Nitrocompounds

The uv absorption spectrum of simple aliphatic nitrocompounds consists of an extended band centered at 2700-2800 A and is most probably associated with an n 7t transition involving oxygen-atom lone-pair electrons . Both the photochemical and thermal decompositions of nitrocompounds are extremely complex, in part owing to secondary reactions between products and substrate although the overall mechanisms are still unclear in many cases, the primary modes of decomposition of some molecules have been established. 

Early work on the photolysis of nitromethane showed that the major products are CH2O, Nj, NO, HjO and CO. It was suggested that the primary process produced isomerization followed by decomposition, viz. 

Support for this type of cleavage is the observation that the yield of CH2O is unaffected by the addition of NO and the identification of the species HNO in flash photolysis experiments . Photolyses in argon matrices at 20° K produced HNO and cw-methylnitrite, and it was suggested that the latter was the intermediate postulated by Hirschlaff and Norrish . However, later experiments demonstrated that methyl nitrite is a major product of the continuous photolysis, and the following mechanism was suggested  

Methyl radicals were indeed detected at short delay times in flash photolysis , and ESR studies have demonstrated the presence of CHj and NO2 radicals . In addition, large yields of CH are formed in the photolysis, presumably by abstraction reactions of CHj . Recently, experiments by kinetic flash photolysis have shown that the primary step leads to C-N cleavage and that the formation of methyl nitrite is explained by step (b). In contrast to previous results the 

For perfluoronitromethane and heptafluoronitropropane, it was established that the primary process produces NO2 and perfluoroalkyl radicals . 

Nitro compounds show two strong bands in the infrared spectrum. One appears near 1550 cm and the other near 1350 cm Although these two bands may partially overlap the aromatic ring region, 1600-1450 cm it is usually easy to see the NO2 peaks. 

O Aliphatic nitro compounds asymmetric stretch (strong), 1600-1530 cm  

FIGURE 2.65 The infrared spectrum of 1-nitrohexane (neat liquid, BCBr plates). 

This section covers compounds with ionic bonds. Included here are carboxylate salts, amine salts, and amino acids. Amino acids are included in this section because of their zwitterionic nature. 

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The characteristic property of aliphatic nitrocompounds of the type RCHiKOj and RjCHNO, is that they are pseiido cids, I. e., whereas they are neutral in the normal form (A), they are able by tautomeric change under the influence of alkali to give the acidic hydroxy form (B) which thus in turn gives the sodium salt (C). When this sodium salt is treated with one equivalent of hydrochloric acid, the acid form (B) is at once regenerated, and then more slowly reverts to the more stable normal form (A). 

Most nitrocompounds react vigorously with metallic sodium during the tests for elements present (p. 321). 

Almost insoluble in cold water. Higher alcohols (including benzyl alcohol), higher phenols (e.g., naphthols), metaformaldehyde, paraldehyde, aromatic aldehydes, higher ketones (including acetophenone), aromatic acids, most esters, ethers, oxamide and domatic amides, sulphonamides, aromatic imides, aromatic nitriles, aromatic acid anhydrides, aromatic acid chlorides, sulphonyl chlorides, starch, aromatic amines, anilides, tyrosine, cystine, nitrocompounds, uric acid, halogeno-hydrocarbons, hydrocarbons. 

Investigations of the solubilities of aromatic compounds in concentrated and aqueous sulphuric acids showed the activity coefficients of nitrocompounds to behave unusually when the nitro-compound was dissolved in acid much more dilute than required to effect protonation. This behaviour is thought to arise from changes in the hydrogenbonding of the nitro group with the solvent. 

Phthalocyanine sulfonic acids, which can be used as direct cotton dyes (1), are obtained by heating the metal phthalocyanines in oleum. One to four sulfo groups can be introduced in the 4-position by varying concentration, temperature, and reaction time (103). Sulfonyl chlorides, which are important intermediates, can be prepared from chlorosulfonic acid and phthalocyanines (104). The positions of the sulfonyl chloride groups are the same as those of the sulfonic acids (103). Other derivatives, eg, chlormethylphthalocyanines (105—107), / /f-butyl (108—111), amino (112), ethers (109,110,113—116), thioethers (117,118), carboxyl acids (119—122), esters (123), cyanides (112,124—127), and nitrocompounds (126), can be synthesized. 

Aromatic nitrocompounds 7.182 - 0.236N -213.14-1- 18.330N For aromatic correction, see- ... 

Excellent yields of the oximes of phenylacetaldehydes are obtained by reduction of 6-nitrostyrenes over Pd-on-C in a pyridine solvent (74,75). The technique gives yields of only about 60% when applied to aliphatic unsaturated nitrocompounds better yields are obtained in acidic media(6 5). Over 5% Rh-on-Al203 in ethanol-acetic acid-ethyl acetate, 2- 6-dinitro-styrenes are converted to 2-nitrophenylacetaldehyde oximes (13). 

