STUDY OF DIRECT UPPER RIM ALKYLATION OF C ALIX[N]ARENES

In this work, we compare the reactivity of calix [n] arene (n = 4, 6, 8) in the direct upper rim isopropylation by isopropyl chloride in 1,2 -dichloroethane with AlCl3 as catalyst. It is shown that isopropylatio n occurs only with calix[8]arene. In the case of calix[4]arene, it is a hydroxyisopropylation which is observed. With calix[6]arene, both re actions take place. These results show that calix[n]arene behaves more and more like a phenol when n increases from 4 to 8. A mechanism of h ydroxyisopropylation is proposed.