Aromatic nitro compounds intermolecular

Aromatic nitro compounds undergo nucleophilic aromatic substitutions with various nucleophiles. In 1991 Terrier s book covered (1) SNAr reactions, mechanistic aspects (2) structure and reactivity of anionic o-complexes (3) synthetic aspects of intermolecular SNAr substitutions (4) intramolecular SNAr reactions (5) vicarious nucleophilic substitutions of hydrogen (VNS) (6) nucleophilic aromatic photo-substitutions and (7) radical nucleophilic aromatic substitutions. This chapter describes the recent development in synthetic application of SNAr and especially VNS. The environmentally friendly chemical processes are highly required in modem chemical industry. VNS reaction is an ideal process to introduce functional groups into aromatic rings because hydrogen can be substituted by nucleophiles without the need of metal catalysts. 

Amination of aromatic nitro compounds is a very important process in both industry and laboratory. A simple synthesis of 4-aminodiphenyl amine (4-ADPA) has been achieved by utilizing a nucleophilic aromatic substitution. 4-ADPA is a key intermediate in the rubber chemical family of antioxidants. By means of a nucleophibc attack of the anilide anion on a nitrobenzene, a o-complex is formed first, which is then converted into 4-nitrosodiphenylamine and 4-nitrodiphenylamine by intra- and intermolecular oxidation. Catalytic hydrogenation finally affords 4-ADPA. Azobenzene, which is formed as a by-product, can be hydrogenated to aniline and thus recycled into the process. Switching this new atom-economy route allows for a dramatic reduction of chemical waste (Scheme 9.9).73 The United States Environmental Protection Agency gave the Green Chemistry Award for this process in 1998.74... 

L. Minier, K. Brower, J.C. Oxley "The Role of Intermolecular Reactions in Thermolysis of Aromatic Nitro Compounds in Supercritical Aromatic Solvents," J.Org.Chem., 56 (1991) 3306-3314. 

An excellent review was given by Frolov, Kuznetsov and Hltsov [52] on the photoreduction of aromatic nitro compounds through intermolecular action. Alcohols and hydrochloric acid supply the hydrogen needed for reduction alcohols are converted into aldehydes, as in reaction (1) and hydrochloric acid... 

Successful partition chromatography requires a proper balance of intermolecular forces among the three participants in the separation process—the analyte, the mobile phase, and the stationary phase. These intermoleculai forces are described qualitatively in terms of the relative polarity possessed by each of the three components. In general, the polai ities of common organic functional groups in increasing order are aliphatic hydrocarbons < olefins < aromatic hydrocarbons < halides < sulfides < ethers < nitro compounds < esters = aldehydes = ketones < alcohols = amines < sulfones < sulfoxides < amides < carboxylic acids < water. 

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