As stated above under TNMe, in Ger during WWII, the prepn of TeNMe by this process was scaled up for use as an intermediate and as a substitute for nitric acid in the V-2 rocket (Ref 26). A pilot plant was built at Newark, NJ for prodn using this procedure. It was destroyed by an expln in 1953 and not rebuilt (Refs 33 44). Other prepns of lesser importance are by the action of Ag nitrite on iodotrinitro-methane (Ref 3) by the action of 90% nitric acid and 25% oleum on malononitrile, yield 45% (Ref 40) by the action of mixed acid on a number of aromatic nitrocompounds, of which nitrobenzene, dinitrobenzene, and nitronaphtha-lene gave the best yields (Ref 13a) and by the action of nitryl chloride on salts of TNMe. 

It is also possible to reduce the nitrocompounds to amines which can be used as flash reducing agents in propints... 

However, for work with accompanying rock, the stronger gelatin permissible with 25 to 30% NG were preferred. One of the later types of Neu-nobelits was No XVI NG 12, AN 54, woodmeal and coal 3, nitrocompounds 3, and alkali chlorides 28%. Its properties were OB to C02 +2.9%, Trauzi block expansion 225.0cc, Fb block crushing 13.0mm, vel of deton 4600m/sec, Qe 643.0cal/g, temp of expl 1828°... 

Nitroaminocompounds or Nitroamines. Compds containing both —N02 and —NH2 radicals attached to different C atoms, eg, nitroaniline, 02N.C6H4.NH2, etc. Nitroamines can be prepd either by the nitration of amines, or by partial reduction of nitrocompounds contg several —N02 groups. Another method is to treat a chloronitrocompound with ammonia, as in the prepn of dinitroaniiine... 

Fig 1 Quenching of the Scintillation Process by Organic Nitrocompounds in Toluene-14C-PPO... 

Aromatic Amine and Nitrocompounds, Their Toxicity and Potential Dangers , US Public Health Bull No 271, Washington, DC (1941), 105 6) Davis (1943), 140... 

Thermal Stability. Satisfactory Refs 1) Beil—not found 2) L.F. Fieser, Aromatic, Aliphatic Nitrocompounds and Nitrate Esters , OSRD 176 (1941) 3) R. 

Nitrocompound Addition to Picric Acid for Melting Point Lowering... 

Proportion Nitrocompounds and their Melting Points in °C Melting Point of the Mixture in °C... 

Conjugate addition to unsaturated nitro-compounds, using the reaction between 1-trimethylsilyloxycyclohex-l-ene and 2-nitropropene, under the influence of SnCI4, to give 2-acetonylcyclohexanone (i.e. the nitrocompound acts as an umpoiung reagent for an acetone moiety). 

Sodium borohydride in methanol selectively reduces the double bond of nitrocompounds (20) while leaving the... 

Debnath AK, Lopez de Compadre RL, Debnath G, Shusterman AJ, Hansch C. Structure-activity relationship of mutagenic aromatic and heteroaromatic nitrocompounds—correlation with molecular orbital energies and hydrophobicity. I Med Chem 1991 34 786-97. 

Aromatic nitrocompounds (see Fig. 21) such as nitrobenzene and the dinitrobenzenes diminish the rate of polymerization of styrene without suppressing it altogether and without introducing an induction periodi.e., they are typical retarders. Larger quantities are required to produce significant reductions in the rate, and the retardation persists throughout the polymerization, suggests... 

Anderson RC, MA Rasmussen, NS Jensen, MJ Allison (2000) Denitrobacterium detoxificans gen. nov., sp. nov., a ruminal bacterium that respires on nitrocompounds. Int J Syst Evol Microbiol 50 633-638. 

The hydrogenation of organic nitrocompounds has received relatively little attention. The only reports on this... 

It is worth noting, however, that up until fairly recently the reduction of aromatic nitrocompounds to the corresponding amines was commonly performed on an industrial scale, e.g. in the synthesis of azo dyes, with a mixture of iron and hydrochloric acid. This so-called Bechamp reduction has an E factor of ca. 15 compared to 1 for catalytic hydrogenation. 

J. Heyrovsky and K. Holleck and B. Kastening pointed out that the reduction of aromatic nitrocompounds is characterized by a fast one-electron step, e.g. 

Other authors also determined by FTIR that organic nitrocompounds are formed as primary products of the NO CH4-SCR reaction on ZSM-5-based catalysts [121-124], They preadsorbed nitromethane on the sample placed in the IR cell and followed by IR its transformation into other intermediates under 02 and NO versus time at different temperatures. For Cu- and Co-ZSM-5, it was shown that around 300°C adsorbed nitromethane is easily converted into isocyanates and then melamine via polymerization of the former species. Both species easily interact with molecular oxygen, while no reaction with NO is observed and the reactivity depends on the temperature and the nature of the transition metal cation. 

During addition of the nitrocompound in methanol to sodium methoxide solution, the temperature must not be allowed to fall much below 50°C. If this happens, excess nitro compound will accumulate and cause a violent and dangerous exotherm. 

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