3 n 3 2 2 Pyridine Pyridazine Py imidine (吡啶) (哒嗪) (咪啶) Quinoline Isoquinoline (喹啉) (异喹啉) N1 28 2 N 3 Piperidine Pyrrolidine Thiazole PU 哌啶)四氢吡咯)(噻唑) 嘌啉)
Pyridine (吡 啶 ） (哒 嗪 ） (咪 啶 ） Pyridazine Pyrimidine N N N 1 2 3 4 1 2 3 4 N N 1 2 3 4 Piperidine (哌 啶 ） (四 氢 吡 咯 ） (嘌 啉 ） Pyrrolidine Purine N H 1 2 3 4 N N 1 2 3 N 4 H S N N N H 5 7 6 8 9 1 2 3 Thiazole （ 噻 唑 ） (喹 啉 ） Quinoline N N Isoquinoline (异喹 啉 ）
19.2 Physical properties and structure of amines 19.2A Physical properties Amines are moderately polar substances; they have boiling points that are higher than those of alkanes but generally lower than those of alcohols of comparable molecular weight. Primary amines Structure bp (c) Ethylamine CH3 CHNH2 Hydrogen-Bonding Secondary amines: Dimethylamine (CH3)2NH 7°C Hydrogen-Bonding Diethylamine (CH3 CH2)2NH 56C Hydrogen-Bonding Tertiary Amines; No hydrogen-bonding Trimethylamine (CH3)N 29C Boiling point is low
19.2 Physical properties and structure of amines 19.2A Physical properties Amines are moderately polar substances; they have boiling points that are higher than those of alkanes but generally lower than those of alcohols of comparable molecular weight. Primary Amines; E CH3CH2NH2 thylamine Structure bp ( oC) 17 oC Secondary Amines; Dimethylamine (CH3 ) 2NH 7 oC Diethylamine (CH3CH2 ) 2NH 56 oC Tertiary Amines; Trimethylamine (CH3 ) 3N 2.9 oC Hydrogen-Bonding Hydrogen-Bonding Hydrogen-Bonding No hydrogen-bonding Boiling point is low
19.2B Structure of amines The nitrogen atom of most amines is like that of ammonia; it is approximately sp3 hybridized. The three alkyl groups(or hydrogen atoms) occupy corners of a tetrahedron; the sp3 orbital containing the unshared electron pair is directed toward the other corner we describe the geometry of the amine by the location of the atoms as being trigonal pyramidal SP hybridized R 1)由于氮上有孤对电子,胺显碱性。 R R 2)胺类可作为亲核试剂 Structure of an amine
19.2B Structure of amines The Nitrogen atom of most amines is like that of ammonia; it is approximately sp3 hybridized. The three alkyl groups (or hydrogen atoms) occupy corners of a tetrahedron; the sp3 orbital containing the unshared electron pair is directed toward the other corner. We describe the geometry of the amine by the location of the atoms as being trigonal pyramidal. N R' R'' R''' SP 3 hybridized Structure of an amine 1） 由 于 氮 上 有 孤 对 电 子 ， 胺 显 碱 性 。 2） 胺 类 可 作 为 亲 核 试 剂
If the alkyl groups of a tertiary amine are all different the amine will be chiral there will be two enantiomeric forms of the tertiary amine In practice, however, resolution is usually impossible because the enantiomers interconvert rapidly. R 6 kcal mol R N IIR N R R Intercomversion of amine enantiomers 叔胺对映体相互转换,难以拆分
If the alkyl groups of a tertiary amine are all different the amine will be chiral. There will be two enantiomeric forms of the tertiary amine. In practice, however, resolution is usually impossible because the enantiomers interconvert rapidly. N R' R'' R''' N R'' R' R''' Intercomversion of amine enantiomers 叔 胺 对 映 体 相 互 转 换 ， 难 以 拆 分 。 6 kcal mol -1
Ammonium salts cannot undergo inversion because they do not have an unshared pair Therefore, those quaternary ammonium salts(季胺盐) with four different groups are chiral and can be resolved into separate (relatively stable)enantiomers R R"IlIlI IIR N——R R R Quaternary ammonium salts such as these can be resolved 季胺盐对映体不能相互转换,可以拆分成单个对映体
Ammonium salts cannot undergo inversion because they do not have an unshared pair. Therefore, those quaternary ammonium salts (季胺盐）with four different groups are chiral and can be resolved into separate (relatively stable) enantiomers. N R' R'' R''' N R'' R' R''' Quaternary ammonium salts such as these can be resolved 季 胺 盐 对 映 体 不 能 相 互 转 换 ， 可 以 拆 分 成 单 个 对 映 体 。 R'''' R'''' + X - + X -