厦门大学化学化工学院：《有机化学》课程教学资源（课件讲稿，双语版）第九章 醛和酮 9.3 醛酮的反应 Reactions of Aldehydes and Ketones

93醛酮的反应 Reactions of Aldehydes and Ketones

Organic Chemistry Organic Chemistry Xiamen Xiamen University University 9.3 醛酮的反应 Reactions of Aldehydes and Ketones

醛酮的反应概貌 O∠氧化 C-C-H 亲核加成还原 活泼a-H的反应

Organic Chemistry Organic Chemistry Xiamen Xiamen University University C H C O H 亲核加成 还原 氧化 活泼α− H的反应 醛酮的反应概貌

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 ƒ 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 ƒ 含氮的亲核试剂 ƒ 含氧的亲核试剂 ƒ 含硫的亲核试剂

1.羰基与含碳亲核试剂的加成 (1The Addition of Gringard Reagents (1)Et2O CH3h2CH-C-CH(CH3)2 CH3 CH,MgBr (2)H3O OH X(CH3)2CH-C-CH(CH3)2 80 CH2CH 空间位阻增大时,加成的产率降低

Organic Chemistry Organic Chemistry Xiamen Xiamen University University 1. 羰基与含碳亲核试剂的加成 (1)The Addition of Gringard Reagents (C H 3 ) 2CH C CH(CH 3 ) 2 O + CH 3CH 2MgBr (1) E t 2 O (2) H 3 O + (C H 3 ) 2CH C CH(CH 3 ) 2 OH CH 2CH 3 80% 空间位阻增大时 加成的产率降低

加成反应的立体化学 当羰基与手性中心相连时 加成存在立体选择性问题 CH3CH2 CH 3-C—C H R g Cram规则1:当C上结合L,MS三个基团 的不对称醛酮进行亲核加成反应时,应当取 如下稳定构象:

Organic Chemistry Organic Chemistry Xiamen Xiamen University University 加成反应的立体化学 当羰基与手性中心相连时 加成存在立体选择性问题 C O R C H CH 3 CH 3CH 2 Cram 规则 1 当 α − C上结合L, M, S三个基团 的不对称醛酮进行亲核加成反应时 应当取 如下稳定构象

M N RL RL 重叠构象 Nu S S R R 全交叉构象

Organic Chemistry Organic Chemistry Xiamen Xiamen University University M L S O R S L M O R Nu S L M O R S L M O R Nu 重叠构象 全交叉构象