September 17, 2021, 10:40:12 PM
Forum Rules: Read This Before Posting


Topic: Mass spectrum  (Read 257 times)

0 Members and 1 Guest are viewing this topic.

Offline xshadow

  • Full Member
  • ****
  • Posts: 403
  • Mole Snacks: +1/-0
Mass spectrum
« on: September 08, 2021, 03:26:08 AM »
Hi!!

I would know the right molecule assocoated to tjis mass mass spectrum

Is there a site that can give me the right molecule  ???
Thanks
« Last Edit: September 08, 2021, 04:36:09 AM by Borek »

Offline Babcock_Hall

  • Chemist
  • Sr. Member
  • *
  • Posts: 4878
  • Mole Snacks: +286/-21
Re: Mass spectrum
« Reply #1 on: September 08, 2021, 12:56:50 PM »
Here are some thoughts.  You can sometimes apply the rule of 12 and the nitrogen rule to good effect.  Try subtracting the mass of a fragment from M.  More specifically, your spectrum has an unusual feature.  I am only familiar with two functional groups that often display this feature (there might be others).  Identifying likely functional groups might cut the territory down.

Offline xshadow

  • Full Member
  • ****
  • Posts: 403
  • Mole Snacks: +1/-0
Re: Mass spectrum
« Reply #2 on: September 11, 2021, 03:13:54 AM »
Here are some thoughts.  You can sometimes apply the rule of 12 and the nitrogen rule to good effect.  Try subtracting the mass of a fragment from M.  More specifically, your spectrum has an unusual feature.  I am only familiar with two functional groups that often display this feature (there might be others).  Identifying likely functional groups might cut the territory down.

Hi Babcock !!

Usually the -1 loss with an high peak is an aldehyde...

But I also see a -18 loss (water) that I think is typical of alcahol and carboxylic acid (perhaps COOH gives -17 not 18)....I also see a -28 loss so there sould be a C=O!
Also I see a 76 instad a 77...can it mean that the ring has two substituents?   maybe an aldehyde and an alcohol??

PS: I also see that when I loss the aldehydic group (29) I get 93, that should be phenyl + alcohol.

THANKS

PS: what do you mean with  nitrogen rule? That if M+* is even I don't have nitroger or at least 2N/4N ecc ??
« Last Edit: September 11, 2021, 04:53:53 AM by xshadow »

Offline Babcock_Hall

  • Chemist
  • Sr. Member
  • *
  • Posts: 4878
  • Mole Snacks: +286/-21
Re: Mass spectrum
« Reply #3 on: September 11, 2021, 10:17:24 AM »
Other functional groups with a substantial M-1 are alkynes and some amines and alcohols.  I would subtract the mass of the heteroatom(s) and apply the rule of 12.

When there are an odd number of nitrogens, the value of M is a odd number.
« Last Edit: September 11, 2021, 10:28:44 AM by Babcock_Hall »

Sponsored Links