Ch18 Amines(pdf) - KFUPM Open Courseware

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Synthetic Origin of Aryl Diazonium SaltsArHAr NO 218.9The Hofmann EliminationAr NH 2+Ar N NThe Hofmann Eliminationa quaternary ammonium hydroxide is the reactantand an alkene is the productis an anti eliminationthe leaving group is a trialkylaminethe regioselectivity is opposite to the Zaitsev rule.Quaternary Ammonium Hydroxidesare prepared by treating quaternary ammmoniumhalides with moist silver oxideAg 2 OCH 2 N(CH3 ) 3 I –H 2 O, CH 3 OH+CH 2 N(CH3 ) 3HO –
The Hofmann EliminationMechanismon being heated, quaternary ammoniumhydroxides undergo eliminationCH 2+ N(CH3 ) 3+ H 2 OH–••••O••HHO ••••CH 2H(69%)160°CCH 2N(CH+ 3 ) 3+CH 2 N(CH3 ) 3HO –•• N(CH3 ) 3RegioselectivityRegioselectivityElimination occurs in the direction that givesthe less-substituted substituted double bond. This is calledthe Hofmann rule.CH 3 CHCH 2 CH+ N(CH3 ) 3CH 3H 2 C CHCH 2 CH 3heat+(95%)Steric factors seem to control the regioselectivity.The transition state that leads to 1-butene 1isless crowded than the one leading to cisor trans-2-butene.HO –CH 3 CHCHCH 3(5%)
Page 1 and 2: Chapter 18Amines18.1Amine Nomenclat
Page 3 and 4: Secondary and Tertiary AminesName a
Page 5 and 6: Geometry at NCompare geometry at N
Page 7 and 8: Physical Propertiesboilingpoint:CH
Page 9 and 10: Preparation of AminesTechniques fal
Page 11 and 12: Gabriel Synthesisgives primary amin
Page 13 and 14: ExampleOONHNH+ C 6 H 5 CH 2 NH 2H 2
Page 15 and 16: Synthesis of Amines via AzidesS N 2
Page 17 and 18: Synthesis of Amines via AmidesOCOHo
Page 19 and 20: Example: Secondary amines give tert
Page 21 and 22: Step 2••O••••-•• O
Page 23 and 24: Basicity Constant (K b ) and pK bK
Page 25 and 26: Basicity of Amines in Aqueous Solut
Page 27 and 28: Effect of Substituents on Basicity
Page 29 and 30: ImidazoleWhich nitrogen is protonat
Page 31 and 32: (aqueous)CH 2 CH 3+NCH 2 CH 3CH 2 C
Page 33 and 34: Nitrosyl Cation and NitrosationNitr
Page 35 and 36: Nitrosation of Primary AlkylaminesN
Page 37: Nitrosation of N-AlkylarylaminesNsi

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