Chapter 11. Alcohols from carbonⅤ I compounds (由羰基化合物制醇). Oxidation-reduction and organometallic compounds (氧化还原和有机金属化合物) 11.1 Introduction Carbonyl(4E) compounds are a broad group of compounds that includes aldehydes, ketones, carboxylic acids and esters R R H R RO The carbonyl group An aldehyde A ketone A carboxylic acid A carboxylate ester 羰基 醛 酮 羧酸 酯
Chapter 11. Alcohols from carbonyl compounds (由羰基化合物制醇）. Oxidation-reduction and organometallic compounds (氧化-还原和有机金属化合物） 11.1 Introduction Carbonyl (羰基）compounds are a broad group of compounds that includes aldehydes, ketones, carboxylic acids, and esters. O The carbonyl group R H O R R' O R HO O R R'O O An aldehyde A ketone A carboxylic acid A carboxylate ester 羰 基 醛 酮 羧 酸 酯
11.1A Structure of the carbonyl group 120 1. C-sp* hybridization 2. The bond angles is 120 1200 3. It is a trigonal planar structure 4. The carbon-oxygen double bond 120° consists of sigma-a bond and a pi-bond 120 120 120 Polarization of the T-bond Resonance structures
11.1A Structure of the carbonyl group O 120 o 120 o 120 o 1. C-sp 2 hybridization 2. The bond angles is 120 o . 3. It is a trigonal planar structure 4. The carbon-oxygen double bond consists of sigma-a bond and a pi-bond O 120 o 120 o 120 o O O O O + − + O- Polarization of the - bond Resonance structures
11.1B Reaction of carbonyl compounds with nucleophiles NU 8+8 u Polarization of the T-bond TH Reduction OH [OJ Oxidation
11.1B Reaction of carbonyl compounds with nucleophiles O + − Polarization of the - bond :Nu + - O - Nu O OH [ H ] Reduction [ O ] Oxidation
NabHg or lianG IH]」 Reduction OH IO Oxidation KMno R NaBH4 or LiAlH4 ROH o H RCH,OH [H Reduction nucleophilic addition h
O OH [ H ] Reduction [ O ] Oxidation NaBH4 or LiAlH4 KMnO4 R H O R H O- [ H ] Reduction NaBH4 or LiAlH4 + H - H ROH RCH2OH nucleophilic addition
11.2 Oxidation Reduction reactions in organic chemistry Reduction of an organic molecule usually corresponds to increasing its hydrogen content or to decreasing its oxygen content. oxygen content decreases oxygen content decreases IHI H R—cH2OH OH R Reduction Reduction Carboxylic acid Aldehy Aldehyde Alcohol oxvgen content decreases THI R—cH2OH R——cH3 Reduction Alcohol Alkanes
11.2 Oxidation-Reduction reactions in organic chemistry Reduction of an organic molecule usually corresponds to increasing its hydrogen content or to decreasing its oxygen content. R O OH [ H ] Reduction R O H Carboxylic acid Aldehyde oxygen content decreases R O H [ H ] Reduction R CH2OH Aldehyde Alcohol oxygen content decreases [ H ] Reduction R CH3 Alcohol Alkanes oxygen content decreases R CH2OH
The opposite of reduction is oxidation Thus, increasing the oxygen content of an organic molecule or decreasing its yarogen content is an oXidation oxygen content increases> LOT R—cH3一 R—cH2OH一 RCHO RCOOH Alkanes H Alcohols H H oxygen content decreases o o LO R——CH R一cH2C RCHCI2- RCO Alkanes H H
The opposite of reduction is oxidation. Thus, increasing the oxygen content of an organic molecule or decreasing its hydrogen content is an oxidation. oxygen content decreases [ O ] R CH2OH Alkanes Alcohols oxygen content increases R CH3 [ H ] [ O ] [ H ] RCHO [ O ] [ H ] RCOOH [ O ] R CH2Cl Alkanes R CH3 [ H ] [ O ] [ H ] RCHCl 2 [ O ] [ H ] RCCl 3
11.3 Alcohols by reduction of carbonyl compounds H R OH R—cH2OH Reduction Carboxvlic acid 1° Alcohols IHI R OR R—cH2OH+ROH Reduction 1° Alcohols IH R—cH2OH Reduction Aldehyde 1° Alcohols IHI R R Reduction Ketone 20 Alcohols
11.3 Alcohols by reduction of carbonyl compounds R O OH [ H ] Reduction R CH2OH Carboxylic acid 1 o Alcohols R O OR' [ H ] Reduction R CH2OH 1 o Alcohols + R'OH R O H [ H ] Reduction R CH2OH Aldehyde 1 o Alcohols R O R [ H ] Reduction R H C Ketone 2 o Alcohols OH R
H R OH LiAIF R—cH2OH Reduction Carboxylic acid Lithium Et2o 1° Alcohols aluminum hydride 1. LiAlH,/Et,O OH H3C—CH2OH 2.H2O Acetic acid Ethanol CH 1. LiAIH,/Et,0 H3C COOH H3C CH2OH 2.H2O CH. 3 CH 3 2, 2-Dimethylpropanoic acid Neopentyl alcohol新戊醇 (92%)
R O OH R CH2OH Carboxylic acid 1 o Alcohols [ H - ] Reduction + LiAlH4 Lithium aluminum hydride Et 2O H3C O OH H3 C CH2OH H3C CH3 COOH 2,2-Dimethylpropanoic acid 1. LiAlH4 / Et 2O 2. H2O Acetic acid Ethanol CH3 1. LiAlH4 / Et 2O 2. H2O H3C CH3 CH2OH CH3 Neopentyl alcohol 新 戊 醇 (92%)
The nabh is also reduced reagent IHI CH3CH2CH2CHO NaBH4-CH3 CH, CH,CH,OH Reduction Butanal Sodium HbO 1-Butanol Borohydride CH CCH3 t NaBH-IH CH3CH2CHCH3 Reduction Butanone Sodium H20 OH B borohydride 2-Butanol
CH3 CH2 CH2 CHO Butanal 1-Butanol [ H- ] Reduction NaBH4 Sodium Borohydride H2 O + CH3 CH2 CH2 CH2 OH CH3 CH2 CCH3 Butanone 2-Butanol [ H - ] Reduction NaBH4 Sodium Borohydride H2 O + CH3 CH2 CHCH3 O OH The NaBH4 is also reduced reagent
The mechanism for the reduction of a ketone by sodium borohydride and lithium aluminum hydride LiAl hoH H H→H NaBH4 nucleophile addition Hydride transfer Alcohols Sodium borohydride(nabha is a milder reducing agent than lithium aluminum hydride lialh4). Lithium aluminum hydride will reduce acids. Esters, aldehydes, and ketones but sodium borohydride will reduce only aldehydes and ketones
The mechanism for the reduction of a ketone by sodium borohydride and Lithium aluminum hydride O LiAlH4 NaBH4 [H - ] Hydride transfer O - H HOH H OH Alcohols nucleophile addition Sodium borohydride (NaBH4 ) is a milder reducing agent than lithium aluminum hydride (LiAlH4 ). Lithium aluminum hydride will reduce acids. Esters, aldehydes, and ketones; but sodium borohydride will reduce only aldehydes and ketones