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In organic chemistry, nitration is a general class of chemical processes for the introduction of a nitro group (−NO 2) into an organic compound.The term also is applied incorrectly to the different process of forming nitrate esters (−ONO 2) between alcohols and nitric acid (as occurs in the synthesis of nitroglycerin).
Pyridine is a basic heterocyclic organic compound with the chemical formula C 5 H 5 N. It is structurally related to benzene, with one methine group (=CH−) replaced by a nitrogen atom (=N−). It is a highly flammable, weakly alkaline, water-miscible liquid with a distinctive, unpleasant fish
The oxidation of pyridine can be achieved with a number of peracids including peracetic acid and perbenzoic acid. [3] Oxidation can also be effected by a modified Dakin reaction using a urea-hydrogen peroxide complex, [4] and sodium perborate [5] or, using methylrhenium trioxide (CH 3 ReO 3) as catalyst, with sodium percarbonate. [6]
Compared to benzene, the rate of electrophilic substitution on pyridine is much slower, due to the higher electronegativity of the nitrogen atom. Additionally, the nitrogen in pyridine easily gets a positive charge either by protonation (from nitration or sulfonation) or Lewis acids (such as AlCl 3) used to catalyze the reaction. This makes the ...
The first reaction is the formation of the N-2,4-dinitrophenyl-pyridinium salt (2). This salt is typically isolated and purified by recrystallization. The formation of the DNP-pyridinium salt. Upon heating a primary amine with the N-2,4-dinitrophenyl-pyridinium salt (2), the addition of the amine leads to the opening of the pyridinium ring.
A workup step with acid is included to ensure formation of 2-aminopyridine. Reaction progress can be measured by the formation of hydrogen gas and red color from σ-adduct formation. [3] Sodium amide is a handy reagent for the Chichibabin reaction but handling it can be dangerous and caution is advised. [4] σ-adduct (Meisenheimer adduct) formation
Synthesis of nucleosides involves the coupling of a nucleophilic, heterocyclic base with an electrophilic sugar. The silyl-Hilbert-Johnson (or Vorbrüggen) reaction, which employs silylated heterocyclic bases and electrophilic sugar derivatives in the presence of a Lewis acid, is the most common method for forming nucleosides in this manner.
The reaction mechanism involves the acylation and activation of the acid 1 to the mixed anhydride 3. The amide will serve as a nucleophile for the cyclization forming the azlactone 4. Deprotonation and acylation of the azlactone forms the key carbon-carbon bond. Subsequent ring-opening of 6 and decarboxylation give the final keto-amide product.