Methylidyne radical

The formation of prompt NO increases the complexity of the nitrogen chemistry in gas flames considerably. This is illustrated in Fig. 14.9, which shows the most important reaction paths in prompt NO formation, as well as fuel nitrogen conversion—two mechanisms that share some common features. Prompt NO is, as the name indicates, a very rapid mechanism. The initiating step (R117) takes place in the flame zone, where methylidyne radicals (CH) may be formed in significant quantities. 

Carbenes are known intermediates in the photodecomposition of diazo-compounds. Insertions of singlet methylene, generated by photoelimination of nitrogen from diazomethane, into 2,3-dimethyl-2,3-epoxybutane and into acetonitrile have been described. Methylene and other photochemically generated carbenes (43) add efficiently to 2-acetoxyacrylonitrile to give the corresponding 1-acetoxy-l-cyanocyclopropanes (44). The formation of methylidyne radicals by irradiation of diazomethane in the presence of hydrogen, however, does not seem to involve an intermediate carbene. ... 

The methylidyne radical (CH ) was detected by Becker et al. (1984) during the photolysis of diazomethane in the presence of H- and 0-atoms. 

The methylidyne radical CH has five valence electrons. Two non-bonding electrons may be assigned to the 2s AO on the C atom, and two electrons to a 2c C-H bonding orbital formed by linear combination of the C 2p orbital with the H I5 orbital. This description is in agreement with the unusually long C-H bond distance. The unpaired electfon has an angular momentum around the molecular z-axis, = hl2n, and must therefore occupy one of the orbitals on the C atom. 

Daugey N, Ganbet P, Retail B, Costes M, Bergeat A, Dorthe G. (2005) Kinetic measurements on methylidyne radical reactions with several hydrocarbons at low temperatures. Phys. Chem. Chem. Phys. 7 2921-2927. 

The first such molecule detected in the interstellar medium was the methylidyne radical (CH) in 1937. While Saha, 1937 [289] proposed the identification of some... 

To investigate whether the species in the plasma is changed by the ion irradiation to the IL, optical emission spectra (OES) in the gas plasma region are measured as shown in Fig. 10, where the IL and SUS plate are used as (a) the cathode electrode in A-mode and (b) the anode electrode in B-mode. In A-mode, the spectrum peak at 390 nm, which corresponds to methylidyne radical (CH), is observed only in the presence of the IL [Fig. 10(a)]. In B-mode, on the other hand, the CH peak is not clear both in the presence and absence of the IL. 

Nem Nemes, L., Szalay, P.G. Rydberg-Klein-Rees potential function calculations for the ground (X H) and excited (B X ) states of the methylidyne (CH) radical. Models in Chemistry 136 (1999) 205-214. 

Progressive removal of hydrogen atoms from methane yields the radicals CH3 (methyl), CH2 (methylene), and CH (methylidyne). These very unstable species may be studied in electric discharges. The C-H bond distances and bond dissociation energies are listed in Table 13.3... 

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