Mononitro isomers

Nitration of cinnolin-4(lFf)-one yields a mixture of the 3-nitro (0.9%), 5-nitro (0.38%), 6-nitro (58.4%), 7-nitro (0.36%) and 8-nitro (39.9%) derivatives. The 3-nitro isomer is postulated to result from nitration of the free base, while the other mononitro isomers are formed from the protonated molecule. 

Ramdahl, T., J. A. Sweetman, B. Zielinska, R. Atkinson, A. M. Winer, and J. N. Pitts, Jr., Analysis of Mononitro Isomers of Fluoranthene and Pyrene by High Resolution Capillary Gas Chromatography/Mass Spectrometry, J. High Resolut. Chro-matogr. Chromatogr. Commun., 8, 849-852 (1985). 

If the initial molar ratio of nitric acid is 2 1, the yield of 3-nitro-1-benzylpyrrole is diminished and l-benzyl-2,4-dinitropyrrole (4, 15%) is also obtained. Nitration of either the 2- or the 3-mononitro isomer gives... 

MONONITRO DERIVATIVES OF NAPHTHALENE Both the mononitro isomers, a and p, are known ... 

Nitration of thiophene 2-carbaldehyde has been reported to give a mixture of all three mononitro isomers in the ratio 3-nitro (62%), 4-nitro (15%), and 5-nitro (23%). This mixture could not be condensed with 2-acetylpyridine in NaOH instead, the thiophene ring was ruptured <2006S1295>. 

An aromatic substrate, which was successfully used to identify nitrate ions in real-life postexplosion cases, was tert-butylbenzene [57]. The dried aqueous extract was acidified with concentrated sulfuric acid and reacted with the tert-butylbenzene, producing five products all three mononitro isomers and two dini-tro isomers (2,4- and 2,6-). The reaction products (sometimes not all the five products) were easily identified by GC-MS, using EL An idea to improve the sensitivity of this method (P. Pigou, personal communication, 1998) is based on the assumption that the second nitration step may lower the sensitivity. Hence,... 

The impurities present in aromatic nitro compounds depend on the aromatic portion of the molecule. Thus, benzene, phenols or anilines are probable impurities in nitrobenzene, nitrophenols and nitroanilines, respectively. Purification should be carried out accordingly. Isomeric compounds are likely to remain as impurities after the preliminary purifications to remove basic and acidic contaminants. For example, o-nitrophenol may be found in samples ofp-nitrophenol. Usually, the ri-nitro compounds are more steam volatile than the p-nitro isomers, and can be separated in this way. Polynitro impurities in mononitro compounds can be readily removed because of their relatively lower solubilities in solvents. With acidic or basic nitro compounds which cannot be separated in the above manner, advantage may be taken of their differences in pK values (see Chapter 1). The compounds can thus be purified by preliminary extractions with several sets of aqueous buffers... 

Relatively little is known concerning the substitution reactions of the carbolines. The most studied reaction is that of nitration. Nitration of l-methyl-j8-carboline gave two mononitro derivatives. The highermelting isomer, which was formed predominantly (57% yield), was shown to be 6-nitro-l-methyl-j8-carboline (253 R = CH3) by its conversion into 6-bromo-l-methyl-j5-carboline the latter was synthesized unambiguously from 5-bromotryptophan and acetaldehyde. The lower melting isomer, recovered in 20% yield, was presumed to be the 8-nitro derivative (254), although this was not established. Nitration of j8-carboline with concentrated nitric acid at 35° has been reported to yield 6-nitro-j3-carboline (253 R = H) as the sole product. Only the 6-nitro derivatives (255) were isolated on nitration... 

If an unfractionated mixt of the mononitro-toluene isomers is used (ie, the product of straight nitration of toluene), TNT with a mp of 78.7° is produced. If the starting material is free from m-nitrotoluene, TNT with a mp of 80.6° is claimed... 

