A Bronsted acid functionalized periodic mesoporous organosilica and its application in catalytic condensation and THP protection/deprotection reactions

In this work we report the synthesis of a periodic mesoporous organosilica (PMO) derived from 1,4bis(triethoxysilyl)benzene (BTEB) and its functionalization with propane sulphonic acid groups via the post synthetic grafting method according to modified procedures from the literature. The material contains an acid loading of approx. 0.50 mmol/g. Being applied in various catalytic reactions, it shows moderate to little activity in condensation reactions. In THP-protection of alcohols the material is highly efficient and superior to known silica supported sulphonic acid catalysts. The activity in the corresponding deprotection reaction is comparable to typical catalysts used in this field. In addition, the acidic PMO is recyclable without any loss of activity over three catalytic runs. The mesoporous material was thoroughly characterized by solid-state CP-MAS NMR to follow the functionalization process, powder XRD to show the 2D hexagonal structure that remains pristine through all modifications and BET measurements that show a high surface area between 1185 m(2)/g and 681 m(2)/g and a stable pore diameter of around 50 A. (C) 2017 Elsevier Inc. All rights reserved.