Chm 222
Spring 2015, Exercise Set 6
Reactions of the C-C π Bond
Mr. Linck
c
Boniface
Beebe Productions
January 19, 2016
Version 2.0.
Note: Problems that continue from the previous one are marked with an asterisk.
6.1. Learning Organic Chemistry
Review your notes from the last lecture. Summarize the subjects that were covered.
Present that summary to another student in the class.
6.2. Nomenclature
Name the alkenes 1 and 2.
6.3. NMR
A compound of formula C3 H4 Cl2 has a 1 H nmr with peaks at 1.8 δ(d, 3) and 5.9 δ(q,
1). What is the compound?
6.4. Heat of Formation
What is the heat of formation? HINT: The name answers it all if you only know
“formed from what”?
6.5. Stability of Alkenes
Here is a list of alkenes along with their heat of formation: (E)-2-heptene, -74.2
kJ/mole; (Z)-2-heptene, -70.7; (E)-3-heptene, -73.2; (Z)-3-heptene, -69.4; (E)-3-methyl3-hexene -76.9. For each, draw the Lewis structure and compute the heat of combustion. Rationalize your results. HINT: The heat of formation of CO2 is -393.5 kJ/mole
and that of H2 O is -241.8 kJ/mole.
6.6. Stability of Alkenes
Order the alkenes 3, 4, and 5 in terms of increasing stability.
6.11
2
6.7. E,Z Nomenclature
It the two groups of highest priority on each end of an alkene are on z same side,
which isomer is it?
6.8. E,Z Nomenclature
Draw the isomers of 2-methyl-2,4-hexadiene and name them.
6.9. Structure of Alkenes
Give the structure of (Z)-1-bromo-1,2-difluoroethene and of (E)-1-chloro-3-ethyl-4methyl-3-heptene.
6.10. NMR
A compound of formula C10 H20 has a 1 H nmr with peaks at 5.30 δ(s, 1) and 0.97 δ(s,
9). What is a possible structure for the compound?
6.11. NMR
A compound of formula C5 H8 O2 has a 1 H nmr with the following peaks at 2.08 δ(s,
3), 4.57 δ(d, 2), and a collections of peaks in the region of 5.2 δ(g, 1)and 5.9 δ, (g, 2).
The former looks like four peaks of equal intensity; the exact positions are 5.18, 5.20,
5.22, and 5.25 δ. The latter is garbage, but there is some hint that it is a collection
of triplets, such as a doublet of triplets, or a doublet of doublet of triplets. What is
the compound and how do you rationalize the peaks? HINT: It is relatively easy to
Chm 222, Section 1
Exercise Set 6
6.23
3
Hydrogen type
geminal
cis
trans
J in cps
0 to 3
8 to 12
14 to 16
Table 1: Splitting constants for hydrogens on alkenes.
get the compounds structure. Understanding this relatively complicated nmr is more
useful. Pay attention to Table 1.
6.12. E,Z Nomenclature
Is compound 6 (E) or (Z)?
6.13. E,Z Nomenclature
Is compound 7 (E) or (Z)?
6.14. Alkene Stability
Which is more stable, 1-methylcyclohexene or 8?
6.15. Reactions
The alcohol 9 is dehydrated in strong acid with removal of the product. What is the
product? Why?
6.16. Review the Questions One Asks in a Retrosynthetic Analysis
What are the questions you ask in order to do a retrosynthetic analysis?
6.17. Alkenes as Nucleophiles
What aspect of bonding allows alkenes to act as nucleophiles?
6.18. Carbon Level and Alkenes*
What is the carbon level of an alkene?
6.19. Carbon Level and Alkenes as Nucleophiles**
What happens to the carbon level when an alkene attacks H+ ?
6.20. Alkenes as Nucleophiles***
At what site does the positive charge reside after an alkenes has acted as a nucleophile?
6.21. Alkenes as Nucleophiles****
If Br– reacts with the carbocation to complete the reaction, what happens to the
carbon level?
6.22. Retrosynthetic Analysis
Starting with 2-methyl-3-pentanone, how would you make 2-methyl-2-pentene?
