LICHROSORB(R) RP8

White powder

Excipient.

Before use as a drying agent, silica gel is heated in an oven, then cooled in a desiccator. Conditions in the literature range from heating at 110o for 15hours to 250o for 2-3hours. Silica gel has been purified by washing with hot acid (in one case successively with aqua regia, conc HNO3, then conc HCl; in another case it was digested overnight with hot conc H2SO4), followed by exhaustive washing with distilled water (one week in a Soxhlet apparatus has also been used), and prolonged oven drying. Alternatively, silica gel has been extracted with acetone until all soluble material was removed, then dried in a current of air, washed with distilled water and oven dried. Silica gel has also been washed successively with water, M HCl, water, and acetone, then activated at 110o for 15hours. Silicon monoxide [10097 -28 -6] M 44.1, m > 1700o, d 4 2.18. Purify the monoxide by sublimation in a porcelain tube in a furnace at 1250o (4hours) in a high vacuum (10-4mm) in a stream of N2. It is obtained as brownish black scales. [Schenk in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I p 696 1963.]