Reduction reaction nitro groups

Other possibilities are the reduction of nitro groups by applying the sample solutions to adsorbent layers containing zinc dust and then exposing to hydrochloric acid vapors [110] 3,5-Dinitrobenzoates and 2,4-dinitrophenylhydrazones can also be reduced in the same way on tin-containing silica gel phases [111] Cellulose layers are also suitable for such reactions [112] Seiler and Rothweiler have described a method of trans-salting the alkali metal sulfates to alkali metal acetates [113]... 

The NH2 groups can be diazotized and reduced in the presence of thiosulphates and different metal ions. The effect of some metal ions, namely Fe ", Sn, Cu +, and Co on the graft yield of cotton modified with aryl diazonium groups via its reaction with 2,4-dichloro-6-(p-nitroaniline)-5-triazine in the presence of alkali and followed by reduction of nitro group was studied [4]. 

Nitrocycloalkanones can be successfully C-allylated by Pd(0)-catalyzed reaction with various allyl carbonates and 1,3-dienemonoepoxides under neutral conditions, as shown in Eqs. 5.56 and 5.57, respectively.801 The product of Eq. 5.56 is converted into cyclic nitrone via the reduction of nitro group with H2-Pd/C followed by hydrolysis and cyclization.80b... 

The catalytic reduction of nitro groups is usually achieved using heterogeneous catalysts, although the iridium complex 28 has been shown to be effective for the reduction of p-nitroanisole 29 to the corresponding aniline 30 using isopropanol as the hydrogen donor (Scheme 8) [30]. In the reduction of some nitroarenes, azo compounds (Ar-N=N-Ar) could be formed as by-products or as the major product by variation of the reaction conditions. 

Table 15.3 Reductive and hydrolytic microbiaUy-mediated reactions of synthetic pesticides. R organic moiety Ar aromatic moiety (BoUag and Liu 1990) Reduction of nitro group...

Nitro Reduction. Aromatic amines are susceptible to reduction by both bacterial and mammalian nitroreductase systems. Convincing evidence has been presented that this reaction sequence is catalyzed by CYP. It is inhibited by oxygen, although NADPH is still consumed. Earlier workers had suggested a flavoprotein reductase was involved, and it is not clear if this is incorrect or if both mechanisms occur. It is true, however, that high concentration of FAD or FMN will catalyze the nonenzymatic reduction of nitro groups. 

Many organic compounds can be reduced by reaction with a source of electrons and a source of protons. (Previous examples include the Clemmensen reduction and the reduction of nitro groups to amino groups described in Chapter 17.) Often this is accomplished... 

The reduction of azo compounds using sodium hydrosulfite (Na2S204) and NaOH is an important reaction, as it provides an indirect method for the amination of phenols and naphthols (Fig. 13.49). The reduction of nitro groups in anthraquinone compounds works best when a mild reducing agent (e.g., sodium hydrosulfide, NaSH) is used. In this way one avoids reducing the quinoid system. 

An aryl halide can also be coupled to an amine using metal catalysis. The reaction represents an alternative to the classical methods for the synthesis of aryl amines, such as reduction of nitro groups and nucleophilic aromatic substitution (see Chapter 8). 

In catalytic hydrogenation, chlorine is replaced by hydrogen in chlorinated aromatic hydrocarbons (equations 41 and 42), phenols (equation 43), amines (equation 44), carboxylic acids (equation 45), and nitro compounds (equation 46). - Hydrogenolysis of chlorine in chloronitro compounds takes precedence over reduction of nitro groups, provided that contact with the halogen-free product is not too long. The reaction is achieved using palladium on carbon or tetrakis(triphenylphos-... 

Ru(CO)5 is less frequently used than Fe(CO)5 for organic synthesis or as a starting material as a zero-valent ruthenium complex because of its ease of decomposition to Ru4(CO),2 [99]. Dodecacarbonyltriruthenium is very useful for these purposes. It has been showm to be an active catalyst for the hydrogenation of olefins [100], carbonyla-tion of ethylene [101], hydroformylation of alkenes [102], water-gas shift reaction [103], and reduction of nitro groups [104], and recently, C—H bond activation [105] and coupling of diynes with CO [106]. 

A ligand-free Suzuki coupling protocol indicates employment of Pd(OAc)2 in PEG-400, in which nanoparticles of Pd are generated in situ. More conventionally, NaOMe is used as a base for coupling at room temperature. Under certain coupling reaction conditions reduction of nitro group(s) also occurs, ... 

Sterically hindered positions of l-aryl-4,6-diamino-l,3,5-dihydrotriazines (135) have been substituted by the triflate group. As shown in Scheme 40, reduction of nitro groups and diazotization-azidation reactions in the benzene ring are straightforward <93JHC849>. 

The reactivity of the porphyrins and metalloporphyrins will be described mainly using octaethylporphyrin and protoporphyrin derivatives. Reactions of TPP and chlorophyll a derivatives are mentioned only on the occasion of P-formylation and the reduction of nitro groups, which yield important educts for synkinetic reactions. The reversible reactions described for -substituted reactions also work with meso-tetraphenylporphyrins. 

Two well defined waves/peaks have been observed (Ej/2 values at —0.41 V and —0.83 V Ep values at -0.53 V and -0.90 V) for the reduction of EPN in acetate buffer of pH 4.0 at 25 % DMF. With increasing pH and alcohol concentration, the half-wave potential/peak potential values are found to be shifted to more negative potentials. This behaviour can be discussed on the basis of the presence of an adsorbed film of solvent molecules at the electrode surface which increases the activation energy of the reaction and retards the reaction rate. These observed waves/peaks correspond to the reduction of nitro group present in EPN to yield hydroxylamine in the first stage and form hydroxylamine to amine in the next stage. Only one wave/peak has been observed in the alkaline medium which may be attributed to the reduction of nitro group to hydroxylamine because the observed current is equal to that observed in the first wave in acidic media. 

---