OXIDATION—REDUCTION REACTIONS AND ORGANOMETALLIC COMPOUNDS
A STUDENT WHO HAS MASTERED THE MATERIAL IN THIS SECTION SHOULD BE
ABLE TO:
1.
Predict the product(s) when given the starting materials and reaction conditions of reactions
of the following types:
Oxidation of 1˚ and 2˚ alcohols using pyridinium chlorochromate (PCC); and of 1˚ and 2˚
alcohols and aldehydes using chromic acid and potassium permanganate.
Reduction of ketones, aldehydes, carboxylic acids, and esters with LiAlH4 and of ketones
and aldehydes with NaBH4 .
Reactions of alkyl and aryl halides with Li and Mg in the presence of ether.
Reactions of alkyllithium reagents with CuI.
Reactions of Grignard reagents and alkyllithium reagents with acids, ethylene oxide,
ketones, aldehydes, and esters.
Reactions of lithium dialkylcuprates with 2˚ cycloalkyl, methyl, and 1˚ alkyl halides
(Corey-House).
2.
Propose syntheses of compounds using the reactions listed in Objective 1 above (also using
reactions from previous modules).
Grignard and alkyllithium reagents react with:
Formaldehyde to give 1˚ alcohols with one more carbon atom than the starting
material.
Ethylene oxide to give 1˚ alcohols with two more C’s than the starting material.
Aldehydes to give 2˚ alcohols.
Ketones and esters to give 3˚ alcohols.
3.
Identify unknowns, and propose methods for identifying unknowns, using simple chemical
tests. New test: Chromic acid (H2 CrO4 or CrO3 /H2 SO 4 ), positive (the red chromic acid
solution gives a green suspension) for 1˚ alcohols, 2˚ alcohols, and aldehydes.
Tests learned previously (which you will need to know) include: Br2 /CCl4 , KMnO4 (cold),
AgNO3 /alcohol, Ag(NH3 )2 +, and solubility in conc. H2 SO 4 . Information about unknowns
may also include IR and NMR data. This also is review from previous chapters.
145
A STUDENT WHO HAS MASTERED THE OBJECTIVES ON THE PREVIOUS PAGE
SHOULD BE ABLE TO SOLVE THE FOLLOWING PROBLEMS AND RELATED ONES:
1.
Predict the product(s) of each of the following reactions (if any).
O
||
b) H-C
Li
Br -------->
ether
O
NaBH4
||
COCH 3 ----------->
c)
C5 H5 NH + CrO3 ClCH2 CH2 OH --------------------------->
a)
O
||
C-H
H3 O +
--------> ---------->
d)
MgBr +
e)
CH2 Li + CH 3 OH --->
O
||
f) (CH3 )2 CHMgBr + CH3 C-OH --->
O
H3 O +
||
g)
MgBr + CH3 C-CH3 --------> ---------->
O
||
H3 O+
h) CH3 CH2 MgBr + H-C-H ---> ------->
O
H3 O+
||
i)
C-OCH 3 --------> ---------->
CH2 MgBr +
j)
2.
Br + LiCu(CH 3 )2
ether
Propose syntheses of each of the following compounds, from the given starting material
and any other needed reagents.
a)
CH2 OH from
O
||
C-OH
146
O
||
b) CH3 CCH3 from CH3 CH=CH 2
c)
OH
|
CHCH 3 from
d)
CH2 CH2 CH2 OH from
e)
CH2 CH2 CO2 H from
Br
CH2 OH
CH3
f) octane from 1-bromobutane
g) octane from 1-butene
147
3.
For these questions, choose the answers from this list of possible compounds.
CH2 OH
CH3
A.
B.
C.
CH2 OH
CH3
D.
O
||
E.
CH2 Br
F.
Br
G.
a) Which of the compounds is soluble in concentrated H2 SO 4 and gives a positive
chromic acid test and a negative Br2 /CCl4 test?
b) Which of them has a peak at 1710 cm-1 in its IR spectrum?
c) Which one is insoluble in concentrated H2 SO 4 and gives negative KMnO4 (cold) and
AgNO3 /alcohol tests?
d) Which of them has both a broad peak at 3400 cm-1 and a peak at 1640 cm-1 in its IR
spectrum?
e) Which one is soluble in concentrated H2 SO 4 and gives negative chromic acid, Br2 /CCl4 ,
and AgNO3 /alcohol tests?
f) Which one is soluble conc. H2 SO 4 , and gives positive chromic acid and Br2 /CCl4 tests?
g) Which one gives a positive test with KMnO4 (cold), a negative test with H2 CrO4 , and a
postive AgNO3 /alcohol test?
h) Which of them has no peaks in its proton NMR spectrum above δ 1.5?
148
ANSWERS TO THE PROBLEMS:
1.
a)
O
||
b) H-C
c)
Br
Li
-------->
ether
(Note that the
equation is not
balanced.)
