Reactions of nitrogen atoms

There have been very few experiments measuring the product energy disposal in the reactions of nitrogen atoms. Recent studies [503] on the reaction 

The reaction N + N02 can produce two different sets of reaction products, N20 + O and NO + NO [505]. In the first case, .FV is 0.37 of this, vibrational excitation 40% appears in stretching vibrations of the N20 and 60% appears in the bending mode. However, these values are not independent as product molecules are formed with more than one mode excited. About 70% of N20 molecules are formed with one quantum of v3 and up to 10 quanta of v2 excited, 20—25% are produced with vx excited, either alone or with v2, but only 3% have both the stretching modes (vY and v3) excited. Clearly, the reaction dynamics are complex. In the parallel reaction 

Kinetic studies show that only 18% of all NO product molecules are formed in these levels and only 10% of the total reaction energy appears in vibrational levels v = 2—7. The reaction 

---

The reaction of CBr4 with potassium is reported to generate free C atoms and the rate constants for reaction with methane, ethylene, and benzene have been reported. The reaction of nitrogen atoms with CN radicals has also been used as a C atom source. Carbon atoms have also been produced by passing organics through a microwave discharge. ... 

The CN radical can be produced by the reaction of nitrogen atoms with almost any organic compound, a process which has been extensively studied by electronic emission specttoscopy. The electronic sttucture of CN in its ground state and two relevant excited states may be written in the following simple molecular orbital form. 

The reaction of nitrogen atoms with NO2 was shown to give rise to NO, O2 and N2O but no rate coefficients were determined. The rate coefficient for (1) now appears to be about 2x 10 l.mole . sec. This reaction is frequently used to estimate N atom concentrations. 

The kinetic data for reaction of nitrogen atoms with ethylene are summarized in Table 37, where much of the work is by Herron and co-workers. The very much lower rate coefficients for reaction of nitrogen atoms as compared with the analogous hydrogen atom addition should be noted (roughly a factor of ten). 

The aziridinyl radical (640) is postulated as the major intermediate in the reaction of nitrogen atoms with 1,1-dichloroethylene. ... 

Acyl derivatives of azoles containing two different environments of nitrogen atoms can rearrange. For example, 1-acyl-1,2,3-triazoles are readily isomerized to the 2H-isomers in the presence of triethylamine or other bases the reaction is intermolecular and probably involves nucleophilic attack by N-2 of one triazole on the carbonyl group attached to another (74AHC(16)33). 

Draw the Lewis structure for the hypothetical molecule N6, consisting of a six-membered ring of nitrogen atoms. Using bond enthalpies, calculate the enthalpy of reaction for the decomposition of N6 to N2(g). Do you expect N6 to be a stable molecule ... 

Fig. 38. Complexes synthesized by the reaction of chromium atoms with 1,4-diphenylbutane at the temperature of liquid nitrogen. From ref. (201).

Figure 1.5 Plot of computed reaction barriers for dissociation at Eaa. for N2 dissociation as a function of nitrogen atom adsorption energy on surface terrace and stepped surface [2]. The upper curve is for surface terrace of (111) type of fee crystals, and the lower curve presents data on the stepped surfaces.

The right-hand part of Fig. 7.7 corresponds to the second-order desorption of nitrogen atoms from a rhodium surface. As the desorption reaction corresponds to N -I- N —> N2 -I- 2 the rate is indeed expected to vary with A characteristic feature of second-order desorption kinetics is that the peaks shift to lower temperature with increasing coverage, because of the strong dependence of the rate on coverage. 

The basis of the demonstration can be based on already published data on the surface reaction between NOz and adsorbed organic compounds. Yokoyama and Misono have shown that the rates of N02 reduction over zeolite or silica are proportional to the concentration of adsorbed propene [29], whereas Il ichev et al. have demonstrated that N02 reacts with pre-adsorbed ethylene and propylene on H-ZSM-5 and Cu-ZSL-5 to form nitro-compounds [30], Chen et al [2-4] have observed the same nitrogen-containing deposits on MFI-supported iron catalysts. The question on the pairing of nitrogen atoms is not considered here. 

A similar reaction with diphenyldiazomethane gives phosphabicyclohexene 102 exclusively by elimination of nitrogen atom from initial cycloadduct 101 (Scheme 31) [105],... 

The second stage of the reaction is of particular interest. It is essentially an intramolecular reaction between the anion and the cation. The phosphorus atom of the anion is able to react nucleophilically at the ring carbon atom with amines similar to reactions of 1,3,2,5-dioxaborataphosphori-nanes with amines or 1,3,5-diazaphosphorinanes. The cation is the 1,3,5-diazaphosphorinane derivative. Thus, the reaction between the anion and the cation is a series of nucleophilic attacks of nitrogen atoms, belonging to the cation, at carbon atoms of the anion. 

An analysis of the principal methods for construction of compounds with 1,2,5-oxadiazole heterocyclic units was published in CHEC(1984) and CHEC-II(1996) < 1984CHEC(6)393, 1996CHEC-II(4)229>. In this chapter only reactions that lead to the formation of 1,2,5-oxadiazole cyclic fragments are considered. The functionalization or replacement of substituents of heterocyclic ring as well as oxidation or deoxidation of nitrogen atoms are described in Section 5.05.4. 

---