Amines - Chp 19

Question 1

NH2 group added to a benzene is called…

Answer 1

Aniline.

Question 2

Which has lower b.ps? Tertiary or secondary/primary amines? Why?

Answer 2

Tertiary b/c it cannot H-bond.

Question 3

______ amines are soluble in water.

Answer 3

Small

Question 4

Do all amines accept H-bonds from water and alcohols?

Answer 4

Yes.

Question 5

Give the order of basicity of amines from least to greatest in gas phase.

Answer 5

NH3 < RNH2 < R2NH < R3N
(tertiary is the highest/most basic)

Question 6

Give the order of basicity of amines from least to greatest in solution phase.

Answer 6

NH3 < R3N < RNH2 < R2NH

Question 7

Amines react as ______
with compounds that
contain _______________.

Answer 7

bases; acidic protons

Question 8

Amines can react as both Nu and bases. True or false?

Answer 8

True.

Question 9

Which has less s character? Sp3 or sp2?

Answer 9

sp3

Question 10

Which is less basic? Amides or amines?

Answer 10

Amides

Question 11

Electron donating groups makes the amine more ________ than ________.

Answer 11

basic; aniline

Question 12

List 5 electron donating groups.

Answer 12

-NH2
-OH
-OR
-NHCOR
-R (ex.CH3)

Question 13

List at electron withdrawing groups.

Answer 13

-CHO
-COR
-COOH
-CN
-NO2
-SO3H
-NR3+

Question 14

List in order of increasing basicity.
Pyrrole, piperidine, pyridine, aniline

Answer 14

pyrrole, aniline, pyridine, piperidine

Question 15

How does resonance affect basicity?

Answer 15

It decreases it.

Question 16

Which has a higher s-character? sp3 or sp2? What does it mean?

Answer 16

sp2; the more tightly the lone pair is held, and the weaker the base.

Question 17

Electron withdrawing groups makes the amine ______ basic than aniline.

Answer 17

less

Question 18

Which is more basic between amide and amine? Why?

Answer 18

Amide b/c the electron pair on the nitrogen is delocalized.

Question 19

Aldehydes or ketones reacting with primary amines forms what?

Answer 19

Imine
C=N-R’

Question 20

Aldehydes or ketones reacting with secondary amines forms what?

Answer 20

=C-NR’2

Question 21

Is NH2 a strong activator or deactivator? Ortho, para, or meta?

Answer 21

Activator; ortho and para director.

Question 22

Aromatic substitution of pyridine goes to which position? Why?

Answer 22

Meta position; 2 or 4-position would have an unfavorable resonance structure in
which the positive charge is localized on the nitrogen

Question 23

Nucleophilic substitution of pyridine goes to which position? Why?

Answer 23

Ortho and para position (2- or 4-position); b/c it places a negative charge on the N.

Question 24

Primary or secondary amines react with acid halides to form what?

Answer 24

Amides.
(through nucleophilic acyl substitution)

Question 25

Hofmann elimination convert amine to _______ using ___ (E1E2) elimination.

Answer 25

alkene; E2

Question 26

What is the difference b/w E2 elimination reactions using alkyl halides and amines?

Answer 26

Alkyl halides form a more substituted major product while amines form the less substituted major product.

Question 27

Nitrous acid (HNO2) reacts with 1° alkylamines and arylamines to form…

Answer 27

diazonium salts

Question 28

Acylation–reduction converts a secondary amine to __________ using _____ reagent.

Answer 28

tertiary amine; LiAlH4