[Xenonman]

I MARKED BOTH 14C's as 13C's. PLEASE BEAR WITH IT.

Boredom stuck again and I tried to think in what would happen after a 14C decayed while in a compound. Tried first with ethene and noticed I don't know what would happen to the hybridization.

At first I only considered the hybridization thought it was most likely to remain as sp² because both carbons were sp². Then I tried working on a mechanism to find methylamine as the preferred product over the methenamine, as the N⁺ can easily take an electron from the π bond.

Then I tried with ethane. No more π bonds, so the electron has to come from the σ bond to the C, H or T. Since the N-H bond has the biggest difference in electronegativity, I suppose that taking the electron from the N-H bond makes more sense, if any at all.

Are these mechanisms believable?



==============
While typing this I remembered the nitrogen is somewhat stable when cationic, so it may not take the electron from the π bond at all.

Being decay such a wicked thing, I suppose all of them are probable, with the first one being more likely because it made more sense when I posted this.

[Borek]

You are assuming carbon after decay stays in place. It doesn't - it recoils, plus, the electron emitted ionizes the surroundings (total energy released being 156 keV). So, what you get after decay is more similar to the pile of rubble than to house in which someone just replaced a door knob

[Archer]

(total energy released being 156 keV)

I didn't ever really consider this energy release. Considering EI-MS is normally set to about 70 eV and that is usually enough energy to ping off one electron.

2000 times more energy probably knocks off a few more.

[Xenonman]

Taking this into consideration, the newly formed N would "rush" away from the carbon it was bonded to. The nearby carbons would have their electrons escaping from their orbits, ionizing wherever they found a spot, and leaving their former carbons cationic, so thirsty for electrons they would try taking some of the atoms nearby.

Sounds like a post apocalyptic scenario actually. Would that happen?

[Enthalpy]

When the electron gets the full 156keV (the antineutrino uses to get most of it, leaving mean 39keV to the electron) the nitrogen's recoil energy (in a random direction) is 6.2eV or 600kJ/mol: that's about as much as the C=C bond, which will be broken sometimes, shaken often.

The ejected electron of maximum 156keV loses 3MeV*cm²/g in liquid water, which has atomic numbers similar to your ethylene. That's 3MeV/cm or 1meV/300pm, so the electron passes very often by or through a molecule without doing anything, just because it's so fast. The damage is spread in wide surroundings.

Then you have the reaction of the previously carbon shells that suddenly feel one proton more. The 1s shell at carbon has ionisation energies of 38keV and 47keV, but at nitrogen 53keV and 64keV
http://www.webelements.com/carbon/atoms.html
this difference exceeds the previous contributions. Or compare the third ionization of a nitrogen atom, 4578eV, with the second of a carbon atom, 2353eV.

This can make a molecule kaputt, beyond the usual mechanisms of chemical reactions.

[Xenonman]

It's falling to pieces, falling to pieces!
The last post provides a much clearer definition of the ensuing chaos after one single decay.

Thanks all