Chm 222, Section 1
Exercise Set 6
6.33
4
6.23. Regioselective Reactions
If 2-pentanone is treated with methyl magnesium bromide followed by strong acid
with removal of the product, what is that product? Be regioselective.
6.24. Mechanism for Alkenes Acting as Nucleophiles
When alkenes act as nucleophiles, what is the difference between the process when
the electrophile is H+ and when the electrophile is anything else?
6.25. Stereochemistry*
What is the difference in stereochemistry for the two kinds of reactions outlined in
the last problem?
6.26. Stereoselective Reactions
Use epwa to show that the addition of Br2 to cyclohexene produces trans-1,2-dibromocyclohexane.
What is the conformation of this material? Is it a chiral molecule? Is it a single enantiomer?
6.27. Stereochemistry and Reactions
Determine the stereochemistry (R or S at each chiral center) of the addition of Cl2
to (E)-2,3-difluoro-2-butene.
6.28. Stereochemistry and Reactions*
Is the product in the last problem a racemic mixture, a diastereomeric mixture, or a
meso compound?
6.29. Synthesis and Diastereomers**
How could you prepare a diastereomer of the product of problem 27?
6.30. Stereochemistry and Enantiomers
Is it possible to produce a single enantiomer from a reaction between an alkene and
Br2 ? HINT: I am looking for the general answer but pay attention to a specific
exception to it.
6.31. Stereochemistry and Reaction*
(E)-2-pentene is treated with Br2 . What is the product? Pay attention to stereochemistry.
Chm 222, Section 1
Exercise Set 6
6.39
5
6.32. Rearrangement
Which of the cations 70-73 are likely to show a proton migration? Why?
6.33. Rearrangement
Which of the cations 70-73 are likely to show a methyl migration?
6.34. Spectroscopy
A compound with IR: 3211, 1643 cm−1 and 1 H nmr 1.011 δ(s, 4.5), 4.820 δ(g, 0.48),
4.926 δ(g, 0.51), and 5.834 δ(d of d, J values of 17.5 and 10.4, 0.5) is treated with
HBr. The product has no interesting IR peaks, but shows a 1 H nmr of 1.08 δ(d, 12),
1.76 δ(s, 12), and 1.85 δ(heptet, 2). What are the molecules?
6.35. Reaction Mechanism*
Use epwa to show the mechanism of the reaction in the last problem. HINT: Remember that hydrogen ion does not “bridge” effectively.
6.36. Reactions and Mechanism
Compound 10 is treated with Br2 in a non-aqueous solution in the presence of a large
amount of tetraethylammonium chloride. What is (are) the product(s)? HINT: The
tetraethylammonium cation is a spectator ion.
6.37. Regioselectivity and Reactions
What is the product of the reaction of propene with ICl? HINT: Think about the
mechanism to get the right answer. However, before you go on, try to establish what
issue I am worried about?
6.38. Synthesis
Which alkenes can be used to produce 1-bromo-1-methylcyclopentane? HINT: Notice
the tense of the first noun.
Chm 222, Section 1
Exercise Set 6
6.52
6
6.39. Synthesis*
How would your answer to the last problem differ if you used DBr and you wanted
the D on the methyl group?
6.40. Synthesis**
How would you prepare the alkene that is your answer to the last problem?
6.41. Mechanism and the Nucleophilic Part of Attack of Alkenes
Show the mechanism and stereochemistry of the addition of (dilute) Br2 in methanol
to 1-methylcyclohexene.
6.42. Regioselectivity and Reaction
Compound 11 is treated with (dilute) Br2 in ethanol. What is(are) the product(s)?
6.43. Learning Organic Chemistry
Review your notes from the last lecture. Summarize the subjects that were covered.
Present that summary to another student in the class.
6.44. Mechanism
Use epwa to show the mechanism of reaction of 1-butene in aqueous acid where the
anion of the acid is a poor nucleophile.
6.45. Synthesis
How would you prepare 12 from an alkene?
