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Acid-catalysed nitrosation of methanol, thioglycolic acid, and water in acetonitrile using alkyl nitrites or nitrous acid (except in the case of water), is kinetically zero order in the substrate, consistent with rate-limiting NO+ formation.

Rate constants have been determined by stopped-flow spectrophotometry for the nitrosation in water of the following alcohols and carbohydrates : methanol, ethanol, propan-1-ol, propan-2-ol, ethane -1,2-diol, propane1,2,3-triol, mannitol, sucrose, and glucose, in some cases at 25° and others at O°. In all cases the reactions were reversible, forming equilibrium concentrations of the corresponding alkyl nitrites. With a large excess of the alcohol present over the total nitrous acid concentration, the observed first-order rate constants increased linearly with the alcohol concentration, and from the slope and the intercept the rate constants for the forward and reverse reactions were obtained. Both reactions were acid-catalysed and also catalysed by chloride and bromide ion. The forward reaction is interpreted as one involving O-nitrosation by H2NO2+(or NO+), NOCl, or NOBr. For methanol, rate constants for attack by nitrosyl chloride and by nitrosyl bromide were 2.1 × 105 and 2.0 × 104 l mol–1 s–1, respectively. There was little difference between the rate constants for chloride ion and bromide ion attack for the reverse reaction, suggesting that the reactions for attack on the protonated alkyl nitrite are very rapid, possibly approaching the diffusion-controlled limit. There was a decrease in the overall equilibrium constant for the non-halide ion-catalysed pathway, along the series MeOH, EtOH, PriOH, and ButOH; the value for the latter was so small as to make the quantitative determination of the rate constants impossible by this method. This decrease was due almost entirely to a decreasing value for the forward rate constant along the series, which implies that a steric effect is operational. All the carbohydrates studied had very similar equilibrium constants of ca. 1.5. In contrast the nitrosation of N-acetylpenicillamine gave the thionitrite quantitatively at low acidities. Again the reaction was acid- and halide (and thiocyanate) ion-catalysed and the reactivity sequence NOCl > NOBr > NOSCN was established. For both the alcohols and the thiol, the forward rate constants are well below the diffusion controlled values and are several powers of ten less than the corresponding values for the reactions of aniline. The results are discussed in terms of the nucleophilicities of the oxygen and sulphur sites for the forward reaction and in terms of the protonation equilibria of the nitrites and thionitrite for the reverse reaction.

Fluorescence from electronically excited nitric oxide has been observed during the photolysis at 147 and 123 nm of alkyl nitrites, trifluoronitrosomethane, and 2-methyl-2-nitrosopropane, while photolysis of NOCN leads to electronically excited cyanide radicals.

The apparent dipole moments of ten, and the apparent molar Kerr constants of seven, alkyl nitrites as solutes in carbon tetrachloride at 25� are recorded and discussed in terms of assumptions that the dissolved species are either (a) mixtures of two planar forms in which the R-O and K=O bonds have an s-cis : s-trans relationship, or (b) mixtures of many non-planar rotamers, definable by angles of twist 4 between the planes containing the R-O and S=O units. On basis (b) the observed properties are average values, theoretically predictable only when potential energies as functions of � become known. "Effective" conformations for MeO-N=O and Me3CO-N=O having � values of 98� and 146.5� can be inferred from the ∞(mK2) values found for these esters.

Trans-esterification of chiral secondary carbinols with symmetric nitrite esters occurs readily in polar solvents at 25° without racemization or inversion, and provides a convenient source of chiral nitrite esters for stereochemical studies of optically active alcohols and for photochemical syntheses.

The cationic nitrosyls, [IrCl3(NO)L2]+(L = PPh3, AsPh3) react with alcohols to give neutral iridium(III) complexes containing bound alkyl nitrites, IrCl3(RONO)L2(R = Me, Et, Pr). These reactions parallel the formation of complexes containing alkoxycarbonyl groups as ligands by alkoxide-ion attack on cationic carbonyl complexes. The nitrite complexes revert to the parent nitrosyls with acids and it is suggested that this reaction bears upon the mechanism of formation of nitrosyl complexes in the frequently used preparations which make use of alkyl nitrites, N-nitroso-reagents, nitrous acid, and NO+ salts. New routes to the dinitrosyl cations, [Ir(NO)2L2]+, and preparations of Ir(NO)(AsPh3)3, are also reported.

The reactions of dinitrogen trioxide with primary and secondary amines have been studied. All secondary amines formed the N-nitrosamine. Primary aromatic amines gave the diazonium nitrite but the corresponding aliphatic compounds gave a variety of products including alkyl ammonium nitrites, alkyl nitrites, and alkenes. In some cases n-alkylamines gave products with a branched alkyl group.

IN flash photolysis experiments involving methyl nitrite, transient absorption bands at 1999, 2036 and 2064 A were seen1 faintly at 50 µsec, increasing in intensity slowly to a maximum at 2.5 msec and almost disappearing by 25 msec. These bands did not appear for any other nitrite tested. The reasons1 for these bands being attributed to CH3O· (being produced originally in a metastable excited state) were that this free radical, together with NO·, was expected to result from the alkyl nitrites which are in fact accepted sources of RO· (despite the early investigations2 in which the primary photochemical process in CH3ONO was deduced to be dissociation to the molecules HNO and H2CO), the observation of the expected partner fragment NO at the smallest delay times (50 µsec), and the virtual elimination of HNO, HCO, and formaldehyde in an excited state as the appropriate carrier.