[Isay12]

i have to find out what this compound is, i attempted to label the spectra but i am sure that its not right, pls help me, (i wrote on the image)
i think it has a benzene ring and c=o bond
https://imgur.com/nQxRFLT

[Babcock_Hall]

What do you know about sp²-CH stretching frequencies versus sp³-CH frequencies?  If you have an aromatic ring, where should the C-C frequencies appear?

[DrCMS]

• In the NMR if the peak at ~8 is 2H from Ar-H and the peak at 7.4 is also 2H from Ar-H what do you think the peak at 7.6 might be?
• Also in the NMR what group might give a single peak at ~2.6 that integrates as 3H?
• Yes in the IR you have correctly spotted the carbonyl peak.

What possible structures can you draw that have the 3 different groups above? 
How can you tell those apart and determine which material you have?

[Isay12]

What do you know about sp²-CH stretching frequencies versus sp³-CH frequencies?  If you have an aromatic ring, where should the C-C frequencies appear?

i think it around 1500 it would be the medium peak at 1599 and 1583.6 right

[Isay12]

• In the NMR if the peak at ~8 is 2H from Ar-H and the peak at 7.4 is also 2H from Ar-H what do you think the peak at 7.6 might be?
• Also in the NMR what group might give a single peak at ~2.6 that integrates as 3H?
• Yes in the IR you have correctly spotted the carbonyl peak.

What possible structures can you draw that have the 3 different groups above? 
How can you tell those apart and determine which material you have?

1. is it the remaining H that is also connected to the benzene ring
2. i figured out that the single peak would a methyl group i think?
3. i thought about it and the only one structure that could match up with both spectra is c6h5c(o)ch3. i thought it was a 4-methyl benzaldehyde but there was no signal at 10ppm
its a ketone rather than an aldehyde?

[Babcock_Hall]

What do you know about sp²-CH stretching frequencies versus sp³-CH frequencies?  If you have an aromatic ring, where should the C-C frequencies appear?

i think it around 1500 it would be the medium peak at 1599 and 1583.6 right

There are several peaks associated with C-C bonds in an aromatic ring, and I think that you have identified some of them.  We can mentally draw a line at 3000 cm^-1 to separate the two kinds of C-H stretches.  Shorter, stiffer bonds have higher frequencies, all else held equal.