Dehydration of Methylcyclohexanol
Dehydration of Methylcyclohexanol
Dehydration of Methylcyclohexanol
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Experiment 9 <strong>Dehydration</strong> <strong>of</strong> <strong>Methylcyclohexanol</strong> 1<br />
Prelab Worksheet:<br />
What is the purpose <strong>of</strong> this experiment?<br />
Physical constants.<br />
Name Formula M.W. g/mole m.p. o C b.p. o C Density g/mL<br />
4-methyl-1-<br />
Cyclohexanol<br />
Aldrich #153095<br />
Concentrated (14.7 M)<br />
Phosphoric Acid<br />
Aldrich #695017<br />
85 wt. % in water<br />
5% Sodium<br />
Bicarbonate<br />
Saturated Aqueous<br />
NaCl 32.5% w/v<br />
Magnesium<br />
Sulfate<br />
C 7 H 14 O 114.19 -41 171-173 0.914<br />
H 3 PO 4 98.0 21 158 1.685<br />
NaHCO 3 84.0 ~0 ~100 ~1.0<br />
NaCl 58.44 ~ -10 ~100 ~1.2<br />
MgSO 4 120.4<br />
Name Solubility Safety Information<br />
Methyl<br />
Slightly miscible with water; Flammable<br />
cyclohexanol miscible with alcohols and Irritating to eyes, nose, throat and skin.<br />
Concentrated<br />
Phosphoric Acid<br />
5%<br />
Sodium<br />
Bicarbonate<br />
Saturated Aqueous<br />
NaCl<br />
32.5% w/v<br />
Magnesium<br />
Sulfate<br />
nonpolar solvents<br />
Soluble in water and alcohol.<br />
Insoluble in non-polar solvents<br />
sol in water 100g/L,<br />
some sol in alc,<br />
insol in nonpolar solvents<br />
sol in water 32.5% w/v,<br />
insol in alc,<br />
insol in nonpolar solvents<br />
sol in water,<br />
some sol in alc,<br />
insol in nonpolar solvents<br />
Corrosive. Moderately toxic by ingestion<br />
and skin contact. A severe eye and skin<br />
irritant and a systemic irritant by inhalation.<br />
safe. Weak base.<br />
salty<br />
Moderately toxic. Irritating dust<br />
References:<br />
1) Merck Index, 11th ed.<br />
2) www.chemfinder.com<br />
3) Hazardous Chemical Desk Reference, Lewis and Sax, 1987<br />
4) Aldrich catalog online<br />
5) Phosphoric Acid MSDS http://www.jtbaker.com/msds/englishhtml/p3973.htm<br />
6) aqueous NaCl http://www.vwrsp.com/msds/10/RC7/RC7219.5-1.pdf
Experiment 9 <strong>Dehydration</strong> <strong>of</strong> <strong>Methylcyclohexanol</strong> 2<br />
I. The reaction equation:<br />
1) Write the reaction equation?<br />
2) Calculate the number <strong>of</strong> moles <strong>of</strong> methylcyclohexanol and phosphoric acid.<br />
3) What is the limiting reagent? Keep in mind that phosphoric acid is a catalyst and not a<br />
reactant.<br />
4) What is the theoretical yield (in grams) <strong>of</strong> your predicted product?<br />
5) What is the mass <strong>of</strong> water that would be generated by this reaction?<br />
6) What is the atom economy <strong>of</strong> this reaction? Atom economy =<br />
(molecular mass <strong>of</strong> target product x 100%)/(molecular mass <strong>of</strong> the reactants)<br />
Complete the table for your predicted alkene product:<br />
Name Formula M.W. g/mole Refractive<br />
Index (N 20 D)<br />
b.p. o C<br />
Density g/mL<br />
Solubility<br />
Safety Information<br />
Source(s):
Experiment 9 <strong>Dehydration</strong> <strong>of</strong> <strong>Methylcyclohexanol</strong> 3<br />
II. Procedure<br />
1) How is the reaction yield maximized? (Hint: Le Chatelier)<br />
2) At what temperature does the reaction occur?<br />
3) Does the order <strong>of</strong> addition matter? (alcohol acid or acid alcohol)<br />
4) What is in the distillate?<br />
5) What is left behind in the distilling round bottom?
Experiment 9 <strong>Dehydration</strong> <strong>of</strong> <strong>Methylcyclohexanol</strong> 4<br />
III. Side reactions.<br />
1) What do you think are two more possible dehydration products?<br />
2) Complete the table for your predicted alkene product:<br />
www.acros.com is a good place to look.<br />
Name Formula M.W. g/mole Refractive<br />
Index (N 20 D)<br />
b.p. o C<br />
Density g/mL<br />
Solubility<br />
Safety Information<br />
3) What is one other possible side product?
Experiment 9 <strong>Dehydration</strong> <strong>of</strong> <strong>Methylcyclohexanol</strong> 5<br />
IV. Work-up<br />
1) Look back at II 1) in this handout. What are the two roles <strong>of</strong> hydrodistillation?<br />
2) Look back at II. 4) in this handout. How does the liquid-liquid extraction help to purify<br />
the alkene product?<br />
3) Why add the base NaHCO 3 to the aqueous phase in the liquid-liquid extraction C. 3. in<br />
the procedure?<br />
4) What is the role <strong>of</strong> MgSO 4 or Na 2 SO 4 in C. 7. in the procedure?<br />
5) What are two ways that product is could be “lost” in this workup?
Experiment 9 <strong>Dehydration</strong> <strong>of</strong> <strong>Methylcyclohexanol</strong> 6<br />
V. Devise a flowchart (not a list!) for this reaction.
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