Chromium sulfates

Modem chrome-tanning methods are weU controUed and employ an extensive knowledge of the chemistry of the system. The most common chromium-tanning material used is basic chromium sulfate [12336-95-7] Cr(0H)S04, made by the reduction of sodium bichromate with sulfur dioxide or by sulfuric acid and a sugar. 

Leather Taiming. Oxahc acid is used as a pH modifier in leather tanning by tannin and basic chromium sulfate. It also functions as a bleaching agent for leather (qv). 

The reaction is cataly2ed by all but the weakest acids. In the dehydration of ethanol over heterogeneous catalysts, such as alumina (342—346), ether is the main product below 260°C at higher temperatures both ether and ethylene are produced. Other catalysts used include siUca—alumina (347,348), copper sulfate, tin chloride, manganous chloride, aluminum chloride, chrome alum, and chromium sulfate (349,350). 

Aluminum citrate Chromium sulfate Ferrochromo-lignosulfonate Manganese nitrate Potassium hichromate Sodium bichromate Ferric acetylacetonate Ammonium ferric oxalate... 

Chromium sulfates U.S. exports, 6 544t U.S. imports for consumption, 6 545t Chromium(II) sulfide, 6 532 Chromium surface conversion, 6 552—554 Chromium tin orchid cassiterite, formula and DCMA number, 7 347t Chromium tin pink sphene, formula and DCMA number, 7 348t Chromium trioxide... 

The chromium sulfate tends to aggregate in large lumps. The stirrer should therefore be rigid and at least an inch away from the bottom of the flask. 

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 carbonyl see Chromium and chromium compounds) Chromium potassium sulfate see Chromium and chromium compounds) Chromium sulfate see Chromium and chromium compounds)... 

The most popular tanning solution in current use is termed 33% basic chromium(III) sulfate and corresponds to the empirical formula CrOHSCV In older procedures, chromate was often reduced at the plant using glucose/sulfuric acid mixtures. At present, 33% basic chromium sulfate is provided as either a solution (chrome liquor) or as a commercially available powder,120 of constant, but at present slightly uncertain, chemical composition. 

However, examiningthe E-factor for this reaction, we see that for every three moles of benzophenone we produce one mole of chromium sulfate and six moles of water. The molecular weight of benzophenone is 182.2 gmoH1, so every kilogram of benzophenone contains 5.48 moles of benzophenone. This means that for every kilogram of benzophenone we generate 5.48/3 = 1.83 moles (or 0.717 kg) of... 

Five grams (0.0135 mol) of tris(biguanido) chromium (III) 1-hydrate is dissolved in 200 ml. of water and treated with a solution of 5,7 g. (0.043 mol) of ammonium sulfate in 10 ml. of water. The sparingly soluble tris(biguanide)-chromium sulfate is precipitated with liberation of ammonia. The mixture is heated on the water bath, whereby... 

Synonyms Chrome alum, Chromium and potassium sulfate, Potassium chromium sulfate. Appearance Dark violet-red crystals (ruby red by transmitted light) or light violet powder. Uses Preparation of chrome alum fixing bath as hardening agent for gelatin. 

Cardiovascular Effects. Information regarding cardiovascular effects in humans after inhalation exposure to chromium and its compounds is limited. In a survey of a facility engaged in chromate production in Italy, where exposure concentrations were 0.01 mg chromium(VI)/m3, electrocardiograms were recorded for 22 of the 65 workers who worked in the production of dichromate and chromium trioxide for at least 1 year. No abnormalities were found (Sassi 1956). An extensive survey to determine the health status of chromate workers in seven U.S. chromate production plants found no association between heart disease or effects on blood pressure and exposure to chromates. Various manufacturing processes in the plants resulted in exposure of workers to chromite ore (mean time-weighted concentration of 0-0.89 mg chromium(ni)/m3) water-soluble chromium(VI) compounds (0.005-0.17 mg chromium(VI)/m3) and acid-soluble/water-insoluble chromium compounds (including basic chromium sulfate), which may or may not entirely represent trivalent chromium (0-0.47 mg chromium/m3) (PHS 1953). No excess deaths were observed from cardiovascular diseases and ischemic heart disease in a cohort of 4,227 stainless steel production workers from 1968 to 1984 when compared to expected deaths based on national rates and matched for age, sex, and calender time (Moulin et al. 1993). No measurements of exposure were provided. In a cohort of 3,408 individuals who had worked in 4 facilities that produced chromium compounds from chromite ore in northern New Jersey sometime between 1937 and 1971, where the exposure durations of workers ranged from <1 to >20 years, and no increases in atherosclerotic heart disease were evident (Rosenman and Stanbury 1996). The proportionate mortality ratios for white and black men were 97 (confidence limits 88-107) and 90 (confidence limits 72-111), respectively. 

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