Theoretical study on the mechanism of the ¹CHCl + NO₂ reactions

Abstract

The radical-molecule reaction mechanism of (1)CHCl with NO(2) has been explored theoretically at the B3LYP/6-311G(d, p) and CCSD(T)/6-311G(d, p) (single-point) levels of theory. Thirteen minimum isomers and 29 transition states are located. The initial association between (1)CHCl and NO(2) proceeds most likely through the carbon-to-middle-nitrogen attack leading to an energy-rich adduct a (HClCNO(2)), which is found to be a barrierless process. Staring from a, the most feasible channel is to undergo a concerted O-shift and C--N bond rupture leading to product P(2) (NO + HClCO). The minor product pathways are the direct O-extrusion of a to P(3) (O + HClCNO-cis) as well as the 1,3-H-shift of a to isomer b (ClCNOOH) followed by a concerted OH-shift leading to d (HOClCNO), which will dissociate to product P(8) (NO + ClCOH) via C--N cleavage. Because the transition states and isomers involved in the most feasible channel all lie below the reactants, the title reaction is expected to be rapid, as is consistent with the measured rate constant at 296 K. The comparison with the analogous reactions (3)CH(2) + NO(2) are discussed. The present study may be useful for further experimental investigation of the title reaction.

Recent Progresses towards the Strengthening of Cyclopropene Chemistry

“…Et 3 B might act as H-donor, yet experiments to support this fact are pending. In contrast, when the process was initiated by Et 2 Zn (50), radical species 198 might be reduced also with 50 to form intermediate 199, which underwent 1,2-H shift followed by C-C cleavage and loss of a chloride to form skipped diene 197.…”

“…(Scheme 21). 49 Beyond mechanistic considerations, 50 this strategy has been subsequently implemented for the synthesis of a variety of highly substituted furans.…”

“…Ketone allylation through an interesting multicomponent reaction involving silver carbene intermediates was disclosed by Endo et al 66 The process comprised of the isomerization of cyclopropenes to a silver vinyl carbene 140, which was further trapped with diethylzinc (50) to generate nucleophilic species 141. Finally, reaction with ketones gave the allylation product (Scheme 31).…”

Theoretical study on reaction mechanism of the fluoromethylene radical with nitrogen dioxide

“…Recently, we perform a detailed theoretical investigation on the 1 CHCl ϩ NO 2 reaction. 24 The possible reaction pathways are summarized as:…”

“…In addition, recently, we have built up the potential energy surface of the analogous 1 CHCl ϩ NO 2 reaction. 24 Now, the sequential question is whether the mechanism of the title reaction 1 CHF ϩ NO 2 is similar to the 1 CHCl ϩ NO 2 reaction or not? In view of its importance and limited information, a detailed theoretical study of the title reaction is therefore desirable to establish the mechanism of the title reaction and make comparisons on the mechanism as well as the product distribution between 1 CHF with NO 2 and 1 CHCl with NO 2 reactions to gain insight into the halocarbene chemistry.…”