Hydrate, and Bis 2,4-pentanedionato chromium II

ANYHDROUS CHROMIUM (H) ACETATE, CHROMIUM (II) ACETATE 1-HYDRATE, AND BIS (2,4-PENTANEDIONATO) CHROMIUM (II) 

Procedures for the preparation of chromium(II) acetate have been presented in three of the preceding volumes of Inorganic Syntheses. In Volume VI it is pointed out that the methods described earlier - require complicated apparatus, whereas a glove box can be used more easily to provide an inert atmosphere. Complete displacement of air from a dry-box, however, often is difficult. A technique has been developed which involves a less cumbersome closed system used in conjunction with a dry-bag for transfers.  

More important is the nature of the product prepared. Although the previous procedures for the synthesis of chromium (II) acetate imply that the product is anhydrous, other sources indicate that it is hydrated. Thermo-gravimetric experiments performed on moist fresh products show that the deep red material is the 1-hydrate and that there are no higher hydrates of appreciable stability. The 1-hydrate can be obtained by heating the moist reaction product for about 45 minutes at 58 in a stream of nitrogen flowing at 400 ml./hour or by pumping on the 

Before and during reactions, the apparatus is flushed with nitrogen which is purified by treatment with an aqueous 

When the apparatus has been flushed, a boiling solution of 16 g. (0.20 mol) of anhydrous sodium acetate dissolved in 35 ml. of water is added through E A slow nitrogen flow is maintained, and a solution of 9 g. (0.034 mol) of chromium(III) chloride 6-hydrate in 15 ml. of 0.4 N sulfuric acid is poured into the top of the redactor. The rate of flow of the chromium solution can be controlled by stopcock B. If too fast a rate is used, there is a possibility of incomplete reduction. Distilled water is poured after the chromium chloride imtil the effluent is only slightly colored by chromium. This requires approximately 125 ml. 

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Aminomethanesulfonic acid, synthesis 31 Anhydrous chromium(II) acetate, chromium(Il) acetate 1-hydrate, and bis(2,4-pentanedionato)chromium(II), synthesis 32... 

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