Amines - classification quaternary ammonium salts 3o

Nomenclature To name aliphatic amines, name the alkyl groups bonded to the amine nitrogen and then add the suffix “amine”: (CH3)3CNH2 C2H5NHCH3 ethylmethylamine t-butylamine Systematic nomenclature adds the suffix to the name of the hydrocarbon: CH3CH2NH2 C2H5NHCH3 ethanamine N-methylethanamine

Nomenclature In the IUPAC system, the -NH2 group is called the amino group. The prefix “amino” (or “methylamino”, “diethylamino” etc.) is therefore used in naming complex molecules. 4-aminobutanoic acid -aminobutyric acid H2NCH2CH2CH2CO2H H2NCH2CH2OH 2-aminoethanol ethanolamine 2-methylaminoheptane

Nomenclature m-nitroaniline 3-nitrobenzenamine N-ethyl-N-methylaniline N-ethyl-N-methylbenzenamine

Nomenclature Salts of amines are named by replacing the suffix amine by ammonium:- ethylammonium sulfate trimethylammonium nitrate anilinium chloride

Physical Properties Tertiary amines, having no N-H bonds, cannot form hydrogen bonds (N-H-------H). 1o and 2o amines can! Their intermolecular association by hydrogen bonding reduces their volatility relative to hydrocarbons of similar molecular weight. Amines having less than six carbon atoms show an appreciable water solubility.

Preparation - alkylation

Preparation - reduction of nitro compounds 1º amine

Preparation - reductive amination amphetamine

Preparation - reduction of nitriles

Preparation - Hofmann degradation phentermine - an appetite suppressant

Hofmann degradation

Reactions - basicity stronger base weaker base

Reactions - basicity Kb: CH3NH2 = 4.75x10-4, NH3 = 1.78x10-5, C6H5NH2 = 4.26x10-10

Reactions - basicity Kb: CH3NH2 = 4.75x10-4, NH3 = 1.78x10-5

Reactions - basicity

Reactions - basicity

Substituent effects Substituents attached to the aromatic ring which are electron attracting reduce the basicity of amines. Electron-repelling substituents increase amine basicity.

Action of nitrous acid + 1. NaNO /H 2 RNH ROH 2 2. H O/ D 2

Aromatic diazonium salts

Sandmeyer reaction

Gattermann reaction

Aromatic diazonium salts

Aromatic diazonium salts Synthesis of phenols Substitution by H

Synthesis of the three bromotoluenes oops

Synthesis of the bromotoluenes

Synthesis of m-bromotoluene

Coupling Reactions of Diazonium Compounds An electrophilic attack...... p-(dimethylamino)azobenzene

congo red

Preparation of substituted amides

Preparation of substituted amides

Nomenclature of Substituted Amides

Sulfanilic acid ? mp > 280-300o OH- - soluble H+ - insoluble dipolar ion - a zwitterion “zwitter” - hermaphrodite

Sulfa drugs sulfanilimide

Spectroscopic Properties N-H - stretching 3300 - 3500 cm-1 1o amines show 2 high intensity peaks NMR - the amino H gives a peak which can be found almost any where in the spectrum (similar to the -O-H proton).

Problems Try problems 20.21 (a) - (d), 20.22 (a) - (e), 20.23 (a) - (e), 20.24, 20.26, 20.30, 20.31, 20.37, 20.38, 20.39, 20.44, and 20.46.