Isomerism in Aromatic Compounds
5.11 There are three isomeric dichlorobenzenes. One compound is nonpolar. Which one?
5.12 The boiling points of benzyl alcohol (C6H5CH2OH) and anisole (C6H5COCH3)) are 205 and 154°C, respectively. Explain this difference.
5.13 There are four isomeric substituted benzene compounds with the molecular formula C8H10. Name each compound.
5.14 There are three isomeric substituted benzene compounds with the molecular formula C6H3Br3. Name each compound.
Nomenclature of Aromatic Compounds
5.15 Identify each of the following as an ortho-, meta-, or para-substituted compound:
(a) methylparaben, a food preservative
HO C
O OCH3
CH3
C O
N(CH2CH3)2 (b) DEET, an insect repellent
5.16 Identify each of the following as an ortho-, meta-, or para-substituted compound:
(a) resorcinol monoacetate, a germicide used to treat skin conditions
O C HO
O CH3
(b) salicylamide, an analgesic
C O NH2
OH 5.17 Name each of the following compounds:
CH2CH3
(a)
CH2CH3
CH(CH3)2
(b) (c)
CH3
CH3 CH3
(a) an antiseptic agent used to treat athlete’s foot (b) a disinfectant OH
CH3
CH3
Cl
OH
Cl 5.19 Name each of the following compounds:
5.18 Name each of the following compounds:
Br (a)
NH2
(b) (c)
CH3
Br OH
Br Cl Cl
5.20 Draw the structure of 3,4,6-trichloro-2-nitrophenol, a lampricide used to control sea lampreys in the Great Lakes.
Exercises 161 5.21 Draw the structure of each of the following compounds:
(a) 5-isopropyl-2-methylphenol, found in oil of marjoram (b) 2-isopropyl-5-methylphenol, found in oil of thyme
(c) 2-hydroxybenzyl alcohol, found in the bark of the willow tree
5.22 N,N-Dipropyl-2,6-dinitro-4-trifluoromethylaniline is the IUPAC name for Treflan®, a herbicide. Draw its structure. (The prefix N signifies the location of substituents on a nitrogen atom.)
Electrophiles and Ring Substituents
5.23 Predict whether –SCH₃ is an activating or deactivating group. Will it be an ortho,para-directing group or a meta-directing group?
5.24 The sulfonamide group is found in sulfa drugs. Is it an activating or deactivating group. Will it be ortho,para-directing or meta- directing?
S NH2
O
O
5.25 What product results from the Friedel-Crafts alkylation of benzene using 1-chloro-2-methylpropane and aluminum trichloride?
5.26 Alkylation of benzene can be accomplished using an alkene such as propene and an acid catalyst. Identify the electrophile and the product.
5.27 Indicate on which ring and at what position bromination of each compound will occur.
N C H O
5.28 Indicate on which ring and at what position nitration of each compound will occur.
CCl3
Isomerism in Aromatic Compounds
5.29 Draw the oxidation product of each compound in Exercise 5.17 when reacted with potassium permanganate.
5.30 Predict the oxidation product of each of the following compounds when reacted with potassium permanganate.
(a) (b) (c)
N
5.31 Free radical bromination of propylbenzene yields essentially one product. What is its structure? Suggest a reason why other isomers are not formed.
5.32 Treatment of allyl benzene with dilute acid causes isomerization to an isomeric compound, Suggest its structure and propose a mechanism for its formation.
Synthesis of Aromatic Compounds
5.33 What reagent is required for each of the following reactions? Will an ortho,para mixture of products or the meta isomer predominate?
(a) nitration of bromobenzene (b) sulfonation of nitrobenzene (c) bromination of ethylbenzene (d) methylation of anisole
5.34 What reagent is required for each of the following reactions? Will an ortho,para mixture of products or the meta isomer predominate?
(a) bromination of benzoic acid (b) acetylation of isopropylbenzene (c) nitration of acetophenone (d) nitration of phenol
5.35 Starting with benzene, describe the series of reagents and reactions required to produce each of the following compounds.
(a) p-bromonitrobenzene (b) m-bromonitrobenzene (c) p-bromoethylbenzene (d) m-bromoethylbenzene
5.36 Starting with benzene, describe the series of reagents and reactions required to produce each of the following compounds.
(a) m-bromobenzenesulfonic acid (b) p-bromobenzenesulfonic acid (c) p-nitrotoluene (d) p-nitrobenzoic acid
5.37 Starting with either benzene or toluene, describe the series of reagents and reactions required to produce each of the following compounds.
(a) 3,5-dinitro-l-chlorobenzene (b) 2,4,6-trinitrotoluene (c) 2,6-dibromo-4-nitrotoluene
5.38 Starting with either benzene or toluene, describe the series of reagents and reactions required to produce each of the following compounds.
(a) 2,4,6-tribromobenzoic acid (b) 2-bromo-4-nitrotoluene (c) 1-bromo-3,5-dinitrobenzene
5.39 Starting with either benzene or toluene, describe the series of reagents and reactions required to produce each of the following compounds.
(a) m-bromophenol (b) m-bromoaniline (c) p-methylphenol
5.40 Starting with either benzene or toluene, describe the series of reagents and reactions required to produce each of the following compounds.
(a) m-bromophenol (b) m-bromoaniline (c) p-methylphenol
5.41 Starting with either benzene or toluene, describe the series of reagents and reactions required to produce each of the following compounds.
(a)
Cl
(b) (c)
Br
Cl
CH3 CH3
Br
Metabolic Oxidation of Aromatic Compounds
5.42 Explain why aromatic hydroxylation of chlorpromazine, an anti-psychotic drug, occurs at the indicated position and in that ring.
S S