Download Synthesis of benzil

Synthesis of benzil
Renan Gongora
Spring 2017
Outline
• Tetracyclone
• Retrosynthesis
O
• Alcohol Oxidation
• Acyloin Condensation
• Ylide
• Benzoin
• Acyloin Condensation
• Reflux
• Recrystallization
H 2O
H 2O
• Analyze Crude
• Caclulate % yield
• Get into pairs
2
2
Tetracyclone
Used to make Shvo’s Catalyst
(top structure)
Oxidative coupling of primary
alcohols to esters
Oxidation of alcohols to form
ketones
Aldehyde, ketone and imine
hydroboration
O
O
Recall how low your yield was
for the isopentyl acetate lab,
this method could increase
yield
O
You’re not
making this
but you could
Brian L. Conley, Megan K. Pennington-Boggio, Emine Boz, and Travis J. Williams "Discovery,
Applications, and Catalytic Mechanisms of Shvo’s Catalyst" Chemical Reviews, 2010,
volume 110, pp. 2294–2312. doi:10.1021/cr9003133
3
Retrosynthesis
O
Imagine if you
wanted to make this
compound, how
could I make it using
simple/inexpensive
materials?
O
O
O
O
OH
O
4
Synthesis: The next two weeks
(separate lab reports)
H 2N
N
O
S
H 2N
N
S
O
O
OH
N
N
N
N
OH
OH
H2O/EtOH
1:3 v/v
This week!!
HNO3
O
Synthesis
1) Reflux in acid
2) Quench with Water
3) Purify
O
O
OH
O
HNO3
benzoin
Oxidation
benzil
Which carbon was oxidized?
Protip: You can determine if a carbon has been oxidized if
there are less hydrogen atoms connected to it or if there
are more oxygen atoms connected to it.
6
Procedure
O
OH
(2.5 g)
Only start refluxing
after setup has been
approved!
H 2O
HNOOH
(12
mL)
(10 mL)
3
H 2O
50 mL
RBF
set
up
NaOH
reflux
with gas
trap
7
7
Procedure
Only start refluxing
after setup has been
approved!
H 2O
H 2O
NaOH
≈60 mins
or until
no more
NO2 (g)
cool to r.t.
O
crude
Stir
unitl crystallization
If no crystals form
cool with an ice bath
(40 mL)
Vacuum Filter
Washing with cold
DI water twice
(25 mL)
(10 mL)
SLOWLY
quench with
cool DI water and pour
reaction mixture
into
OH
(10 mL)
water
O
OH
Procedure
filter
to Vacuum
dispose filtrate in
acid waste
Recrystallization
O
O
O
OH
Recall the purpose of your select solvent is
At elevated temperatures: completely dissolve
your product
but
At lower temperatures: your product should be
i_s_l_b_e
Procedure
O
O
O
OH
under ice bath
until crystals form
enough
EtOHOHjust(10
mL)
(≈0.5g/5mL
of EtOH)
OH
(10 mL)
100 mL
RBF
MILDLY heat
NaOH
until
completely
dissolved
sit
at r.t.
11
Recrystallization Procedure
O
O
O
OH
Vacuum Filter Weigh
Washing with cold filter
EtOH (5 m LX 2) paper
O
O
before
this
step
to Vacuum
DI H 2O
EtOH
(you calculate this
volume)
12
Recall Reflux
• Prevents
solvent loss
H 2O
H 2O
• Prevents
buildup of
pressure
13
Outline
• Tetracyclone
• Retrosynthesis
O
OH
O
O
• Alcohol Oxidation
• Acyloin Condensation
• Ylide
• Benzoin
O
• Acyloin Condensation
• Reflux
• Recrystallization
• Analyze Crude
• Caclulate % yield
• Get into pairs
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14
Questions?
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