2.4- Dinitrobenzoic acid Compound

Dinitrobenzenesulphenyl chloride 3.5- Dinitrobenzoic acid (ii) N-Nitro compounds... 

Crystals of stoichiometric 1 1 mixtures of compounds that can complex with each other have been shown to form preferentially to pure crystals of the individual components. In some cases these crystals may have potential non-linear optical properties. An interesting example is the 1 1 mixture of p-aminobenzoic acid and 3,5-dinitrobenzoic acid. (15) A view of the crystal structure is shown in figure 3. Examination of this figure leads one to the hypothesis that the preference for the mixed crystal may be due to a) a more stable H-bonding interaction between the different benzoic acids in the hetero-dimer than in the homo-dimer b) the ability of the mixed crystal (hetero- dimers) to H-bond between their amino and nitro groups. It is likely that both of these factors play a role in the stability of the crystal structure. Calculational modelling can aid in determining the importance of these factors. 

Figure 6.2 demonstrates this in the case of a ground water sample from the former ammunition site in Elsnig (Germany). Many unknown compounds could be identified in the non-target analysis, e.g. 2,4-dinitrobenzoic acid (2,4-DNBA) and 3,5-dinitrophenol (3,5-DNP) which are major components (see Figure 6.2(a) and Table 6.1). 

In the non-target analysis of this sample, carried out by LC-NMR and LC-MS, TNT-typical biodegradation products such as 2-amino-4,6-dinitro-toluene and 4-amino-2,6-dinitrotoluene were detected, although smaller quantities of 2-amino-4,6-dinitrobenzoic acid, trinitrobenzene and 2,2/6,6/-tet-ranitro-4,4/-azoxytoluene could also be identified. The NMR chromatogram further reveals that the soil was also contaminated by PAHs. Several late-eluting compounds could be identified as PAHs. 

Fig. 4.13. Separation of acidic compounds in columns packed with (a) 5 pm Spherisorb-ODS and (b) 5 pm Spherisorb-SAX materials. In (a) the mobile phase was composed of 60% acetonitrile in 2mM phosphate buffer (pH 2.2) and in (b) the mobile phase was composed of 50% acetonitrile in 20 mM phosphate buffer (pH 2.2). The compounds were 1, 3,5-dinitrobenzoic acid 2, p-nitrobenzoic acid 3, p-bromobenzoic acid 4, o-toluic acid 5, benzoic acid 6, o-bromobenzoic acid. Reprinted from ref. [102] with permission. Copyright Elsevier 2000.

Aromatic dinitro compounds may be selectively reduced by hydrazine in the presence of transition metal catalysts.136 Pitre and Lorenzotti obtained 3-amino-5-nitrobenzoic acid in 82% yield by treating 3,5-dinitrobenzoic acid with Raney Ni and an appropriate amount (3.6 equiv) of hydrazine in water (eq. 9.57).137 Similarly, 2,4-dinitrophe-nol and 2,4-dinitroaniline were reduced to 2-amino-4-nitrophenol and 2-amino-4-nitroaniline, respectively, with 10% Pd-C and hydrazine in ethanol solution. 

Selective reduction of functional groups can be achieved by chemical modification of the LiALH4 for example, lithium tri(t-butoxy)aluminium hydride [LiAIH(t-OBu)3] is a more selective reagent, and reduces aldehydes and ketones, but slowly reduces esters and epoxides. Nitriles and nitro groups are not reduced by this reagent. Carboxylic acids can be converted into the aldehyde via acid chloride with lithium tri(tert-butoxy) aluminium hydride at a low temperature (—78°C). The nitro compounds are not reduced under this condition. Thus, selective reduction of 3,5-dinitrobenzoic acid (6.45) to 3,5-dinitrobenzaldehyde (6.47) can be achieved in two steps. First, 6.45 is converted into 3,5-dinitrobenzoyl chloride (6.46) and then LiAlH(t-OBu)3 reduction of 6.46 gives 6.47. 

G) Identification of Monohydroxy Compounds. The evolution of hydrogen chloride, when acetyl chloride or phosphorus trichloride is added to a compound, indicates the possible presence of a hydroxy group. For identification purposes a derivative should be prepared. 3, 5-Dinitrobenzoic acid forms crystalline derivatives with hydroxy compounds. The melting points of the esters are utilized for identification. 

DinitrobenzoyI chloride. Place in an eight-inch tube 2 g of 3,5-dinitrobenzoic acid and 4 g of phosphorus pentachloride. Heat in the hood with a small smoky flame for five minutes. In the beginning the tube is heated to start the reaction and thereupon the flame is removed until the reaction has subsided. Then the flame is adjusted so that the vapors condense at about the middle of the tube. Allow to cool for one minute and pour carefully into a small evaporating dish. Cool and transfer the sohd to a paper drying disc or to several filter-paper circles. Press with the spatula so as to force the phosphorus oxychloride into the absorbent medium. After ten minutes transfer the crude 3,5-dinitrobenzoyl chloride into a small bottle or tube. The crude material is satisfactory for the preparation of derivatives of the lower hydroxy compounds. 

