Related Experiment Video
Updated: Oct 3, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Dehalogenation of aromatic halides using metallic calcium in ethanol
Y Mitoma1, S Nagashima, C Simion
1Tohwa Institute for Science, and Department of Industrial Chemistry, Faculty of Engineering, Tohwa University, Fukuoka, Japan. mitoma@tohwa-u.ac.jp
Abstract:
The scope and limitations of the dehalogenation of aromatic halides 1 and 4a-p using metallic calcium in ethanol at room temperature were revealed. The cleavage of the carbon-chlorine bond on the aromatic ring bearing electron-donating group was difficult compared to the one bearing electron-withdrawing group. Moreover, we applied this method to the dechlorination of polychlorinated biphenyls (PCBs) in transformer oil. It was also found that the dechlorination took place easily under mild conditions. The existence of PCBs residue in the reaction at room temperature was less than 0.04% according to the GC-MS analysis. The chlorine was identified as calcium chloride.
More Related Videos
09:45Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene
Published on: March 20, 2017
19:58Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions
Published on: July 30, 2017
Related Concept Videos
Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
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...
Base-Promoted α-Halogenation of Aldehydes and Ketones
Halogenation of Alkenes
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 Halides to Alcohols: Grignard Reaction
Grignard reagents are a source of carbanions and function as nucleophiles. The mechanism begins with the nucleophilic attack by the carbanion at the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs,...
Acid Halides to Alcohols: LiAlH4 Reduction
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
Electrophilic Addition to Alkynes: Hydrohalogenation