[Dolphinsiu]

Deduce a structure consistant with the following data

C = 58.38%, H = 9.80% (C:H = 1:2)

(EI) m/z (abundance %): 207 (10), 205 (30), 204 (12), 192 (15), 190 (45), 170 (10), 164 (11), 162 (33), 157 (11), 156 (100)

(207:205 = 1:3, Cl is existed, 205 imply at least one N, 205 - 156 = 49 imply -CH2Cl fragmentation. The overall formula is C10H20NOCl)

IR (cm-1) : 2900, 1650

1H NMR (CDCl3):
1. 0.9 (6H,d)
2. 1.0 (6H,d)
3. 1.1 (3H,d)
4. 2.3 (1H,m)
5. 2.5 (2H,m)
6. 3.5 (2H, bd)

What I predict is:
                             
                                 (3)
       
                          CH3  CH3  O   
                           l       l      ll
(H3C)2 - N - CH2 - C  -   C  -   C - CH2Cl
                           l       l
                          CH3   H
 
   (2)           (5)    (1)    (4)         (6)

Does my prediction have problems?

[Dan]

Does my prediction have problems?

I'm afraid so. I don't have time to check this in detail right now, but...

Your structure is not consistant with your formula (no N in the structure).
You have a C with a valency of 5.

                     CH3  CH3  O   
                      l       l      ll
(H3C)2 - CH2 - C  -   C  -   C - CH2Cl
                      l       l
                     CH3   H

IR does not support the presence of a ketone. Looks like an amide.

[Dolphinsiu]

Sorry! I have not typed N (typing mistakes)

[Dolphinsiu]

                              O
                              ll
If 1650 really imply  - C - N (CH3)2


Fragmentation of -CH2Cl is still correct!

Then

I will predict
                       (4)
              CH3   H               O
              l         l                ll
Cl - CH2 - C  -    C -    CH2 -  C  - N - (CH3)2
              l         l
              CH3    CH3
      (6)    (1)      (3)     (5)                   (2)

Is my second prediction close to yours?

But from Mass spectrum

190 and 162 imply the loss of 15(CH3) and 43(COCH3) respectively!

So I still don't know the actual structure!

[Dan]

I don't think that structure accounts very well for the nmr data. The methyl groups on N would peak at higher ppm, and the splitting patterns are not consistent with that structure.

I haven't come up with anything that gives a good correspondance to the nmr data either. Are you sure that both 6H, d are in fact doublets and not two singlets?

ie. is it possible that 6H, d is actually 2 x 3H, s?
Can you get any more info on the structure of the multiplets?

Also, 43 in the MS could be an isopropyl group, Me₂CH. An isopropyl group may also be responsible for a 6H, d in the nmr.

[Dolphinsiu]

I just copy from my past paper. I also don't have any idea in this question! Actually I am weak in predicting the unknown cpds!