厦门大学化学化工学院：《有机化学》课程教学资源（课件讲稿，双语版）Chapter 7 Alkenes and Alkynes I：（7.11-7.16）The Acidity of Terminal Alkynes

ORGANIC CHEMISTRY Chapter 7 7. 11 The Acidity of Terminal Alkynes Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 7.11 The Acidity of Terminal Alkynes

ORGANIC CHEMISTRY Chapter 7 Sp CH≡CHCH2=CH2CH3=CH3 K p 25 50 Relative basicity Ch=C CH2=CH CH3-CH Relative acidity H2O>ROH >RC=CH >NH3 >CH2=CH2> CH3-CH pka15716-1725 38 44 50 Relative basicity OH <Ro< RC=C NH, CH,=CH CH3-CH, Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 CH CH CH2 CH2 CH3 CH3 sp sp2 sp3 pKa 25 44 50 Re CH C > > > > pKa 15.7 16-17 25 38 44 50 Relative Basicity OH < < RO RC C < NH2 < CH2 CH < CH3 CH2

ORGANIC CHEMISTRY Chapter 7 o acetylenic hydrogens can be deprotonated with relatively strong bases(sodium amide is typical 2Na NH3(liq 2NanH H2 NH3(0 NaNH CH三CH+NaNH2-33 CH三CNa NaC≡CNa NH3() CH3C=CH NaNH 2 ChrC=cna 33 The products are called alkynides Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 Acetylenic hydrogens can be deprotonated with relatively strong bases (sodium amide is typical) 2Na + NH3(liq.) 2NaNH2 + H2 −40 CH CH + NaNH2 NH3(l) −33 CH CNa NaC CNa NaNH2 CH3C CH + NaNH2 NH3(l) −33 CH3C CNa The products are called alkynides

ORGANIC CHEMISTRY Chapter 7 RC≡CH+HOBr-RC≡CBr+H2O CH≡CH+Ag(NH3 AgC≡ CAgy white CH≡CH+Cu(NH CuC≡ CCu red Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 RC CH + HOBr RC CBr + H2O CH CH + Ag(NH3)+ AgC CAg white CH CH + Cu(NH3)+ CuC CCu red

ORGANIC CHEMISTRY Chapter 7 7.12 Replacement of the acetylenic Hydrogen atom of Terminal alkynes Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 7.12 Replacement of the Acetylenic Hydrogen Atom of Terminal Alkynes

ORGANIC CHEMISTRY Chapter 7 CH3CH CH, Br CH三CNa CH≡CCH2CH2CH 1)NaNH? CH2C≡ CCH,CH2CH (2)CH3I o Only primary alkyl halides can be used or else elimination reactions predominate R RC=C. Br/nucleophilic, RC=C-CH, R+NaBr substitution N H S、2 H Sodium 1°Alk alkylide halide R H PHC RC≡C: RC≡CH+RCH=CHR"+Br C—BrE2 g 2°Akyl halide Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 CH CNa CH CCH2CH2CH3 (1) NaNH2 CH3C CCH2CH2CH3 (2) CH3I CH3CH2CH2Br Only primary alkyl halides can be used or else elimination reactions predominate

ORGANIC CHEMISTRY Chapter 7 7. 13 Hydrogenation of Alkenes Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 7.13 Hydrogenation of Alkenes

ORGANIC CHEMISTRY Chapter 7 Pd. Pt or ni CH=CH +h CH3-CH3 25°C Pd. Pt or ni CH2CH=CH + h CHr CH-CH 25°C Catalytic hydrogenation An unsaturated compound A saturated compound Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 CH2 CH2 CH3CH CH2 + H2 + H2 Pd, Pt or Ni 25°C CH3 CH3 Pd, Pt or Ni 25°C CH3CH2 CH3 Catalytic hydrogenation An unsaturated compound A saturated compound

ORGANIC CHEMISTRY Chapter 7 7.14 Hydrogenation: The Function of the Catalyst Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 7.14 Hydrogenation: The Function of the Catalyst

ORGANIC CHEMISTRY Chapter 7 Hydrogenation of an alkene is an exothermic reaction R-CH=CH-R+H.Pt R-CH2CH一R+heat o both hydrogen atoms usually add from the same side of the molecule-syn addition Pt C=C C-C∴ H H H-H C=C C-C lL C=C X-Y X-Y A syn addition(顺式加成) An anti addition(反式加成) Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 Hydrogenation of an alkene is an exothermic reaction. R CH CH R + H2 R CH2 CH R + heat Pt Both hydrogen atoms usually add from the same side of the molecule — syn addition. C C Pt H H + C C H H C C X Y + C C X Y C C X Y + C C X Y A syn addition (顺式加成) ( An anti addition 反式加成)