Chromium chlorides

Vanadium chloride, chromium chloride," and the combined use of tributylphosphine and thphenyldisulfide are also effeedve in promoting the reduedve Nef reacdon. 

Cobalt boride has been used for reducing unsaturated aldehydes to unsaturated alcohols improved results are obtained by addition of ferric chloride or chromium chloride (6S). It is a low-activity catalyst. 

Vanadium chloride, 2 chromium chloride,33 and the combined use of tributylphosphine and diphenyldisulfide34 are also effective in promoting the reductive Nef reaction. 

Chromium is a trace mineral that is necessary to process carbohydrates and fats, as well as to help cells respond properly to insulin—an especially important function for people with diabetes. Chromium, in its safest form, can be found in whole grains, seafood, green beans, peanut butter, and potatoes. As a dietary supplement, chromium is available in several forms, including chromium picolinate, chromium chloride, chromium nicotinate, and high-chromium yeast. 

Cr-ZSM-5 catalysts prepared by solid-state reaction from different chromium precursors (acetate, chloride, nitrate, sulphate and ammonium dichromate) were studied in the selective ammoxidation of ethylene to acetonitrile. Cr-ZSM-5 catalysts were characterized by chemical analysis, X-ray powder diffraction, FTIR (1500-400 cm 1), N2 physisorption (BET), 27A1 MAS NMR, UV-Visible spectroscopy, NH3-TPD and H2-TPR. For all samples, UV-Visible spectroscopy and H2-TPR results confirmed that both Cr(VI) ions and Cr(III) oxide coexist. TPD of ammonia showed that from the chromium incorporation, it results strong Lewis acid sites formation at the detriment of the initial Bronsted acid sites. The catalyst issued from chromium chloride showed higher activity and selectivity toward acetonitrile. This activity can be assigned to the nature of chromium species formed using this precursor. In general, C r6+ species seem to play a key role in the ammoxidation reaction but Cr203 oxide enhances the deep oxidation. 

Reactions with salts. This procedure is more limited and is illustrated by the use of chromium chloride solutions under reflux for partial dealumination of Y and X zeolites (19), as well as of erionite (20). It is assumed that in this case a partial substitution of chromium for aluminum takes place, leading to the formation of Si-O-Cr bonds in the framework (19). Up to 40 percent of aluminum was removed by this method. Zeolites can also be dealuminated with solutions of ammonium fluorosilicate (107). 

Trifluoromethanesulfonic acid Methanesulfonic acid, trifluoro- (8,9) (1493-13-6) Chromium(ll) chloride, anhydrous Chromium chloride (8,9) (10049-05-5)... 

Pinacol formation from ketones and aldehydes by cathodic reduction has been enhanced in the presence of Cr(II) complexes. Electrolysis of a mixture of ben-zophenone (364) and chromium chloride hexahydrate in a DMF-NaCl04 system... 

Some chromium compounds (e.g., chromium chloride, chromic hydroxide, chromic phosphate) are used as catalysts for organic chemical reactions. 

Excerpt 4D is from Chemical Research in Toxicology. The authors investigate the genotoxicity of three different chromium (Iff) compounds (chromium chloride,... 

In the third set of results (not included in excerpt 4D), the authors examine how Cr + affects gyrase, an enzyme that regulates the ability of supercoiled DNA to relax. Results, however, are reported only for chromium chloride, not for chromium oxalate or chromium nitrate. By omitting these latter two compounds, the authors illustrate what we call a broad-to-narrow approach. At the start of a research project, there are typically many variables however, as knowledge is gained, some of these variables can be eliminated. In this case, chromium oxalate... 

Plaper et al. (2002) use a stand-alone Discussion section, rather than a combined R D section. According to the move structure in figure 5.1, a separate Discussion section should begin with a brief reminder of a specific result or set of results this is essentially how Plaper et al. (2002) begin. The authors first remind the readers about the study in general (in the first two sentences) then, in the third sentence, they remind the readers specifically about the Pro-Tox (C) assay with chromium chloride. 

PI Many studies have shown that not only Cr but also CD cause damage inside the cells. In this work, three CD compounds were examined for their impact on genotoxicity and cell proliferation in vitro. Chromium chloride added to E. coli strains in the Pro-Tox (C) test system induced lacZ gene transcription from several stress promoters. (Adapted from Plaper et al., 2002)... 

P3 When E. coli test strains were treated with chromium nitrate, the induction profile obtained was very similar to chromium chloride profile (data not shown). The promoters that were induced indicate that the action of Cr + was on DNA. However, none of the 13 stress promoters responded to chromium oxalate at any of the concentrations... 

Synonyms Chromium dioxychloride chromium dioxide dichloride chromium oxychloride chromium chloride oxide... 

Other methods have appeared, but have been less frequently used, e.g. chromium chloride in acetone 140- 143 (y/yfe infra) and dissolving alkali-metal reductions.144,145 Hydrogenolysis with palladium/hydrogen has also given the monoreduced cyclobutanone.99,100... 

Preparation of Nickel, Cobalt, or Chromium Chloride. When working with chlorine for a long period, prepare it by reacting con-... 

Fig. 61. Apparatus for preparing metal (nickel, cobalt, chromium) chlorides...

Spill 0.5 g of powdered metallic nickel (cobalt or chromium) into a boat and place it in the middle part of the quartz tube. Switch on the furnace. Dry the system with a stream of dry carbon dioxide during 30-40 min at 150-200 °C use a thermocouple). Stop the carbon dioxide stream and fill the apparatus with dry chlorine. How can one tell that the apparatus is filled with chlorine Raise the furnace temperature to 700-750 °C. (When synthesizing chromium chloride. 

Assemble an apparatus (see Fig. 61). Place the dry beads into a porcelain or quartz tube and perform chlorination at 750-800 °C during one hour. Ghromium(III) chloride can sublime, therefore see that the tube outlet is not clogged by the product. Cool the apparatus in a stream of chlorine. Extract the beads from the tube and mechanically separate the chromium chloride formed on their surface from the unreacted charcoal. In what other ways can anhydrous chromium(III) chloride be obtained ... 

Knapp discovered in 1858 that chromium chloride converted raw skins into leather, but he failed to realize the commercial significance of his discovery. Others developed his ideas. A two-bath process due to Schultz (1894) and an adaptation of Knapp s original one-bath process by Dennis (1893), meant that by the early twentieth century chromium tannage was commercially important. At present it accounts for the vast majority of leather production. 

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