Chromium sulfate, anhydrous

The preparation of salts containing the [Cr(en)3]3+ cation from anhydrous chromium sulfate has been described previously in Inorganic Syntheses,1 and the merits of this, and other, methods have been reviewed.9 A more rapid route to this cation involves refluxing CrCl3 6H20 in methanol with ethylenediamine and zinc metal, which allows the substitution to proceed by way of the kineti-cally labile chromium(II) species.10 All of these preparations yield hydrated salts the procedure described below leads to anhydrous [Cr(en)3] Br3. 

Chromium oxychloride, formation of, by CrCl2, 1 126 Chromium(II) salts, 6 144 Chromium (III) sulfate, anhydrous, 2 197... 

Cadmium chloride Calcium sulfate Cetyl betaine Chromium sulfate, basic Gallic acid Lead thiocyanate Manganese chloride (ous), anhydrous Manganese chloride (ous), tetrahydrate Potassium aluminate PPG-17 Sodium alum Sodium arsenite Sodium oleoamphohydroxypropylsulfonate Sodium phosphate dibasic dihydrate Sodium polymetaphosphate... 

According to the Colour Index (1971 Cl 77305), chromium sulfate (Ct2(S04)3) is said to occur in three forms (a) a violet or red anhydrous form (b) Cr2(S04)3.15H20, which is dark green (c) Cr2(S04)3.18H20. It is prepared by treating chromium hydroxide with sulfuric acid and then crystallising, and has been used in green paints, varnishes and inks. 

Chromium ammonium sulfate (I2H2O) [34275-72-4 (hydr) I3548-43-I (anhydr)] M 478.4, m 94 loses 9H2O then dehydr at 300 , d 1.72. Crystd from a saturated aqueous soln at 55° by cooling slowly with rapid mechanical stirring. The resulting fine crystals were filtered on a Buchner funnel, partly dried on a porous plate, then equilibrated for several months in a vacuum desiccator over crude chromium ammonium sulfate (partially dehydrated by heating at 100° for several hours before use) [Johnson, Hu and Horton J Am Chem Soc 75 3922 1953]. 

Hydrated and anhydrous chromium(II) hydrazinium sulfates (N2H5)2Cr(S04)2 are known. They are air-stable, and in the latter (from isomorphism with the Zn11 complex) each metal ion is coordinated to the nitrogen atoms of two hydrazinium ions and four 6 atoms of bridging sulfato anions.135... 

Twenty grams of chromium nitrate 9-hydrate, or 0.05 moles of the hydrated sulfate or chloride, are fused with 30g of potassium thiocyanate as in (I), and the melt allowed to cool in a desiccator and then triturated with 25ml portions of ethyl acetate until no more material dissolves. The violet liquid is filtered a small green residue remains behind together with the potassium nitrate, sulfate, or chloride. The ethyl acetate extract is evaporated to dryness on the steam bath and the violet residue is further dried in vacuo. The anhydrous salt is violet. 

This material is prepared exactly as described for the corresponding ethyienediamine salt, using 30ml of pn and 21g of anhydrous chromium (III) sulfate. 

No reaction was observed when 86.5g of anhydrous di-propylenetriamine were heated with 27g of dehydrated chromium (III) sulfate on the steam bath. There was no sign of decomposition even after 4 hours at 2G0°C. A drop of water added as catalyst made no difference. 

If tri8(ethylenediamine)chromium(III) chloride is prepared by the method of Rollinson and Bailar,7 it is worthy of note that if the dehydration of the hydrated chromium (III) sulfate is performed in a vacuum oven (2-3 mm. Hg, 70-80°C.) the anhydrous sulfate is obtained in a much more reactive form so that the reaction with ethylenediamine, when started by local heating, proceeds by itself and is finished within an hour. Editor s note For an alternative preparation, see Inorganic Syntheses, 10, 33 (1967) also ref. 26. 

A solution of 1.58 g (5.68 mmol) of tetrabutylammonium chloride in 28 mL of water is added rapidly with stirring to a solution of 0.54 g (5.4 mmol) of chromium trioxide in 14 mL of water at room temperature. The tetrabutylammonium chromate is extracted with 200 mL of chloroform. The chloroform solution is concentrated to 6 mL, and a solution of 0.5 g (2.71 mmol) of benzhydrol in 4 mL of chloroform is added with stirring. After 3 h at 60 °C, the mixture is diluted with ether, and the solution is poured into 1 N sodium hydroxide. The ether layer is washed with a saturated solution of sodium chloride, dried with anhydrous sodium sulfate, and evaporated to give 0.450 g (91%) of benzophenone, mp 45-47 °C. 

Chromium ammonium sulfate (I2H2O) [34275-72-4 (hydrate), 13548-43-1 (anhydrous)] M 478.4, m 94 loses 9H2O then dehydrates at 300°, df 1.72. Crystallise the double salt from a saturated... 

To a 100 mL, two-necked, round-bottomed flask equipped with a nitrogen inlet and outlet was added 26 mL of dry and degassed THF containing 600 mg RJi)-(-)-N,N -his(3-trifluoromethylsalicylidene)-rrans-cyclohexane-l,2-diamine (1.31 mmol). To this yellow solution was then added 111 mg anhydrous chromium(n) chloride (1.44 mmol). The resulting brown solution was stirred for 3 h under a blanket of nitrogen and then exposed to air for a further 3 h. The brown solution was diluted with 120 mL fcrt-butyl methyl ether, washed with 80 mL saturated ammonium chloride, and 80 mL of brine. The organic phase was dried over sodium sulfate, and the solvent was removed in vacuo to yield 489 mg -... 

The method outlined here is similar to the latter but obviates the separation of potassium sulfate from the product. The new methods described below for obtaining various tris (ethylenediamine) chromium(III) salts with anhydrous chromium(III) sulfate as the starting material can be used also for preparing the corresponding propylenediamine derivatives. ... 

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