浙江大学 英文 有机化学.ppt

1、Organic Chemistry,俞永平 浙江大学药学院,1710 ; Tel: 87217325,Organic Reactions, Synthesis,The first organic synthesis was accomplished by Friedrich Wohler in 1828,Alkanes and Cycloalkanes,Alkanes: Cycloalkanes Alkanes are characterized by a general inertness to many chemical reagents When heated, alkanes can

2、react with chlorine, bromine,Synthesis of alkanes and cycloalkanes,A: Hyrogenation of alkenes and alkynes General Reaction,Synthesis of alkanes and cycloalkanes,Specific examples,Synthesis of alkanes and cycloalkanes,Synthesis of alkanes and cycloalkanes,B: Reduction of Alkyl Halides General Reactio

3、n: Zinc atoms transfer electrons to carbon atom of alkyl halide,Synthesis of alkanes and cycloalkanes,Specific Examples,Synthesis of alkanes and cycloalkanes,Alyklation of terminal alkynes General reaction Specific reaction,Synthesis of alkanes and cycloalkanes,Specific reaction,Alkyl Halides: Nucle

4、ophilic Substitution and Elimination Reactions,When does the carbon-halogen bond break,Does it break at the same time that the new bond between the nucleophile and the carbon forms,A Mechanism for the SN2 Reaction,Reaction: Mechanism,The stereochemistry of SN2 Reaction,The nucleophile attacks from t

5、he back side, that is, from the side directly opposite the leaving group. This mode of attack causes a change in the configuration,The stereochemistry of SN2 Reaction,A Mechanism for the SN1 Reaction,Reactions: Step 1,A Mechanism for the SN1 Reaction,Step 2: Step 3,The stereochemistry of SN1 reactio

6、ns,Reactions that involve racemization,Factors affecting the rates of SN1 and SN2 reaction,The structure of the substrate The concentration and reactivity of the nucleophile The effect of the solvent The nature of the leaving group,The effect of the structure of the substrate,SN2 Reactions Simply al

7、kyl halides show the following general order of reactivity in SN2 reactions: (steric effect) Methyl primary secondary (tertiary-unreactive,Factors favoring SN1 versus SN2 reactions,Factor SN1 SN2 Substrate 3o Methyl1o2o Nucleophile Weak Lewis Bas Strong Lewis base Solvent Polar protic (alcohols, H2O

8、) Polar aprotic(DMF, DMSO) Leaving group I- Br- Cl- F- For both SN1 and SN2,Functional group transformations using SN2 reactions,Elimination reactions (dehydrohalogenations) of alkyl halides,A Mechanism for the E2 Reaction,Reaction Mechanism,A mechanism for the E1 Riaction,Reaction: Mechanism: Step

9、1 Step 2,Substitution versus Elimination,Nucleophilic substituion and elimination often compete with each other SN2 versus E2 Primary halide Seconday halides,Substitution versus Elimination,Tertiary halides,Substitution versus Elimination,Use a strong sterically hindered base,Substitution versus Eli

10、mination,Use of a weakly basic ion or acetate ion(CH3CO2-) increases the likelihood of substitution,Alkenes and Alkynes: synthesis of alkenes via elimination reactiong,Dehydrohalogenation of Alkyl Halides Dehydration of Alcohols Debromination of vic-Dibromides,E2 Reactions: The orientation of the do

11、uble bond in the product,The stereochemistry of E2 Reactions,E2 Elimination where there are two axial cyclohexane -Hydrogens,E2 Elimination where only Eligible axial cyclohexane -Hydrogen is from a less stable conformer,Dehydration of Alcohols,General reaction: The relative ease of dehydration is in

12、 the following order,Acid-catalyzed dehydration of secondary or tertiary alcohols: An E1 reaction,Dehydration of primary alcohol: An E 2 reaction,Rearrangements during dehydration of secondary alcohols,Rearrangements during dehydration of secondary alcohols,Rearrangements during dehydration of secon

13、dary alcohols,Alkenes by debromination of vicinal dibromides,Synthesis of alkynes by Elimination Reactions,Synthesis of alkynes by Elimination Reactions,Hydrogenation of alkynes,Syn addition: Anti addition,Alkenes and Alkynes: Addition Reaction,Addition to Alkenes,Addition of Hydrogen Halides to Alk

