Kinetics and mechanism of the reaction of acetonyl radical, CH3C(O)CH2, with Br2

Abstract

The low pressure fast discharge flow method with laser induced fluorescence detection of CH 3 C(O)CH 2 was employed to study the kinetics of the reaction CH 3 C(O)CH 2 + Br 2 → CH 3 C(O)CH 2 Br + Br (1) at 298, 323 and 365 K. The rate coefficient at room temperature is k 1 = (2.33 ± 0.04 (2σ)) × 10 -12 cm 3 molecule -1 s -1 , which increases slightly with increasing temperature. Quantum chemistry (G2) and theoretical rate theory (conventional TST) computations have supplied results in qualitative agreement with experiment. The relatively slow rate of reaction (1) can be due to the resonance stabilization of the acetonyl radical.

Photoredox-Catalyzed Generation of Acetonyl Radical in Flow: Theoretical Investigation and Synthetic Applications

“…Acetonyl radical has recently attracted attention from the scientific community for its surprisingly high concentration in the troposphere and its role in affecting NO X , HO X , and O 3 cycling . However, its application in synthesis is rather limited and not exempt from drawbacks.…”

Universal Group 14 Free Radical Photoinitiators for Vinylidene Fluoride, Styrene, Methyl Methacrylate, Vinyl Acetate, and Butadiene

“…Accordingly, H abstraction from DMC (CH 3 –O–CO–O–CH 3 ) generates a reactive, nucleophilic primary radical (CH 3 –O–CO–O–CH 2 • ), which adds selectively to the CH 2  side to VDF, leading to the CH 3 –O–CO–O–C H 2 –CH 2 – CF 2 – ( b DMC H , t, 2H, δ = 3.75 ppm, b DMC ′H , s, 3H, δ = 4.34 ppm, and b DMC F , δ = −93.2 ppm) DMC initiator chain end − (Figures S2, S4, and S6). Similarly, acetone provides a primary, β-carbonyl stabilized, less reactive acetonyl , CH 3 –CO–CH 2 • radical, and the corresponding CH 3 –CO– CH 2 –CH 2 – CF 2 – ( b acet H , 3H, δ = 2.05 ppm, b acet ′H , 2H, δ = 2.15 ppm, and b acet F , 2F, δ = −94.5 ppm) − , chain end (Figures S3, S5, and S6). R 3 Sn· may add reversibly to solvent alkyl carbonyls, but the resulting transient tertiary radicals (i.e., (CH 3 O) 2 (R 3 SnO)­C· or (CH 3 ) 2 (R 3 SnO)­C·) are unlikely to initiate VDF.…”