[EMAIL PROTECTED] wrote: > In reply to Jed Rothwell's message of Mon, 08 Dec 2008 16:33:37 -0500: > Hi, > [snip] >> "The mass-13 species cannot be a CH molecule >> created in the mass spectrometer because when >> organic molecules are broken down, products with >> M/e range from 5 to 11 are not created. > > ...but we are looking at 13 here, not 5-11. > > It should be obvious that if you hit phenanthrene or a derivative hard enough, > you can break just about any sized chunk off it.
Maybe. On the other hand, organic molecules apparently cleave into characteristic chunks, rather than just blowing apart into all possible combinations. See, for example, a page of example cleavage points for selected molecules: http://www.chem.arizona.edu/massspec/example_html/examples.html Based on that, it seems possible that Mizuna may be stating a well known fact (well known among certain organic chemists, I mean) when he says you won't see CH as a breakdown product from phenanthrene. Note particularly carboxylic acid, which contains two CH groups, yet apparently doesn't show a peak at 13. (OTOH, come to think of it, if they're splitting out individual atoms, they must be hitting the molecules really hard rather than just cleaving them into a few big pieces. Hmmm.) > As I pointed out on this list > twice already, the CH combination is just about all phenanthrene is made of > (10 > or the 14 C atoms have a single H attached, and the other 4 have none at all), > so it stands to reason that when you forcefully break up the molecule, you are > going to get lots of CH radicals. > Perhaps the confusion arises because he is expecting a molecule and not > considering a radical. > >> C2H2^2+ >> might be a possible candidate, but this cannot >> appear as a fragment from decomposed organic >> molecules, but only from synthesis." > [snip] > Regards, > > Robin van Spaandonk <[EMAIL PROTECTED]> > >
