In my opinion, any chemical based explosive is out of the question. The thing is, high energy kinetic impact will turn the shell (and part of the ship's armor) into plasma : basically an indiscernable soup of nucleons and electrons. I don't think any chemical reaction is possible at this point (since chemical reactions are based on atoms/molecules destroying bonds and forming new ones).
I see two possible solutions :
- Make your explosive not chemical, so... go for nukes.
- Make your kinetic impactor not too fast in order to actually allow some kind of reaction. But I recommend using handwavingly powerful explosive to overcome the greatly reduced damage output of a conventionnal ("not too fast") shell.
In both cases, please note that an explosion in simple contact with the hull of the ship won't make much damage (compared to a purely kinetic impact). Your explosive have to be inside the hull to maximize its potential, so go for a penetrating shell before going boom. But once again, the difference between penetrating and vaporizing ultimately depends on the composition of the armor and the shell.