Chemical Forums

Please login or register.

Login with username, password and session length

Sponsored links

Pages: [1] 2   Go Down

Author Topic: Base peak for 1-phenyl-1-butanone  (Read 4505 times)

0 Members and 1 Guest are viewing this topic.

s30.93a

  • Regular Member
  • ***
  • Mole Snacks: +0/-2
  • Offline Offline
  • Posts: 31
Base peak for 1-phenyl-1-butanone
« on: January 26, 2017, 06:53:47 AM »

Mc Lafferty can occur for C=O or C=C, thus yielding 105 and 121 as two peaks, but which one will be base peak?
Logged

MOTOBALL

  • Full Member
  • ****
  • Mole Snacks: +37/-5
  • Offline Offline
  • Posts: 296
Re: Base peak for 1-phenyl-1-butanone
« Reply #1 on: January 26, 2017, 08:34:10 AM »

The base peak is that with the greatest relative intensity, so what determines rel int. Once an ion has been formed?
Logged

s30.93a

  • Regular Member
  • ***
  • Mole Snacks: +0/-2
  • Offline Offline
  • Posts: 31
Re: Base peak for 1-phenyl-1-butanone
« Reply #2 on: January 26, 2017, 08:48:39 AM »

Obviously, the most stable cation will resemble base peak, if C=O will break its α-β bond -C-O+H will form, in other case -C-C+H will be formed. Please correct me if I'm wrong and thus the latter is preferred
Logged

MOTOBALL

  • Full Member
  • ****
  • Mole Snacks: +37/-5
  • Offline Offline
  • Posts: 296
Re: Base peak for 1-phenyl-1-butanone
« Reply #3 on: January 27, 2017, 09:00:34 AM »

Ionization of R1-CO-R2 will give R1-CO+ and R2-CO+
Which in your case will be more stable ?
Logged

s30.93a

  • Regular Member
  • ***
  • Mole Snacks: +0/-2
  • Offline Offline
  • Posts: 31
Re: Base peak for 1-phenyl-1-butanone
« Reply #4 on: January 27, 2017, 10:13:17 AM »

Ionization of R1-CO-R2 will give R1-CO+ and R2-CO+
Which in your case will be more stable ?

I think it depends on the stability of the radical R2° or R1° as R-CO+ is stabilised by back bonding. please correct if i'm worng
I made these structures depending on Mc Lafferty, please tell which one will be base peak?
Logged

MOTOBALL

  • Full Member
  • ****
  • Mole Snacks: +37/-5
  • Offline Offline
  • Posts: 296
Re: Base peak for 1-phenyl-1-butanone
« Reply #5 on: January 27, 2017, 10:21:10 AM »

Ionization of R1-CO-R2 will give R1-CO+ and R2-CO+
Which in your case will be more stable ?
Logged

MOTOBALL

  • Full Member
  • ****
  • Mole Snacks: +37/-5
  • Offline Offline
  • Posts: 296
Re: Base peak for 1-phenyl-1-butanone
« Reply #6 on: January 27, 2017, 10:24:39 AM »

I don't believe that your drawn structure is 1-phenyl-1-butanone.
Please check !
Logged

AWK

  • Retired Staff
  • Sr. Member
  • *
  • Mole Snacks: +445/-78
  • Offline Offline
  • Gender: Male
  • Posts: 6186
Re: Base peak for 1-phenyl-1-butanone
« Reply #7 on: January 27, 2017, 01:57:21 PM »

Search NIST for MS of butyrophenon
Logged
AWK

MOTOBALL

  • Full Member
  • ****
  • Mole Snacks: +37/-5
  • Offline Offline
  • Posts: 296
Re: Base peak for 1-phenyl-1-butanone
« Reply #8 on: January 27, 2017, 05:21:14 PM »

Search NIST for MS of butyrophenon

AWK,
Why provide the answer on a platter, when our job is to help them think it through for themselves?
Logged

AWK

  • Retired Staff
  • Sr. Member
  • *
  • Mole Snacks: +445/-78
  • Offline Offline
  • Gender: Male
  • Posts: 6186
Re: Base peak for 1-phenyl-1-butanone
« Reply #9 on: January 27, 2017, 05:39:12 PM »

s30.93a discusses other compound (2-propyl-3,4-dihydro-2H-naphthalen-1-one). Two main peaks of butyrophenon are 105 and 77. Title of thread is incorrect.
Logged
AWK

s30.93a

  • Regular Member
  • ***
  • Mole Snacks: +0/-2
  • Offline Offline
  • Posts: 31
Re: Base peak for 1-phenyl-1-butanone
« Reply #10 on: January 28, 2017, 02:03:12 AM »

No, i want to know base peak for both the compounds.
The latter which I posted has more possibilities for Mc Lafferty.
I want to know which of the fragmentation is preferred, thus I'll subsequently apply that fact to 1-phenyl-1-butanone
Logged

s30.93a

  • Regular Member
  • ***
  • Mole Snacks: +0/-2
  • Offline Offline
  • Posts: 31
Re: Base peak for 1-phenyl-1-butanone
« Reply #11 on: January 28, 2017, 02:06:16 AM »

Search NIST for MS of butyrophenon

AWK,
Why provide the answer on a platter, when our job is to help them think it through for themselves?

I already knew such databases, but looking for reasons.
Logged

AWK

  • Retired Staff
  • Sr. Member
  • *
  • Mole Snacks: +445/-78
  • Offline Offline
  • Gender: Male
  • Posts: 6186
Re: Base peak for 1-phenyl-1-butanone
« Reply #12 on: January 28, 2017, 04:44:57 AM »

Then start from easier compound - butyrophenone. Show us McLafferty rearrangement
and two α-cleavages for this compound.
Logged
AWK

s30.93a

  • Regular Member
  • ***
  • Mole Snacks: +0/-2
  • Offline Offline
  • Posts: 31
Re: Base peak for 1-phenyl-1-butanone
« Reply #13 on: February 01, 2017, 08:20:24 AM »

Then start from easier compound - butyrophenone. Show us McLafferty rearrangement
and two α-cleavages for this compound.

These are the two possible rearrangements.
Logged

AWK

  • Retired Staff
  • Sr. Member
  • *
  • Mole Snacks: +445/-78
  • Offline Offline
  • Gender: Male
  • Posts: 6186
Re: Base peak for 1-phenyl-1-butanone
« Reply #14 on: February 01, 2017, 08:27:05 AM »

These not give ions 105 and 77 which are most abundant in the spectrum of butyrophenone. Check α-cleavages.
Logged
AWK
Pages: [1] 2   Go Up
 

Mitch Andre Garcia's Chemical Forums 2003-Present.

Page created in 0.07 seconds with 24 queries.