Elimination: Second Order
Second order elimination involves the concerted (concurrent) ejection of a nucleofuge and an electrofuge, or a pair of radicals to generate a pi-system.

As the mechanism is concerted, it is an orbital symmetry controlled process. FMO symmetry arguments predict (and experiment demonstrate) that the Efg and Nfg must be diaxial (at 180°) for the elimination to proceed.

For more information look in the Chemogenesis webbook sections on fragmentation reactions and elimination reactions.