Chapter 17 Flashcards
Reduction of Carbonyl Compounds (reagents)
1) simple metal hydrides (not normally used)
LiH, NaH, KH
2) complex metal hydrides
Li+AH4-,Na+BH4-
Reduction of Carbonyl Compounds (mechanism)
1) source of H- plus ethoxide
2) H3O+
What reagent should I use for each?
aldehydes & ketones - NaBH4
carboxylic acids & esters - LiAH4
Reduction of esters (mechanism)
see notes
Alcohols from Carbonyl Compounds: Grignard Reaction (effects on ketones, aldehydes, esters, formaldehyde, carboxylic acids)
see notes
Things Grignard doesn’t work with
alkyl halides +
1) OH,NH,SH,CO2H
2) cyH,cyR,cyNR2,C=-N,NO2,SO2R (base)
3) ketones (react w/ self)
Alcohols from Carbonyl Compounds Grignard mechanism
see notes
alcohols from alkyl halides
mechanism!
PBr3, SOCl2 (methyl, 1, 2)
HX (3)
sulfonate esters
ROH + TsCl –> ROTs + HCl
ROH->alkenes
1)H3O+, THF, 25 C (tertiary)
POCl3 2 or 3 ROH, 0 C
1 ROH, heat (secondary and teritary)
ROH->esters
1) carboxylic acid + CH3OH, HCl, heat
Oxidation of Alcohols
1 - aldehyde or carboxylic acid
aldehyde if use milder oxidizers such as PCC, PDC, DMP
2 - ketone
Oxidators of alcohol
milder - PCC, PDC, DMP(CH2Cl4)
less mild: CrO3 (H3O+), Na2Cr2O7/H2SO4, K2Cr2O7/H2SO4(H2O)
What are the three steps in protecting an alcohol?
1) introducing a protecting group
2) carrying out the desired reaction
3) removing the protecting group
Mechanism of adding and taking away protecting group
1) (CH3)3SiCl/(CH3CH2)3N aka Et3Ni
2) H3O+
Hydroquinone structure
see notes
Cresol structure
see notes
phenol + primary alcohol acid base
see notes
17.10 oxidation of phenols to quinones
1) Fremy’s salt (KSO3)2NO or AgO (mild oxidizer)
