Alkyl nitrites ethyl nitrite

The reagent also can be generated in situ from an alkyl nitrite (ethyl nitrite or amyl nitrite) and hydrochloric acid or hydrochloric acid in methanol, ethanol, or acetic acid. ... 

In most cases diazonium salts are not isolated, but are converted into products by reactions that can be carried out in situ. Moreover, it is actually recommended not to isolate these salts, not even for purification purposes, as many of them have a tendency to explode. In addition, the high solubility of most diazonium salts in water makes precipitation from this medium difficult. Therefore, to obtain solid diazonium salts the recommended method for many decades was to carry out diazotizations in ethanol followed by precipitation with ether. As inorganic salts of nitrous acid are scarely soluble in ethanol, Knoevenagel recommended alkyl nitrites (ethyl or isopentyl nitrite) as diazotization reagents as long ago as 1890. Various other solvents have subsequently been used for diazotizations with alkyl nitrites (see Saunders and Allen, 1985, p. 23 ff.), but as a method for obtaining solid diazonium salts this has been superseded by the isolation of diazonium tetrafluoroborates and, to a lesser degree, of hexafluorophosphates. 

The submitters used amyl nitrite U.S.P. from Mallinckrodt Chemical Works isoamyl nitrite supplied by Matheson, Coleman and Bell is apparently the same material. They found that other alkyl nitrites (ethyl, w-butyl, 1-butvl, amyl) may be used with equal success. Subsequent to the checking of this procedure, they reported that the amount of nitrite can be reduced to a 20% molar excess. 

The reaction of alkyl halides with metal nitrites is one of the most important methods for the preparation of nitroalkanes. As a metal nitrite, silver nitrite (Victor-Meyer reaction), potassium nitrite, or sodium nitrite (Kornblum reaction) have been frequently used. The products are usually a mixture of nitroalkanes and alkyl nitrites, which are readily separated by distillation (Eq. 2.47). The synthesis of nitro compounds by this process is well documented in the reviews, and some typical cases are listed in Table 2.3.92a Primary and secondary alkyl iodides and bromides as well as sulfonate esters give the corresponding nitro compounds in 50-70% yields on treatment with NaN02 in DMF or DMSO. Some of them are described precisely in vol 4 of Organic Synthesis. For example, 1,4-dinitrobutane is prepared in 41 -46% yield by the reaction of 1,4-diiodobutane with silver nitrite in diethyl ether.92b 1-Nitrooctane is prepared by the reaction with silver nitrite in 75-80% yield. The reaction of silver nitrite with secondary halides gives yields of nitroalkanes of about 15%, whereas with tertiary halides the yields are 0-5%.92c Ethyl a-nitrobutyrate is prepared by the reaction of ethyl a-bromobutyrate in 68-75% yield with sodium nitrite in DMF.92d Sodium nitrite is considerably more soluble in DMSO than in DMF as a consequence, with DMSO, much more concentrated solutions can be employed and this makes shorter reaction times possible.926... 

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) ... 

Condensations with alkyl nitrites and nitrates, however, are not so generally applicable as the true ethyl acetoacetate reaction, and the possibility is not excluded that they proceed in another way compounds with mobile hydrogen might first he added to the inorganic part of the ester by means of an aldol condensation. The fact that fluorene, which contains no active double bond at all, combines with ethyl nitrate (as well as with ethyl oxalate) and sodium ethoxide in the same way, yielding oci-nitrofluorene, seems to support this second theory (W. Wislicenus). 

Many alkyl nitrites are thermally unstable and may readily decompose or explode on heating [1], Methyl nitrite explodes more violently than ethyl nitrite [2], Lower alkyl nitrites have been known to decompose and burst the container, even in refrigerated storage [3], Individually indexed compounds are f Butyl nitrite, 1658 f fert-Butyl nitrite, 1659... 

Alkyl nitric esters can also be formed by acting on alkylhydroperoxide with ethyl nitrite ... 

