Nitrogen cation reactions

It is thought that the function of the glue or gelatin is to combine with very slight traces of heavy metal cations, for example Cu, which are known to catalyse the nitrogen-forming reaction. 

Chalcogen-nitrogen cations can be generated by the reactions of homopolyatomic chalcogen cations with azides. For example, the... 

Electrophilic substitutions normally occur at C2, the position next to the nitrogen, because reaction at this position leads to a more stable intermediate cation having three resonance forms, whereas reaction at C3 gives a less stable cation with only two resonance forms (Figure 24.6). 

The simplest intermediate of the nitrogen cation type is the nitronium ion, the active species in most aromatic nitration reactions. There is both cryoscopic and spectroscopic (Raman and infrared) evidence for its existence.802 On the other hand, it has a structure with quaternary rather than electron deficient nitrogen, a structure compatible with the centrosymmetric geometry demanded by the spectra. The Raman line at 1400 cm.-1 has been assigned to the totally symmetric vibration of the linear triatomic molecule. 

Many products contain 0.1-0.4% nitrogen (<0.05 DS), but more highly substituted products accessible from dry cationization are available. Germany allows the use of starch products with up to 1.6% nitrogen from reaction with 2,3-epoxypropyl-trimethylammonium chloride. A petition has been filed with the US Food and Drug Administration that proposes that 2,3-epoxypropyltrimethylammonium chloride be allowed in food-contact articles.23 The current allowable level is 5%. 

To a stirred solution of the phenol ether (20.7 mg, 0.126 mmol) and thiophenol (27.8 mg, 0.252 mmol) in hexafluoro-2-propanol (1 ml) was added BTI (81 mg, 0.189 mmol), at room temperature, under nitrogen. The reaction mixture soon turned green, due to the formation of a radical cation. After 30 min of stirring the solution was concentrated and the residue purified by column cromatography (silica gel, hexane-ethyl acetate) to give the title compound (23 mg, 67%) as an oil. 

Nitrogen cationic surfactants can also be created by the use of difunctional small molecule amines which, after formation of an amide or ester bond, leave an amine residue which is suitable for quaternization as shown in eqs 6.1.9-6.1.11. The amine residue is then reacted with a suitable alkylating agent to form the cationic. Similarly, reaction of a triglyceride with diethylene triamine gives initially the diamide which, under appropriate conditions, can be cyclized to imidazoline [16] ... 

The corresponding Tc-N-C bond angles of 128.3(4)°, 126.6(4)°, and 129.1(4)°, however, seem to offer little distinction between neutral and anionic nitrogen. Cationic complexes of the type [TcC12L]+ have been prepared by the reaction of [TcCl4(PPh3)2] with the tetradentate ligands (27) (310). 

Sulfur-Nitrogen Cations and Anions. The simple cation, NS2, is the analogue of the nitronium (N02) ion it is made by the reaction ... 

Orientation in electrophilic and nucleophilic reactions of aromatic compounds can be predicted with the aid of the reactivity index of MO theory. Electrophiles will attack positions of higher electron densities, larger superdelocalizability (electrophile), and the lower localization energy (electrophile). On the other hand, nucleophilic attack is preferred at positions of lower electron densities, larger superdelocalizability (nucleophile), and lower localization energy (nucleophile). Table XXIII shows reactivity indexes of some aromatic nitrogen cations. 

C, and 457°C, respectively [127], Such high temperatures are only tolerated by most liquids for a short time. For example, after 10 h, even at temperatures as low as 200°C, [RMlm][PF ] and l-decyl-3-methyhmidazolium triflate show an appreciable mass loss [179], The ILs with low thermal stability are [EMIm][X], where X=[Tf N]-, [MjN]-, and Br [68], Phosphonium ILs with [Tf N]- or [NCCN) ]-anions decompose completely to volatile products in a single step. The degradation products indicate that Hofmann elimination process and/or dealkylation reactions occurred. Conversely, ILs based on nitrogen cations do not decompose completely... 

Non-aromatic diazonium cations decompose in the presence of nucleophiles with nitrogen elimination, and do not effect coupling reactions. However, some heterocyclic diazonium compounds were found to have reactivity similar to that of arenediazonium compounds, including production of coupling derivatives. Such is the case of 1,3,4-thiadiazolinediazonium cations (reaction 32) and diazonium betaines (reaction 33). ... 

However, it is not known whether the electron is removed from the carbon or a nitrogen. The reaction is first order in the oxidant, so the formation of the radical cation is the ratedetermining step of the reaction. The chain process which follows the formation of the radical cation yields the products shown in Scheme 2. 

A diazonium salt is formed when NO reacts with an amine. The lone pair of the amine attacks the NO cation, and then water is lost. The mechanism is actually quite simple, but it does involve a lot of proton transfers. There is, of course, an anion associated with the nitrogen cation, and this will be the conjugate base (CP usually) of the acid used to form NO. This reaction is known as diazotization. 

The added hydroxyl function may, of course, also be removed by externally available protons, for example, in highly acidic solutions. In this case the sulfur-centered radical cation will, however, not couple with the nitrogen but associate with the sulfur of an unoxidized molecule to form the dimeric (>S Sradical cation, reaction (69b). 

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