Selective homologation routes to 2,2,3-trimethylbutane on solid acids.

Sailing the seven 'C's: 2,2,3-Trimethylbutane (triptane) selectively forms from dimethyl ether at low temperatures on acid zeolites. Selective methylation at less-substituted carbons, relative rates of methylation to hydrogen transfer as a function of chain size, slow skeletal isomerization, and beta-scission cracking of triptyl chains and their precursors are intrinsic properties of carbenium ions and account for the remarkable triptane selectivities within C(7) .