очистка муравьинки

[baklan]

Товарищи, кто может подсказать способ очистки продажной муравьнки от воды? Полкило сульфата магния как-то сыпать неохота.

[rombach]

Formic acid [64-18-61 M 46.0 (anhydr), f 8.3O, b 2S0/40mm, 100.7°/760mm, d 1.22, n
1.37140, n25 1.36938, pKZ5 3.74. Anhydrous formic acid can be obtained by direct fractional distillation
under reduced pressure, the receiver being cooled in ice-water. The use of P2O5 or CaC12 as dehydrating agents
is unsatisfactory. Reagent grade 88% formic acid can be satisfactorily dried by refluxing with phthalic anhydride
for 6h and then distilling. Alternatively, if it is left in contact with freshly prepared anhydrous CuSO4 for
several days about one half of the water is removed from 88% formic acid: distn removes the remainder. Boric
anhydride (prepared by melting boric acid in an oven at a high temperature, cooling in a desiccator, and
powdering) is a suitable dehydrating agent for 98% formic acid; after prolonged stirring with the anhydride the
formic acid is distd under vacuum. Formic acid can be further purified by fractional crystn using partial freezing.

[amik]

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