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The reaction of phosphorus pentachloride (PCl 5) with phosphorus pentoxide (P 4 O 10). 6 PCl 5 + P 4 O 10 → 10 POCl 3. The reaction can be simplified by chlorinating a mixture of PCl 3 and P 4 O 10, generating the PCl 5 in situ. The reaction of phosphorus pentachloride with boric acid or oxalic acid: [12] 3 PCl 5 + 2 B(OH) 3 → 3 POCl 3 + B ...
The reaction of a substituted amide with phosphorus oxychloride gives a substituted chloroiminium ion (2), also called the Vilsmeier reagent. The initial product is an iminium ion (4b), which is hydrolyzed to the corresponding ketone or aldehyde during workup. [7] The Vilsmeier–Haack reaction
The reaction of pyridine with bromomethyl ketones gives the related pyridinium salt, wherein the methylene group is highly acidic. This species undergoes a Michael-like addition to α,β-unsaturated carbonyls in the presence of ammonium acetate to undergo ring closure and formation of the targeted substituted pyridine as well as pyridinium bromide.
4-Dimethylaminopyridine (DMAP) is a derivative of pyridine with the chemical formula (CH 3) 2 NC 5 H 4 N. This white solid is of interest because it is more basic than pyridine, owing to the resonance stabilisation from the NMe 2 substituent.
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 ...
This reaction type is linked to many forms of neighbouring group participation, for instance the reaction of the sulfur or nitrogen lone pair in sulfur mustard or nitrogen mustard to form the cationic intermediate. This reaction mechanism is supported by the observation that addition of pyridine to the reaction leads to inversion. The reasoning ...
[1] [2] The initial reaction product is a dihydropyridine which can be oxidized in a subsequent step to a pyridine. [3] The driving force for this second reaction step is aromatization. This reaction was reported in 1881 by Arthur Rudolf Hantzsch. A 1,4-dihydropyridine dicarboxylate is also called a 1,4-DHP compound or a Hantzsch ester.
The amide group can be involved in hydrogen bonding to other nitrogen- and oxygen-containing species.. The predominant solid state form is 2-pyridone. This has been confirmed by X-ray crystallography which shows that the hydrogen in solid state is closer to the nitrogen than to the oxygen (because of the low electron density at the hydrogen the exact positioning is difficult), and IR ...