Related Experiment Video
Updated: Jul 30, 2026

Molecular Beam Mass Spectrometry With Tunable Vacuum Ultraviolet (VUV) Synchrotron Radiation
Published on: October 30, 2012
Direct VUV photolysis of chlorinated methanes and their mixtures in a nitrogen stream
T Alapi1, K Van Craeynest, H Van Langenhoeve
1Department of Inorganic and Analytical Chemistry, University of Szeged, P.O. Box 440, H-6701 Szeged, Hungary.
Abstract:
The gas-phase decomposition of CCl(4), CHCl(3) and CH(2)Cl(2) and their binary mixtures was studied in a flow-type reactor in a nitrogen gas stream, using a low-pressure mercury vapour lamp covered with a high-purity silica quartz sleeve. The 184.9 nm vacuum-ultraviolet (VUV) light emitted is able to rupture the C-Cl bond in these target substances. For H-containing compounds, the decomposition takes place not only by direct photolysis, but also by H abstraction by .Cl formed during the direct photolysis of the target substances. The relative contributions of direct photolysis and .Cl-sensitized reactions to the decomposition were estimated at different initial concentrations. The addition of CCl(4) to CHCl(3) or CH(2)Cl(2) increased their decomposition rates via increase of the .Cl concentration, whereas the addition of CH(2)Cl(2) to CHCl(3) decreased its degradation rate, suggesting that CH(2)Cl(2) acts as a .Cl radical scavenger. The variation of the product distribution confirms the effect of the composition of the irradiated gas mixtures on the relative contributions of .Cl-sensitized reactions and direct photolysis.
Related Concept Videos
Carboxylic Acids to Methylesters: Alkylation using Diazomethane
Hydrolysis of Chlorobenzene to Phenol: Dow Process
Radical Substitution: Halogenation of Alkanes and Alkyl Substituents
In the initiation step of the reaction, the chlorine molecule undergoes homolytic cleavage in the presence of light or heat, forming two highly reactive chlorine radicals. Propagation occurs in two...
Cycloaddition Reactions: MO Requirements for Photochemical Activation
Flame Photometry: Overview
Fast Reactions

