Dear Sir. Concerning your issue about the carbon nmr chemical shift of methyl group in acetyl group. I think the following below links may help you in your analysis:

http://www.people.fas.harvard.edu/~ekwan/nmr%20pdfs/lecture%202.pdf

https://www.ucl.ac.uk/nmr/NMR_lecture_notes/L2_3_web.pdf

https://www.chem.wisc.edu/areas/reich/nmr/c13-data/cdata.htm

Thanks

Dear Sherif Arafa,

Please see the attached tables of C-13 chemical shifts.

I hope that this will help.

Best of luck in your research. AF

Dear Sherif Arafa,

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Best wishes in your research. AF