Carbonyl Group
contains an oxygen atom and two lone parts that allow it to function as a weak Lewis base and has a highly polarized carbon-oxygen bond making the carbonyl group electrophilic
carbon and oxygen are sp2 hybridized and are on the same plane as the two additional groups with bond angles with carbon of 120°
Oxidation of Alcohols
PCC, CH2Cl2
forms an aldehyde
PCC, CH2Cl2
Oxidation of Alcohols to form Aldehydes
Ozonolysis of Alkenes
- O3, CH2Cl2
2. (CH3)2S
- O3, CH2Cl2
2. (CH3)2S
Ozonolysis of Alkenes to form Aldehydes or Ketones
Hydration of Alkynes
H2O, H+, Hg2+
yields enols that tautomerize to carbonyls
H2O, H+, Hg2+
Hydration of Alkynes to form Aldehydes or Ketones from Enols
Friedel-Crafts Acylation
RCOCl, AlCl3
makes ketone substituent on benzene
RCOCl, AlCl3
Friedel-Crafts Acylation
Selective Alcohol Oxidation
CrO3, H2SO4, acetone, 0°C
CrO3, H2SO4, acetone, 0°C
Selective Alcohol Oxidation
Selective Oxidation of Allylic Alcohols
MnO3, CHCl3, 25°C
MnO3, CHCl3, 25°C
Selective Oxidation of Allylic Alcohols
NaBH4 or LiAlH4
hydride reagents, reduce carbonyls
Reduction of Carbonyls
NaBH4 or LiAlH4
Nucleophilic Addition-Protonation of Carbonyls
basic conditions, strong nucleophiles
nucleophile attacks carbonyl carbon, pushes e- from DB to oxygen to form alkoxide ion, addition of water, O attacks H in water to form OH
Electrophilic Protonation-Addition
acidic conditions, weak or neutral nucleophile
e- on O attack H+, NuH attacks carbonyl C, e- pushed to O to eliminate + charge, H is abstracted from Nu group
Carbonyl Hydrates
R2C(OH)2
formed when water attacks a carbonyl facilitated by acid or base
base catalyzed is nucleophilic addition-protonation
acid catalyzed is electrophilic protonation-addition
Hydration of Carbonyls
OH is added to carbonyl C to form R2C(OH)2
reversible
EWG increase + charge at C and makes more reactive, ketone equilibrium lies to left and aldehyde equilibrium lies to the right
Hemiacetals
OH
R-C-OR’
H
formed from aldehyde reversibly, formation is not favorable
if excess alcohol and H+ is present will form an acetal
Hemiketals
OH
R-C-OR’
R
formed from ketone reversibly, formation is not favorable
if excess alcohol and H+ is present will form an ketal
Acetals
OR’
R-C-OR’
H
can be isolated by neutralizing the acid catalyst
adding excess H2O will shift equilibrium to the left (acetal hydrolysis)
Ketals
OR’
R-C-OR’
R
Acetal Protecting Groups
formation is reversible
can be used to protect the carbonyl group using diols
Diols
convert aldehydes and ketones to cyclic acetals which are more stable
Cyclic Acetalization
aldehyde + diol (OHCH2CH2OH) =(H+)=> cyclic acetal + H2O
Thiols
HSCH2CH2SH
react with carbonyl to form thioacetals using a Lewis Acid (BF3, ZnCl2)
Thioacetals
sulfur analogs of cyclic acetals
Thioacetal Formation
HSCH2CH2SH, ZnCl2, (CH3CH2)2O, 25°C
HSCH2CH2SH, ZnCl2, (CH3CH2)2O, 25°C
Thioacetal Formation
Thioacetal Hydrolysis
H2O, HgCl2, CaCO3, CH3CH
removes thiol group and restores aldehyde or ketone
H2O, HgCl2, CaCO3, CH3CH
Thioacetal Hydrolysis
Thioacetal Desulfurization
Raney Ni, H2
removes thiol group and replaces it with 2 H atoms
Raney Ni, H2
Thioacetal Desulfurization
Imines
RNC(R’)2
formed from hemiaminals by losing H2O and forming CN
can be isolated if water is removed by continuous distillation of the reaction mixture
Hemiaminals
R H
N
R2-C-OH
formed from ketones or aldehydes by adding R-NH2
Enamine
unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary amine
Deoxidation
reduction of the carbonyl group to CH2
can occur by Clemmensen reduction, thioacetal desulfurization or the Wolff-Kishner Reduction
Hydrazones
R
R-C=N-NH2
formed by condensation of a hydrazine (H2N-NH2) with aldehyde/ketone
H2N-NH2, CH3CH2OH
formation of a hydrazone
Wolff-Kishner Reduction
hydrazone decomposes when treated with base at high temperatures
R
R-C=N-NH2 + NaOH =(HOCH2CH2)2O, 180-200°C=> RCH2R’ + N2
Cyanohydrins
formed when hydrogen cyanide adds reversibly to a carbonyl
CN
Ph-OH
reagents: NaCN, conc. HCl
NaCN, conc. HCl
formation of cyanohydrin from ketone/aldehyde
Phosphorous Ylide
reagent in nucleophilic additions that contains a carbocation stabilized by an adjacent positively charged phosphorous group
Wittig Reaction
phosphorous ylide attacks ketones/aldehydes to form C=C
produces mostly cis product
conjugation in the ylide produces trans products
R=P(C6H5)3, THF
Witting Reaction Reagents
Witting Reaction Reagents
R=P(C6H5)3, THF