6.46. Reactions
What would be the product if you treated 8 with ICl?
6.47. Stereoselective Synthesis
How would you prepare (4R),(5S)-4,5-dibromooctane?
6.48. Stereoselective Synthesis*
In the last problem, you should be worried about getting an (apparently) chiral
compound from achiral starting materials. What is the answer to that worry?
6.49. Stereoselective Synthesis**
How would you prepare a racemic mixture of (4R),(5R)-4,5-dibromooctane and (4S),(5S)4,5-dibromooctane?
6.50. Mechanism
What is the product when 13 is treated with acid (with removal of product or water)?
Use epwa.
6.51. Mechanism
Use epwa to show the mechanism of the reaction of 2-methyl-2-pentene with H+ in
methanol.
Chm 222, Section 1
Exercise Set 6
6.63
7
6.52. Mechanism
Show the product when HBr is added to 1-phenyl-1-propene. Use epwa.
6.53. Mechanism
When Br2 is added to trans-2-butene in CH3 OH saturated with LiCl, three products
are found. Use epwa to show what they are. HINT: This is NOT a stereochemical
problem.
6.54. Mechanism
Use epwa to show what happens to 2-methyl-1-pentene when reacted with Hg(OAc)2
followed by BH–4 . HINT: Do not epwa the BH–4 step.
6.55. Reactions
Show the product(s) of the reaction of 3-methyl-cyclopentene with Hg(OAc)2 in
methanol, followed by treatment of the product with BH–4 in methanol.
6.56. Mechanism
Explain how 14 is converted to 15 by treatment with Hg(OAc)2 in a non-nucleophilic
solvent followed by treatment with BH–4 .
6.57. NMR and Mechanism
The natural philosopher of rural Arkansas, the wonderful Boniface Beebe, had a
bottle of 2,3- dimethyl-1-butene; he ran the 1 H nmr and found a rather complicated
spectrum. Predict what he saw in that spectrum.
6.58. NMR and Mechanism*
Boniface Beebe took the 2,3-dimethyl-1-butene and reacted it with H+ in a dry
medium without any good nucleophile. He was completely befuddled when he isolated a material with a single 1 H nmr signal at 1.64 δ and 13 C nmr signals at 123 δ
and 18.9 δ . Use epwa to show Bonnie what happened.
6.59. Mechanism
Styrene, phenylethene, is treated with H3 PO4 , an acid whose conjugate base is a poor
nucleophile . The product has a M+ of 208 and shows no peaks in the 1 H nmr between
4 δ and 6 δ. Use epwa to show what happened.
6.60. Reactions
What product is formed when 1-butene is treated with (1) BH3 · THF; (2) H2 O2 in
base; (3) H+ ?
6.61. Mechanism and Reactions
Compound 16 is treated with (1) BH3 · THF; (2) H2 O2 in base; (3) H+ . What is the
product? Use epwa.
Chm 222, Section 1
Exercise Set 6
6.67
8
6.62. BBN
If we haven’t covered it in class, determine the structure of BBN. This reagent is very
good at putting a hydroxyl group on the terminal end of an alkene. Why?
6.63. Reactions*
BBN is reacted with 3-hexene and then treated with basic peroxide and acid. What
is the product? HINT: BBN can be used (more conveniently) in place of BH3 · THF.
6.64. Reactions
BBN is reacted with 18 and then treated with basic peroxide and acid. What is the
product? HINT: See last problem.
6.65. Hydroboration
What property of H2 O2 makes it very useful for removing a boron from a carbon
skeleton?
6.66. Boron Addition and Leaving Groups*
Because of the weakness of the O-O bond in peroxide, OH– is a reasonable leaving
group. After BH3 has attacked an alkene, the C-B bond is ruptured after attack
by H2 O2 by a rearrangement driven the good leaving group. Use epwa to show this
process.
Chm 222, Section 1
Exercise Set 6
6.75
9
6.67. Boron Addition and Leaving Groups**
Presumably any reagent that can act as a nucleophile and has a good leaving group
can play the role of the H2 O2 in the last problem. Use epwa to show how NH2 Cl can
do this. What is the good leaving group?
