1 Dr Nahed Elsayed

Learning Objectives Chapter ten discusses the following topics and by the end of this chapter the students will:  Know the structure and classification of amines  Know the naming rules for amines & precedence order of functional groups in compounds have more than one functional group.  Know the physical properties of amines  Know the effect of lone pair of electrons of N atom on basic properties of amines  Know the different methods used insynthesis of amines  Know the different methods used in synthesis of amines  Know the reactions of amines; in addition to behaving as bases amines can be nucleophiles.

Structure & Classification Amines : is a class of organic compounds that contain the NH 2 group Amines are derivatives of ammonia that have one or more of the hydrogen replaced with alkyl and/ or aryl group. and/ or aryl group. Amines are formed in many biological systems. So it used in drugs and medicines. Classification Of Amines primary (1°) aminessecondary (2°) aminestertiary (3°) amines primary (1°) amines secondary (2°) aminestertiary (3°) amines R N : H H R H R R

Common Nomenclature Of Amines   The common names of amines are derived by listing the name (s) of the group (s) surrounding the nitrogen (in alphabetical order) and adding the suffix amine.(N.B. if two vowels come together ; the first must be omitted e.g. ethanamine).   Symmetrical 2° & 3° amines (i.e. the substituents surrounding the N atom are identical) are named by adding the multiplication prefix (di or tri) to the name of the alkyl group. MethylamineBenzylmethyl amine Trimethylamine  Structures with higher priority groups, the NH 2 group is called amino

IUPAC Names Of Primary Amines  If the compound does not contain a functional group except amino group, then the compound is named by finding the longest alkane chain containing then the compound is named by finding the longest alkane chain containing the amino group and replacing the e in the IUPAC name by the suffix amine the amino group and replacing the e in the IUPAC name by the suffix amine 5-Methyl-3-hexanamine 5-Aminoheptanoic acid 3-Amino-2-butanol  However if the compound contain other functional groups then the order of precedence determines which group are named with prefix or suffix. (see the precedence table on slide 6)  The highest precedence group takes the appropriate suffix with all other groups taking the prefix (es), however = or Ξ bonds only take suffix form (ene, yne respectively). the prefix (es), however = or Ξ bonds only take suffix form (ene, yne respectively).

Class Functional group Prefixsuffix Carboxylic acids Cyclic alknes or alkenes with COOH group COOH oic acid carboxylic acid Aldehydes Cyclic alknes or alkenes with CHO group -CHOFormylalcarbaldehyde ketone-C=Ooxoone Alcohols-OHhydroxyol Amines -NH 2 aminoamine Ethers-ORalkoxy- Alkenes and aAlkynes = & Ξ bonds - ene & yne Precedence Order of Functional Groups (Descending Order)

 They have common names accepted by the IUPAC system, but if the benzene ring contain groups of higher priorities (COOH > CHO > C=O > OH > NH 2 ) in this case the amino group is added as a prefix. Aniline o-Nitroaniline p-Toluidine p-Aminophenol Naming Of Aromatic Amines

Physical Properties of Amines Solubility :   All amines are capable of forming hydrogen bonds with water, alcohols (solvents having OH group) thus they are soluble in water.  The lower molecular weight amines with up to six carbons show appreciable solubility in water. Boiling point :   Because they possess a polar N-H bond, primary and secondary amines are capable of forming hydrogen bonds among their molecules; therefore they have: higher boiling points than alkanes but lower than alcohols (alcohols form stronger h-bonds than amines).  Tertiary amines can not form H-bonds among their molecules and their molecules are more branched thus they have the lowest boiling points among amines.

Basicity Of Amines  Aromatic amines less basic than aliphatic amines  Electron donating (releasing) groups on N atom increase the basicity  Electron withdrawing groups decrease the basicity Base strength :

145 Chem. 10 1) Alkylation of Ammonia: 2) Reduction of Nitro groups: 3) Reduction of Nitriles: 4) Reduction of Amides: Preparation Of Amines

11 Salts Formation: Amides Formation: Imines Formation: Diazonium Salts Formation: Reaction of Amines Diazonium salt (benzene diazonium chloride)

12 Questions Write the structure of p-nitrobenzylamine? How to prepare ethylamine from acetamide? Why are aliphatic amines is more basic than aromatic amines? Select the stronger base from each pair of compounds?

Questions?