Li
O
||
NaBH4
COCH 3 -----------> HOCH 2
O
||
COCH 3
C5 H5 NH + CrO3 ClCH2 CH2 OH --------------------------->
O
||
CH2 C-H
O
||
H3 O +
C-H --------> ---------->
d)
MgBr +
e)
CH2 Li + CH 3 OH --->
OH
|
CH
CH3 + CH3 OLi
O
O
||
||
f) (CH3 )2 CHMgBr + CH3 C-OH ---> (CH3 )2 CH2 + CH3 C-OMgBr
O
OH
H3 O +
||
|
g)
MgBr + CH3 C-CH3 --------> ---------->
C(CH3 )2
O
||
H3 O+
h) CH3 CH2 MgBr + H-C-H ---> ---------> CH3 CH2 CH2 OH
O
H3 O +
||
i)
CH2 MgBr +
C-OCH 3 --------> ---------->
OH
|
CH2 CCH2
j)
2.
Br + LiCu(CH 3 ) 2
ether
j)
CH3 + CuCH 3 + LiBr
Syntheses:
a)
O
LiAlH4 acid
||
--------->
------>
C-OH
CH2 OH
149
+ CH3 OH
H3 O+
CH3 CH=CH 2 + H2 O -------> CH3 CHOHCH3
b)
O
H2 CrO4
||
then CH3 CHOHCH3 -----------> CH3 CCH3
O
||
CH3 CH acid
MgBr -----------> ------->
Mg
Br ------->
ether
c)
OH
|
CHCH 3
O
HBr
d)
Mg
CH2 OH --------> -------->
CH2 MgBr ---------->
ether
H3 O+
CH2 CH2 CH2 OH
O
Br2
Mg
CH3 -------> --------> ----------->
light
ether
e)
<
CH2 CH2 CH2 OH
H2 CrO4
CH2 CH2 CO2 H
2 Li
f)
Br
ether
Li
Cu
ether
2
Li
+ LiBr
(CH 3 CH 2 CH 2CH 2) 2 CuLi
HBr
g)
Li
3.
Cu
ether
ether
CH 3 (CH 2 ) 6CH 3
2 Li
Br
peroxides
2
Br
ether
(CH 3 CH 2 CH 2CH 2) 2 CuLi
a) B b) E c) A d) D e) E f) D g) G h) A
150
Li
Br
ether
+ LiBr
CH 3 (CH 2 ) 6CH 3
Name __________________________________________________ Second Drill Test (Sample)
Organic Chemistry 2220
Answer All Questions
1)
Predict the product or products (if any) of each of the following reactions. 5 pts each.
a)
CH2 CH2 OH
PCC
b) (CH3 )2 CHLi
OH
C-O-CH 2 CH3 + NaBH4
||
O
O
||
H2 SO 4
d) CH3 OCH 2 CH2 CH2 CH2 C-H + CrO3
c)
O
||
e) CH3 C-O-CH 2 CH3 + CH3 CH2 MgBr
(excess)
2)
Which of the compounds shown rapidly decolorizes a reddish-brown Br2 /CCl4 solution, is
soluble in concentrated H2 SO 4 , and does not react with chromic acid? 5 points.
OH
3)
OH
Br
Br
Propose a synthesis of each of the compounds shown, from the given starting material and
any other needed reagents. Points: (a) 6, (b) and (c) 7 each.
a) (CH3 )2 CHCH 2 OH from (CH 3 )2 CHCO 2 H
b)
CHCH 3
|
OH
from
c) CH3 CH2 CO2 H from CH3 Br
151
Name __________________________________________________ Second Drill Test (Sample)
Organic Chemistry 2220
Answer All Questions
1.
Predict the product(s) (if any) of each of the following reactions.
a) CH 3 CH 2 -Li + CH 3C
C-H
b) CH 3 CH 2 COOH + CH 3 Li
c)
O
O
C
C
CH3
NaBH4/H2 O
OCH3
O
PCC
d) CH 3 CCH 2 CH 2CH 2OH
O
O
C-OH
e) H-C
2.
CH 2Cl 2
LiAlH 4 , ether
H 2O
Complete the following reactions by filling in the missing reactants(s) or reagents.
OH
O
a) CH3-C
?
O
CH3 CCH2Ph
+ PhOH
CH2 Ph
b)
3.
?
+ CH3Br
ether
CH3CH(CH 3)2
Consider the molecule
CH 2CH 2 OH
Which of the following reagents will not give a positive test with this compound?
A. cold concentrated H2 SO 4
B. CrO3 / H2 SO 4
C. Br2 /CCl4
D. Ag(NH3 )2 +
E. Dilute KMnO4/H2 O
152
4.
Which of these compounds is insoluble in water, gives a positive chromic acid test, and
gives negative Br2 /CCl4 and AgNO3 in alcohol tests?
A. CH 3 CH 2OH
C.
B. HO
CH 3
D. (CH 3 )2CCH 2CH 3
OH
OH
5.
Which of these reactions is a reduction?
A. RCH2 OH
B. RC-H
RCO2 H
RCOOH
D. More than one of these
E. All of these
O
C. RC-H
RCH2OH
O
6.
Propose a synthesis of each of the compounds shown, from the given starting material and
any other needed reagents.
a)
CH 2CH 2 OH from
b) (CH 3 )2CHCH 2 CH 2OH
7.
Br
from (CH 3) 3 CH
Circle each compound which does not give a Grignard reagent when reacted with Mg metal.
A. BrCH 2 C
CH B. CH 3CHCH 2Br
Br
C.
N(CH 3 ) 2
COOH
153
D. CH 3OCH 2CH 2 Br