ORGANIC - BRUICE 8E CH. 19 - MORE ABOUT...

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ORGANIC - BRUICE 8E

CH. 19 - MORE ABOUT AMINES

CONCEPT: AMINE NOMENCLATURE

The degree of the amine directly determines how it will be named.

1o Amines: Add the suffix –amine is to the name of the alkyl substituent. If the alkyl substituent’s name ends with an –e

replace it with –amine.

EXAMPLE: Name the following 1o Amines.

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If a higher priority functional group is present then the suffix –amine changes into the prefix –amino.

EXAMPLE: Name the following multi-functional amine.

2o and 3o amines: If different alkyl groups are attached the largest alkyl group is chosen as the parent name, and the other

alkyl groups are N-substituents.

EXAMPLE: Name the following amines

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CONCEPT: AMINE AKLYATION

Alkyl halides are susceptible to nucleophilic attack by amines. This mechanism is called ___________

However, this reaction has little synthetic value because multiple alkylations will usually occur:

● The only way to avoid is will excessive amounts of amine.

Amine Polyalkylation Mechanism:

EXAMPLE: Propose a synthesis for the following compound.

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CONCEPT: AMINES BY REDUCTION

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CONCEPT: NITROGENOUS NUCLEOPHILES

Three of the reagents used in amines by reduction can be found as excellent nucleophiles.

● They can participate in __________ reactions when there is a good leaving group present.

□ ____________

□ ____________

□ ____________

Additionally, ________ can act on acid chlorides to produce ___________________ (not an SN2 mech, we’ll get to it later!)

□ ____________

EXAMPLE: Provide the major product for the following reaction.

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CONCEPT: SNAr ADDITION-ELIMINATION MECHANISM

Unlike EAS, where addition is initiated by the presence of a strong electrophile, addition-elimination can also be initiated by

a strong nucleophile in the presence of a good aryl leaving group.

● Reaction has similarities to SN2 but it is not _____________________

● Known as Addition-Elimination Nucleophilic Aromatic Substitution, SNAr or ipso-substitution.

An early method of preparing phenol called the Dow Process used chlorobenzene, NaOH and high heat to force SNAr.

.

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CONCEPT: THE MEISENHEIMER COMPLEX

The Dow Process, a typical SNAr reaction, requires tons of heat and pressure to proceed forward.

● This is due to the instability of the anionic sigma-complex

● Withdrawing groups or Heteroatoms to the Ortho or Para positions (WHOP) stabilize the intermediate

□ A classical trinitrobenzene Meisenheimer Complex can proceed in room temperature

EXAMPLE: Use resonance structures to determine which of the following ipso-substitutions is more favored.

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EXAMPLE: Which of the following compounds will most readily undergo nucleophilic aromatic substitution in the addition-

elimination pathway?

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PRACTICE: Provide the structure and name of the intermediate formed from the reaction of 1-bromo-2,4,6-

trinitrobenzene with one equivalent of sodium methoxide.

PRACTICE: Provide the major organic product for the following reaction.

PRACTICE: Provide the major organic product for the following reaction.

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PRACTICE: Which of the following compounds is most likely to undergo nucleophilic aromatic substitution via the

addition-elimination Pathway?

PRACTICE: Which of the following compounds is most likely to undergo nucleophilic aromatic substitution via the

addition-elimination Pathway?

N

Cl

N

Cl

NN

N+ O

-O

Cl

NN

Cl

N+

O-

O

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CONCEPT: COPE ELIMINATION

Amines are easily oxidized. Tertiary amine oxides have the ability to self-eliminate, favoring a Hofmann Product.

● The tertiary amine oxide, or N-oxide, contains a dative (also known as dipolar) covalent bond.

□ This represents that both electrons came from one atom. Denoted as N → O in some texts

Cope Elimination Mechanism:

EXAMPLE: Predict the product for the following reaction.

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ORGANIC - BRUICE 8E CH. 19 - MORE ABOUT...

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