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Chemistry Forums for Students => Organic Chemistry Forum => Organic Chemistry Forum for Graduate Students and Professionals => Topic started by: tricyclic on March 22, 2021, 06:58:52 PM

Title: ESI MS on Boc-amine
Post by: tricyclic on March 22, 2021, 06:58:52 PM

Do you normally see the [M+H] on secondary Boc-amine under LC-ESI MS? I have hard time seeing it, but by NMR it should be the Boc-amine structure. Should I increase the acidity of the mobile phase? Should I increase the temperature of the probe to thermally cleave the Boc to see the free amine + H? Thanks!

Title: Re: ESI MS on Boc-amine
Post by: MOTOBALL on March 25, 2021, 02:22:45 PM

Do you see [M+H] minus C4H8 or some other ?
Perhaps HOCOC4H9?

If you are using trifluoroacetic acid, this gives very strong ion pairs MH pos CF3 COO neg that are neutral.
Might have to switch to formic acid.

Title: Re: ESI MS on Boc-amine
Post by: OrganicDan96 on April 25, 2021, 01:52:12 PM

think what might happen to the BOC group

Title: Re: ESI MS on Boc-amine
Post by: kriggy on April 29, 2021, 03:55:46 AM

Not sure what system are you using but you might try direct injection into the MS and fine tune the ionization parameteres for your compound to ionize. At least, thats what we do on waters