生物化学Chapter22Amines 课件.ppt

Chapter 22 Amines  The important organic reactions of amines (nucleophiles) are with the common electrophiles : alkyl halides? via nucleophilic substitution, aldehydes or ketones via nucleophilic addition carboxylic acid derivatives, especially acid chlorides or anhydrides via nucleophilic acyl substitution. §22.1 Nomenclature Functional group suffix = -amine Functional group prefix = amino The suffix -amine is added to the name of the alkyl substituent. Alternatively, the suffix –amine can be used in place of the final –e in the name of the parent compound. Primary amines are named in the IUPAC system in several ways depending on their structure. For simple amines, the suffix -amine is added to the name of the alkyl substituent. Alternatively, the suffix –amine can be used in place of the final –e in the name of the parent compound. An -NH2 group, when not the principal group, is named by the prefix amino-. Symmetrical secondary and tertiary amines are named by adding the prefix di- or tri- to the alkyl group. Unsymmetrically substituted secondary and tertiary amines are named as N-substituted primary amines. The largest alkyl group is chosen as the parent name, and the other alkyl group are considered N-substituents on the parent (N since they’re attached to nitrogen). §22.2 Structure and Bonding The amine functional group consists of an N atom bonded either to C or H atoms via s bonds. Both the C-N and the N-H bonds are polar due to the electronegativity of the N atom. The trigonal (三角形的) pyramidal(金字塔形的, 锥体的) arrangement of bonds around nitrogen is shallower in aryl amines vs alkyl amines. Structure and Bonding in Amine The bonding in amines is similar to the bonding in ammonia. The nitrogen atom is sp3 hybridized, with the three substituents occupying three corners of a tetrahedron and the nitrogen nonbonding lone pair of electrons occupying the forth corner. This is a result of resonance delocalisation of the lone pair into t