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Related Concept Videos

Preparation of Alkynes: Dehydrohalogenation02:34

Preparation of Alkynes: Dehydrohalogenation

Introduction
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.
α-Hydroxy Ketones via Reductive Coupling of Esters: Acyloin Condensation Overview01:19

α-Hydroxy Ketones via Reductive Coupling of Esters: Acyloin Condensation Overview

The pinacol and McMurry reactions involve the reductive coupling of ketones or aldehydes. Similarly, the bimolecular reductive coupling of two ester molecules in the presence of sodium metal in an aprotic solvent yields an α-hydroxy ketone product. The α-hydroxy ketone is also called acyloin, so the reaction is referred to as ‘acyloin condensation.’
E2 Reaction: Stereochemistry and Regiochemistry02:43

E2 Reaction: Stereochemistry and Regiochemistry

Elimination reactions of alkyl halides can yield one or more alkenes depending on the specific regiochemical and stereochemical considerations. While the regiochemistry of the reaction governs the location of the double bond in the product, the stereochemical requirements often influence the geometry.
When a substrate with two different β hydrogens undergoes an E2 elimination, the presence of a strong base can yield two regioisomeric alkenes. The more-substituted alkene is the major product and...
Preparation of Alkynes: Alkylation Reaction02:27

Preparation of Alkynes: Alkylation Reaction

Introduction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Radical Formation: Elimination00:51

Radical Formation: Elimination

Another method of radical formation is the elimination process. It is the opposite of the addition route and is driven by the instability of the radical. For example, as depicted in Figure 1, dibenzoyl peroxide yields a pair of unstable radicals upon homolysis. Given its instability, this radical spontaneously undergoes elimination via a C–C bond cleavage to form a relatively more stable phenyl radical. The mechanism involves cleavage of the bond between the α and β positions with respect to...
Elimination Reactions02:25

Elimination Reactions

A nucleophile can react with an alkyl halide to give the substitution product by displacing the halogen. Or it can function as a base to give the elimination product by deprotonation of the neighboring carbon to form an alkene. In an elimination reaction, the substrate loses two groups from adjacent carbons forming at least one π bond. The carbon attached to the halogen is called the α carbon, while the adjacent carbon is called the β carbon; hence, these reactions are called β elimination or...

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Related Experiment Video

Updated: Jul 15, 2026

Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
06:46

Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate

Published on: June 21, 2017

One-shot double elimination process: a practical and concise protocol for diaryl acetylenes.

Akihiro Orita1, Hisataka Taniguchi, Junzo Otera

  • 1Department of Applied Chemistry, Okayama University of Science, Ridai-cho, Okayama 700-0005, Japan. orita@high.ous.ac.jp

Chemistry, an Asian Journal
|April 19, 2007
PubMed
Summary

A novel one-shot synthesis efficiently produces diaryl acetylenes using lithium hexamethyldisilazide. This method facilitates various substitutions, offering a versatile route to complex organic molecules.

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Retropinacol/Cross-pinacol Coupling Reactions - A Catalytic Access to 1,2-Unsymmetrical Diols
10:12

Retropinacol/Cross-pinacol Coupling Reactions - A Catalytic Access to 1,2-Unsymmetrical Diols

Published on: April 4, 2014

Synthesis of Esters Via a Greener Steglich Esterification in Acetonitrile
06:52

Synthesis of Esters Via a Greener Steglich Esterification in Acetonitrile

Published on: October 30, 2018

Related Experiment Videos

Last Updated: Jul 15, 2026

Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
06:46

Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate

Published on: June 21, 2017

Retropinacol/Cross-pinacol Coupling Reactions - A Catalytic Access to 1,2-Unsymmetrical Diols
10:12

Retropinacol/Cross-pinacol Coupling Reactions - A Catalytic Access to 1,2-Unsymmetrical Diols

Published on: April 4, 2014

Synthesis of Esters Via a Greener Steglich Esterification in Acetonitrile
06:52

Synthesis of Esters Via a Greener Steglich Esterification in Acetonitrile

Published on: October 30, 2018

Area of Science:

  • Organic Chemistry
  • Synthetic Chemistry

Background:

  • Diaryl acetylenes are important structural motifs in organic synthesis.
  • Existing synthetic methods may lack efficiency or versatility.

Purpose of the Study:

  • To develop a novel, efficient, one-shot method for synthesizing diaryl acetylenes.
  • To explore the scope and limitations of the developed synthetic strategy.

Main Methods:

  • A one-pot reaction involving arylmethyl sulfone, aryl aldehyde, and chlorodiethylphosphate.
  • Use of lithium hexamethyldisilazide (LiHMDS) as a base in tetrahydrofuran (THF).
  • Sequential aldol reaction, phosphorylation, and double elimination.

Main Results:

  • Good yields of various diaryl acetylenes were achieved.
  • The reaction tolerated diverse substituents including halogens, CF3, ethoxycarbonyl, dimethylamino, TMS-acetylene, pyridinyl, and thienyl groups.
  • Halogen substitution accelerated the process, yielding unsymmetrical products without dehalogenation.
  • Methoxy-substituted compounds yielded moderately, but improved with lithium diisopropylamide (LDA).

Conclusions:

  • The developed one-shot process provides an efficient and versatile route to diaryl acetylenes.
  • The method is amenable to a wide range of functional groups, enhancing its synthetic utility.
  • Optimization using different bases like LDA can improve yields for specific substrates.