9.3 Stereochemistry of the lonic Addition to an alkene * CH3 CH, CH-CH2 HCl CHrcHCHcH 3 8+8 Cl (土}2- Chlorobutane We got a racemic form? Do you know why
9.3 Stereochemistry of the Ionic Addition to an alkene CH3 CH2 CH=CH2 + HCl CH3 CH2 CHCH3 * Cl (±)-2-Chlorobutane + − We got a racemic form? Do you know why?
CH3 CH2CH=CH2 HCl- CHCH, CHCH δ8 (±}-2- Chlorobutane CH2H CH H3C CI Cl Cl l ○c○ HIIIIIE Cl CH2 CH CH2CH H3 CH2C Achiral, trigonal (S)-2-Chlorobutane Planar carbocation (R)-2-Chlorobutane (50%) (50% Enantiomers A recemic form(外消旋体)
CH3CH2CH=CH2 + HCl CH3CH2CHCH3 * Cl (±)-2-Chlorobutane + − H + CH2H C + H CH2CH3 Cl - H3C Cl H3CH2C H Cl - CH3 Cl H CH2CH3 Achiral, trigonal ( S )-2-Chlorobutane Planar carbocation (50%) ( R )-2-Chlorobutane (50%) Enantiomers A recemic form (外 消 旋 体 ）
9.4 Addition of sulfuric acid to alkenes Step 1, The alkene accep (H) from sulfuric acid to form a carbocation Slow +HO—S—0H C—C O Alkene Sulfuric acid Carbocation Step 2, The carbocation reacts with a hrdrogen sulfate ion to form an alkyl hydrogen sulfate OSO2OH fast H Carbocation Hydrogen Sulfate ion Alkyl hydrogen sulfate 硫酸氢根负离子 烷基氩硫酸酯
9.4 Addition of sulfuric acid to alkenes + HO S OH O O C C H + Step 1, The alkene accepts a proton (H + ) from sulfuric acid to form a carbocation Sulfuric acid Carbocation Slow Alkene C C H + Carbocation + -O S OH O O Hydrogen Sulfate ion 硫 酸 氢 根 负 离 子 C C H OSO2OH Alkyl hydrogen sulfate 烷 基 氢 硫 酸 酯 fast Step 2, The carbocation reacts with a hrdrogen sulfate ion to form an alkyl hydrogen sulfate
The addition of sulfuric acid is also regioselective(区域选择 性) Mar's addition HOSO,O CH3CHCH2 CH3CHCH More stable carbocation OSO2OH Isopropyl hydrogen CH3CH=CH2+HO—s—0H sulfate 硫酸氢异丙酯 Propene Sulfuric acid HOSO,O CH3CH2CH CH3 CH2 CH2OSO3H Anti Mars addition Less Stable carbocation Propyl hydrogen sulfate 硫酸氢正丙酯
The addition of sulfuric acid is also regioselective (区域选择 性） + HO S OH O O Propene Sulfuric acid CH3CH=CH2 CH3CHCH2 + CH3CH2CH2 + Mar's addition Anti Mar's addition More Stable carbocation Less Stable carbocation HOSO2OCH3CHCH3 OSO2OH Isopropyl hydrogen sulfate 硫 酸 氢 异 丙 酯 HOSO2OCH3CH2CH2OSO3H Propyl hydrogen sulfate 硫 酸 氢 正 丙 酯
9. 4A Alcohol from alkyl hydrogen sulfates (从硫酸氢乙酯制醇 Alkyl hydrogen sulfates can be easily hydrolyzed to alcohols by heating them with water Mar's addition HOSOO CH3CH=CH2+HO—S—0H CH3CHCH2 一CH3CHCH3 More stable carbocation OSO2OH Propene Sulfuric acid Isopropyl hydrogen sulfate H2O 硫酸氢异丙酯 CH3 CHCH3 H,So OH Isopropanol
9.4A Alcohol from alkyl hydrogen sulfates (从硫酸氢乙酯制醇） Alkyl hydrogen sulfates can be easily hydrolyzed to alcohols by heating them with water + HO S OH O O Propene Sulfuric acid CH3CH=CH2 CH3CHCH2 M + ar's addition More Stable carbocation HOSO2O - CH3CHCH3 OSO2OH Isopropyl hydrogen sulfate H2O 硫 酸 氢 异 丙 酯 Heat CH3CHCH3 OH + H2 SO4 Isopropanol