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Related Concept Videos

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.
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.
Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation02:24

Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation

Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation02:47

Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation

Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
Alkynes to Aldehydes and Ketones: Acid-Catalyzed Hydration02:40

Alkynes to Aldehydes and Ketones: Acid-Catalyzed Hydration

Introduction
Analogous to alkenes, alkynes also undergo acid-catalyzed hydration. While the addition of water to an alkene gives an alcohol, hydration of alkynes produces different products such as aldehydes and ketones.
Electrophilic Addition to Alkynes: Halogenation02:38

Electrophilic Addition to Alkynes: Halogenation

Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.

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Related Experiment Video

Updated: Jun 4, 2026

The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes
10:51

The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes

Published on: April 10, 2015

Synthesis of Ru alkylidene complexes.

Renat Kadyrov1, Anna Rosiak

  • 1Evonik Degussa GmbH, Rodenbacher Chaussee 4, 63457 Hanau-Wolfgang, Germany.

Beilstein Journal of Organic Chemistry
|February 3, 2011
PubMed
Summary
This summary is machine-generated.

This study details the synthesis of ruthenium alkylidene complexes, crucial precursors for metathesis catalysts. Researchers investigated the dynamic behavior and preferred conformations of these complexes in solution using NMR spectroscopy.

Keywords:
alkylidene complexesmetathesisrotation barrierruthenium

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

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Synthesis and Evaluation of a Ruthenium-based Mitochondrial Calcium Uptake Inhibitor
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Synthesis and Evaluation of a Ruthenium-based Mitochondrial Calcium Uptake Inhibitor

Published on: October 26, 2017

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Last Updated: Jun 4, 2026

The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes
10:51

The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes

Published on: April 10, 2015

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

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Synthesis and Evaluation of a Ruthenium-based Mitochondrial Calcium Uptake Inhibitor
07:12

Synthesis and Evaluation of a Ruthenium-based Mitochondrial Calcium Uptake Inhibitor

Published on: October 26, 2017

Area of Science:

  • Organometallic Chemistry
  • Catalysis
  • Organic Synthesis

Background:

  • Ruthenium alkylidene complexes are vital precursors for olefin metathesis catalysts.
  • Understanding their dynamic behavior is key to catalyst design and application.

Purpose of the Study:

  • To robustly synthesize Ru alkylidene complexes of the type (PCy(3))(2)Cl(2)Ru=CHR.
  • To investigate the dynamic behavior and conformational preferences of these complexes in solution, particularly when R is a 2-naphthyl or 2-thienyl group.
  • To quantify the rotational energy barrier around the (Ru=)CH-C(thienyl) bond.

Main Methods:

  • Robust synthesis of ruthenium alkylidene complexes.
  • Solution-state dynamic behavior studies using proton nuclear magnetic resonance ((1)H NMR) spectroscopy.
  • Estimation of energy barriers for bond rotation.

Main Results:

  • Successful synthesis of (PCy(3))(2)Cl(2)Ru=CHR complexes.
  • Identification of preferred conformations in solution for complexes with R = 2-naphthyl and 2-thienyl.
  • Quantification of the energy barrier for rotation around the single (Ru=)CH-C(thienyl) bond as ΔG(≠) (303K) = 12.6 kcal/mol.

Conclusions:

  • The synthesized Ru alkylidene complexes serve as effective precursors for metathesis catalysts.
  • The dynamic behavior and conformational preferences of these complexes have been elucidated.
  • The rotational dynamics provide insights into the stability and reactivity of these organometallic compounds.