A new anionic clay, alpha-magnesium hydroxide, was synthesized by hydrolysis of magnesium acetate in propylene glycol. The structure of this alpha-hydroxide is similar to that of hydrotalcites. It consists of positively charged magnesium hydroxide layers arising out of partial protonation of the hydroxyl groups of the [Mg(OH)(2)] layers and loosely held anions in the interlayer region. As expected it ages readily in water to give beta-magnesium hydroxide, brucite. While anion-exchange reactions of alpha-magnesium hydroxide could not be carried out in aqueous medium a number of anion-exchange reactions could be carried out successfully in ethanol medium. (C) 2010 Elsevier Inc. All rights reserved.