13. Benzene and its Derivatives

Question 1

Aromatic compound

Answer 1

-benzene or one of its derivative

Question 2

Aliphatic compound

Answer 2

-alkane, alkene, alkyne

Question 3

Arene

Answer 3

-compound containing one or more benzene rings

Question 4

Aryl group

Answer 4

-group derived from arene by removal of a H atom and given the symbol Ar–

Question 5

Michael Faraday (1825)

Answer 5

-discovered benzene (simplest aromatic compound)

Question 6

Friedrich August Kekule (1872)

Answer 6

-proposed first structure for benzene
-six-membered ring with alternating single and double bond

Question 7

Resonance hybrid

Answer 7

-molecule best described as a composite of two or more Lewis structures
-Linus Pauling

Question 8

Aromatic sextet

Answer 8

-closed loop of six electrons (two from the second bond of each double bond) characteristic of benzene ring

Question 9

Monosubstituted alkylbenzenes

Answer 9

-derivatives of benzene (i.e. ethylbenzene)
-usually IUPAC retains common name
-toluene, styrene, phenol, anisole, aniline, benzaldehyde, benzoic acid

Question 10

Phenyl group (Ph—)

Answer 10

C6H5—, the aryl group derived by removing a hydrogen atom from benzene

-in molecule containing other functional groups, phenyl group are often named as substituent
(i.e. 4-Phenyl-1-butene)

Question 11

Two substituents on benzene ring

Answer 11

-3 isomers possible

-locate substituents by either numbering or locators
•ortho (o) 1,2- (Greek straight)
•meta (m) 1,3- (after)
•para (p) 1,4- (beyond)

-when one substituents impart special name to compound (i.e. —CH3, —OH, —NH2, —COOH), name the compound as a derivative of that parent molecule. That substituent occupies number 1
(i.e. 4-bromobenzoic acid, 3-chloroaniline, 1,3-dimethylbenzene)

Question 12

Three or more substituent

Answer 12

-specify locations by numbers
-when one substituents impart special name to compound, name the compound as a derivative of that parent molecule. That substituent occupies number 1
-when none imparts special name, locate substituents before ending benzene

Question 13

Polynuclear aromatic hydrocarbon (PAHs)

Answer 13

-contains two or more benze rings, each of which shares teo carbon atoms with another benzene ring
-imagine honeycomb
-naphthalene, anthracene, phenanthrene

Question 14

Characteristic Reactions of Benzene and its derivatives

Answer 14

-substitution at a ring carbon
(Aromatic substitution)

Question 15

Halogenation

Answer 15

-in the presence of iron catalyst

Benzene + Cl2 ➡️ chlorobenzene

Question 16

Nitration

Answer 16

-heat benzene or its derivatives with mixture of concentrated nitric and sulfuric acid, hydrogen atom bonded to ring is replaced by a nitro (-NO2) group

Question 17

Sulfonation

Answer 17

-heating aromstic compound with concentrated sulfuric acid results to ARENESULFONIC ACID (strong acids)
-preparation of synthetic detergents

Question 18

Phenols

Answer 18

-compound containing –OH group bonded to benzene ring
-named as derivatives of phenols or by common name
(3-methylphenil, 1,2-benzenediol)
-weak acids

Question 19

Autoxidation

Answer 19

-oxidation requiring oxygen and no other reactant
-radical chain proces that converts an R—H group to R—O—O—H group (HYPEROXIDE)

Question 20

Chain length

Answer 20

-number of times the cycle of chain propagation steps repeats