trityl ether protection group

behaves like Bn ether.very bulky, so better selectivity towards primary alcohol.

forming:
trityl chloride, TEA, DCM

easily falled off when contact with Silica gel.(during column)
pretreat the silica gel with 1% TEA in P.E. can prevent it completely.

can be removed by hydrogenation(pd/c, H2), addition of Py can preserve it.