CH;CH2CH2 H Br…C-0< Alcohol as a Nucleophile HH R ROH is weak nucleophile RO-is strong nucleophile New O-C bond forms,O-H bond breaks. => Chapter 11 11
CH3CH2CH2 C H H Br O H H Chapter 11 11 Alcohol as a Nucleophile • ROH is weak nucleophile • ROis strong nucleophile • New O-C bond forms, O-H bond breaks. => C O H R X
CH3CH2CH2 Alcohol as an Electrophile HH OH-is not a good leaving group unless it is protonated,but most nucleophiles are strong bases which would remove H+. ·Convert to tosylate (good leaving group)to react with strong C-Nuc bond forms, C-O bond breaks nucleophile (base) => Chapter 11 12
CH3CH2CH2 C H H Br O H H Chapter 11 12 Alcohol as an Electrophile • OHis not a good leaving group unless it is protonated, but most nucleophiles are strong bases which would remove H+ . • Convert to tosylate (good leaving group) to react with strong nucleophile (base) => C O H + C-Nuc bond forms, C-O bond breaks
CH3CH2CH2 BrC-0 Formation of Tosylate Ester HH H-0 0=S=0 CH3 CH; CH: p-toluenesulfonyl chloride ROTs, TsCl,“tosyl chloride a tosylate ester Chapter 11 13
CH3CH2CH2 C H H Br O H H Chapter 11 13 Formation of Tosylate Ester p-toluenesulfonyl chloride TsCl, “tosyl chloride” C O H CH3 S Cl O O N CH3 O S O H O C CH3 S O O O C ROTs, a tosylate ester =>