Pressure-dependent gas phase NMR studies of syn-anti exchange in alkyl nitrite/C02 mixtures reported PiP values of 312,166,26, and <3 torr for MeONO, ethyl nitrite, n-propyl nitrite, and n-butyl nitrite, respectively [75], For all the nitrites studied, experimental rate constants were modeled using RRKM theory. This study concluded that the agreement between the rate constants calculated using RRKM... 

Until relatively recently no kinetic studies on the nitrosation of alcohols had been reported, presumably since the reactions are very rapid and require special techniques. Some kinetic measurements on the reverse reaction, the hydrolysis of alkyl nitrites have been reported here conventional kinetic methods were used. Early workers examined the reactions of the series methyl, ethyl, i-propyl and t-butyl nitrites in an acetic acid-acetate buffer and found a small increase in rate constant along the series (Skrabal et a ., 1939). Later Allen measured the rate constants for the hydrolysis of a number of alkyl nitrites in aqueous dioxan solvent for both acid- and base-catalysed reactions (Allen, 1954). The rate constants for the O-nitrosation of alcohols were determined indirectly by measurement of the overall equilibrium constant for the process, by noting the change in the rate constant for the nitrosation of phenol in the presence of added alcohols. These, combined with the known data for the reverse hydrolysis reaction, enabled the rate constants for the forward reaction to be obtained (Schmid and Riedl, 1967). The reactivity sequence MeOH > EtOH > i-PrOH > t-BuOH was deduced, and attributed to a steric effect. 

Significant contribution towards elucidation of the overall mechanism comes from investigations of the pyrolysis on ethyl nitrite " . Arrhenius parameters for the pyrolysis of some alkyl nitrites are shown in Table In the... 

Nitrosolysis of camphor ethyl acetal with ethanolic ethyl nitrite in sulphur dioxide yields the orthoester oxime (205) which is rapidly dehydrated by excess acetal to the orthoester nitrile which then reacts with sulphur dioxide to form the ester nitrile and diethyl sulphite.Further papers in this section include the full paper on ozonolysis of silyl ethers (Vol. 5, p. 33), another synthesis of camphor-enol trimethylsilyl ether (cf. Vol. 6, p. 41)/°° the conversion of camphor oxime with Grignard reagents into the corresponding imine with no aziridine formation/° the preparation of (206) by treating bornylene with trichloroacetyl isocyanate/ the oxidation of thiocam-phor to the 5-oxide and alkylation in the presence of thallium(i) ethoxide to a/S-unsaturated sulphoxides/ and the free-radical C-3 alkylation of camphor with alkenes. " ... 

A potentially serious problem looms in the path of those who would like to give this reaction a try. The problem is that alkyl nitrites such as methyl or ethyl nitrite are not easily purchased. The reason for this is their use in products which were formerly on sale under such names as "Rush," "Locker Room," or "Jock Aroma." Inhaling this class of substances produces an intense head rush, and disorientation. In many states, these substances are now classified as controlled substances. In all cases, this properly necessitates great care on the part of the chemist in handling this material, lest he be overcome. These nitrites are easily made in large... 

Similar reactions have been carried out by various investigators using ethyl nitrite, amyl nitrite,and other alkyl nitrites in aqueous or alcoholic solution in the presence of potassium hydroxide or potassium ethylate. In the procedure given below butyl nitrite is used. It is more easily prepared and handled than ethyl nitrite. It may also be used for the preparation of sodium azide. 

Excimer laser photolysis of ethyl nitrite was studied at 248 and 351 nm as a function of O2 pressure (Zellner). In contrast to methyl nitrite, the photolysis produced not only C2H5O radicals but also methyl radicals with high yield. This study indicates that photolysis of higher alkyl nitrites is not an appropriate source for the laboratory generation of alkoxy radicals. 

NH,N0g Alkyl-, Butyl-, Amyl-, Isoamyl nitrite p-ClCgHfiO-ONO NO2-NO BF -NOCl, NOBr Alkyl nitrate, Ethyl -, Amyl -Acetyl-... 

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