Picoline-Chromium VI Oxide

The procedure is the same as for the pyridine compound. The product is a yellow-tan cake. Yields are approximately quantitative. Anal. Calcd. for 2C6H7N-Cr03 Cr, 18.17. Found total Cr, 18.41, 18.28 Cr6+, 18.34, 18.14. 

4-PICOLINE CHROMIUM (VI) OXIDE 2C6H7N + Cr03 2C6II7N-Cr03 

A weighed sample of the product (approximately 1 g.) is dissolved in a 3 % perchloric acid solution, with gentle heating in a water bath if necessary. To determine ehromium-(YI), aliquot portions of the solution are acidified with 10% 

The amount of reduction of the chromium may be determined by oxidizing aliquot portions of the above solution and determining the total chromium content. The oxidation is effected by acidifying the sample with 10% sulfuric acid and heating nearly to boiling. A small crystal of silver nitrate and approximately 2 g. of ammonium peroxydisul-fate are added for every 50 ml. of solution. The treated solution is evaporated to one-half its former volume, cooled, apd diluted to 50 ml. The remainder of the procedure is the same as that used for hexavalent chromium. 

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Cr03-2C H)N 3 (and 4)-Picoline-chromium(VI) oxide, 4 95 CrOaClK Potassium monochloro-chromate, 2 208... 

Cr(NH3)6]Cl3 Hexamminechro-mium(III) chloride, 2 196 [Cr(NHs)6](N03)3 Hexammine-chromium(III) nitrate, 3 163 Cr02Cl2 Chromyl chloride, 2 205 Cr03-2C6H6N Pyridine-chromium (VI) oxide, 4 94 Cr03-2C6H7N 3 (and 4)-Picoline-chromium(VI) oxide, 4 95 CrOsClK Potassium monochloro-ehromate, 2 208... 

Chromium (VI) oxide, addition compounds with pyridine and 3-and 4-picoline, 4 94, 95 analysis of, 4 95... 

Pyridine and picoline addition compounds of chromium (VI) oxide, synthesis 33 Biurea, synthesis 8 Urazine, synthesis 9 Carbohydrazide, synthesis 10... 

Effects of cationic (cetylpyridinium chloride, CPC) and anionic (SDS) micelles on the rate of reaction of chromium(VI) oxidation of formaldehyde have been studied in the presence and absence of picolinic acid. Cationic micelles (CPC) inhibit whereas anionic micelles (SDS) catalyze the reaction rates that could be attributed to electrostatic interactions between reactants (cationic metal ions and catalyst H+) and ionic head groups of ionic micelles. Experimentally determined kinetic data on these metaUomicellar-mediated reactions have been explained by different kinetic models such as pseudophase ion-exchange (PIE) model, Monger s enzyme-kinetic-type model, and Piszkiewicz s cooperativity model (Chapter 3). The rate of oxidation of proline by vanadium(V) with water acting as nucleophile is catalyzed by aqueous micelles. Effects of anionic micelles (SDS) on the rate of A-bromobenzamide-catalyzed oxidation of ethanol, propanol, and n-butanol in acidic medium reveal the presence of premicellar catalysis that has been rationalized in light of the positive cooperativity model. ... 

Urinary excretion rates have been measured in humans after oral exposure to several chromium compounds (Finley et al. 1996b). A group of four male and two female volunteers ingested capsules containing chromium(ni) picolinate at a dose of 200 pg/day for 7 days, to ensure that chromium deficiency was not a confounding factor. They then ingested 0.005 mg/kg/day chromium(VI) as potassium chromate (3 days), and 1.0 mg/kg/day chromium(III) as chromic oxide (3 days), with 3 days... 

With oxides containing higher chromium contents, the Lomi process proceeds very slowly since vanadous picolinate is not able to reduce Cr(III). If the chromium concentration in the oxide exceeds 15%, the dissolution rates will become unacceptably low. Therefore, in such applications, the Cr(III) must first be oxidized to Cr(VI) by an appropriate preoxidation step (AP and NP steps, see below). In order to save this time-consuming additional step, attempts have been made to replace V(II) by another reducing cation. Only a combination of Cr(II) with nitrilo triacetic acid or with EDTA shows a faster reaction, but it suffers from insufficient thermal stability thus, it cannot be used in the decontamination of systems and circuits. 

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