Ch. 24

Question 1

Amines

Answer 1

Organic derivative of ammonia

Question 2

Are arylamines and heterocyclic amines or alkylamines more basic? Why?

Answer 2

Alkylamines are more basic b/c the nitrogen lone-pair electrons are delocalized by interation with the aromatic pi system and resonance stabilization is lost when protonated

Question 3

Heterocyclic Amines

Answer 3

Compounds with one more nitrogen atoms as part of a ring

Question 4

How are alkylamines prepared?

Answer 4

1. SN2 reaction of ammonia/amine with an alkyl halide

2. Gabriel Amine Synthesis

Question 5

Reductive Amination Reaction

Answer 5

Ketone/aldehyde is treated with amine in the presences of a reducing agent. (ex. NaBH4)

Question 6

What are amines a result of?

Answer 6

Hofmann and Curtius rearrangements of carboxylic acid derivatives

migration of the -R group bonded to the carbonyl carbon to yield a product that has one less carbon atom than the starting material

Question 7

Hofmann Elimination

Answer 7

E2 elimination of amines to yield alkenes

1. Quaternized treatment with iodomethane (CH3I)
2. Heated with silver oxide (Ag2O)

Question 8

Diazotization

Answer 8

Conversion of arylamines with nitrous acid into arenediazonium salts (ArN2+X-)

Question 9

Sandmeyer Reaction

Answer 9

Replacement of diazonio group with other subsitutents to give variety of substitued aromatic compounds.

Question 10

Diazonium Salts undergo? What is the result?

Answer 10

Coupling with phenols and arylamines; brightly colored azo compounds

Question 11

What common function group is the most abundant and have the richest chemistry?

Answer 11

Amines

Question 12

Are amines basic or nucleophilic? Why?

Answer 12

Both; due to the domination of the lone-pair electrons on nitrogen

larger the Kb; smaller the pKb= stronger the base; weak acid ~vice versa
larger the Ka; smaller the pKa= weaker the base; strong acid~ vice versa

Question 13

How does electron-withdrawing substituents affect substitued aniline? What about electron donating substituents?

Answer 13

EWS = weaken the basicity
EDS = increase basicity

Question 14

Are alkylamines basic or acidic?

Answer 14

Basic; pH=7.3; exist almost entirely in their protonated form

Question 15

Saturated Heterocyclic Amines vs Unsaturated Heterocyclic Amines

Answer 15

Saturated have the same chemistry as their open-chain analogs
Unsaturated are aromatic; (ex. imidazole, pyridine, and pyrimidine)
Amides (ex. pyrrole) are nonbasic b/c all electrons are used in bonding

Question 16

How are arylamines prepared?

Answer 16

1. Nitration of an aromatic ring

2. Reduction

Question 17

What are reductive methods of amines?

Answer 17

LiAlH4 reduction of amides, nitriles and azides

Question 18

Amines Reactions

Answer 18

1. SN2 reaction with alkyl halides
2. Nucleophilic acyl substitution with acid chlorides
3. Hofmann Elimination; E2 Elimination

Question 19

What can be prepared from arenediazonium salts?

Answer 19

Aryl chlorides, bromides, iodides, and nitriles

Question 20

Reduction of nitriles reagents

Answer 20

1. NaCN or

2. 1.LiAlH4,ether 2. H2O

Question 21

Reduction of amides reagents

Answer 21

1. LiAlH4, ether

2. H2O

Question 22

Reduction of nitrobenzenes reagents

Answer 22

1. H2, Pt or
2. Fe, H3O+ or
3. SnCl2, H3O+

Question 23

SN2 Alkylation of alkyl halides reagent

Answer 23

NaOH

Question 24

SN2 Alkylation of alkyl halides reactants/products

Answer 24

Ammonia –> Primary
Primary –> Secondary
Secondary –> Tertiary
Tertiary –> Quarternary ammonium

Question 25

Gabriel Amine Synthesis reagents

Answer 25

1. 1. KOH 2. R-X | 2. NaOH, H2O

Question 26

Reduction of Azides reagents

Answer 26

1. Na+ -N3, ethanol | 2. 1. LiAlH4, ether 2. H2O

Question 27

Reductive Amination reagents

Answer 27

NH3, NaBH4/NaBH(OAc)3

Question 28

Hoffman Rearrangement reagents

Answer 28

NaOH, Br2, H2O

Question 29

Curtius Rearrangement reagents

Answer 29

1. Na+ -N3, ethanol | 2. H2O, heat

Question 30

Hoffman Elimination Reagents

Answer 30

1. CH3I | 2. Ag2O, heat

Question 31

Diazotization reactants

Answer 31

HNO2, H2SO4

Question 32

Structure of Amines

Answer 32

three amine bonds with lone pair occupy the corners of a tetrahedron

Question 33

Properties of Amines

Answer 33

1. amine with three different substituents is chiral 2. two amine enantiomers interconvert by pyramidal inversion 3. rapid at room temperature 4. amines with fewer than 5 carbons are water-soluble and form hydrogen bonds 5. smell nasty

Question 34

Do amines or alkanes have higher boiling points?

Answer 34

Amines

Question 35

What type of amines do not undergo reductive amination?

Answer 35

Tertiary amines

Question 36

Sandmeyer Reaction reactants/prodcuts

Answer 36

CuCl, CuBr, or NaI --> aryl halides CuCN --> aryl nitriles Cu2O and Cu(NO3)2 --> Phenols

Question 37

Diazonium Coupling Reaction

Answer 37

electrophilic aromatic substitution usually occuring at the p-position of the activated ring

Question 38

Heterocylic amines undergo what reaction?

Answer 38

Electrophilic substitution; reaction occurs at the 2-position b/c the positions are more stable

Question 39

Is pyridine a stronger or weaker base than pyrrole? How about alkylamines? Pyrimidine?

Answer 39

Pyridine is a stronger base than pyrrole but a weaker base for alkylamines. Pyridine is a more basic than pyrimidine.

Question 40

Pyridine

Answer 40

nitrogen-containing analog of benzene

Question 41

Pyrimidine

Answer 41

Two nitrogens in the 1 and 3 positions of a six-membered ring

Question 42

What does the reactivity of polycyclic heterocylic compound depend on?

Answer 42

Type of heteroatom and size of the ring

Question 43

Purines

Answer 43

4 nitrogens (3 pyridine-like and 1 pyrrole-like) in a fused ring

Question 44

Primary and secondary amines IR absorption range?

Answer 44

Primary: 3350-3450 cm-1 Secondary: 3350 cm-1 sharper and less intense than alcohol absorptions

Question 45

Nitrogen Rule

Answer 45

compound with an odd number of nitrogens has an odd numbered molecular weight/ion.