A Review of “Organic Chemistry” in First Term Part A Some Important Concepts and Structure 1. Different kinds of Organic Compounds. Alkanes Saturated Cycloalkanes Compd. Alkyl halides Alcohols Alkenes Unsaturated Alkynes Diene Compd. Arenes Reactive intermediates Hybrization C atoms Geometric structure Alkyl Carbocations Allylic Radicals Benzyl 2. Formation of Chemical bonds. Stereoisomers C–C σbond Configurational isomers C–Hσbond Enatiomers(R,S) cis-trans C=C double bonds Diatereomers Isomers: C C Triple bonds Meso-isomers (Z),(E) Racemic mixture Structure Optical Chiral Resoactivity Achiral CH3CH2 nace Optical Mole. CHCH CH3CH form 2 Symetric Symetric 3. Bilingual nomenclature. Unsymetric elements Constitutional 4. Isomers Stereoisomers Newman Projections Fischer Conformers 5. Aromaticity Chair conformation 6. Organic acids and bases 7. Substitutent effects Problem 1 The structure of Comp. A is represented by the constitution shown: CH3 CH CH CH CH2 Br Cl (a) How many of the optical isomers? (b) Write the Fischer projections of the optical isomers and give the IUPAC names. (c) Sight down the C3–C4 bond, and draw the most stable Newman projection formulas of the optical isomers . (d) Identify the relationship of these optical isomers. Problem 2 Write a structural formula for the most stable conformation of the each of the following compounds: (a) cis-Cyclohexadiol. (b) trans-4-tert-Butyl-1-methylcyclohexane. Give the stable H (c) conformer. CH 3 CH3CH2 CH3 H H Part B. Organic Reactions 1. Radical Reactions a. Halogenation of alkanes. b. α- Halogenation of alkenes. c. Reactions of NBS. d. Anti-Markovnikov addition: (HBr–ROOR) Substrates Nucleophile OH/H2O, EtO /EtOH, O a. Alkyl halides CH3CO , RS , I . 2. Nucleophilic C N, C C, N N N Substitutions b. Alcohols: HX, PX3, SOCl2 I TSCl or MsCl ROTs R X NaOR HX 3. Elimination R OH C C H HX Substrates Electrophiles HX, X2, X2+H2O, +/H O Alkenes H 2 4. Electrophilic Alkynes (HgSO4/H2SO4/H2O) additons B H /H O –OH -, 2 6 2 2 Conjugated 1,2-adddition 1,4-addition dienes cycloaddition 5. Aromatic Halogenation Electrophilic Nitration substitutions Sufonation Friedel-Crafts reactions Alkenes H2 / Pd,Ni… Dienes H Alkanes 6. Hydrogenations 2 Alkynes Pd,Ni… H2 cis-Alkenes Lindlar-Pd or P-2 Catalyst Na or Li trans-Alkenes O Liq. NH3 RCOOH C C Alkenes O3 O Aldehydes H 2O,Zn or Ketones 7. Oxidations O3 Carboxyl Alkynes Acids H 2O,Zn Benzoic + Alkylbenzens: Na2Cr2O7/H acid Part C. Organic Synthesis a. The transformation of functional groups Organic Synthesis b. The change of C skeleton c. The shift of functional groups Part D. Mechanism of Organic Reactions SN1 Reactions Rearrangea. The formation of E1 Reactions ment Addition of HX a carbocation to alkenes Aromatic Electrophilic substitution b. The halonium ion: Addition of X2 to a alkene c. Bimolecular SN2 Reactions Transition States E2 Reactions Reactions Table 1 Over summary of SN1,SN2, E1 and E2 reactions CH3X Methyl RCH2X 1° R2CHX 2° Bimolecular reactionly Gives SN2 reactions Gaves mainly SN2, except with a hindered-strong base [e.g.,(CH3)3CO-] and then gives mainly E2 Gaves mainly SN2, with weak base (e.g.,I-,CN -, N3-,RCO2-) and mainly E2 With stronger bases(e.g.,RO -) R3CX 3° SN1/E1 or E2 In solvolysis give SN1/E1,and at low