Download CHEM 122: Introduction to Organic Chemistry Chapter 5: Alcohols

CHEM 122: Introduction to Organic Chemistry
Chapter 5: Alcohols, Ethers, and Thiols.
1. Which of the following are secondary alcohols?
CH 3
HO
OH
OH
a)
b)
(CH3)3COH
c)
d)
2. Which of the alcohols in Problem 1. Are primary? Which are tertiary?
3. Write the IUPAC name of each compound.
OH
OH
a)
b)
HO
OH
OH
c)
OH
OH
d)
HO
e)
OH
f)
4. Draw a structural formula for each of the following alcohols.
a)
b)
c)
d)
e)
f)
Isobutyl alcohol
1,4-Butanediol
5-Methyl-1-hexanol
1,3-Pentanediol
trans-1,4-Cyclohexanediol
3,3-Dimethylcyclohexanol
5. Both alcohols and phenols contain an –OH group. What structural feature
distinguishes these two classes of compounds? Illustrate your answer by drawing
the structural formulas of a phenol with six carbon atoms and an alcohol with six
carbon atoms.
6. Explain in terms of noncovalent interactions (intermolecular forces) why the lowmolecular-weight alcohols are more soluble in water than the low-molecularweight ethers.
7. Show hydrogen bonding between the oxyge3n of diethyl ether and a hydrogen of
water.
8. Arrange these compounds in order of increasing boiling point. Values in oC are
-42, 78, 117, and 198.
a)
b)
c)
d)
CH3CH2CH2CH2OH
CH3CH2OH
HOCH2CH2OH
CH3CH2CH3
9. From each pair, select the compound that is more soluble in water.
a) CH3OH
or
CH3OCH3
OH
CH2
b) CH3CHCH3
or
c) CH3CH2CH2SH
CH3CCH3
or
CH3CH2CH2OH
10. Give the structural formula of an alkene or alkenes from which each alcohol can
be prepared.
a)
b)
c)
d)
e)
2-Butanol
1-Methylcyclohexanol
3-Hexanol
2-Methyl-2-pentanol
Cyclopentanol
11. Both 2,6-diisopropylcyclohexanol and the intravenous anesthetic Propofol are
insoluble in water. Show how these two compounds can be distinguished by their
reaction with aqueous sodium hydroxide.
OH
2,6-Diisopropylcyclohexanol
OH
2,6-Diisopropylphenol (Propofol)
12. Write equations for the reaction of 2-butanol with these reagents.
a) H2SO4, heat
b) K2Cr2O7, H2SO4
13. Show how to convert cyclohexanol to these compounds.
a)
b)
c)
d)
Cyclohexene
Cyclohexane
Cyclohexanone
Bromocyclohexane
14. Show reagents and experimental conditions to synthesize each compound from 1propanol.
Br
Br
Br
(e)
(d)
(f)
OH
(b)
O
(c)
(a)
OH
(g)
OH
O
(i)
(h)
O
H
15. Write the common name for each ether.
O
a)
b)
[CH3(CH2)4]2O
c)
CH3CHOCHCH3
16. Write the IUPAC name of each thiol.
SH
a)
CH3CH2CHCH3
b)
CH3CH2CH2CH2SH
c)
17. Write the common name for each thiol in Problem 16.
18. Explain why methanethiol, CH3SH, has a lower boiling point (6oC) than
methanol, CH3OH (65oC), even though methanethiol has a higher molecular
weight.
19. Draw structural formulas and write IUPAC names for the eight isomeric alcohols
with the molecular formula C5H12O.
20. Draw structural formulas and write common names for the six isomeric ethers
with the molecular formula C5H12O.
21. 1,4-Butanediol, hexane, and 1-pentanol have similar molecular weights. Their
boiling points, arranged from lowest to highest, are 69oC, 138oC, and 230oC.
Which compound has which boiling point?
22. Of the three compounds given in Problem 21., one in insoluble in water, another
has a solubility of 2.3 g/100g water, and one is infinitely soluble in water. Which
compound has which solubility?
23. Show how to prepare each compound from 2-methylcyclohexanol.
O
a)
CH 3
b)
CH 3
d)
CH 3
OH
c)
CH 3
24. The mechanism of the acid-catalyzed dehydration of an alcohol to an alkene is the
reverse of the acid-catalyzed hydration of an alkene. The dehydration mechanism
occurs by the following three steps: Step 1: Add a proton. Step 2: Break a bond
to form stable molecules or ion. Step 3: Take away a proton. These three steps
are illustrated here by the dehydration of 2-butanol to give 2-butene. Use curved
arrows to show the flow of electrons in each step; that is, show how each bondmaking or bond-breaking step occurs.
Step 1:
OH
H+
H O H
H O H
Step 2:
+ H2O
Step 3:
+ H+
and
H
25. Use the reactions we learned in Chapter 3 and this chapter to show how to bring
about the following chemical transformations. Some transformations will require
only one step. Others will require two or more steps.
OH
a)
HO
b)
O
c)
O
d)
O
CH2OH
OH
e)
CH3
f)
OH