CHEM 2124
Unit 2
Worksheet 2
1) Why does benzene undergo a substitution reaction with Br2 while cyclohexene
undergoes an addition reaction?
2) Which is more stable, cyclobutadiene or 1,3-butadiene? Explain
3) Is the [10]annulene shown below aromatic? Explain.
4) Classify cyclopentadienyl cation as aromatic, antiaromatic, or nonaromatic. Assume
planarity of the π network
5) Provide the structure of the major organic product which results when phenanthrene is
treated with Br2 in carbon tetrachloride.
6) Provide an acceptable name for the compound below.
7) Provide an acceptable name for the compound below.
8) Provide the structure of m-nitrophenol.
9) Provide the structure of indole.
10) The IR spectrum of m-xylene contains stretches which are characteristic of most
aromatic hydrocarbons. List the peaks (in cm-1) associated with the aromatic C=C stretch
and the aromatic C–H stretch.
11) How many distinct trichlorobenzene isomers are possible?
12) When cyclohexene is treated with KMnO4, H2O, the syn-1,2-diol is produced. What
reaction occurs when benzene is similarly treated?
13) Nitrogen's lone pair electrons occupy what type of orbital in pyridine?
A) s
B) sp
C) sp2
D) sp3
E) p
14) Provide the structure of p-aminobenzoic acid.
15) Which step in an electrophilic aromatic substitution reaction is typically rate
determining, formation of the sigma complex or loss of H+ by the sigma complex to form
the product? Explain.
16) Provide a detailed, stepwise mechanism for the reaction of benzene with Br2 and
FeBr3. Make sure to include the activating reaction between Br2 and FeBr3 in your
mechanism.
17) Under what reaction conditions does the electrophilic chlorination of aromatic
compounds usually occur?
A) Cl2, AlCl3
B) Cl2, H2O
C) Cl2, CCl4
D) NaCl, H2O
E) NaCl, CH3OH
18) In electrophilic aromatic substitution reactions the nitro group is:
A) a m-director since it destabilizes the meta sigma complex more than the ortho, para.
B) a m-director since it destabilizes the meta sigma complex less than the ortho, para.
C) an o,p-director since it stabilizes the ortho, para sigma complex more than the meta.
D) an o,p-director since it stabilizes the ortho, para sigma complex less than the meta.
E) none of the above.
19) Draw the three major resonance structures of the sigma complex intermediate in the
reaction of acetophenone with HNO3/H2SO4 to yield o-nitrotoluene. Circle the
resonance form which is less stable than the other two.
20) Provide the structure of the major mono-nitration product of the compound below.
21) Which of the following compounds will undergo bromination most rapidly using Br2,
FeBr3?
A) p-methylacetanilide
B) bromobenzene
C) acetanilide
D) benzenesulfonic acid
E) dibromobenzene
22) Provide a detailed, stepwise mechanism for the following reactions.
23) Provide the structure of the major organic product of the following reaction.
24) Provide a detailed, stepwise mechanism for the following reaction.
25) Provide a series of synthetic steps by which p-nitrophenol can be prepared from
benzene.
26) Which of the following compounds is least reactive in the nucleophilic aromatic
substitution reaction with NaOH?
A) 2,4-dinitrochlorobenzene
B) m-nitrochlorobenzene
C) o-nitrochlorobenzene
D) p-nitrochlorobenzene
E) 3,5-dinitrochlorobenzene
27) Provide the structures of the major organic products of the following reaction.
28) Provide the structures of the major organic products in the following reaction.
29) Provide the structure of the major organic product in the following reaction.
30) Provide the structure of the major organic product in the following reaction.
31) Provide a series of synthetic steps by which p-methylanisole can be prepared from pcresol.
32) Provide the structure of the major organic product(s) in the following reaction.
33) Which of the following compounds will not undergo Friedel-Crafts acylation when
treated with CH3CH2COCl, AlCl3?
A) toluene
B) p-xylene
C) anisole
D) ethoxybenzene
E) benzophenone
34) Provide the major organic product of the following reaction.
35) Provide the major organic product of the following reaction.
36) Which of the following is an incorrect statement about the bromination of benzene by
Br2 and FeBr3?
A) FeBr3 functions to increase the electrophilicity of Br2.
B) Formation of the sigma complex is the rate-determining step of the mechanism.
C) The carbanionic intermediate is resonance stabilized.
D) There are two carbon-containing intermediates in the mechanism.
E) The final step of the mechanism is loss of H+.
37) Provide the major organic product that results when benzene is treated with the
following sequence of reagents: 1. Br2, FeBr3 2. HNO3, H2SO4.
38) Show how the following product can be made from benzene.
39) Predict the major organic product resulting from the following sequence of reactions.