Nucleophilic Carbon Species",

Elimination reactions

Chapter 7: Alkenes and Alkynes I

Chapter 5. C-C Bonds with Stabilized Carbanions

Chap. 4. C-C Bonds with Unstabilized Carbanions

Miscellaneous Reactions of Synthetic Importance

Organ metallic Compounds

Chapter 10 Organohalides

CONTENTS  INTRODUCTION  REACTION  MECHANISM  APPLICATION  SCOPE  CONCLUSION  REFERENCE.

CONTENTS  INTRODUCTION  REACTION  MECHANISM  APPLICATION  SCOPE  CONCLUSION  REFERENCE.

Presentation transcript:

Carbanions: Formation and Reactions Part 1

The C-C bonds of a molecule under construction constitute its scaffolding. Reactions which form new C-C bonds are exceptionally useful synthetically. SN2 reactions, which use a carbanion as a nucleophile represent one solution to this problem.

General Types of Carbanions

Formation of Stabilized Carbanions Note that, for this reaction to succeed, the carbanion must be a weaker base than the base employed to deprotonate its conjugate acid.

Bases often used to form (stabilized) carbanions Increasing Basicity

Formation of Alkynyl Anions (can be formed by deprotonation)

Alkynes

Reactions of Alkynyl Anions

Other Carbanions Formed by Deprotonation (Enolate Anions)

Grignard and Organolithium Species (Unstabilized Carbanions)

Formation of Organometallics by Reaction of Organohalides with Magnesium and Lithium Metal

Formation of Carbanions by Halogen-Metal Exchange Reactions This works when R’-M is a more stable organometallic (carbanion) than R-M. This reaction is often used to form vinyl- and aryl- carbanions, where the sp 2 hybridized orbital has more ‘s-character’ than the starting sp 3 hybridized orbital.

Formation of Organometallics by Halogen-Metal Exchange

Reactions of Organomagnesium and Organolithium Species