Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Halogenation of Alkenes

Halogenation of Alkenes

Halogenation is the addition of chlorine or bromine across the double bond in an alkene to yield a vicinal dihalide. The reaction occurs in the presence of inert and non-nucleophilic solvents, such as methylene chloride, chloroform, or carbon tetrachloride.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.

Acid-Catalyzed α-Halogenation of Aldehydes and Ketones

Acid-Catalyzed α-Halogenation of Aldehydes and Ketones

By replacing an α-hydrogen with a halogen, acid-catalyzed α-halogenation of aldehydes or ketones yields a monohalogenated product
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...

ortho–para-Directing Deactivators: Halogens

ortho–para-Directing Deactivators: Halogens

Halogens are ortho–para directors. They are more electronegative than carbon. Therefore, as ring substituents, they can withdraw electrons through the inductive effect and deactivate the aromatic ring towards electrophilic substitution. Halogens also have an electron-donating resonance effect on the ring, which influences the orientation of the incoming electrophile. If an electrophile attacks at the ortho or the para position, the halogen donates electrons and stabilizes the intermediate...

Base-Promoted α-Halogenation of Aldehydes and Ketones

Base-Promoted α-Halogenation of Aldehydes and Ketones

α-Halogenation of aldehydes and ketones is a reaction involving the substitution of α hydrogens with halogens in the presence of a base. The reaction begins with the abstraction of α hydrogen by the base to produce a nucleophilic enolate ion. This intermediate undergoes a subsequent nucleophilic substitution with the halogen to produce a monohalogenated carbonyl compound. If the starting substrate has more than one α hydrogen, it is difficult to stop the reaction...

Radical Halogenation: Thermodynamics

Radical Halogenation: Thermodynamics

The thermodynamic favorability of a reaction is determined by the change in Gibbs free energy (ΔG). ΔG has two components- enthalpy (ΔH) and entropy (ΔS). The entropy component is negligible for alkane halogenation because the number of reactants and product molecules are equal. In this case, the ΔG is governed only by the enthalpy component. The most crucial factor that determines ΔH is the strength of the bonds. ΔH can be determined by comparing the energy...

Formation of Halohydrin from Alkenes

Formation of Halohydrin from Alkenes

An alkene, such as propene, reacts with bromine in the presence of water to yield a halohydrin. Halohydrins contain a halogen and a hydroxyl group attached to adjacent carbons. When the halogen is bromine, it is called a bromohydrin, while a chlorohydrin has chlorine as the halogen.

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Systemic trade-offs between core and accessory genomes govern stress adaptation in <i>Rhodococcus erythropolis</i>.

mSystems·2026

Same author

Programmable, multiplexed and orthogonal gene control in bacteria with attenuated Cas13d systems.

Nature biotechnology·2026

Same author

Beyond petrochemicals: challenges and opportunities in industrial-scale biomanufacturing.

Nature communications·2026

Same author

The transcriptional repressor PheR regulates uptake and catabolism of phenanthrene in Sphingobium sp. SHPJ-2.

The Journal of biological chemistry·2026

Same author

Metabolic engineering of <i>Escherichia coli</i> for the biosynthesis of nylon 6 and nylon 6,6 monomers.

Proceedings of the National Academy of Sciences of the United States of America·2026

Same author

Harnessing Microbial Bioremediation and Wastewater Valorization for Production of (Methyl)muconates via Engineered Metabolic Pathways in Aromatic Pollutant Mixtures.

Environmental science & technology·2026

Search research articles

Related Experiment Video

Updated: Jan 12, 2026

Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H2 Production in Aqueous Aerobic Conditions

Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H2 Production in Aqueous Aerobic Conditions

Published on: October 5, 2019

Halogenases and dehalogenases: mechanisms, engineering, and applications.

Jing Luo¹, Na Li¹, Jia Wang¹

¹State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China. tanghongzhi@sjtu.edu.cn.

Natural Product Reports

|November 3, 2025

Summary

Nature

More Related Videos

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding

Published on: March 24, 2018

Light-driven Enzymatic Decarboxylation

Light-driven Enzymatic Decarboxylation

Published on: May 22, 2016

Related Experiment Videos

Last Updated: Jan 12, 2026

Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H2 Production in Aqueous Aerobic Conditions

Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H2 Production in Aqueous Aerobic Conditions

Published on: October 5, 2019

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding

Published on: March 24, 2018

Light-driven Enzymatic Decarboxylation

Light-driven Enzymatic Decarboxylation

Published on: May 22, 2016

Area of Science:

Biocatalysis and Synthetic Biology
Environmental Biotechnology
Green Chemistry

Background:

Halogenated organic compounds (HOCs) are vital in pharmaceuticals, agrochemicals, and materials.
Traditional synthesis of HOCs involves hazardous reagents and environmental pollution.
Biocatalytic approaches using halogenases and dehalogenases offer sustainable alternatives.

Purpose of the Study:

To review recent advancements in halogenase and dehalogenase research.
To highlight the integration of these enzymes in biosynthetic and remediation platforms.
To discuss future directions for industrial and environmental applications.

Main Methods:

Enzyme discovery and characterization
Protein engineering for enhanced activity and stability
Development of scalable biocatalytic platforms
Mechanistic studies of halogenation and dehalogenation reactions

Main Results:

Expanded repertoire of halogenases (electrophilic, radical, nucleophilic) and dehalogenases.
Engineered enzymes (e.g., tryptophan halogenases, fluorinases) show improved efficiency.
Demonstrated potential for biocatalytic HOC production and pollutant degradation.
Progress in integrating enzymes into synthetic biology and bioremediation strategies.

Conclusions:

Halogenases and dehalogenases provide eco-friendly routes for HOC synthesis and degradation.
Protein engineering and platform development are key to unlocking industrial potential.
Further research on enzyme stability and robustness is essential for widespread application.