The Solvent-Like Nature of Silica Particles in Organic Solvents

摘要

Kamlet-Taft's #alpha# (hydrogen bond donor acidity) and #pi#~* (dipolarity/polarizability) values of various silica batches measured in various solvents are presented. The #alpha# and #pi#~* parameters for the various solid acids are analyzed by means of Fe(phen)_2(CN)_2 (cis-dicyano-bis(1,10)-phenanthroline-iron(II), 1), Micher's ketone (4,4'-bis-(dimethylamino)-benzophenone, 2) and two hydrophilic derivatives of 2, (4-dimethylamino)-4'-(di-2-hydroxyethyl)-amino-benzophenone (3a) and 4,4'-bis-(di-(2-hydroxyethyl)-amino)-benzophenone (3b) as well as coumarin 153 (4) as solvatochromic surface polarity indicators. Apparent #beta# (hydrogen bond acceptor basicity) parameters for the bare silica have been evaluated by means of an aminobenzodifuranone dye (5) as solvatochromic probe.