Product Channels of the CN + HCNO Reaction

Abstract

The kinetics of the reaction of CN radical with fulminic acid (HCNO) was studied by transient infrared absorption spectroscopy with the primary goal of resolving whether the dominant product channel is NO + HCCN (1a) or HCN + NCO (1b). HCN, HCCN, and NO reaction products were directly detected. In some experiments, (15)N(18)O reagent was included in the reaction mixtures in order to suppress possible secondary chemistry due to NCO radicals. Several other possible secondary reactions were also investigated and found to be very slow. The resulting product branching fractions of φ(1a) = 0.98 ± 0.07 for NO + HCCN and φ(1b) ≤ 0.07 for HCN + NCO, respectively, were obtained at 298 K. The potential energy surface (PES) of the reaction was calculated by ab initio methods at several levels of coupled-cluster theory. The calculations show pathways to channels (1a) and (1b) with nearly identical energetics and a substantial dependence on the level of theory used, suggesting that multireference calculations are needed to accurately predict the experimental results.

The ammonium nitrate and its mechanism of decomposition in the gas phase: a theoretical study and a DFT benchmark

“…This index gives a qualitative assessment of the multi-configurational character, and a threshold of 0.02 has been suggested as a limiting value. 55 However values up to 0.05 are commonly found for radicals 63,64 and a range between 0.02 and 0.03 could be still considered as acceptable. 65,66 Thus computed energies for TS 1 could be affected by a small error (roughly estimated to be 1-2 kcal mol À1 ) which does significantly affect the barrier (about 72 kcal mol À1 ).…”

Reaction kinetics of the CN radical with primary alcohols

“…CN reactions with a variety of molecules have been previously studied, including both saturated and unsaturated hydrocarbons [1][2][3][4][5][6][7], O 2 [1,[8][9][10][11][12][13][14][15][16], NO [15,17], and NO 2 [16,17]. Past work in our laboratory has included study of CN reactions with O 2 [18,19], NO 2 [20], OCS [21], CS 2 [22], SO 2 [22], and HCNO [23,24]. To date, however, there is no literature on the kinetics of CN reactions with alcohols.…”

Product channels in the 193-nm photodissociation of HCNO (fulminic acid)

“…Reaction (10) will not suppress reaction (3), CN + HCNO, because the CN+NO reaction is slow at the low pressures used in these experiments. Reaction (3) produces HCCN radicals [4,7] which then react with 15 In these experiments, however, we detect the non-labeled HC 14 N isotope, which is not affected by this secondary chemistry. The nitrogen-15 labeling is therefore important for this experiment (the oxygen-18 labeling is not).…”

“…HCNO (fulminic acid) is the less stable isomer of isocyanic acid; the kinetics of several reactions involving HCNO has only recently been studied [3][4][5][6][7]. There is only one previous study of the photochemistry of HCNO, an infrared laser spectroscopic study from our laboratory that identified five separate photolysis channels in the 248 nm photodissociation of this molecule [8].…”