Sodium carbonate.heptahydrate

T. Thomson6 discovered that crystals of heptahydrated sodium carbonate,... 

Magnesium sulfate heptahydrate Calcium sulfate dihydrate Sodium carbonate decahydrate... 

Calcium-free magnesium carbonate. Dissolve 24 6 g of analytical reagent grade magnesium sulphate (heptahydrate) in 200 ml of water and add 20 per cent sodium hydroxide solution until a precipitate just forms. Heat the mixture to 80° and add, while stirring, a hot solution of 10 6 g of anhydrous sodium carbonate in 200 ml of water. Allow to cool, filter off the precipitate, wash thoroughly with water and dry at 110°. 

FIGURE E.5 Each sample contains 1 mol of formula units of an ionic compound. From left to right are 58 g of sodium chloride (NaCl), 100 g of calcium carbonate (CaCO,), 278 g of iron(ll) sulfate heptahydrate (FeS04-7H.0), and 78 g of sodium peroxide (Na. O,). 

Fig. 17.5 RSR 13 Heptahydrate Sodium Salt. The sodium atom is in light blue, water atoms are large red spheres, carbons yellow, nitrogen dark blue, and oxygens red. This particular RSR 13 salt was not soluble enough for use in clinical trials.

The crystals of this salt prepared by T. Thomson s process were formerly stated to be sodium octohydrated carbonate, Na2C03.8H20, but H. Lowel proved that this is a mistake the product is Bodium heptahydrated carbonate. The /8-hepta-hydrated carbonate is less soluble than the a-salt, and more soluble than the decahydrated carbonate, so that a soln. Bat. with the a-salt is supersaturated with respect to the j8-salt, and the decahydrated salt. The transformation of the a- into the /8-variety occurs while the salt is in contact with its mother liquid at very variable temp.—sometimes at 23°, more often below 10°. The /3-salt effloresces in dry air, and passes into the monohydrated carbonate at about 32°. An appreciable amount of heat is developed during the crystallization of a supersaturated soln., and this iB greater for the -heptahydrated carbonate than for the a-Balt but less than for the decahydrated carbonate. The temp, rose from 20 5° to 22 5° during the crystallization of the /3-salt from a sat. soln. 

To a stirred solution of 122 mg of ll,15-dideoxy-ll-acetoxy-16-methyl-15-oxo-18,19-tetradehydro-5,6,7-trinor- 4,8-inter-m-phenylene PGI2 in 10 ml of methanol was added 150 mg of cerium chloride heptahydrate, and then the solution was cooled in an ice bath, and 15 mg of sodium borohydride was added to the solution. After 10 min, to the mixture was added 2 ml of aqueous saturated solution of sodium hydrogen carbonate, and the mixture was further stirred for 10 min. 

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