Silicic acid light anhydrous

Aerosil Cab-O-Sil Cab-O-Sil MSP-, colloidal silica fumed silica light anhydrous silicic acid silicic anhydride silicon dioxide fumed Wacker HDK. 

Silicon Dioxide occurs in nature as agate, amethyst, chalcedony, flint, quartz, sand, and tridymite. Silicon dioxide is obtained by acid precipitation from a sodium silicate solution to yield veiy fine particles. If silicon dioxide is obtained by the addition of sodium silicate to a mineral acid, the product is termed a silica gel. The pharmaceutical industry uses colloidal silicon dioxide, which is a submicroscopic fumed silica prepared by the vapor phase hydrolysis of a silica compound, such as silicon tetrachloride. Other names for colloidal silicon dioxide include light anhydrous silicic acid, silicic anhydride, and silicon dioxide fumed. Colloidal Silicon Dioxide NF must meet the following standards ... 

Iodo-4-penten-l-yl 11-Methoxycarbonylundecyl Tellurium (Sodium Borohydride Reduction) Into an argon-purged, 100-m/ flask are placed a magnetic stirrer, 343 mg (0.5 mmol) of bis[ll-methoxycarbonylundecyl] dilellurium and 20 ml of methanol. Excess sodium borohydride is added and the mixture is stirred until it becomes colorless. 354mg (1.1 mmol) of l,5-diiodo-4-pentene are added, the mixture is stirred for 0.5 h, diluted with water, and extracted twice with diethyl ether. The combined diethyl ether extract is washed with water, dried with anhydrous sodium sulfate, and the solvent is evaporated. The residue is dissolved in 2 ml of benzene and chromatographed on a silicic acid column (1 x 20 cm) slurried in petroleum ether. The column is eluted with 200 ml of petroleum ether and then with 400 ml of benzene. Fractions of 20 ml are collected and fractions 16-19 are combined and evaporated yield 130 mg (22%) light yellow oil. 

C. Nital is perhaps the most common etchant and stain for silicates and improves with age. Nital is 1.5 mL of nitric acid (HNO ) in 100 mL of ethyl, methyl, isopropyl, or amyl alcohol. The author routinely uses asolution of 1 mL of HNOj and 99 mL of anhydrous isopropyl alcohol. The solution quickly reacts in 6 to 10 seconds with alite and belite. At a 0.05% dilution the reaction time is 20 to 40 seconds. Ono (1995) relates alite reactivity to color produced with 0.2% nital. Depending on the relative reactivity of silicates, alite normally turns blue to green, belite is brown to blue—both silicates showing details of internal structure. Nital superimposed on a 20-second potassium hydroxide etch turns C3A light brown and colors the silicates. 

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