X, and the p-xylene complex at 100-120°C. Charge transfer is a factor in the host-guest complex of 4-methyl-3,5-dinitrobenzoic acid with 2,6-dimethylnaphthalene.74 Charge transfer with tetranitrofluorenone has also been used to remove 60% of the dialkyldibenzothiophenes from petroleum that contains 1920 ppm sulfur, although no inclusion compound is involved.75 As polynitro compounds are often explosive, a better charge acceptor is needed. 

During the past few years, acylnitroso Diels-Alder cycloadditions have been used as the key step in several natural product total syntheses. Retey et al. ° have used the adduct from cyclopentadiene and the acylnitroso compound derived from 3,5-dinitrobenzoic acid to synthesize the antitumor compound neplanocin A (16) (Scheme 3-XI). 

Griess was a very careful and accurate experimenter. He discovered quina-zoline derivatives by the action of cyanogen on anthranilic acid, and the colour reaction with nitrites and m-phenylenediamine. He also used mixed solutions of sulphanilic acid and a-naphthylamine as a test for nitrites, this reagent being improved by IloBvay. Griess discovered the diaminobenzoic acids, dinitrobenzoic acids, methyl orange, and various azo-compounds. ... 

The halogen in an aromatic compound (e.g., 4-chloro-3,5-dinitrobenzoic acid) can be made to react with amino group (e.g., p-aminobenzoic acid) in solid state at 180° C to give the corresponding amine (Scheme 21). 

Sterols are separated as 3,5-dinitrobenzoic acid derivatives by thin layer chromatography and, after reaction with 1,3-diaminopropane, are determined quantitatively with high sensitivity in the form of a Meisenheimer adduct. Sterols and triterpene alcohols are silylated and then analysed by gas chromatography. One application of this method is illustrated by the detection of 5% coberine in cocoa butter (Fig. 3.44). The compounds a-amyrine and lup-20(29)-en-3P-ol (Formula 3.113a and 3.116) serve as indicators. They are present in much higher concentrations in some cocoa butter substitutes than in cocoa butter. Coberine is a cocoa butter substitute made by blending palm oil and shea butter (the shea is an African tree with seeds that yield a thick white fat, shea butter). 

Second series of derivatives. It is convenient when a second series of derivatives can be prepared from the derivatives in a simple way, and when the identification constants of the second series prove definitely the identity of the tested substance. For example, alcohols are identified as esters of 3,5-dinitrobenzoic acid, and these give addition compounds with 1-naphthylamine, etc. 

Among other nitro compounds used for the reaction, 2,4-dinitro-phenol (58), 3,5-dinitrosalicylic acid (reduced to 3-amino-5-nitrosalicylic acid) (59, 60), 4,6-dinitroguaiacol (61), sodium-l-nitroanthraquinone-5-sul-fonate (62), 3,5-dinitrophthalic acid (63), 3,4-dinitrobenzoic acid (64, 65), and m-dinitrobenzene (66) should be mentioned. 

Crystals suitable for single-crystal structure determination of three representative compounds showed that the expected intermolecular interactions and stoichiometries were present. The crystal structure determination of la, obtained from the reaction between 1 and 3,5-dinitrobenzoic acid, shows the expected 1 2 co-crystal. The assembly is facilitated by an O-H N hydrogen bond between the O-H group on the carboxylic acid and the pyrazol-l-yl nitrogen atom (Fig. 1). 

Found in m-dinitro compounds examined where other additional groups, if any, were ortho to the nitro. Not found in sym-trinitro compounds but present in 2,3,4- and 2,4,5-trinitrotoluene. Absent in 3,5-dinitrobenzoic acid and 4,6-dinitro-o-cresol. It appears that a group meta to the nitro inhibits the band. 

The melting points of these esters are usually much lower than those of the corresponding 3 5 dinitrobenzoates their preparation, therefore, offers no advantages over the latter except for alcohols of high molecular weight and for polyhydroxy compounds. The reagent is, however, cheaper than 3 5 dinitrobenzoyl chloride it hydrolyses in the air so that it should either be stored under light petroleum or be prepared from the acid, when required, by the thionyl chloride or phosphorus pentachloride method. 

Esterification of the hydroxyl groups with a chromophore contributing acid levels the polarity effects and strengthens the detectability. The method even separates mixed bromo-chloro compounds (Fig. 7). We see the separation of the dinitrobenzoate esters of trichloropentaerythritol (6.67 min.), monobromodichloro-pentaerythritol (7.35 min.), dibromomonochloropentaerythritol (8.11 min.), 5, 4 and 1 (8.99, 10.25 and 11.71 min.), in that order. 

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