Sulfonation-nitration approach

Finally, certain 3-substituted compounds can be prepared by utilizing the - meta) directing powet (cf. Section IV,B) of some groups in the 2-position which afterward can be removed. 3-Nitrothiophene is prepared by nitration of 2-thiophenesulfonyl chloride and by removal of the sulfonic acid group of the 4-nitro-2-sulfonyl chloride formed with superheated steam. Another approach to 3-nitrothio-phene is to nitrate 2-cyanothiophene, separate the 4-nitro-2-cyano-thiophene from the 5-isomer, hydrolyze, and decarboxylate. A final method of preparation of 3-nitrothiophene is by simultaneous de-bromination and decarboxylation of 5-bromo-4-nitro-2-thiophene-carboxylic acid obtained through the nitration of methyl 5-bromo-2-thiophenecarboxylate. 

For the synthesis of bidentate ligands, supramolecular approaches have led to a renaissance in homogeneous catalyst discovery (Chapters 2, 4, 8, 9,10), and in a few cases even monodentate ligands have been modified in a supramolecular fashion (Chapter 8, Section 8.2). Combinations of monodentate ligands can be left to chance and in several instances this has led to successful, new catalysts [96]. Such heterocombinations can form spontaneously for steric or electronic reasons or the reactivity of the combinations can be different such that on certain occasions highly enantioselective catalysts are obtained. There are many ways to synthesize the desired heterocombinations selectively and the ionic modification outlined in Section 10.4 is only one of them since nitration (followed by reduction to amines) and sulfonation are robust methods, the ionic route may prove useful. Hydrogen bonding between different donor-acceptors (Chapters 2 and 8), Lewis add-base interactions (Chapter... 

As mentioned earlier in situ approach has also been used for the synthesis of conducting polymer-metal hybrid nanocomposites. Xu et al. [35] have reported the decoration of PPy nanotubes with gold nanoparticles by an in situ reduction process. They prepared PPy nanotubes by MO-FeCl3 self-degrade template method and then reduced HAuCLi within PPy nanotubes in the presence of different surfactants such as sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB) and Tween-80. Nanowires of silver PAni nanocomposites have been reported via in situ polymerization method [36]. In this method aniline is oxidized by ammonium persulfate (APS) in the presence of dodecylbenzene sulfonic acid (DBSA) and silver nitrate (AgN03). In another approach gold-PAni core-shell... 

---