Physical Properties
Substance
Structure
Molecular
MW
MP (°C)
Formula
(g/mol)
BP
Density
(°C)
(g/mL)
N/A
N/A
Benzophenone
2-Propanol
N/A
Acetone
N/A
Benzopinacol
N/A
N/A
Benzopinacolone
N/A
N/A
Acetic Acid
(glacial)
N/A
Ethanol
N/A
Iodine
N/A
N/A
Reactions:
Synthesis of Benzopinacol
2
O
+
Ph
OH
Ph
Benzophenone
Note: Ph = phenyl
h
HO Ph
Ph
Ph
+
O
Ph OH
2-Propanol
Benzopinacol
Acetone
Moles of Benzophenone:
grams of Benzophenone x 1/MW of Benzophenone
Moles of 2-Propanol:
mL of 2-propanol x density of 2-propanol x 1/MW of 2-propanol
Acetic acid:
Catalyst (This will not be the limiting reagent).
Limiting Reagent:
Theoretical Yield:
Moles of LR x MW of product (benzopinacol) x 1 mole Benzolpinacol
2 moles Benzophenone
Synthesis of Benzopinacolone
Ph Ph
Ph OH
Ph
Ph
HO Ph
Benzopinacol
CH3CO2H
Ph
Ph
O
Benzopinacolone
Moles of Benzopinacol: Based on grams of benzopinacol you have for THIS reaction
grams of Benzopinacol x 1/MW of Benzopinacol
mL of acetic acid (Calculate in lab after you know the yield of Benzopinacol)

You need to use enough acetic acid to make a 0.5 M solution of Benzopinacol in acetic acid.
0.5 M solution of Benzopinacol in acetic acid (0.5 M = 0.5 moles / liter)
moles of benzopinacol
Liters of acetic acid
=
XXX moles benzopinacol
=
0.5M
1000 mL
mL of acetic acid =
Liters of acetic acid
=
??? liters
0.5M
x
1000 mL
=
??? liters
1 liter
x
=
1 liter
moles of acetic acid (Calculate in lab after you know the yield of Benzopinacol):
mL of acetic acid x density of acetic acid x 1/MW of acetic acid
1 mole
??? mL acetic acid
x
1.049 g/mL
x
= ??? mmol acetic acid
60.05 g
Iodine:
Catalyst (This will not be the limiting reagent).
Limiting Reagent:
Theoretical Yield:
Moles of LR x MW of product (benzopinacolone)
??? mL
Mechanisms: Provide the arrows for each step. You can tape this into your notebook or
neatly write it in by hand.
Benzophenone to benzopinacol:
Step 1: hydrogen abstraction from 2-propanol
Ph
Ph
+
O
H
OH
Ph
Excited triplet state
of benzophenone
H
O
+
OH
Ph
Ph
benzhydrol radical
OH
Ph
Step 2: hydrogen abstraction from 2-propanol radical
Ph
Ph
O
Ph
+
H O
H
O
+
O
Ph
acetone
Ph
OH
Ph
Step 3: dimerization (Combine the 2 benzhydrol radicals)
Ph
Ph OH
Ph
+
HO
OH
Ph
Ph
Ph
Ph
HO Ph
Benzopinacol
Benzopinacol to benzopinacolone:
O
H
Ph O H
Ph
Ph
HO Ph
Ph OH
O
H
+
Ph
Ph
HO Ph
Benzopinacol
Ph
Ph
Ph
HO Ph
O
Ph Ph
Ph
Ph Ph
Ph
Ph
OH
Ph
O H
O
O
Ph Ph
Ph
Ph
O
Benzopinacolone
Calculations:
Percent Yield for benzopinacol and benzopinacolone
Actual Yield
Percent Yield =
x 100%
Theoretical Yield
+
H
O