Alkyl nitrites formation

AT-Alkyl methanesulfonamides, 23 685 Alkyl monoperoxycarbonic acid, 18 466 Alkylnaphthalenes, 17 84-85 dispersant moieties, 8 706t Alkyl naphthalene sulfonates, 24 146 Alkylnickel, re-complexes of, 17 116 Alkyl nitrites, formation of, 17 165-166 Alkylonium salt hydrates, 14 171... 

Since alcohols and carbohydrates readily form equilibrium concentrations of alkyl nitrites which are themselves inactive as direct nitrosating agents (see below), it is to be expected that the addition of alcohols and carbohydrates will inhibit N-nitrosation of amines. This has been shown to be the case for aniline derivatives, and the reduction in the measured first order rate constants can be accounted for quantitatively by such equilibria (Aldred and Williams, 1982). But since alkyl nitrite formation is a rapid equilibrium process, it is not possible, at least for the aniline derivatives studied, to suppress N-nitrosation completely this way. This is in contrast to the effect of thiols discussed in Section 9. In another study (Kurechi et al., 1980), the same effect was observed at pH 3 for the nitrosation of dialkylamines, whereas at pH 5 there was claimed to be a rate enhancement on addition of alcohols, an effect which was not explained. 

The benzyl ligand of benzylbis(dimethylglyoximato)pyridine cobalt complex has been selectively converted to 3,5-dibenzyl-l,2,4-oxadiazole by a reaction with alkyl nitrite in the presence of light (426). The reaction proceeds by the in situ formation of an oxime and a nitrile oxide (Scheme 1.44). 

Akerboom, T. P. M., Ji, Y., Wagner G., Sies, H., Subunit specificity and organ distribution of glutathione transferase-catalysed S-nitrosoglutathione formation from alkyl nitrites in the rat. Biochem. Phamacol. 53 (1996), p. 117-120... 

The esters of nitrous acid are characterised by their high velocities of formation and hydrolysis. They are almost instantaneously decomposed by mineral acids and in the method of preparation given this has been taken into account. The slightest excess of hydrochloric acid must be avoided. Advantage is taken of this property of the alkyl nitrites in all cases where it is desired to liberate nitrous acid in organic solvents (in which metallic nitrites are insoluble). Examples addition of N203 to olefines, preparation of solid diazonium salts (p. 286), production of isonitroso-derivatives from ketones by the action of HN02. This synthesis is often also carried out in the manner of the acetoacetic ester synthesis, with ketone, alkyl nitrite, and sodium ethylate the sodium salt of the isonitrosoketone is formed (cf. in this connexion p. 259) ... 

One of the two enthalpies of formation for the tertiary alkyl nitrites is most probably incorrect. As seen in Table 1, not only is the slope for the liquid-phase data less negative than that for the gas-phase data, but it is much less steep than all other liquid-phase data of which we know. Part of the discrepancy is due to the inverted order of the archival enthalpies of vaporization t-butyl nitrite = 34.4 kJmol-1 and t-pentyl nitrite = 33.5 kJ mol 1. 

This observation was made by Coon, in Reference 90. To the best of our knowledge, there are no experimental data for the enthalpy-of-formation difference of simple nitroarenes and aryl nitrites such as PhN()2 and PhONO. Given earlier enunciated complications regarding measurements of alkyl nitrites, we are not surprised by this gap in our knowledge. 

At higher acidities the S-nitrosation reaction of thiourea leads to the formation of urea64 (equation 28) via, it is believed, the intermediate formation of the S-nitroso species. The reaction can also be brought about by nitrosamines or alkyl nitrites as the carriers of NO+. Reaction is thought to involve nucleophilic attack of the intermediate by water or the elimination of HSNO giving a carbodiimide, which is then hydrated. 

S-Nitrososulphinates can be made by treating sulphinic acids with N2O4 at about —20 °C in ether (equation 32)76. Use of nitrous acid on alkyl nitrites leads to the formation of the corresponding hydroxylamines (equation 33) in a reaction where it is believed that the first formed nitrososulphinate nitrosates another molecule of the reactant sulphinic acid77. 