6.68. Boron Addition and Leaving Groups***
Use epwa to show how NH2 OSO–3 , which is called hydroxylamine-O-sulfonic acid, can
replace NH2 Cl of the last problem. What is the good leaving group?
6.69. Synthesis
Show how to synthesize 3-cyclohexyl-propylamine from 17.
6.70. Mechanism and Predictive Thinking
When 19 is treated with formic acid, HC(O)OH, 20 is formed. Use epwa to suggest
a mechanism for this reaction. HINT: A carboncation acts as an electrophile in the
process.
6.71. Mechanism
Arkansas’s great natural philosopher, Boniface Beebe, better known to his friends as
Bonnie, tried to make 22 from 21. He used the three steps:
a. Treat 21 with Mg to give 23.
b. Treat 23 with pentanal followed by dilute acid to give 24.
c. Treat 24 with concentrated HCl to yield 22.
Use epwa to show the mechanism of what happens during these steps. The last failed
to give what Bonnie wanted. What did happen? HINT: You are to figure out what
23 and 24 are.
6.72. Learning Organic Chemistry
Given what you now know, what advantage does a Wittig reaction have over acid
catalyzed dehydration of an alcohol for making an alkene?
6.73. Odd Reaction
Boniface Beebe, the most famous of the natural philosophers from rural Arkansas,
reacted cyclopentyl-ethene with HBr. The 1 H nmr of the product clearly showed the
presence of an ethyl group, and there were no signals indicating a proton strongly
deshielded by a bromine atom. “Great leaping green iguana,” he bellowed. “What
happened?” Indeed.
6.74. Odd Reaction
When 1,3,6-trimethyl-1,3-cyclohexadiene is treated with HBr two products each containing a single bromine atom are obtained. What are the products? Use epwa to
explain. HINT: Be sure you look for ways to stabilize any intermediate.
Chm 222, Section 1
Exercise Set 6
6.88
10
6.75. Regioselectivity and Reactions
Three hydration reactions of (E)-2-phenyl-3-methyl-3-hexene are carried out. The
first with sulfuric acid in water; the second with Hg(OAc)2 followed by BH–4 ; and
the third with BH3 · THF followed by basic peroxide and then acid. Give the three
products; use epwa to show details of the reactions, including the peroxide cleavage
of the B-C bond.
6.76. Retrosynthetic Analysis
How would you prepare butanal from 1-butene?
6.77. Synthesis of Epoxides
Can you make an epoxide from an aldehyde or ketone? Show how.
6.78. Synthesis of Epoxides*
Can you make an epoxide from an alkene? Show how.
6.79. Reactions
Use epwa to show the product of reaction of 18 with MCPBA followed by treatment
with ethyl magnesium iodide and then weak acid.
6.80. Synthesis
How would you synthesize 25 from 18?
6.81. Retrosynthetic Analysis
How would you prepare 26 from 27 and other carbon containing compounds?
6.82. Retrosynthetic Analysis
How would you prepare 26 from 3-cyclohexyl-2-pentene and other carbon containing
compounds?
6.83. Synthesis and Predictive Thinking
How would you prepare 28 from ethanoic acid?
6.84. Chirality
Is 2,3-dimethyl-2-pentene chiral?
6.85. Reaction and Stereochemistry*
Show that formation of the epoxide of the alkene in the last problem, followed by
attack with AlH–4 gives a racemic mixture (as it must).
6.86. Stereochemistry and Reaction
Cyclohexene is treated with MCPBA to form A, which is isolated. The compound A
is then treated with ethyl Grignard, followed by water and H+ . Is the final product
cis or trans? Use epwa to show the mechanism.
6.87. Synthesis
How would you make the alcohols 29-32 from alkenes? HINT: See the next problem.
Chm 222, Section 1
Exercise Set 6
6.95
11
6.88. Reactions*
Depending on your choice of method, you may have a difficulty with the last compound in the last problem. What would that difficulty be? How could you make it
efficiently from an alkene?