14、enes: Markovnikovs Rules,Modern statement of Markovnikovs Rule,An Exception to Markovnikovs Rule,The sterochemistry of the reaction,Stereochemistry of the addition of halogens to alkenes,Halohydrin formation,Divalent carbon compounds: Carbens,Oxidation of alkenes: syn hydroxylation,Oxidative cleavag

15、e of alkenes,Ozonolysis of Alkenes,Addition reactions of alkynes,Radical Reaction,Radical addition to alkenes: The anti-Markovnikow addition of hydrogen bromide,Reaction Mechanism,Alcohols from Alkenes through Oxymercuration-Demercuration,The net orientation of addition of H- and OH is in accordance

16、 with Markovnikovs,A Mechanism for the Reaction,Hydroboraton: Synthesis of Organoboraton,Conversion of alcohols into mesylates and tosylates,Mesylates and Tosylates in SN2 Reaction,Conversion of alcohols into alkyl halides,The Williamson Synthesis of Ethers,Epoxides,The addition of oxygen to the dou

17、ble bond in an epoxidation reaction is a syn addition,Reactions of Epoxides,In base-catalyzed ring opening, attack by the alkoxide ion at the less substituted carbon atom In the acid catalyzed ring opening of an unsymmetrical epoxide, the nucleophile attacks at the more substituted carbon atom,Anti

18、hydroxylation of alkenes via epoxides,Alcohols from carbonyl compounds. Oxidation-Reduction and Organometallic Compounds,Reduction of aldehydes and ketones by hydride transfer,Overall summary of Reduction Reactions,Overall Summary of Oxidation Reactions,Formation of Organolithium and Grignard Reagen

19、ts,Reactions of Grignard and Organolithium Reagents,Lithium Dialkylcuprates: The Corey-Posner synthesis,Conjugated Unsaturated Systems,Allylic halogenation with a low concentration of X2,Allylic halogenation using N-bromosuccinimide,Conjugate addition:1,2 versus 1,4 addition,Conjugate addition:1,2 v

20、ersus 1,4 addition,The Diels-Alder Reaction,Diels-Alder reaction is favored by the presence of electron-withdrawing groups in the dienophile and electron-releasing groups in the diene,The Diels-Alder Reaction,The reaction is syn addition and the configuration of the dienophile is retained,Stereochem

21、istry,The diene, of necessity, reacts in the s-cis conformation rather than the s-trans,The Diels-Alder reaction occurs primarily in an endo rather than an exo fashion when the reaction is kinetically controlled,Electrophilic aromatic substitution reactions,Synthetic Applications of Friedel-Crafts A

22、cylations: The Clemmensen reduction,Halogenation of the side Chain. Benzylic Radical,Oxidation of the side chain,Use of Protecting and Blocking Groups,Use of Protecting and Blocking Groups,The Birch Reduction,Addition Reaction of Aldehydes and ketones,Grignard Reaction: Reformatsky Reaction,Addition

23、 of Hydride ion,General Reaction,Addition of Hydrogen Cyanide,Eg,Addition of Yields,Addition of Alcohols,Addition of Derivative of ammonia,The Wolff-Kishner Reduction,The Baeyer-Villiger Oxidation of Aldehydes and Ketones,Migratory aptitude: Pay attention to the mechanism,Tollens Test(silver Mirror

24、Test,Reactions via Enoles and Enolate Anions,Halogenation of ketones The haloform reaction,The aldol reaction: The addition of Enolate anions to aldehydes and ketones,Claisen-Schmidt reaction,Condensations with nitroalkanes and Nitriles,Cyclizations via aldol condensation,Lithium Enolates,Direct Alk

25、ylation of ketones via Lithium Enolates,Conjugate addition,Organocopper reagents add almost exclusively in the conjugate manner,Michael additions,Carboxylic acids and their derivatives,a-halo acids,Decarboxylation of carboxylic acids,Reactions of Nitriles,The Mannich Reaction,Synthesis of Enamines:

26、Stork Enamine Reactions,Acetoacetic ester synthesis,Amines: Diazotizatoin of primary Arylamines,The Hofmann Elimination,Hofmann rule: Yield mainly the least substituted alkene,The Cope Elimination,The Cope elimination is a syn elimination,Phenols and Aryl halides,Williamson synthesis,Claisen Rearrangement,有机化学反应,加成反应 （亲电.亲核） 取代反应 （亲电.亲核） 消除反应 氧化还原反应 格氏试剂反应 -H活性反应 重排反应 其它反应,1.加成反应,加硫酸（符