CH 220C Aldol Condensation
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32 Terms
Acetophenone MSDS
moderate FH NC NM
Ethanol MSDS
severe FH NC PM
trans-p-anisalacetophenone MSDS
Flammable toxic fumes NC NM
p-anisaldehyde MSDS
slight FH NC NM
NaOH MSDS
NFH NC NM
How do we isolate product in ketone self-condensations?
Continuous extraction of product
How do we control aldol reactions?
Make the enolate first then add the reactant
Why does acetophenone not react with itself?
Steric hindrance
Why does acetophenone favor reacting with p-anisaldehyde?
more sterically available carbons
What are we looking for in IR?
Shift in carbonyl peak
Why are carbonyls so reactive?
Polarization of carbon-oxygen pi bond
Acidity of alpha hydrogens
Where does the polarization arise from in a carbonyl?
dipolar resonance structure and high electronegativity of oxygen
Presence of carbonyl allows for molecule to become
nucleophilic through enol formation
Enolate ions are ___ than enols
more reactive
How do alpha carbons become nucleophilic?
Deprotonation to form enolate ion
Keto-enol tautomerization
Enolates react with electrophiles at the alpha-carbons to give:
net substitution of alpha hydrogen for electrophile
Why are do carbonyls increase acidity?
inductive effect from oxygen and delocalized negative charge
Hydroxylic solvents
Catalytic process
Why does dehydration occur?
Acidic alpha-hydrogen and good leaving group
Microscale yield
30-40%
Good yield
70%
Why does dehydration occur in this experiment?
Forms new pi bond that is conjugated with the aromatic ring and carbonyl function
Formation of an extended conjugated system:
increases molecule stability
Acetophenone IUPAC
1-phenylethan-1-one
P-anisaldehyde IUPAC
4-methoxybenzaldehyde
Intermediate aldol IUPAC
3-hydroxy-3-(4-methoxyphenyl)-1-phenylpropan-1-one
trans-p-anisalacetophenone IUPAC
E-3-(4-methoxyphenyl)-1-phenylprop-2-en-1-one
Why do we rinse with ethanol?
neutralizes residual base and dissolves impurities
What percentage of NaOH?
50%
How much of acetophenone and p-anisaldehyde?
0.2 mL
How much ethanol?
1 mL
What kind of control is the dehydration under?
thermodynamic