Use molecular formula to determine degrees of unsaturation: 2 points IHD = # of

Question

Use molecular formula to determine degrees of unsaturation: 2 points IHD = # of (rings + p bonds)

Identify major peaks in IR spectrum, if any: 4 points Use the IR data tables in your lab manual and organic textbook to determine if there are characteristic signals corresponding to the various functional groups.

Assign the signals in the 1H NMR spectra to specific protons.

Assign carbons to the peaks in the 13C NMR spectrum  

Give the structure of the compound

Unknown 093i Copyright © 1994 3H 2H 1H 2H 2H 2H 7 PPH 6 4.0 3. 3.0 2. 2.0 1.5 PPM 1.0 10 Proton NMR IT 200 180 160 140 120 100 80 6040 20 PPM 0 Carbon 13 NMA

Explanation / Answer

4-propoxybenzaldehyde

Major IR values:

C= O 1750 – 1700 cm-1 for aldehyde carbonyl (C= O )

C-H   2900 – 2700 cm-1 for aldehyde (C-H )

C-O-C 1200 – 1180 cm-1 for ether linker

signals in the 1H NMR spectra to specific protons :

1H singlet for aldehyde proton at 9.9

2H doublet for aromatic close to carbonyl group of aldehyde at 7.9

2H doublet for aromatic close to propoxy group   at 7.9

2H triplet for O-CH2 group at 4.0

2H multiplet   for -CH2 group at 1.8

3H triplet    for –CH3 group at 1.0

13C NMR : (please consider the signals for carbon in 13C NMR From left to right )

1 carbon = for carbonyl group (-CHO)is about 191

1 carbon = for ring carbon which is attach to oxygen is about 160

2 carbon = for ring carbon which is close to carbonylgroup is about 131

1 carbon = for ring carbon which is attach to carbonyl group is about 130

2 carbon = for ring carbon which is close to oxygen group is about 131

1carbon = for carbon which is attach to oxygen(-OCH2) is about 50

1carbon = for carbon of –CH2- group is about 22

1carbon = for carbon of –CH3 group is about 10

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