temperature SN1 is favored and gaves mainly E2 with stronger bases(e.g.,RO -) Part E. Stereoselectivity of Reactions 1. Catalytic hydrogenations of alkynes: H2 / Lindlar-Pd Syn-addition P-2 catalyst Li or Na / Liq. NH3: Anti-addition 2. Addition of X2 to Alkenes: Anti-addition 3. Hydroboration-Oxidation of alkenes: Syn-addition Syn-addition 4. Epoxidation of Alkenes: 5. SN2 Reactions: Inversion of configuration TsCl Retention of configuration SN1 reaction: 6. E2 Reaction: Anti-Elimination racemization R OH R OTs Part F. Regioselectivity of Reactions 1. Electrophilic addiitons of alkenes: Markovnikov’s rule 2. Addition of HBr to a alkene in the presence of ROOR: Anti-Markovnikov’s rule 3. Elimination: Zaitsev’s rule 4. Aromatic electrophilic substitution of substituted benzenes: Directing effect of substituents on aromatic ring Part G. Identification of Organic Compounds 1. Ozonolysis of alkenes and alkynes. 2. Oxidations of Alkenes by KMnO4. 3. Additions of Br2 to Alkenes. 4. Reactions of Terminal alkynes with Ag(NH3)NO3 or Cu(NH3)Cl. 5. Reactions of conjugated dienes with maleic anhydride. 6. Oxidations of alkylbenzenes to benzoic acid …… 1. C N HBr HCN NaCN Br C N CH3 2. CH3 CHCH2 I Isobutyl iodide (CH3)3C NaOEt Cl EtOH NaI Acetone CH3 CH3 CH3 C N (CH3)3C Cl tert-Butyl chloride HI HBr CH CH33 CH CH2 ROOR CHCH CHCH22 IBr ROOR CH3 CH CH33 CHCH2 I 3. H3C CH3 N3 C H C H Et Et (S)-sec-Butyl azide H3C H C Et OH HBr (R)-sec-Butyl alcohol CH3 NaN 3 DMSO C N3 NaN3 CH3CHBrCH2CH3 H3C H3C H C OH TsCl OH H C H Et Racemization SN2 Reaction OTs NaN3 acetone Et Et (R)- (R)- N3 C CH3 H Et (S)- Problems to Chapter 8 CH2Br P246 7.22 (d) CH3CH2CHCH2CH2CH3 1-Bromo-2-ethylpentane 2- 乙基-1-溴戊烷 3-Bromomethylhexane 7.29 (a) SN2 Rate Br < CH2Br p-π conjugation (c) also. Electronic effect CH3 ONa CH3Br + CH3 CH3 CH3 Br CH3ONa + CH3 CH3 CH3 7.30 CH3O CH3 CH3 (c) (f) O O CH3COCH3 CH3CO Na O + CH3 Br CH3COH + HO CH3 7.32 SN1: SN2: CH3 CH3 C Cl > CH3 Cl CH2Cl > Steric hindrance CH3 CH2Cl > CH3 C Cl CH3 Cl > crowding 7.34 (a) (b) Br CN CH3CH2CCH2CH3 NaCN CH3CH2CCH2CH3 CH3 CH3 CH3 CH3 CH3CHCH2CH2CH2OH HBr NaBr CH3CHCH2CH2CH2Br CH3 CH3CHCH2CH2CH2Br (c) SN2 OH CH3CH CH3CH2CCH3 HBr H 2SO4 CH3 CCH3 CH3 CH3CH CCH3 CH3 CH2(CH2)4CH3 7.35 Ch.P196 O CH3C O Br H3C C H (R)-2-Bromooctane C2H5O > HO > C6H5O > CH3CO2 > H2O CH2(CH2)4CH3 C Br H3C O CH3C O H C OOCCH3 H3C SN1 CH2(CH2)4CH3 CH2(CH2)4CH3 + CH3COO H (S)- (R)- Retention Racemic-forms C CH 3 H Inversion 7.48 (a) (b) 7.49 Br CH CHCH3 KOH E1 CH2 Br OCH3 CHCH3 CH3OH heat CHCH3 CH3 H CH3 KOH Br HH H SN1 Br H H CH3 Br H HO CH3 CH3 E2 7.50 BrPh CH3 KOH ( ) EtOH Ph H HC 3 Ph CH3 C C Ph CH3 (Z)-2,3-Diphenyl-2-butene Br Ph Ph H 7.51 (a) CH3 H CH3 CH3 KOH CH3 H Br (b) H3C H3C CH3 CH3CHCBr CH3 CH3COOH heat CH3C CH3 C CH3 Br CH3Ph 7.52 H H3C H (2R,3S)-2-Bromo-3-phenylbutane Br Ph H3C H H CH3 Ph (Z)-2-Phenyl-2-butene 7.53(E) 7.55 CH 3 C H HO CH3 H H3C EtONa CH2CH3 CH3 H2SO 4 H C CH2CH3 H2O SN1 H2O CH3 CH3 C H HO CH2CH3 + C HO H CH2CH3 7.58 Br Ph Br C CH2CH2 C Ph H H PhCH2CHBrCHBrCH2Ph A You should comprehend well the meaning of the following reactions : 1.Hydroboration-Oxidation of alkenes. 2. Diels-Alder Cycloaddition Reaction. 3. Friedel-Crafts Alkylation of Arene. 4.SN2 Reaction. 5.The Williamson Synthesis of Ethers.