6.89. Learning Organic Chemistry
Review your notes from the last lecture. Summarize the subjects that were covered.
Present that summary to another student in the class and ask for criticism.
6.90. Mechanism
When 33 is treated with acid, one isolates 34. Use epwa to suggest a mechanism.
6.91. Rearrangement
When HBr reacts with 35 one obtains a cyclohexane derivative. Use epwa to predict
the product and to explain why it forms.
6.92. Reactions
When 36 is treated with acid, it forms a cyclic compound. Show using epwa.
6.93. Reactions
What are the products of ozonolysis (followed by treatment with Zn) of 37?
6.94. Reactions
Compound 38 is the result of ozonolysis (followed by H2O2 treatment). What is the
original alkene?
Chm 222, Section 1
Exercise Set 6
6.102
12
6.95. Reactions
Give the product when 39 is hydrogenated over Pd (C); show stereochemistry.
6.96. Reactions
Determine the product when 40 is reduced over Pd(C) by H2 .
6.97. Synthesis and Stereochemistry
How would you prepare the cis-1,2-diol and the trans-1,2-diol of cyclohexane starting
with cyclohexene.
6.98. Synthesis
How would you prepare 41?
6.99. Reaction
What would be the product(s) of 41 with BH·3 THF followed by basic peroxide and
then dilute acid?
6.100. Synthesis
How would you prepare 42 from 43?
6.101. Reactions and Predictive Thinking
Use O2 H– , the anion of hydrogen peroxide, to attack the β position of an α,β unsaturated ketone. Show using epwa that the enolate anion product can produce an
epoxide. HINT: Write the enolate anion in the “negative charge on carbon resonance
form” and note that OH− is a good leaving group from a peroxide linkage due to the
weakness of the O-O bond.
Chm 222, Section 1
Exercise Set 6
6.113
13
6.102. Retrosynthetic Analysis
How would you prepare 44 from compounds with three carbon atoms or less?
6.103. Predictive Thinking
Although somewhat slow, the addition of BH3 · THF is reversible. Use epwa to show
how 5-decene allowed to stand in the presence BH3 · THF for a time might yield
4-decene.
6.104. Predictive Thinking*
Use epwa to show how 5-decene allowed to stand in the presence BH3 · THF for a
long time might yield 1-decanol when treated with hydrogen peroxide. HINT: As
always, think about what drives that reaction; in this case, those thoughts are a
trivial exercise.
6.105. Reactions and Spectroscopy
When 36 is treated with Hg(OAc)2 and then BH–4 in a non-nucleophilic solvent one
obtains a compound with no broad strong peak in the 3000-3500 cm−1 region of the
IR. The compound has a M+ of 114 and contains only C, H, and O. Use epwa to
account for these facts.
6.106. Reactions
What is the product when 1-methyl-cyclopentene is treated with O3 followed by
H2 O2 ?
6.107. Stability of Carbocation Intermediate
Where will the charge reside on the carbocation intermediate when HCl reacts with
propene?
6.108. Stability of Carbocation Intermediate*
Which cation will be more stable, that formed on a tertiary carbon or that formed
on a carbon attached to two other CH3 groups and a bromine? Why?
6.109. Reactions and Predictive Thinking**
What do you predict is the product of HCl reacting with 1-bromopropene? Use epwa
to justify.
6.110. Synthesis
Starting with propene and cyclopentanone, how would you prepare 45? HINT: Pay
attention to regioselectivity in the steps.
6.111. Stereochemistry
One can use D2 instead of H2 in hydrogenations. What would the product be if
cyclohexene were treated with D2 over Pd(C)? Specify stereochemistry.
Chm 222, Section 1
Exercise Set 6
6.122
14
6.112. Reactions
What products would you find from treatment of 49 with O3 , followed by reaction
with Zn?
6.113. Reactions
What product(s) would you find if you treated 49 with H2 O2 with OsO4 catalyst?
Specify stereochemistry. HINT: OsO4 is expensive; the same reaction occurs with the
mixture given in this problem as with pure OsO4 .
