Chromium acetate hydroxide

Peak urinary chromium concentrations were observed at 6 hours (the first time point examined) in rats exposed intratracheally to 0.44 mg/kg chromium(in) as chromium acetate hydroxide or chromium(VI) as sodium dichromate (Gao et al. 1993). Chromium urinary concentrations decreased rapidly, falling from 4,535 pg chromium/g creatinine at 6 hours to 148 pg chromium/g at 72 hours for the chromium acetate hydroxide and from 2,947 pg chromium/g creatinine at 6 hours to 339 pg chromium/g at 72 hours for sodium dichromate. 

Amounts of total chromium were measured in lymphocytes, blood, and urine after intratracheal administration of either sodium dichromate(VI) or chromium(III) acetate hydroxide (a water-soluble chromium(III) compound) to male Wistar rats (Gao et al. 1993). The total amount of chromium administered was 0.44 mg Cr/kg body weight for each compound. The highest concentrations in tissues and urine occurred at 6 hours after treatment, the first time point examined. Mean chromium concentrations (n= 4 rats per time point) from treatment with chromium(III) were 56.3 pg/L in whole blood, 96 pg/L in plasma, 0.44 pg/1010 in lymphocytes, and 4,535.6 pg/g creatinine in urine. For treatment with chromium(VI) the levels were 233.2 pg/L for whole blood, 138 pg/L for plasma,... 

In the presence of acetate ions and the absence of other tervalent metal ions, chromium(III) hydroxide is not precipitated. The precipitation of chromium(III) hydroxide is also prevented by tartrates and by citrates. 

Chromate, if present, would normally be precipitated at a pH of about 5-5, but the sodium nitrite treatment in B reduces it to the tervalent state. Chromium(III) hydroxide is not precipitated in the acetic acid-acetate solution unless present in very large amounts. 

A solution is prepared in a flask from 5 ml. (an excess) of l,l,l-trifluoro-2,4-pentanedionet and 100 ml. of 2,2-dimethoxypropane. The moist filter paper containing the chromium (III) hydroxide is transferred intact to this solution. To this mixture is then added, dropwise from a buret, 1.7 ml. (0.03 mol) of glacial acetic acid. The chromium(III) hydroxide slowly dissolves to give a solution which appears red by transmitted light. The flask is stoppered, shaken occasionally, and then allowed to stand overnight at room temperature. Essentially all of the chromium(III) hydroxide reacts in this time. 

I. Excess glacial acetic acid is added to the light blue-green A-chromium (III) hydroxide (for preparation see p. 1345). The reaction proceeds with appreciable evolution of heat. The crystals (which precipitate after a few hours) are separated from the mother liquor, washed thoroughly with acetone and ether, and dried over H3SO4. 

A muddy blue or greenish blue color indicates the presence of chromium(III), which will react with the sodium acetate solution to afford a chromium(lll) hydroxide gel that will make the final filtration step... 

With Acyl Halides, Hydrogen Halides, and Metallic Halides. Ethylene oxide reacts with acetyl chloride at slightly elevated temperatures in the presence of hydrogen chloride to give the acetate of ethylene chlorohydrin (70). Hydrogen haUdes react to form the corresponding halohydrins (71). Aqueous solutions of ethylene oxide and a metallic haUde can result in the precipitation of the metal hydroxide (72,73). The haUdes of aluminum, chromium, iron, thorium, and zinc in dilute solution react with ethylene oxide to form sols or gels of the metal oxide hydrates and ethylene halohydrin (74). 

H. 8-Hydroxyquinaldine (XI). The reactions of 8-hydroxyquinaldine are, in general, similar to 8-hydroxyquinoline described under (C) above, but unlike the latter it does not produce an insoluble complex with aluminium. In acetic acid-acetate solution precipitates are formed with bismuth, cadmium, copper, iron(II) and iron(III), chromium, manganese, nickel, silver, zinc, titanium (Ti02 + ), molybdate, tungstate, and vanadate. The same ions are precipitated in ammoniacal solution with the exception of molybdate, tungstate, and vanadate, but with the addition of lead, calcium, strontium, and magnesium aluminium is not precipitated, but tartrate must be added to prevent the separation of aluminium hydroxide. 

A mixture of 10 mmol of the allyl bromide and 10-15 mmol of the aldehyde, dissolved in 20 mL of THF, is added dropwise at — 5 to 0°C to the chromium(II) chloride solution in THF prepared by method A or B. The mixture is stirred for 36 h at this temperature and then 15 mL of sat. sodium hydroxide and 20 g of anhyd Na2S04 are added stirring is continued for 20 min at 201C. The mixture is filtered over a pad of Celite/Na2S04 (7 l). The filtrate is concentrated and the residue purified, usually by chromatography on silica gel with pentane/diethyl ether or hexane/ethyl acetate. 

Preparation of Chromium(II) Acetate. Assemble an apparatus as shown in Fig. 126. Fill wash bottles 2 and 3 with an alkaline solution of pyrogallol, and columns 4, 5, and 6 with solid granulated sodium hydroxide. 

---