Sodium dichromate—sulfuric acid

The glassware was cleaned in a sodium dichromate-sulfuric acid bath, washed with aqueous 10% ammonium hydroxide, and rinsed with water. The extent of enolization apparently depends on the care taken in washing the glassware and conducting the distillation. 

Sodium dichromate, Sulfuric acid See Sodium dichromate Sulfuric acid, Trinitrotoluene... 

Toluidines 2,4,6-Trinitrotoluene 1,3,5-Trioxane Urea Vinylidene chloride Nitric acid Sodium dichromate, sulfuric acid Oxidizing materials, acids Sodium nitrite, phosphorus pentachloride Chlorosulfonic acid, nitric acid, oleum... 

Chromic acid etch (sodium dichromate-sulfuric acid) Maximum-strength... 

The sodium dichromate-sulfuric acid process has been found by some to be superior to other ferric chloride methods for the prebond treatment of copper. This dichromate-sulfuric acid method is also defined by ASTM D 2651. Nitric acid and ferric chloride etching processes have also been found to be useful for copper, brass, and bronze substrates in certain applications. 

Generally only solvent cleaning and abrasion are necessary for surface preparation of polystyrene parts. Methanol and isopropanol are acceptable solvents for solvent cleaning of polystyrene. For maximum bond strength the substrates can be etched with sodium dichromate-sulfuric acid solution at elevated temperature. Table 16.14 shows the results of a study on the durability of joints formed between polystyrene and aluminum with different types of adhesives exposed to different environments. 

Suppose you have just synthesized heptanoic acid from heptan- l-ol. The product is contaminated by sodium dichromate, sulfuric acid, heptan- l-ol, and possibly heptanal. Explain how you would use acid-base extractions to purify the heptanoic acid. Use a chart, like that in Figure 20-3, to show where the impurities are at each stage. 

Highly dangerous explodes with shock or heating to 297°C. Various materials can reduce the explosive temperature red lead -(to 192°C), sodium carbonate (to 218°C), potassium hydroxide (to 192°C). Mixtures with sodium dichromate + sulfuric acid may... 

Aldehydes or ketones containing a cyclopropyl group adjacent to the carbonyl group can be converted to ring-opened carbonyl compounds by several different types of two-electron reduction processes. The most widely used method employs lithium metal in liquid ammonia as the reductant. The cyclopropyl ketone is usually dissolved in anhydrous diethyl ether and added to the blue metal-ammonia solution. Occasionally, the order of addition is reversed, and the lithium is added to a solution of the ketone in ammonia and diethyl ether. After a timed interval, the reduction is quenched by adding solid ammonium chloride to give a mixture of alcohols and ketones. This mixture is generally oxidized before isolation, with chromium(VI) oxide/pyridine or with sodium dichromate/sulfuric acid, to solely afford the ketone. 

Sodium dichromate/sulfuric acid Isatins from indigos... 

Sodium dichromate/sulfuric acid Na2Cr20- lH2S0 ... 

Sodium dichromate/sulfuric acid-mercuric propionate Ketones from ethylene derivs. 

Polyolefins, such as polyethylene, polypropylene and polymethyl pentene, as well as polyformaldehyde and polyether, may be more effectively treated with a sodium dichromate-sulfuric acid solution. This treatment oxidizes the surface, allowing better wetting by the adhesive. Flame treatment and corona discharge have also been used. Table 7.20 shows the relative joint strength of bonded polyethylene and other plastic substrates pretreated by these various methods. 

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