Experiment #1
Adam Capriola
2/4/08
Dr. Forman
“Dehydration of 2-Methylcyclohexanol”
I. Pre-Lab Report
A. Introduction
The purpose of this experiment is to analyze the products of the dehydration of 2methylcyclohexanol using gas chromatography. Dehydration of the 2methylcyclohexanol will take place via distillation with sulfuric acid on a microscale
level to yield 1-methylcyclohexene and 3-methylcyclohexene. The proportions of these
two products will then be determined by analyzing the graphs produced by a gas
chromatograph.
B. Main Reaction
2-methylcyclohexanol + H2SO4 = 1-methylcyclohexene + 3-methylcyclohexene +
H3O+
C. Mechanism
The reaction took place via an E1 mechanism. Refer to the attached sheet.
D. Side Reactions
There were no side reactions.
E. Table of Reactants and Product(s)
Compound
2-methylcyclohexanol
Molecular Grams
Weight
Used (g)
(g/mol)
114.2
2.28
Sulfuric Acid
98.078
0.44
Aqueous Sodium
Hydroxide
Anhydrous Calcium
Chloride
1-methylcyclohexanol
3-methylcyclohexanol
40.0
0.24
Moles
Used
(mol)
2.00 x
10-2
4.49 x
10-3
6.00 x
10-3
Melting
Point (ºC)
Boiling
Point (ºC)
Hazards
-9.5
165-166
10
290
Flammable,
irritant
Corrosive
318
1390
Irritant
110.99
772
1600+
Irritant
114.2
114.2
25
-5.5
155
174
Flammable
Flammable
II. Post-Lab Report
A. Experimental Procedure
The experimental procedure was followed pretty much as written. The
fractionating column was not wrapped with aluminum foil and it was not needed to add
additional water to the round bottom flask during heating. The dehydrated 2methylcyclohexanol solution was not centrifuged after being washed and then dried with
calcium chloride. It was allowed to stand for a few minutes instead.
B. Observed Yield and Observed Melting Point or Boiling Point of Product(s)
Area of Peak A = 25
Area of Peak B = 112.5
Percentage of Product A: 18.2%
Percentage of Product B: 81.8%
C. Calucations
Percentage of Product A = (Area of Peak A) / (Area of Peak A + Area of Peak B)
Percentage of Product B = (Area of Peak B) / (Area of Peak A + Area of Peak B)
D. Conclusions
In analysis of the graph produced by the graph chromatograph, the ratio of the
two products produced was about 4 to 1. The product with the higher yield should
theoretically be 1-methylcyclohexanol. This is because the double bond in 1methylcyclohexanol is trisubstituted, which is favored over disubstituted and
monosubstitued double bonds according to Zaitsev’s rule. The product with the lower
yield should be 3-methylcyclohexanol. The double bond in 3-methylcyclohexanol is only
disubstituted, which is less favored. There were a few very small peaks on the graph
which may be negligible. However, I think one of them could possibly be representative
of methylenecyclohexane, which is the third product formed from the dehydration of 2methylcyclohexanol. This proportion of this product would be minute and it is usually
not observed, so this would be highly unlikely.