Related Experiment Video
Updated: Jul 19, 2026

Analyzing the Photo-oxidation of 2-propanol at Indoor Air Level Concentrations Using Field Asymmetric Ion Mobility Spectrometry
Published on: June 14, 2018
Photodissociation of acetaldehyde as a second example of the roaming mechanism
1Department of Chemistry, Cornell University, Ithaca, NY 14853, USA. plh2@cornell.edu
Abstract:
Product state distributions of the CO produced in the 308-nm photolysis of acetaldehyde show clear evidence of two dissociation mechanisms. One is attributed to the conventional transition state mechanism predicted by theory, with high rotational and translational energy of the CO and a pronounced v(perpendicular)J vector correlation. However, as much as 15% of the reaction flux proceeds via another pathway that produces low CO rotational and translational energy, very high CH(4) internal energy, and no correlation between the CO velocity and angular momentum vectors. The attributes of this channel are dynamically similar to the recently reported "roaming atom" mechanism in formaldehyde. We therefore speculate that the second pathway in acetaldehyde also occurs via a roaming mechanism in the CH(3) + HCO exit channel that decays into the CH(4) + CO channel.
Related Concept Videos
[3,3] Sigmatropic Rearrangement of Allyl Vinyl Ethers: Claisen Rearrangement
Aldehydes and Ketones with Alcohols: Hemiacetal Formation
Reactions of Aldehydes and Ketones: Baeyer–Villiger Oxidation
The carbonyl center is activated by...
Mass Spectrometry: Aldehyde and Ketone Fragmentation
Acid-Catalyzed Dehydration of Alcohols to Alkenes
Mass Spectrometry: Molecular Fragmentation Overview
One type of fragmentation pattern is the cleavage of a single bond in the molecular ion. The cleavage leads to a radical and a cation. The cleavage can occur at...

