IR

Question 1

RN-H2

Answer 1

Symmetric: 3300

Anti symmetric: 3400

Question 2

Triple Bond Region

Answer 2

2000-2500

Question 3

C≡N

Answer 3

2250 (strong)

Question 4

C≡C

Answer 4

2100-2250

Question 5

Double bond region

Answer 5

1500-2000

Question 6

C=C

Answer 6

1635-1690

Question 7

Benzene CC bonds

Answer 7

Number of peaks (3) in 1625-1450 region

Question 8

NO2

Answer 8

Symmetric: 1350

Anti symmetric: 1530

Question 9

Carbonyl reference and stretch?

Answer 9

Ketone: 1715

Question 10

Carbonyl strengthened by…

Answer 10

Electron withdrawing groups

Question 11

Acid chloride

Answer 11

1750-1820

Question 12

Amide

Answer 12

1640-1690; N lone pair good for donation hence largely an electron donating group — weakens carbonyl bond

Question 13

Carboxylic acid

Answer 13

1730

Question 14

Ester

Answer 14

1745

Question 15

Aldehyde

Answer 15

1730

Question 16

Acid anhydride

Answer 16

Symmetric: 1820

Anti symmetric: 1750

Question 17

Effect of conjugation?

Answer 17

Lowers base frequency by 20-30 (making bond more like a single bond)

Question 18

Ring effects

Answer 18

6 membered ring: no change. For every carbon less in the ring increase the stretching frequency by 30/35. The bond is not stronger however just harder to deform.

Question 19

O-H

Answer 19

Broad ~3500, the stronger the hydrogen bonding the weaker the O-H bond, lots of different hydrogen binding gives broadness.

Question 20

Frequency of vibration

Answer 20

(1/2pi c)sqrt(k/mu)

Where mu=mM/(M+m)

Question 21

C-H

Answer 21

2900-3200; typically just less than 3000