Nitric acid, esters, nitration

Nitrates s. Nitric acid esters Nitration NCUH 17, 912 ... 

For nitrating on the lab scale, mixts of nitric acid esters or acyl nitrates, eg acetyl nitrate (CH3CONO3) and sulfuric acid may also be used... 

A literature method for preparation of chromyl acetate by interaction of chromium trioxide and acetic anhydride was modified by omission of cooling and agitation. The warm mixture exploded violently when moved [1], A later publication emphasised the need for cooling, and summarised several such previous occurrences [2], An earlier reference attributes the cause of chromium trioxide-acetic anhydride oxidation mixtures going out of control to presence of nitric acid or nitrates in the chromium trioxide, and a simple test to check this point is given [3], Mixtures used as a reagent for the remote oxidation of carboxylic esters are potentially explosive, and must be made up and used at below 25 °C under controlled conditions [4], An attempt to purify the anhydride by warming with 2% w/v of trioxide led to an explosion at 30°C [5],... 

Hinz, B., Schroeder, H., Nitrate tolerance is specific for nitric acid esters and its recovery requires an intact protein synthesis. Biochem. Biophys.Res. Commun. 252 (1998), p. 232-235... 

A. Kekule prepd in 1869 an unstable liquid (known now as Kekule Oil) when he passed ethylene thru a cooled nitric-sulfuric acid mixture, which he designated as ethyleneglycol nitrate-nitrite. Later, Wieland Sakeilarios (Ref 2) showed that this product was a mixt of ethyleneglycol dinitrate and and the nitric acid ester of 2-NitroethyI Alcohol (See also Ref 4)... 

Electrochemical Nitrations. A method developed in 1956 in Sweden by Ohman for prepn of nitric acid esters has been described in several patents. The method consists in anodic oxidation (using a bright platinum anode) in presence of nitric acid, or its salts (such.as Ca nitrate). The compds to be nitrated areunsaturated hydrocarbons (such as ethylene, propylene, butylene, etc), which can be dissolved in nonaqueous solvents (such as acetone). The OH concn is maintained low during the reaction by adding either coned nitric acid or glacial acetic acid. Water should be absent to prevent the formation of various by-products... 

Investigating the types of reaction between nitric acid esters and hydrazine Merrow and van Dolah endeavoured first of all to solve the problem of how nitric acid is formed since the answer could in effect make it possible to establish the position of the linkage to be broken off in an ester molecule. They have established experimentally that during the reaction between alkyl nitrates and hydrazine the nitrite ion is produced very quickly. Later it dwindles away as reaction proceeds. The creation of NO in this process can never arise from the removal of a hydrogen atom in the a-posi-tion, since only an insignificant amount of ester can follow the reaction (31) to form an aldehyde ... 

Inorganic acid esters nitrates (e.g. methyl nitrate, nitroglycol, nitroglycerine), silicates (e.g. ethyl silicate), phosphates (e.g. triphenyl phosphate, tricresyl phosphate), mixed esters of nitric and hydrochloric acid (e.g. chlorohydrin dinitrate). 

Sugar nitric acid esters are also subject to reductive denitration (see p. 9) and to the chemical reactions typical of sugar nitrates. 

CA 32,1556(1938)(Therma[ analysis of various mixts contg nitrates, nitric acid esters and nitro compds) 5)Thorpe 4,(1940),464 5a)Davis(1943),... 

The use of nitrogen dioxide for the selective oxidation of polysaccharides to polyuronic acids was introduced by Kenyon and his coworkers13,63 in 1941. By this means extensive oxidation of the primary alcohol groups in cellulose was obtained, through the mechanism of preferential nitration followed by decomposition of the nitric acid ester with carboxyl forma-tion.68(0< > Apparently some undissociated nitration products also were formed, since infrared absorption studies54 indicated the presence of nitrate radicals in the polyuronic acid. Side reactions produced carboxyl,... 

Suresh et al. investigated the extraction of uranium and thorium by TsBP and TiBP (isomers of TBP with branched carbon chain) as an alternative choice for TBP (47). Higher homologues of TBP, for example, THP and TEHP, were reported to have higher extraction ability with reduced tendency toward third-phase formation (50, 51). The esters with bulkier substituents in place of the butyl group were proposed to be of practical value for the process applications in uranium and thorium separation (54). The LOC of thorium in equilibrium with aqueous nitric acid-thorium nitrate was reported to decrease in the order THP > TAP > TBP. Pathak et al. showed that TEHP can be a better choice for U/Th separation compared to TBP and TsBP (55). 

Certain esters of nitric acid (cellulose nitrate, glyceryl trinitrate) are often referred to as nitro compounds (nitrocellulose, nitroglycerin), but this terminology should be avoided. 

At present nitration is one of the most widely applied direct substitution reactions. This is due to several factors. For example nitration usually proceeds easily, its products can readily be separated from the spent acid, said there is a wide range of possibilities in the practical use of nitro compounds, both as intermediates and end products. The presence of a nitro group in the starting product made it possible to obtain a number of basic organic intermediates such as aniline said benzidine. Dyes with more than one nitro group, such as picric acid were obtained. It has been found that higher nitrated nitro compounds and nitric acid esters have explosive properties and are of practical importance. Some nitro compounds are used in perfumes. Medicinal properties have lately been discovered in certain nitro compounds, eg. chloramphenicol. 

O-nitration, leading to the formation of nitric acid esters, with the nitro group attached to an oxygen atom ... 

Hantzsch opposed the theory of N205 existing in the nitrating mixture HN03 + + H2S04 Due to the importance of the Hantzsch theory in the development of our views on the nature of the nitration process, we shall discuss it in detail. In a number of works Hantzsch [21-23] developed a theory based on Schafer s experiments [24] on the absorption spectrum in ultra-violet light. Schafer s chief observation was, that the spectrum of anhydrous nitric acid in a non-aqueous solvent (hexane, sulphuric acid, etc.) is analogous with the spectra of nitric acid esters,... 

Titov [35] also expressed the opinion that nitric acid esters in sulphuric acid yield nitronium ions, for example in the reaction with ethyl nitrate ... 

Acetic anhydride creates dehydrating conditions, therefore a mixture of nitric acid with acetic anhydride has strong nitrating properties. Moreover in esterification with nitric acid, the acetic acid present in the mixture or formed in the reaction does not hydrolyse the nitric acid ester formed. 

Nitric acid esters can be used as nitrating agents in the presence of sulphuric acid and in some cases in a strongly alkaline medium. 

PROP Organic nitrates are usually termed nitro compounds. These compounds are a combinadon of the nitro (—NO2) group and an organic radical. However, this term is often used to denote nitric acid esters of an organic material. Inorganic nitrates are compounds of metals with the monovalent NO3 radical. 

SAFETY PROFILE A very dangerous fire and explosion hazard when exposed to heat, flame, shock, or oxidizers. It is a powerful high explosive. Nitrostarch is not a definite compound, but a mixture of various nitric acid esters of starch with different degrees of nitration. When heated to decomposition it emits toxic fumes of NOx. See also NITRO COMPOUNDS. 

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