hed (??-1)-hydroxyalkyl having 5 to 8 carbon atoms, branched (??-1)-hydroxyalkyl having from 5 to 8 carbon atoms and in which the hydroxyl is separated from the xanthine nucleus by at least two carbon atoms, methyl and --H;R2 is a member selected from the group consisting of ??-hydroxyalkyl having from 5 to 8 carbon atoms and in which the hydroxyl is separated from the xanthine nucleus by at least