columbia大学有机化学课件22_16_19 html

1、22.16Nitrosation of AlkylaminesH+ OONO NO HH+HH+ + O NO ONO +HHNitrite Ion, Nitrous Acid, and Nitrosyl Cation NO +Nitrosyl Cation and Nitrosation+ NNO N +NO +Nitrosyl Cation and Nitrosation+ N NNO NO + H+nitrosation of secondary amines gives an N-nitroso amineH N NO +H+Nitrosation of Secondary Alkyl

2、aminesNaNO2, HCl (CH3)2NH(CH3)2NNO H O2(88-90%)ExampleN-nitrosodimethylamine (leather tanning)NO(CH ) N3 2NOON-nitrosopyrrolidine (nitrite-cured bacon)N-nitrosonornicotine (tobacco smoke)N NN NSome N-Nitroso AminesRRH+ NO NNNO + H+analogous to nitrosation of secondary amines to this pointHHRH N NO +

3、H+Nitrosation of Primary AlkylaminesR NNO Hthis species reacts furtherNitrosation of Primary AlkylaminesRRH+ O+H N NNO NHHNitrosation of Primary AlkylaminesR + NHHR NNO HH+ NONitrosation of Primary AlkylaminesRRHH+ N NNO HNO +HNitrosation of Primary AlkylaminesRH NNO +HNitrosation of Primary Alkylam

4、inesHnitrosation of a primary alkylamine gives an alkyl diazonium ionprocess is calleddiazotization + O +NNRHRHO H N N+Nitrosation of Primary Alkylamines + +NNNRRNalkyl diazonium ions readily lose N2 to give carbocationsAlkyl Diazonium Ions+ HONONNNH2 N2OHH2O(80%)+(3%)(2%)Fig. 22.5 (p 890)+Example:N

5、itrosation of 1,1-DimethylpropylamineThere is no useful chemistry associated with thenitrosation of tertiary alkylamines.RRRR+ N NNO RRNitrosation of Tertiary Alkylamines22.17Nitrosation of Arylaminesreaction that occurs iselectrophilic aromatic substitutionN(CH2CH3)2N(CH2CH3)21.NaNO2, HCl, H2O, 8CH

6、O2.NO(95%)Nitrosation of Tertiary Arylaminessimilar to secondary alkylamines;gives N-nitroso aminesNaNO2, HCl, H2O, 10CNONHCH3NCH3(87-93%)Nitrosation of N-Alkylarylaminesgives aryl diazonium ionsaryl diazonium ions are much more stable than alkyl diazonium ionsmost aryl diazonium ions are stable und

7、er the conditions of their formation (0-10C)Nitrosation of Primary Arylaminesgives aryl diazonium ionsaryl diazonium ions are much more stable than alkyl diazonium ionsmost aryl diazonium ions are stable under the conditions of their formation (0-10C)+ fast+RNNRN2+ Nslow+ArNArN2Nitrosation of Primar

8、y ArylaminesNH2(CH3)2CNaNO2, H2SO4 H2O, 0-5C+ HSO4(CH3)2CNNHHExample:HArNO2ArNH2Ar+ NArNSynthetic Origin of Aryl Diazonium Salts22.18Synthetic Transformations of Aryl Diazonium SaltsClBrArArFArCNAr+ NArNHIArArOHArTransformations of Aryl Diazonium Saltshydrolysis of a diazonium salt+ NArNH2O, heatOHA

9、rPreparation of PhenolsNH2(CH3)2C1.NaNO2, H2SO4 H2O, 0-5CH2O, heat2.OH(CH3)2C(73%)HHExampleClBrArArFArCNAr+ NArNHIArArOHArTransformations of Aryl Diazonium Saltsreaction of an aryl diazonium salt with potassium iodide+ NArNKIIArPreparation of Aryl IodidesNH2I1.NaNO , HCl2H2O, 0-5CBrBr2.KI, room temp

10、.(72-83%)ExampleClBrArArFArCNAr+ NArNHIArArOHArTransformations of Aryl Diazonium SaltsFAr+ NArNheat the tetrafluoroborate salt of a diazonium ion;process is called the Schiemann reactionPreparation of Aryl FluoridesNH2F1.NaNO2, HCl, H2O, 0-5C2.3.HBF4heatCCH CHCCH CH2323OO(68%)ExampleClBrArArFArCNAr+

11、 NArNHIArArOHArTransformations of Aryl Diazonium SaltsClBrArAr+ NArNaryl chlorides and aryl bromides are prepared by heating a diazonium salt with copper(I) chloride or bromidesubstitutions of diazonium salts that use copper(I) halides are called Sandmeyer reactionsPreparation of Aryl Chlorides and

12、BromidesNH2Cl1.NaNO2, HCl, H2O, 0-5C2.CuCl, heatNO2NO2(68-71%)Example1.NaNO2, HBr, H2O, 0-10CNH2BrClCl2.CuBr, heat(89-95%)ExampleClBrArArFArCNAr+ NArNHIArArOHArTransformations of Aryl Diazonium SaltsCNAr+ NArNaryl nitriles are prepared by heating a diazonium salt with copper(I) cyanidethis is anothe

13、r type of Sandmeyer reactionPreparation of Aryl Nitriles1.NaNO2, HCl, H2O, 0CNH2CNCHCH332.CuCN, heat(64-70%)ExampleClBrArArFArCNAr+ NArNHIArArOHArTransformations of Aryl Diazonium Saltshypophosphorous acid (H3PO2) reduces diazonium salts;ethanol does the same thingthis is called reductive deaminatio

14、n+ NArNHArTransformations of Aryl Diazonium SaltsNaNO2, H2SO4,H3PO2NH2CHCH33(70-75%)Example1)allows introduction of substituents such as OH, F, I, and CN on the ringallows preparation of otherwise difficultly accessible substitution patterns2)Value of Diazonium SaltsNH2NH2NaNO2, H2SO4, H2O, CH3CH2OHBrBrBr2H2OBrBrBr(100%)Br(74-77%)Example22.19Azo CouplingDiazonium salts are weak electrophiles.React with strongly activated aromatic compounds by electrophilic aromatic substitution.Azo CouplingDiazonium salts are weak electrophile