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Amines - classification. 1 o. 2 o. quaternary ammonium salts. 3 o. Nomenclature. To name aliphatic amines, name the alkyl groups bonded to the amine nitrogen and then add the suffix “ amine ”:. C 2 H 5 NHCH 3. (CH 3 ) 3 CNH 2. ethylmethylamine. t -butylamine.
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Amines - classification 1o 2o quaternary ammonium salts 3o
Nomenclature To name aliphatic amines, name the alkyl groups bonded to the amine nitrogen and then add the suffix “amine”: C2H5NHCH3 (CH3)3CNH2 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 amineby ammonium:- ethylammonium sulfate trimethylammonium nitrate anilinium chloride
Physical Properties Tertiary amines, having no N-H bonds, cannot form hydrogen bonds (N-H-------N). 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 - reductive amination amphetamine
Preparation - Hofmann degradation phentermine - an appetite suppressant
Reactions - basicity weaker base stronger 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
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 D 2. H O/ 2
Aromatic diazonium salts Synthesis of phenols Substitution by H
Coupling Reactions of Diazonium Compounds An electrophilic attack...... p-(dimethylamino)azobenzene
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).