[Weekend]

Hi!
First of all, I'd like to say that I'm new at this forum . I have a mass spectre of benzocaine (ethyl p-aminobenzoate, C9H11NO2) I'm trying to analyze which part of the molecule is seperated in each "peak". The spectre can be found at the following URL:
http://img323.imageshack.us/img323/9170/benzocainepx0.gif

So far I found out that the group between 150 and 165 have to be the CH3. So I would be glad, if anyone could help me identify the rest.

[Borek]

So far I found out that the group between 150 and 165 have to be the CH3.

What is mass of CH₃?

[Weekend]

So far I found out that the group between 150 and 165 have to be the CH3.

What is mass of CH³?

Wouldn't that be 15? 12 for Carbon and 3 for each H...

[Borek]

So if its mass is 15, how the mass/charge ratio can reach 150?

[chiralic]

Hi Weekend!

Read page 3 of this link:
http://www.ru.ac.za/academic/departments/pharmacy/chem/2nds/spectutplus.pdf

Chiralic

[Weekend]

So if its mass is 15, how the mass/charge ratio can reach 150?

I understand it like thiis. You have a molecule which has the mass 165, then a part of it is "cut" off, and then the molecule is 150. This means it lost 15 of its mass, which is equal to CH3

[Weekend]

And thank you chiralic it helped a bit

[Borek]

So the 150 peak corresponds to benzocaine minus CH₃, not to CH₃.

[Weekend]

So the 150 peak corresponds to benzocaine minus CH₃, not to CH₃.

Exactly

[Weekend]

So I'm trying to find out what the rest of the peaks are corresponding to

[Yggdrasil]

Since you have a carbonyl, I would expect to see beta cleavage.  Also, since there's an aromatic ring, you may see tropyllium ions, which are common in mass spectra of aromatic compounds.

[chiralic]

Check McLafferty Rearrangement for Aromatic Ester ...and check fragmentation for Aromatic Amine (look at on m/e 65, 66, 92 and 93)