arylene or polar embedded c 1 to c 7 alkylene alkenylene alkynylene or arylene group moiety bridging two or more al atoms m is an integer greater than or equal to 2 and n is a number from 0 01 to 100 such particles after pseudomorphic transformation have a median pore size range from about 15 to about 1000 u00e5 a specific surface area of from about 5 to about 1000 m 2 g and a median size range from about 0 5 u03bcm to about 100 u03bcm if the hybrid alumina based starting materials of formulae ix and x are pseudomorphically transformed in accordance with the method of this invention in the presence of one or more organic metal alkoxides of formulae v vi in the process the resultant product is totally porous particles comprising an organic metal oxide having a composition selected from one or more of formulae xv xviii al 2 o 3 r 2 alo m x r 1 alo y xvi al 2 o 3 r 1 alo x r 2 alo m y xvii al 2 o 3 r 2 alo m x r 2 alo m y xviii wherein r 1 is independently selected in each instance from a substituted or unsubstituted c 1 to c 18 alkyl alkenyl alkynyl or aryl group wherein the substituents are selected from halogen diol amino alcohol amide cyano ether nitro carbonyl epoxide sulfonyl cation exchanger anion exchanger carbamate and urea r 2 is independently selected in each instance from a substituted or unsubstituted c.