Nitration of 2-bromodibenzothiophene 5,5-dioxide gave a mononitro compound tentatively assumed to be the 7-nitro isomer enlarged preparative details of the known 8-nitro-2-bromodibenzothiophene were also described. ... 

Mononitro-bis( dimethylamino)-triphenylm ethane, C23H25N302. Three isomers are described in Beil 13,278-80 [136]... 

Mononitro-diazobutyro.phenone, C1 0H9N3°3 mW 219.20, N 19.17%. The isomer, 4 -Nitro-2-diazo -butyrophenone or 4 Nitro-a-diazo-butyropbenone, [called l-p-Nitrobenzoyl-l diazopropane by Wilds Meader(Ref 2)] C2Hs.C(N2).CO.C6H4.-N02, yel ndIs(from petr eth), mp 97.5-98.5°(dec) sol in AcOH with evoln of N was prepd by reacting diazopropane in eth at -20° with p-nitrobenzoyl chloride(Ref 2). The same compd can be prepd by the method described by Eistert(Ref 3). 

Three isomers are described in the literature. No azido- or diazido-compds were found in Beil cr CA through 1956. Mononitro-, dinitro- and trinitro-acridines are described in the literature but none of them are reported to be expl. If tetranitrocmino-acridine was known it very likely would be an expl because its N0a nitrogen content is ca 15%. 

Preparation of the different nitro derivatives of dialkoxy calix[4]arene crown-6, isolation, and identification of pure isomers of these derivatives should be very useful in subsequent identification of isomers arising from irradiation of calixarenes. For instance, the two isomers of the mononitro derivative (N02 para to alkoxy chain or para to phenoxy) were characterized. From the three possible isomers of the dini-tro derivative, two were isolated and obtained in pure form, thus enabling interpretation of their NMR spectra. The structure of the trinitro derivative was clarified as expected, two nitro moieties are in the para position relative to the two alkoxy chains the third one is para to phenoxy.94... 

The nitration of 2,5-diphenyl-l,3,4,-oxadiazole (44a) was first investigated by Grekov and Azen (61JGU1796), who reported that fuming nitric acid (d 1.51) alone results in a mixture of three isomers, the 2,5-bis(2-nitrophenyl), bis(3-nitrophenyl), and bis(4-nitrophenyl) products in yields of 40, 20, and 27%, respectively. They found that fuming nitric acid in sulfuric acid gives a preponderance of 3-nitrophenyI products with both the mononitro and the dinitro derivatives being obtained in yields of 31 and 38%, respectively. 

Only in the para isomer are all four remaining hydrogens equivalent. Therefore, it can give only one mononitro derivative and must be A ... 

All three isomers are pale yellow substances, with the smell characteristic of mononitro compounds. They are soluble in most organic solvents. The solubility of technical MNT in sulphuric acid is shown in Table 46. Due to the presence of a methyl group, the isomers are much less toxic than nitrobenzene (p. 260). 

Three isomers of mononitro-m-xylene are known, viz. 2-,4-, and 5-nitro-m-xy-lenes ... 

It is often advantageous to separate the isomers from each other (by distillation or by freezing out) in the mononitro stage. 

Mononitrochlorophenol, (02N)Cl.CgH3,0H mw 173 5 5 N 8.07%, Ten isomers are known and described in the literature. Their props methods of prepn are given in Beil Ref Beil 6, 238-4 0, (122) [226-29] Mononitrodiazochlorophenol. See Mononitro-diazochlorobenzoquinone under Benzoquinone and Derivatives... 

Preparation of mononitro toluenes Industrial methods of nitration of toluene Separation of isomers Distillation of crude nUrotx uene Crystallization of p-nitrotoluene Distillation of the mother liquor Continuous vacuum distillation of mononiirotoluene Preparation of pure isomers Dinitrotoluenes Physical properties Thermocbemical properties Chemical properties Toxicity... 

---