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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]
Direct nitration of pyridine is sluggish. [89] [90] Pyridine derivatives wherein the nitrogen atom is screened sterically and/or electronically can be obtained by nitration with nitronium tetrafluoroborate (NO 2 BF 4). In this way, 3-nitropyridine can be obtained via the synthesis of 2,6-dibromopyridine followed by nitration and debromination ...
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).
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.
The acidic proton is the one bound to nitrogen. Deprotonation gives the imidazolide anion, which is symmetrical. As a base, the pK a of the conjugate acid (cited as pK BH + to avoid confusion between the two) is approximately 7, making imidazole approximately sixty times more basic than pyridine. The basic site is the nitrogen with the lone ...
Picolinic acid is an organic compound with the formula NC 5 H 4 CO 2 H. It is a derivative of pyridine with a carboxylic acid (COOH) substituent at the 2-position. It is an isomer of nicotinic acid and isonicotinic acid, which have the carboxyl side chain at the 3- and 4-positions, respectively. It is a white solid although impure samples can ...
Kröhnke condensation of enamino nitrile 20 with enone 21 yielded fused pyridine 22. Figure 5. The mechanism of this Kröhnke-type reaction likely proceeds via a vinylogous cyanamide 23 which undergoes elimination of hydrocyanic acid, deprotonation to form enamine 24 and cyclization to form intermediate 25, which is then dehydrated to form the ...