6.114. Base Catalyzed Elimination
Use epwa to see if you can figure out how 2-bromobutane might form 2-butene when
treated with a base, (CH3 )3 CO– . HINT: This reaction requires specific stereochemistry that you will learn next semester.
6.115. Using Carbon Level to Understand*
What is the carbon levels of 2-bromobutane? What are the carbon levels of 2-butene?
What are the carbon levels of 2,3-dibromobutane? What are the carbon levels of 2butyne?
6.116. Synthesis**
Starting with 2-pentene, prepare 2-pentyne.
6.117. Molecular Identification by Reactions and NMR
A compound, X, that absorbs two moles of H2 per mole of compound under catalytic
hydrogenation conditions. The compound also reacts with O3 followed by H2 O2 . One
product that is isolated is oxalic acid. The other has the following nmr data: 1 H: 2.19
δ(s, 18); 2.71 δ(s, 11.9). 13 C: 29.76 δ(q), 36.96 δ(t), 206.87 δ(s). What is X? Give
your reasoning.
6.118. Molecular Identification by Reactions and Formula
A compound, Y, of formula C10 H18 O reacts with acid (with removal of water) to give
two alkenes, both with formula C10 H16 . The major product, 48, is treated with ozone
followed by Zn, to give only cyclopentanone. What is 48? What is its isomer? What
is Y?
6.119. Synthesis*
How would you prepare compound Y from the last problem starting with cyclopentene?
6.120. Alkyne Reactions
What is the product of reaction of 1-hexyne with excess HCl?
6.121. Alkyne Reactions
What is the product of reaction of 1-hexyne with excess HClO4 in water? HINT:
HClO4 is a very strong acid.
Chm 222, Section 1
Exercise Set 6
6.136
15
6.122. Alkyne Reactions
Give the product of treatment of 3-heptyne with Br2 .
6.123. Synthesis
How would you convert trans-5-decene to cis-5-decene. HINT: It takes more than one
step.
6.124. Reactions
What is the product when 3-cyclopentyl-1-propyne is treated first with BBN and
subsequently with basic peroxide and then acid?
6.125. Reactions
What reagent would you use to convert 2-bromopropane to propene?
6.126. Reactions*
What reagent would you use to convert propene to 1,2-dichloropropane?
6.127. Reactions**
What reagent would you use to convert 1,2-dichloropropane to propyne?
6.128. Reactions***
What reagent would you use to convert propyne to 2-butyne?
6.129. Reactions****
What reagent would you use to convert 2-butyne to butanone?
6.130. Reactions
What reagent would you use to convert 2-butyne to (Z)-2-butene?
6.131. Reactions
What reagent would you use to convert 2-butyne to (E)-2-butene?
6.132. Synthesis
How would you prepare 46 from 47?
6.133. Reactions
What reactions would you use to convert 2-butyne to 49? HINT: You may use any
compounds you wish, including ones with lots of carbon atoms.
6.134. Reduction of a Double Bond
In this and the following three problems we work with the following acids: maleic acid,
50, fumaric acid, 51, and tartaric acid, 52. Show how to carry out the transformation
of 50 to (2R,3S)-52, which is the same as (2S,3R)-52, i.e., a meso compound.
6.135. Reduction of a Double Bond*
How would you convert 50 to (2R,3R)-52 and (2S,3S)-52.
Chm 222, Section 1
Exercise Set 6
6.141
16
6.136. Reduction of a Double Bond**
How would you convert 51 to (2R,3S)-52, which is the same as (2S,3R)-52, a meso
compound.
6.137. Reduction of a Double Bond***
How would you convert 51 to (2R,3R)-52 and (2S,3S)-52.
6.138. Reactions
The great natural philosopher from Beebe, Arkansas, “jus’ down the road a little”
from Conway, Boniface Beebe, tried to make 53 from 54. He used MCPBA followed
by OH– and then H+ . Was he successful? Why or why not? If not, what did he
obtain?
6.139. Synthesis*
How would you prepare 53 from 54?
