《有机化学》英文教学课件：Chap 9 aldehydes and ketones (2012-2)

1、1,Chapter 9 Aldehydes and Ketones,Section 1. Structure and Nomenclature,Aldehydes and ketones all contain a carbonyl group,aldehydes,ketones,lone-pair electrons,An - hydrogen,2,Common names are normally used for the aldehydes containing four carbons or fewer. For systemic names, the “e” of the paren

2、t alkanes name is dropped and the suffix “al” is added. In the priority system the aldehyde group is always number 1, and higher numbers are given to any substituents.,Nomenclature of aldehydes:,3,formaldehyde,acetaldehyde,2-methylpentanal,3-chloropropanal,( mathanal ),( ethanal ),4,3-methylbenzalde

3、hyde,3-chloro-3-phenyl-2-propenal,(Z)-,5,The “e” of the parent alkane is dropped, and the suffix “one” is appended. The number of the carbon atom bearing the carbon-oxygen double bond begins the name. Give the carbonyl group the smallest number as far as possible. Aromatic ketones are often named by

4、 treating the benzene ring as a phenyl group.,Nomenclature of ketones:,6,acetone,(propanone),methyl phenyl ketone,( phenylethanone ),cyclopropyl phenyl ketone,7,( 2,2-dimethyl-1-phenylpropanone ),t-butyl phenyl ketone,3-methyl-2-pentanone,8,4-methoxycyclohexanone,1,4-cyclohexanedione,9,Section 2. Pr

5、eparation,1. Oxidation of alcohols,CrO32C5H5N is called Collins reagent,10,2. Ozonization of alkenes,ozonide,11,Show the major product of the following reaction:,12,3. Friedel-Crafts Acylation Reaction,Acyl chlorides or acid anhydrides react with benzene under the influence of an equivalent (not a c

6、atalytic amount) AlCl3 to form aromatic ketones.,acyl acyl chloride acid anhydride,13,14,Section 3. Chemical Properties,. Nucleophilic Addition,. Reactions at the -position,. Oxidation and Reduction,15,1. Addition of Hydrocyanic Acid,16,cyclohexanone,17,1. All aldehydes include aliphatic and aromati

7、c aldehydes.,2. Aliphatic methyl ketones.,3. Cyclic ketones which the rings contain eight or less carbon atoms.,n8,Summary:,18,2. Addition of sodium bisulfite,19,吊白块、雕白粉,20,The product of bisulfite addition is often a nice isolable solid. So it is also a distinguish reaction. But more important, via

8、 this reaction we can purify aldehydes and some ketones.,21,1. All aldehydes include aliphatic and aromatic aldehydes.,2. Aliphatic methyl ketones.,3. Cyclic ketones which the rings contain eight or less carbon atoms.,n8,Summary:,22,Point out which compounds of the following molecules can react with

9、 sodium bisulfite:,23,3. Addition of water,(geminal diol),24,4. Addition of alcohols,Some ketones also can react with alcohols to form hemiketals and ketals.,25,Acetals or ketals are stable to base, oxidants and reducer. So carbonyl compounds can be protected by converting them into their acetal or

10、ketal forms, and then regenerating as needed.,26,5. Addition of Grignard Reagents,27,6. Addition of derivatives of ammonia,Schiff base,28,29,2,4-dinitrophenyl hydrazine,2,4-dinitrophenyl hydrazone,yellow precipitation,Formation of 2,4-dinitrophenyl hydrazone can diagnose the presence of a carbonyl g

11、roup.,30,. Reactions at the -position,31,1. Aldol condensation,(aldol),32,Mechanism of aldol condensation :,carbanion,intermediate,aldol,33,2,34,Like most intermolecular reaction, the aldol condensation has an intramolecular version. Particularly favorable are intramolecular condensation that form t

12、he relatively strain-free five- and six-membered rings.,35,crossed aldol condensation:,36,2. Haloform reactions,37,haloform,(sodium hypohalide),38,39,silver mirror reaction,. Oxidation and Reduction,cuprous oxide, brick red color,40,Tollens reagent can react with all aldehydes (aliphatic and aromati

13、c), but Fehlings reagent can only react with aliphatic aldehydes. You can use Fehlings reagent to distinguish aliphatic aldehydes and aromatic aldehydes.,41,Reduction:,lithium aluminium hydride,42,Metal hydrides (LiAlH4, NaBH4, and many others) can reduce aldehydes and ketones to give alcohols. Comp

14、are with hydrogenation reaction, application of metal hydrides is more selective. Metal hydrides only reduce the carbonyl group but not carbon-carbon double bond.,43,Zn-Hg/HCl: zinc amalgam,DEG: diethylene glycol, 二聚乙二醇(HOCH2CH2)2 O TEG: triethylene glycol, 三聚乙二醇(HOCH2CH2OCH2)2O,methylene,44,If the

15、start material contains acid sensitive groups, Wolff-Kishner-黄鸣龙 Reduction is applied to reduce the carbonyl group. Clemmensen Reaction is used to those carbonyl compounds which contain base sensitive groups.,45,Cannizzaro Reaction,When a no -hydrogen aldehyde react with concentrated sodium hydroxide solution, some of the aldehyde has been oxidized to carboxylic acid and some reduced to alcohol. This is the Cannizzaro Reaction.,46,The reductive ability of formaldehyde is stronger than most other aldehydes. When excessive formaldehyde react with an