Base-promoted Halogenation OH Enolate ion +X2 HX
Base-promoted Halogenation C O H OH - + X2 C O X + HX C O - C O - Enolate ion
Acid-Catalyzed halogenation OH Enol X X—X+C HX
Acid-Catalyzed Halogenation C O H C O X + HX C OH C O Enol H3O+ H X X +
17.4 The haloform reaction (卤仿反应) CH3 X2 Naoh ONa CHX3 +3H,O Haloform (鹵仿) CH3 Br2 Naoh ONa+ CHBr3 +3H,0 Bromoform (溴仿) cH3+2+NaOH—>〈 ONa+ CHI2+3H,O Iodoform (碘仿) Yellow precipitate Iodoform can test the stuctures of -coch3 or-CHOHCH3 If compound contain it, it give positive iodoform tests
17.4 The haloform reaction (卤仿反应） + X2 + NaOH O CH3 O ONa + CHX3 +3H2O Haloform （ 卤 仿 ） + Br2 + NaOH O CH3 O ONa + CHBr3 +3H2O Bromoform （ 溴 仿 ） + I2 + NaOH O CH3 O ONa + CHI3 +3H2O Iodoform （ 碘 仿 ） Yellow precipitate Iodoform can test the stuctures of –COCH3 or –CHOHCH3 If compound contain it, it give positive iodoform tests
The mechanism of the haloform reaction HGO CH,+ NaoH NaoH X—X CH2X CHX Nao X——X CHX2 CX3- + cX CHX3 +3H,0 OH ONa Holoform (卤仿)
The mechanism of the haloform reaction + NaOH O CH3 O OH + CHX3 +3H2O Holoform （ 卤 仿 ） O CH2 - - H2O X-X O CH2X NaOH O CHX - X X O CHX2 NaOH O CX2 - X X O CX3 NaOH O- OH CX3 + - : CX3 O ONa
17.4A The iodoform test The haloform reaction using iodine and aqueous sodium hydroxide is called the iodoform test Because it allows identification of the following two groups: (H) (H) R CH R—c—cH 3 (Ar) (Ar) OH Positive test for iodoform test
17.4A The iodoform test The haloform reaction using iodine and aqueous sodium hydroxide is called the iodoform test. Because it allows identification of the following two groups: R O CH3 R H C CH3 OH (H) (Ar) (H) (Ar) Positive test for iodoform test