6.140. Reactions
A marine algae converts 55 into 56. The first step of this process involves an enzyme
that adds “Br+ ” to a double bond of 55. Presumably, the enzyme has structural
components that allow a specific double bond in 55 to be converted into a “bromonium
ion”. Given that, outline the remaining steps that occur in the conversion.
Chm 222, Section 1
Exercise Set 6
6.154
17
6.141. NMR and Synthesis
A compound of formula C7 H12 has nmr data as follows: 1 H: 0.903 δ(d, 6), 1.42 δ(q,
2), 1.65 δ(g, 1), 1.912 δ(t, 1), 2.18 δ(t of d, 2); 13 C: 16.46, 22.14, 27.19, 37.56, 68.01,
and 84.63 δ. What is the compound? How would you prepare it from three carbons
or less? HINT: This is a somewhat challenging question.
6.142. Reactions
Suggest a mechanism (use epwa) for the conversion of 57 into 58 when 57 is treated
with Hg(OAc)2 . HINT: Don’t let a stable carbocation be replaced by an less stable
one.
6.143. Reactions
Reaction of 2-hexyne with acidic water is a method of preparing 3-hexanone. Use
epwa to show how.
6.144. Thinking Organic Chemistry*
The method used in the last problem is not very efficient. Why not?
6.145. Synthesis
How would you prepare 2,7-dimethyl-3-octanone from substances with four carbons
or less?
6.146. Synthesis
How would you prepare 59 from 60?
6.147. Synthesis
How would you prepare (E)-3-heptene from 3-heptyne?
6.148. Reactions and Extended Organic Thinking
Give a mechanism by which 62 can be prepared from 61 using Br2 in water. HINTS:
(1) This is “new” chemistry in a sense, but you should be able to use your experience
to do the problem. (2) Need I say this late in the course, “use epwa.”
6.149. Reaction with MCPBA
What will be the product of 1-methyl cyclohexene with MCPBA.
6.150. Reactions*
What happens to the product of the last problem if it is reacted with HBr?
6.151. Reactions*
What happens to the product of problem 149 if it is reacted with SCH–3 ?
6.152. Reactions
What is(are) the product(s) of the attack of HBr on 3,3-dimethyl-1-butene?
6.153. Synthesis
How would you make 1-bromo-3,3-dimethylbutane from 3,3-dimethyl-1-butene?
Chm 222, Section 1
Exercise Set 6
6.154
Chm 222, Section 1
18
Exercise Set 6
6.154
Chm 222, Section 1
19
Exercise Set 6
6.164
20
6.154. Synthesis
How would you synthesize 63 from 1-butanol as your only source of carbon atoms?
HINT: Remember, you can’t make a primary carbocation; see problem 114.
6.155. Epwa and Mechanism
Use epwa to show how 64 is converted to 65 in acid solution.
6.156. Epwa
Show how addition of Br2 to 66 can form 67.
6.157. A Review of the Course
Give three different ways of making 2-bromo-3-methylbutane from substances with
five carbons.
6.158. A Review of the Course
Give two different ways of making the epoxide of 1-methylcyclohexene. HINT: I think
we only have two ways of making epoxides, so the issue here is really only one of what
are the starting materials.
6.159. A Review of the Course
Give four different ways of making butanal.
6.160. Synthesis
How would you make N-methyl-N-butyl amine from butyric acid and other compounds.
6.161. Thinking About Organic Chemistry
A compound, call it D, is treated with methyl-Grignard followed by acid. The products are butanol and tertiary butanol. What is D, the original compound?
6.162. Synthesis
How would you prepare 68 starting with propene as your only source of carbon?
6.163. Reaction Mechanism
When 3-bromo-cyclopentene is reacted with HBr, the only product is trans-1,2dibromo-cyclopentane (a racemic mixture, obviously). Account for this result.
6.164. Epwa and Mechanism
The following reaction occurs. Use epwa to show the mechanism. Be sure that you
indicate the role of the proton. Comment on why this process is efficient.
Chm 222, Section 1
Exercise Set 6
6.164
Chm 222, Section 1
21
Exercise Set 6