Question

1. (15 points) Assign the resonances in the spectrum shown. The resonances on the spectrum are labelled A-D. On the lines provided, write the label that corresponds to each of the groups. The multiplicity (s = singlet, d = doublet, etc) and the integrals are given for each resonance. OCH3 + S, 6H H3 C CH₂ H OCH₃ x D s, 3H d, 2H t, 1H Ppm

if you could also explain how you can determine the answer, I would really appreciate it!

Answer 1

1.

Peaks are given below

S, 6H D S, 3H C d, 2H t, 1H ppm

There are four peaks in the spectrum which can be assigned to four different H with different environments.

Molecule,

och CH₂ Å OCH₃ x 1 MC H₂ 3 2

Peak 1

In this molecule, two OCH₃ are in same environments. So they are of same type, type-1

Totally there are 6 H in type-1 environment. And because they are separated from any CH (type-2) by O atom, so type 1 is not coupled and will give singlet. Since these H are connected to O through the C, their chemical shift will be around 3 (O is deshielding group).

So peak B (s,6H) ---- type-1 H atoms.

Peak 2

Type-2 H is only one Hatom are connected to CH2(type-3).

So by (n+1) rule, (2+1)=3, it will give a triplet.

Since it is connected to 2 O atoms, chemical shift will be higher, around 5. It is peak A (t,1H)

So peak A(t,1H) ---- type 2

peak 3

  

Type-3 H atoms are two (CH2) connected to CH so will give doublet (n+1 rule).

Since it is attached to CO group, chemical shift will be around 2. This is peak C(d,2H)

peak C(d,2H) ----type 3 H

peak 4

Type-4 is CH3 connected to CO. So it is not coupled. It will give singlet.

It is connected to CO, so chemical shift will be around 2.

This is peak D(s,3H)

peak D(s,3H) ---- type 4 H

2 .

Spectrum peak,

s, 1H m, 2H (t, 2H) m, 1H ppm

Since IR peak of 1730 con is presest, There is a CHO, aldehy die group. peak A (s, 1H) (s, 1H) - One hydrogen which is isolated from other Hy group (o n ) (x can be lor2), (so showing singlet) This is o must be our bonded CHO to it. group. To isolate, the other -0-.-H.7 peak. B] - (t, 2H). So it is a Chy group. t means, it is connected to a clt group. - CH2 - City-

peak-c IH peak En Hy attached 6t means 2 equivalest to CH groop (doublet) Ichty CH2 peak-c son, IH) CH group connected to main CH2 sta peak-o m, 2H cu CH₂ group connected diff type af Hydrogen. to

The fact that there are only se atoms and to saill all the discription The structure has to be multiplet This is 2H - peak - Cph O= -CHL CH2 1 3 H- Ć -o. 0 I 4 6- carbons are there all multiplicities are satisfied. OHC-O-CH ₂ -CH2-CH H2-CH - (H₂ CH3