Steric effects H R R-C-Oh>R-C-oh>R-C-OH R R C-0
• Steric effects R C H H OH R C H R' OH R C R'' R' > > OH C O - S S S S S
Generating Alkoxides from alcohols ROH NaH Ro- Na+ +H c2004 Thomson ks/Cole
Generating Alkoxides from Alcohols
CH CH 2 H3C-C-0H +2K- 2H3c-C-0- K++Ho CH CH tert-Butyl alcohol Potassium tert-butoxide CHOH NaH CH0- Na++H Methanol Sodium methoxide CH3CH2OH NaNH CH3 CH2O Na*+ NHs Ethanol Sodium ethoxide OH CH3MgBr 0*MgBr+ CHA Cyclohexanol B bromomagnesium cyclohexoxide
Phenol Acidity p.289 Resonance effect OH O Na Naoh
Phenol Acidity p.289 O - O - O - O - • Resornance effect: OH O - Na+ NaOH
Substituted phenols EWG EDG Electron-withdrawing groups (EWG) Electron-donating groups (EDG) stabilize phenoxide anion, resulting destabilize phenoxide anion, in increased phenol acidi resulting in decreased phenol acidity @2004 Thomson/ Brooks Cole The pk,2of2.46- trinitrophenol(苦味酸) is 0.6, a very strong acid :0: :0: :O: :O: 0: @2004 Thomson/Brooks Cole
Substituted Phenols: • The pKa of 2,4,6-trinitrophenol(苦味酸) is 0.6, a very strong acid