Bichromates, oxidation

Propionaldehyde. Propanol methylacetaldehyde propylaldehyde. CjH-O mol wt 58.08. C 62,04%, H [0.41%, O 27.55%. CHjCHjCHO. Prepd by treating propyl alcohol with a bichromate oxidizing mixture C. D. Hurd, R. N. Meinert, Org. Syn. coll, vol. II, 541 (1943) by passing propyl alcohol vapor over coppar at high temp Sabatier, Stnderens, Compt Rend. 136, 923 (1903) Willimott, Analyst 50, 13 Chem. Zentr. 1925, I, 2097. 

The amoimts of total lipids extracted from plasma or tissues are best determined by gravimetric or photometric procedures. These methods are superior to older procedures, e.g. bichromate oxidation according to Bloor (1928), because they do not alter the material and permit further procedures to be performed or are less time consuming. 

The natural product utahin (162), characterized as the 5,7-diisopropyl derivative of 159, presumably has been synthesized for the first time by oxidation (sodium bichromate) or diazotation of 5-aminohinokitiol (160 ... 

A point that seems to have been coming out of all of our work is that in interactions, especially oxidation-reduction reactions involving oxygenated species, we have to consider such condensations as this. I shouldn t be surprised if they were involved in a lot of the reactions involving simple metal ions which are hydrated. A recent article (2) states that bichromate also condenses with an aquo complex of cobalt with a much higher formation constant than that for CrSCV2 and with... 

Chlorine, derived from a mixture of hydrochloric acid and potassium bichromate in a 1500 c.c. flask, is washed in water, and then led into a 500 c.c. flask containing mercuric oxide covered with five times its volume of water. The flask is fitted with a stopper carrying an inlet tube reaching nearly to the bottom, and an exit tube connected with a fume chamber. This flask stands in water cooled with ice. When the reaction is nearly completed, the mercuric oxide disappears. The flask is agitated periodically. The soln. of hypochlorous acid mixed with mercuric oxide, etc., is distilled the receiver should be connected with the fume chamber. 

Py rodialites were expls based on K chlorate and coal tar, but the tar was previously purified to remove the acids. In order to take care of acidity which could develop in storage, some alkaline carbonate or bicarbonate was incorporated. Some charcoal and other ingredients could also be incorporated and part of chlorate (or even total) could be substituted by other oxidizers, such as nitrates, perchlorates, bichromates, or permanganates Following are some rypical examples of Pyrodialites ... 

Di silver Oxide 4 Acetylene 4 Disllver Chromate (Complex), AgaO 4 CaHa 4 AgaCi04. Or-red crysts, expl ca 157°. Can be prepd from acetylene and a boiling soln of silver bichromate ... 

Bichromate of Lead—2 PbO, CrOj— chrome red— may bo obtained by boiling oxide of lead, or its car-bonato, with on aqueous solution of monochromate of potassa, or by digesting the neutral chromate of lead in a dilute solution of caustic potassa. Liebig prepared it by adding a neutral ebromate to fased nitre, and washing the residuum it is an insoluble, scarlet colored powder. 

Chromate compounds have been considered by many to be the best inhibitors available. They are typically composed of mixtures of sodium bichromate and chromic acid, and art through passivation of the metal surfaces. Passivation involves formation of a tough metal oxide layer or other film on the surfaces. Chromate concentrations of 200 to 1000 ppm in the cooling water are generally required, although for environments where bimetallic influences exist, chromate levels must be much higher. For instance, when steel and copper surfaces are present in the system, chromate levels often exceed 2000 ppm (BETZ 1982, pp. 207, 212). 

The most extensive investigation was carried out by Guiochon and L. Jacqu6 [30] and Guiochon [17, 31]. They used the same thermogravimetric method as in their former experiments, and examined the influence of chromium oxide (0.3-8%), potassium bichromate (0.1-3%), chromium nitrate (1-5%) and also pure chromium (0.033-5.5%) [30]. 

Noteworthy properties were discovered in ammonium trichromate (NH4)3Cr3O10, produced while crystallizing ammonium bichromate from nitric acid, d = 1.39 (Siewert [47]). At 190°C the compound undergoes explosive decomposition, evolving nitric oxide and nitrogen dioxide. 

Bichromate Ammonium dichromate [CAS 7789-09-5] (NH4>2Cr207, red solid, soluble, upon heating evolves nitrogen gas and leaves a green insoluble residue of clirumic oxide. 

Anthraquinone is obtained by oxidation of anthracene using sodium bichromate plus sulfuric add, and is purified by dissolving in concentrated sulfuric acid at 130 Cl and pouring into boiling water, whereupon anthraquinone separates as pure solid, and is recovered by filtration, Further... 

---