The acid hydrolysis of alkyl nitrites (Scheme 53) is inhibited by the presence of /I-cyclodextrin (CD) owing to the formation of 1 1 inclusion complexes that are unre-active or much less reactive than the RONO not complexed. The degree of inhibition... 

Photolysis of primary, secondary, and tertiary alkyl nitrites in benzene indicated that a minimum chain length of five carbon atoms attached to the nitrite grouping is required for appreciable yields of secondary nitroso dimers via the Barton reaction. In the case of primary and secondary nitrites, a chain of length of four carbon atoms or more attached to the nitrite grouping is required for formation of the six-membered intermediate (e.g., A) involved in the Barton reaction.139140... 

Predictably, nitrosation of 2-acetylpyrrole and pyrrole-2-carboxylic esters with alkyl nitrites or nitrous acid preferentially yields the relatively stable 4-nitroso derivatives, whilst 2,4-dialkyl- or -diaryl-pyrroles are nitrosated at the 5-position. Further reaction of the dialkyl and diaryl nitrosopyrroles with an excess of alkyl nitrite in the absence of a base can result in the formation of the nitropyrroles, whereas the reaction with nitrous acid converts the nitrosopyrroles into diazopyrroles (B-77MI30502). 

However, there is only one well-defined example of alkoxide addition. Here the formation of a coordinated alkyl nitrite occurs and the reaction may be reversed by treatment with acid (equation 23). 

Instead of alkyl nitrite, other alkoxyl radical precursors such as ROOH, ROOR, ROI, ROC1, etc. can also be used for the same type of reaction. The high reactivity of these compounds comes from the weak bond dissociation energies in O-O, 0-1, and O-Cl bonds. Another simple method is as follows. Photolytical treatment of alcohol (5) with NIS (AModosuccinimide) provides the tetrahydrofuran skeleton (6), through the formation of alkyl hypoiodite (ROI), homolytic cleavage of the 0-1 bond to form an alkoxyl radical, 1,5-H shift to form a carbon-centered radical, reaction with ROI to form 8-iodoalcohol, and finally ionic cyclization to form a tetrahydrofuran skeleton, together... 

When primary amines are treated with nitrous acid (HONO), or more usually with a nitrite salt or an alkyl nitrite in acid solution, an unstable diazonium salt is formed. You met diazonium salts in Chapter 22 undergoing coupling reactions to give azo compounds, but they can do other things as well. First, a reminder of the mechanism of formation of these diazonium salts. The very first stage is the formation of the reactive species NO+. 

Alkyl nitrites and nitrogen tetroxide together with acid are also effective for the formation of acyl azides from hydrazides under anhydrous conditions. As shown in Scheme 16, the Curtius reaction is especially suitable for the formation of complex reactive molecules. 

The formation of alkyl nitrites, CD3OD, and dimethyl ether as well as the appearance of the alkoxyl radicals indicates the importance of the primary process 72, whereas the low HD content of the hydrogen formed from CH OD seems to favor reaction 73, which... 

The reaction of phenols with nitrous acid gives the ortho- and para-nitroso products, which are formed through a neutral dienone intermediate, the proton loss from the latter being the rate-limiting step" " . It has been shown that the nitrous acid can act as a catalyst for the formation of the nitro derivatives. Thus the conventional preparation of nitro compounds by the oxidation of nitroso compounds may be replaced by methods using an electron-transfer pathway in certain cases. In the latter method, the phenoxide reacts with nitrosonium ion to give the phenoxy radical and nitric oxide radical. The nitric oxide radical is in equilibrium with the nitronium radical by reaction with nitronium ion. The reaction of the phenoxy radical with the nitroninm radical resnlts in the formation of the ortho- and para-mixo prodncts" . Leis and coworkers carried ont kinetic stndies on the reaction of phenolate ions with alkyl nitrites and fonnd that the initially formed product is the 0-nitrite ester, which evolves by a complex mechanism to give the ortho-and the para-nitro products". ... 

Primary and secondary alkyl nitrites under basic conditions eliminate nitrite with concomitant production of a carbonyl group. The nitrite can be estimated by its formation of a diazonium ion with p-aminobenzenesulfonamide, followed by formation of an azo dye. The sequence is termed the Griess test... 

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