Alkalinity reacts with salt formation. Nitrogen atoms do not share electron pairs and can combine with protons or donate electrons. Alkalinity: aniline < pyridine < ammonia < triethylamine < piperidine. Mixture separation, catalyst, acid scavenger, mild oxidant generation, sulfonating agent

Reacts with alkyl halides, acid anhydrides, and acid halides, ~ has nucleophilicity. Pyridine, alkyl halide, quaternary ammonium salt. Pyridine, acid halide N-acylpyridinium salt (better acylating reagent, N has great electron-withdrawing ability, increased positronicity of the carbonyl group, easy nucleophilic addition, pyridine, leaving group). Pyridine and nitronium salt form a salt. Still aromatic

Electrophilic substitution, β position, low activity, same as nitrobenzene. Mercury sulfate, sulfonation, electron-donating group, enhances activity.

Nucleophilic substitution, α position, γ position. In the zizibabin reaction, pyridine and sodium amide, α-aminopyridine, if ~ has a good leaving group (halogen, nitro), nucleophilic substitution will easily occur.

Redox, side chain is oxidized, pyridine, hydrogen peroxide, oxygen added to N, pyridine N-oxide (activates pyridine, positioning effect), easily electrophilic and nucleophilic, α, γ, (used to introduce groups) In the eight-electron structure, the β position is unstable. Reduction, hydrogenation reduction, chemical reagent reduction, product hexahydropyridine

Niacin, nicotinamide, vitamin PP, anti-tuberculosis drug isoniazid, insecticides, vitamin B6

10Πelectronic large Π bond, difficult to dissolve in cold water, easily soluble in hot water

Electrophilic substitution, main substituent, easier than pyridine, more difficult than benzene and naphthalene, 5 and 8 positions

Nucleophilic substitution, on the ring with small electron cloud density, quinoline 2, 4, isoquinoline 1 position

Redox reaction, strong oxidizing agent, benzene ring, peroxyacid, N-oxide. Reduction, hydrogenation, chemical reagents, those with low electron cloud density are preferred

Quinine (anti-malarial), 4-aminoquinoline, 8-aminoquinoline (most effective), camptothecin

Alkalinity and nucleophilicity, monobasic base (nitrogen cation, electron cloud density), less alkaline than pyridine, nucleophilic reaction with alkyl halide, quaternary ammonium salt (usually monoquaternary ammonium salt)

Electrophilic and nucleophilic substitution, electrophilic difficulty (nitrogen atom strongly attracts electrons), 5-position substitution, halogenation can occur. Nitration and sulfonation requires a strong activating group (NH2) on the pyrimidine ring, and nucleophilic substitution is easy at positions 2, 4, and 6. When these positions are halogens, it is easier

Oxidation reaction, benzodiazine oxidation, the benzene ring changes into two COOH, the diazines are similar to pyridine, react with peroxyacid to form a single N-oxide of the diazine, which is easy to be electrophilic and nucleophilic

Corresponds to aniline, glycerol, sulfuric acid, corresponds to nitrobenzene (α, β unsaturated aldehydes and ketones replace glycerol)

sp2 hybridization, p orbital side overlapping large Π bonds, 6, aromatic

Electrophilic substitution at the α position is prone to occur

Dipole moment, two electrical effects, the electron-withdrawing induction effect of heteroatoms and the electron-donating conjugation effect

Solubility in water: pyridine>pyrrole>furan>thiophene

Acidity and alkalinity are unstable to acids and oxidants

Furan derivatives

Pyrrole derivatives

Thiophene derivatives

Physical properties, imidazole has a higher boiling point than pyrazole (intermolecular hydrogen bonding), imidazole linear polymer

Basic azoles

electrophilic substitution

Imidazole, histidine, histamine (allergic reaction)

Thiazole, penicillin, vitamin B1