The correct answer is: A. 2-nitropyridine
Pyridine is a heterocyclic aromatic compound with the chemical formula C5H5N. It is a colorless, water-soluble liquid with a characteristic musty odor. Pyridine is a weak base and is used as a solvent and in the manufacture of pharmaceuticals and pesticides.
Electrophilic nitration is a chemical reaction in which a nitro group (-NO2) is added to an organic compound. The reaction is typically carried out by heating the organic compound with nitric acid and sulfuric acid.
In the case of pyridine, electrophilic nitration occurs at the 2-position of the ring. This is because the 2-position is the most electron-rich position in the ring. The nitro group is an electron-withdrawing group, so it destabilizes the aromatic ring. This destabilization is greatest at the 2-position, which is why the 2-nitropyridine product is the major product of the reaction.
The other options are incorrect because they do not represent the major product of the reaction. Option B is 3-nitropyridine, which is a minor product of the reaction. Option C is 4-nitropyridine, which is also a minor product of the reaction. Option D is 2,4-dinitropyridine, which is a very minor product of the reaction.
In conclusion, the major product of electrophilic nitration of pyridine is 2-nitropyridine.