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Chapter 19. Amines ( 胺）. 19.1 Nomenclature In common nomenclature most primary amines are named as alkylamines. In systematic nomenclature they are named by adding the suffix –amine to the name of the chain or ring system to which the NH 2 group is attached with elision of the final e.
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Chapter 19. Amines (胺） 19.1 Nomenclature In common nomenclature most primary amines are named as alkylamines. In systematic nomenclature they are named by adding the suffix –amine to the name of the chain or ring system to which the NH2 group is attached with elision of the final e
Tertiary Amines(叔胺） In the IUPAC system, the substituent-NH2 is called the amino group.
19.1AArylamines （芳胺） Which arylamines are primary amines, secondary amines, tertiary amines?
19.1B Heterocyclic amines （杂环胺） The important heterocyclic amines all have common names.
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.
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.
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.
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.
19.3Basicity of amines(胺的碱性）: Amine salts （胺盐） Amines are relatively weak bases. They are stronger bases than water but are far weaker bases than hydroxide ions (OH-), alkoxide ions (RO-), and carbanions (C-).
The gas phase the basicities of the following amines increase with increasing methyl substitution:
This is not the order of basicity of these amines in aqueous solution, however. In aqueous solution the order is:
19.3C Aminium salts and quaternary ammonium salts(胺盐和季胺盐） When primary, secondary, and tertiary amines act as bases and react with acids, they form compounds called aminium salts.
When the central nitrogen atom of a compound is positively charged but is not attached to a hydrogen atom the compound is called a quaterary ammonium salt.
Quaterary ammonium hydroxides(季胺碱） Quaternary ammonium hydroxides, however, are strong bases. As solids, or in solution, they consist entirely of quaternary ammonium cations (R4N+) and hydroxide ions (OH-); they are, therefore, strong bases---as strong as sodium or potassium hydroxide.
19.5 Preparation of amines 19.5A Through nucleophilic substitution reactions
19.5BPreparation of amines through reduction of nitro 用硫化氢（hydrogen sulfide)还原二硝基苯，只还原一个硝基。
Mechanism for reductive amination 先亲核加成，然后消除，再还原的胺。
19.5D Preparation of amines through reduction of amides, oximes, and nitriles
19.5E Preparation of amines through the Hofmann and curtius rearrangements 1) Hofmann rearrangement or Hofmann degradation （霍夫曼重排 或霍夫曼降级）---制备伯胺
2）The Curtius rearrangement (库尔提斯重排）--制备伯胺
19.7AReactions of primary aliphatic amines with nitrous acid Primary aliphatic amines react with nitrous acid through a reaction called diazotization（重氮化作用）to yield highly unstable aliphatic diazonium salts(重氮盐）.
19.7D Reactions of tertiary amines with nitrous acid 因氮上没有氢，故在二甲氨基的苯环的对面发生亚硝化。
19.8 Replacement reactions of arenediazonium salts (重氮盐的取代） Diazonium salts are highly useful intermediates in the synthesis of aromatic compounds, because the diazonium group can be replaced by any one of a number of other atoms or groups, including –F, -Cl, -Br, -CN, -OH, and –H.
19.8BThe sandmeyer reaction: Replacement of the diazonium group by –Cl, -Br, or -CN
19.8C Replacement by -I 19.8D Replacement by -F
19.8E Replacement by -OH 19.8F Replacement by -H（Deamination by diazotization) 通过重氮化脱氨基）
19.9 Coupling reactions of arenediazonium salts (重氮盐的偶联反应） Arenediazonium ions are weak electrophiles: they react with highly reactive aromatic compounds—with phenols and tertiary arylamines—to yield azo compounds. This electrophilic aromatic substitution is often called a diazo coupling reaction(偶氮化合物）.
Synthesis of methyl orange 甲基橙的合成 甲基橙的变色范围3.1-4.4
19.10 Reactions of amines with sulfonyl chlorides(胺与磺酰氯的反应） Primary and secondary amines react with sulfonyl chlorides to form sulfonamides (磺酰胺）
19.10AThe Hinsberg test(兴斯堡测试） Sulfonamide formation is the basis for a chemical test, called the Hinsberg test, that can be used to demonstrate whether an amine is primary, secondary, or tertiary.
