Organic 12: Rxns of Arenes - EAS & NAS

Question 0

Nucleophilic aromatic substitution

Answer 0

A reaction in which a nucleophile replaces a leaving group as a substituent on an aromatic ring; substitution mat proceed by an addition-elimination mechanism or an elimination-addition mechanism

Question 1

Electrophilic Aromatic Substitution

Answer 1

Fundamental reaction type exhibited by aromatic compounds; an electrophilic species (E+) replaces one of the hydrogens of an aromatic ring

Question 2

Arenium ion (cyclohexadienyl cation)

Answer 2

Sigma-complex; the carbocation intermediate formed by attack of an electrophile on an aromatic substrate in EAS

Question 3

Friedel-Crafts Reaction

Answer 3

Alkylation of benzene with alkyl halides in the presence of aluminum chloride; one of the most useful synthetic methods in organic chemistry

Question 4

Acyl halides

Answer 4

RC=O

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Question 5

Acylation

Answer 5

Reaction in which an acyl group becomes attached to some structural unit in a molecule

Question 6

Acyl cation (acylium ion)

Answer 6

The cation R-C <triple>O:+</triple>

Question 7

Clemmensen reduction

Answer 7

Most commonly used method for reducing an aryl ketone to an alkylbenzene; employs a zinc-Mercury amalgam in concentrated HCl; zinc is the reducing agent

Question 8

Wolff-Kishner reduction

Answer 8

Another way to reduce aldehyde & ketone carbonyl groups

Question 9

Ortho, para director

Answer 9

A group that when present on a benzene ring directs an incoming electrophile to the positions ortho & para to itself

Question 10

Meta director

Answer 10

A group that when present on a benzene ring directs an incoming electrophile to a position meta to itself

Question 11

Activating

Answer 11

A group that when present in place of a hydrogen causes a particular reaction to occur faster; terms is most often applied to substituents that increase the rate of electrophilic aromatic substitution

Question 12

Deactivating

Answer 12

A group that when present in place of hydrogen causes a particular reaction to occur more slowly; term most often applied to the effect of substituents on the rate of EAS

Question 13

Electron-releasing group

Answer 13

An atom or group that increases the electron density around another atom by an inductive or resonance effect

Question 14

Partial rate factors

Answer 14

In EAS, a number that compares the rate of attack at a particular ring carbon with the rate if attack at a single position of benzene

Question 15

Electron-withdrawing group

Answer 15

An atom or group that decreases the electron density around another atom by an inductive or resonance effect

Question 16

Addition-elimination mechanism

Answer 16

2-stage mechanism for nucleophilic aromatic substitution; in the addition stage, the nucleophile adds to the carbon that bears the leaving group; in the elimination stage, the leaving group is expelled