Chapter 22: Amines

Question 1

Naming simple amines

Primary amines

Answer 1

Replace the suffix “ane” with suffix −yl amine

Question 2

Naming complex amines

Primary amines

Answer 2

1. Identify and name the parent chain that includes the amine group
2. Identify and name substituents
3. Assign locant to each substituent giving the amine carbon the lowest number
4. Assemble substituents alphabetically
5. Assign configurations to any chiral centers
6. Replace “e” with suffix −amine

Question 3

Naming amines with other substituents

Answer 3

When another functional group is present the amino group is generally listed as the substituent

The other functional group takes priority and becomes the suffix

Question 4

Naming secondary and tertiary amines

Answer 4

Question 5

Properties of amines

Answer 5

Due to hydrogen bonding, amines with less than 5 carbons typically water soluble

Primary and secondary amines have higher boiling points than tertiary due to hydrogen bonding

Question 6

Preparing an amine from an alkyl halide with the addition of one carbon

Answer 6

Reagents

1. NaCN
   Followed by
2. LiAlH₄
3. H₂O

Question 7

Preparing an amine from a carboxylic acid

Answer 7

Reagents

1. SOCl₂ (thionyl chloride)
2. excess NH₃
   then
3. LiAlH₄
4. H₂O

Question 8

Preparing an amine from a benzene

Answer 8

Reagents

1. HNO3 (nitric acid) & H₂SO₄
2. Fe or Zn & HCl
3. NaOH

Question 9

Azide synthesis

Answer 9

Reagents

NaN₃ (sodium azide)

Followed by

H₂, Pt
or
1. LiAlH₄
2. H₂O

Mechanism

Converts an alkyl halide to an amine

Question 10

Gabriel synthesis

Answer 10

Reagents

1. Phthalimide
2. KOH
3. H₂NNH₂ (hydrazine) or H₃O⁺

Mechanism

Converts an alkyl halide to an amine

Question 11

Reductive amination

Answer 11

Reagents
NH₃, RNH₂, or R₂NH
&
[H⁺], NaCNBH₃ (sodium cyanoborohydride)

Mechanism

Aldehyde/ketone converted into an imine, then the reduced to the corresponding amine

Question 12

Three methods to synthesize a primary amine

Answer 12

Question 13

Converting a primary amine to a multisubstituted amine

Answer 13

Question 14

Acylation of amines

Answer 14

Reagents

Acid chloride

Mechanism

Converts an amine into an amide

Question 15

Performing Friedel-Crafts reactions with aniline

Answer 15

Question 16

Hofmann elimination

Answer 16

Reagents

1. CH₃I (iodomethane)
2. Ag₂O (silver oxide) , H₂O, heat

Mechanism

Creates an alkene through a Hofmann elimination that favors the least substituted alkene

Question 17

Sandmeyer reaction

Answer 17

Reagents

1. NaNO₂ (nitrous acid) & HCl
2. CuX (copper salt)
   CuBr, CuCl, CuI, or CuCN

Mechanism

Converts aniline to an aryl diazonium salt which can then be converted to a number of products

Question 18

Reactions of aryl diazonium ions

Answer 18

Reagents

HBF₄ (fluoroboric acid)

or

H₂O, heat

or

H₃PO₂ (hypophosphorous acid)

Question 19

Formation of an aryldiazonium salt

Answer 19

Reagents

NaNO₂ (nitrous acid) & HCl

Question 20

Azo coupling

Answer 20

Question 21

Pyrrole

Answer 21

A five-membered aromatic heterocycle ring with one nitrogen

Undergoes EAS faster than benzene; most stable intermediate from substitution at C2

Question 22

Imidazole

Answer 22

A five-membered aromatic heterocycle ring with two non-adjacent nitrogen atoms in meta-substitution

Question 23

Pyridine

Answer 23

A six-membered aromatic heterocycle ring with one nitrogen

Can function as a weak base because the lone pair is not resonance conjugated

Question 24

Pyrimidine

Answer 24

A six-membered aromatic heterocycle ring with two non-adjacent nitrogen atoms in meta-substitution