# Why does ethene react explosively with fluorine?

In this website it is claimed that "[e]thene reacts explosively with fluorine to give carbon and hydrogen fluoride gas", via this equation:

$$\ce{CH2=CH2 + 2F2 -> 2C + 4HF}$$

Why does the fluorine hog the hydrogen atom instead of attacking the $\pi$-bond?

Additionally, may I ask for the mechanism of this reaction?

• It's seems wrong because fluorine reacts very vigorously to form not only fluorinated but also several oxidation products. tetrafluoromethane also formed during the reaction. The exact mechanism is unknow – Khan Sep 4 '16 at 3:48
• @N.ALodhi Would I be correct in saying that the tetrafluoromethane may have formed from the C in the product above? $\ce{C +2F2 -> CF4}$ – DHMO Sep 4 '16 at 3:49
• yes, you are right, here is the link link.springer.com/article/10.1023/B:RJAC.0000024584.69292.6d – Khan Sep 4 '16 at 3:53
• @N.ALodhi However I do suspect that there could be a $\ce{CH2F2}$ intermediate, meaning that the carbon atom is not completely separated before the tetrafluoromethane starts forming. – DHMO Sep 4 '16 at 4:16
• There is no mechanism, in the sense that there are too many things happening all at once. Name just about any remotely sensible particle composed of C, H, F, and it would be there. – Ivan Neretin Sep 4 '16 at 6:54

This is an explosive reaction so it will proceed by many steps usually involving radicals. To get feedback, and so explosion, one step must be of the branched chain form $$\ce{R_1^. + M -> R_2^. + R_3^.}$$ where $\ce{R^.}$ is a radical and $\ce{M}$ a reactant species (e.g. $\ce{CH2=CH2}$). As two radicals are produced for one reactant radical a chain reaction ensues, the reaction rate accelerates and so bang!
The initiation step in your reaction probably forms the radical $\ce{FCH2-CH2^.}$ although I don't know the mechanism.