Download Problem Set 7, KEY

Problem Set 7
1. Name the following alcohols using IUPAC rules. Remember to denote stereochemistry if appropriate!!
OH
Cl
OH
OH
(3S,4S)-4-chloro-6-methyl3-heptanol
5-tert-butyl-3-isopropylcycloheptanol
(3S,5R)-4-ethyl-5-methyl-3-heptanol
2. Draw structures of the following alcohols.
(1R,3R)-3-bromocyclopentanol
HO
5-sec-butyl-6-fluoro-2-methyl-1-nonanol
cyclobutanol
OH
Br
OH
F
3. Draw all possible products of the following dehydration reaction. If more than one product can be formed,
label the MAJOR isomer.
In the space below, draw out the complete mechanism to account for formation of the MAJOR product.
Also, what is the alternative set of reagents we can use to dehydrate an alcohol?
alternate reagents?
OH
H2SO4
POCl3, pyridine
Major
1 4. Reactions that proceed via a carbocation intermediate (SN1 and E1) can give unexpected products. Please
consider the following example:
H2SO4
H2O
OH
+
minor
expected,
but not
observed
major
observed products
How? When you form a carbocation intermediate, they can rearrange to form a more stable carbocation.
Mechanism:
H+
+ H2O
OH
OH2
2o
1,2 Alkyl Shift
H
H2O
H2O
H
3o
5. Propose a mechanism for formation of the following products:
Br
HBr
Br
expected,
but not
observed
OH
H
H Br
+ H2O
OH
OH2
2o
1,2 Hydride Shift
Br
Br
H
3o
2 6. The following reaction is a "ring expansion" rearrangement. Please account for both products.
H3PO4
OH
+
H2O
OH
H+
OH2
H
H 2O
H
H 2O
7. Provide a mechanism for the following transformation:
H2SO4
H 2O
OH
H+
OH
OH2
H
H 2O
8. Provide a mechanism for the following hydride shift:
OH
Br
HBr
OH2
OH
H Br
Br
H
Br
3 9. Draw the major organic product in the box for each reaction. Br
O
2HBr
Br
Br
williamson ether
synth
Cl
O
POCl3
pyridine
NaH
Br
O
SOCl2
OH
HBr
H2SO4
HCl
(CHP10)
PBr3
Cl
Br
E2, bulky base
OH
H2O, H+
CHP 10
SN2 only- tertiary
OH
OH
4 Br
O
O
SN1
mechanism?
H-I
NaH
OH
I
I
SOCl2
SN2 and SN 1
PBr3
mechanism(s) for the
above reaction?
Cl
Br
KOC(CH3)3
E2
mechanism?
HCl
Cl
5