June 21, 2021, 03:14:52 PM
Forum Rules: Read This Before Posting


Topic: Mass spectre of benzocaine  (Read 11310 times)

0 Members and 1 Guest are viewing this topic.

Offline Weekend

  • New Member
  • **
  • Posts: 6
  • Mole Snacks: +0/-0
Mass spectre of benzocaine
« on: December 17, 2006, 03:39:46 PM »
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.

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 26578
  • Mole Snacks: +1724/-402
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Mass spectre of benzocaine
« Reply #1 on: December 17, 2006, 03:50:39 PM »
So far I found out that the group between 150 and 165 have to be the CH3.

??? What is mass of CH3?
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info

Offline Weekend

  • New Member
  • **
  • Posts: 6
  • Mole Snacks: +0/-0
Re: Mass spectre of benzocaine
« Reply #2 on: December 17, 2006, 03:51:38 PM »
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...

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 26578
  • Mole Snacks: +1724/-402
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Mass spectre of benzocaine
« Reply #3 on: December 17, 2006, 04:05:41 PM »
So if its mass is 15, how the mass/charge ratio can reach 150?
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info

Offline chiralic

  • Full Member
  • ****
  • Posts: 234
  • Mole Snacks: +19/-3
  • Gender: Male
  • Test
Re: Mass spectre of benzocaine
« Reply #4 on: December 17, 2006, 04:15:06 PM »

Offline Weekend

  • New Member
  • **
  • Posts: 6
  • Mole Snacks: +0/-0
Re: Mass spectre of benzocaine
« Reply #5 on: December 17, 2006, 04:18:41 PM »
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

Offline Weekend

  • New Member
  • **
  • Posts: 6
  • Mole Snacks: +0/-0
Re: Mass spectre of benzocaine
« Reply #6 on: December 17, 2006, 04:23:57 PM »
And thank you chiralic it helped a bit :)

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 26578
  • Mole Snacks: +1724/-402
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Mass spectre of benzocaine
« Reply #7 on: December 17, 2006, 04:30:05 PM »
So the 150 peak corresponds to benzocaine minus CH3, not to CH3.
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info

Offline Weekend

  • New Member
  • **
  • Posts: 6
  • Mole Snacks: +0/-0
Re: Mass spectre of benzocaine
« Reply #8 on: December 17, 2006, 04:30:59 PM »
So the 150 peak corresponds to benzocaine minus CH3, not to CH3.

Exactly

Offline Weekend

  • New Member
  • **
  • Posts: 6
  • Mole Snacks: +0/-0
Re: Mass spectre of benzocaine
« Reply #9 on: December 17, 2006, 04:31:29 PM »
So I'm trying to find out what the rest of the peaks are corresponding to

Offline Yggdrasil

  • Retired Staff
  • Sr. Member
  • *
  • Posts: 3212
  • Mole Snacks: +482/-21
  • Gender: Male
  • Physical Biochemist
Re: Mass spectre of benzocaine
« Reply #10 on: December 17, 2006, 05:38:02 PM »
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.

Offline chiralic

  • Full Member
  • ****
  • Posts: 234
  • Mole Snacks: +19/-3
  • Gender: Male
  • Test
Re: Mass spectre of benzocaine
« Reply #11 on: December 17, 2006, 11:28:34 PM »
Check McLafferty Rearrangement for Aromatic Ester ...and check fragmentation for Aromatic Amine (look at on m/e 65, 66, 92 and 93)






Sponsored Links