[adamalt]

Anyone knows how to sketch coupled and decoupled 13C Spectrum of:
  CH3COCH2CH3

[ARGOS++]

Dear Adamalt;

Could this be a start piont for you?:   "AIST:SDBS: 2-Butanone”
(Enter your molecular formula & select ¹³C-NMR!)



Good Luck!
                    ARGOS⁺⁺

[adamalt]

It helps a bit but I don't know what is the different between coupled and decoupled and how do you sketch them?

[azmanam]

start here for background.  1H NMR is important for understanding coupling in general, 13C NMR section begins to talk about your situation.  2nd link is further information about coupling and decoupling

http://www.cem.msu.edu/~reusch/VirtTxtJml/Spectrpy/nmr/nmr1.htm
http://www.cem.msu.edu/~reusch/VirtTxtJml/Spectrpy/nmr/nmr2.htm

[ARGOS++]

Dear Adamalt;

You will have to catch/read this from your textbook, because it’s too much to explain it in details.

Hints:
Most or several ¹³C are also relateted/bound to ¹H and they will split the corresponding signal of the ¹³C nucleus.
So one ¹H will split the signal of “its” ¹³C into a Doublett; two will split it into a Triplet, and so on.
Decoupling means that you can observe the ¹³C Signals “without” all this Splitting.

But you will anyway have to study it from the book.

Good Luck!
                    ARGOS⁺⁺