Superbase, definition

Scheme 1.1 Schematic equation for the definition of superbases proposed by Caub ere...

On the other hand, a solid superbase is defined as a solid whose base strength expressed by the basicity function, //, is higher than -h 26. The basis of the definition has been described in the literature. The kinds of solid superbases are shown in Table 1.4 together with their preparation method and pretreatment temperature. 

Addition of alkali metals to certain types of oxides resulted in the formation of very strong base sites. Materials which possess base sites stronger than H- = —26 are caUed superbases. The H- value 26 proposed to be set in conformity vrith the definition of superacid. The critical Ho value for superacid is ca. —12, whidi differs by 19 Ho units from Ho=7, the neutral acid-base strength. The H- value 26 differs from H- = 7 for neutral acid-base strength by 19 H- units. Althou alkali and alkaline earth oxides show superbasicity without the addition of alkali metals, as described in Sections 3.1.1 and 3.1.2, this section deals only with alkali metal-added materials showing strong basicity. The materials which show superbasicity by the addition of alkali metals are limited to alkaline earth oxides and alumina. 

---