EP1467958A1 - PROCESS FOR PREPARING 3,3',5,5',6,6'-HEXAALKYL-2,2'-BIPHENOLS, 3,3',4,4',5,5'-HEXAALKYL-2,2'-BIPHENOLS AND 3,3',4,4',5,5',6,6'-OCTAALKYL-2,2'-BIPHENOLS