931羰基的亲核加成( Nucleophilic Addition To The Carbon-Oxygen Double bond) g The most characteristic reaction of aldehydes and ketones is nucleophilic addition to the carbon-oxygen double bond LC=O H-Nu C-OH N Nucleophilic addition to the carbon-oXygen double bond occurs in either of two general ways
Organic Chemistry Organic Chemistry Xiamen Xiamen University University 9.3.1 羰基的亲核加成(Nucleophilic Addition To The Carbon-Oxygen Double Bond) The most characteristic reaction of aldehydes and ketones is nucleophilic addition to the carbon-oxygen double bond. C O + C OH Nu H Nu Nucleophilic addition to the carbon-oxygen double bond occurs in either of two general ways
反应机理 1)无催化剂或碱性条件下的加成机理 Addition of a Strong nucleophile to an Aldehyde or Ketone R,δ+8 R C=0=R R O、HMR R C-OH Ni Nua Nu ①D The important aspect of this step is the ability of the carbonyl oxygen atom to accommodate the electron pair of the carbon-oxygen double bond
Organic Chemistry Organic Chemistry Xiamen Xiamen University University 反应机理 1) 无催化剂或碱性条件下的加成机理 C O R' R δ − δ + Nu C O R' R Nu H Nu C OH R' R Nu Addition of a Strong Nucleophile to an Aldehyde or Ketone The important aspect of this step is the ability of the carbonyl oxygen atom to accommodate the electron pair of the carbon-oxygen double bond
2)酸催化下的反应机理 Acid-Catalyzed Nucleophilic Addition to an Aldehyde or Ketone + C O=C=OH← C--ouI: Nu-H Slow H C-OH =--C-OH ①D +NuH Nu
Organic Chemistry Organic Chemistry Xiamen Xiamen University University 2) 酸催化下的反应机理 Acid-Catalyzed Nucleophilic Addition to an Aldehyde or Ketone C O H + C OH C OH C OH Nu Nu H Sl o w H H + C OH Nu
3)反应活性: 醛>脂肪酮>芳香酮 环酮>脂肪酮 a In general, aldehyde are more reactive in nucleophilic addition than are ketones C R H R R Aldehyde Ketone Carbonyl carbon is Carbonyl carbon is more positive less positive
Organic Chemistry Organic Chemistry Xiamen Xiamen University University 3) 反应活性 醛 > 脂肪酮 > 芳香酮; 环酮 > 脂肪酮 In general, aldehyde are more reactive in nucleophilic addition than are ketones. R C H O δ + δ − R C R O δ + δ − Ald ehyd e Ke t o n e Carbony l c a rbon i s m ore p o sitive Carbony l c arbon i s less p o sitiv e
4)亲核试剂的分类 g■含碳的亲核试剂RMgX,HCN,C 含氮的亲核试剂RNH2,R2NH,H2NG 含氧的亲核试剂H2O.ROH g·含硫的亲核试剂 Naso3,RSH
Organic Chemistry Organic Chemistry Xiamen Xiamen University University 4) 亲核试剂的分类 含碳的亲核试剂 RMg X , HCN , C RNH 2 , R 2NH , H 2 N − G H 2O . ROH NaHS O 3 , RS H 含氮的亲核试剂 含氧的亲核试剂 含硫的亲核试剂