Alkaline cupric oxide

Alkali lignin was oxidized with alkaline cupric oxide at atmospheric and superatmospheric pressure after first etching the lignin with alumi-... 

Alkaline Cupric Oxide Oxidation after Preliminary Etching . 

Table 6.2.10. Aromatic products from the alkaline cupric oxide oxidation of chlorinated pine kraft pulp 1...

Alkaline cupric oxidation of coals produced phenolic acids (p-hydroxy and 3,4 hydroxy-benzoic acids, 4 hydroxy l,2 and 4-hydroxy l,3 benzenedicarboxylic acids), which are known as characteristic lignin oxidation products. The results indicate that lignin-like polymers are incorporated into macromolecules of coals and still are identifiable in lower rank coals. 

In general, commonly used oxidants destroy phenolic rings or give complex products (25, 26). Some of the oxidants such as nitrobenzene produce reaction byproducts that may interfere with the analysis of the oxidation products (23, 27, 28). To obtain lignin oxidation products from coals, we resorted to the alkaline cupric oxide oxidation method which has been applied successfully to analysis of lignins in plants (23), fulvic and humic acids (24, 27), and land-derived marine sediments (23). 

Valine.—This amino acid is contained mixed with leucine in the fractions of the esters which boil between 6o° and 90° C. Its isolation and separation from leucine is of extreme difficulty, since these compounds, as well as their copper salts into which they are converted by boiling with freshly precipitated cupric oxide, tend to form mixed crystals. Its isolation was only effected by these means in certain cases, and its amount is really much more than the figures represent from its yield. It is best characterised by conversion into its phenylhy-dantoine derivative by treatment with phenyl isocyanate in alkaline solution. The phenylureido acid is first formed, and this loses a molecule of water, as shown by Mouneyrat, and is changed into its anhydride or phenylhydantoine by treatment with hydrochloric acid. The following reactions occur —... 

Reducing sugars Accurately weigh 7 g of sorbitol and transfer to a 400 mL beaker with 35 mL of water and mix. Add 50 mL of alkaline cupric tartrate test solution, and cover the beaker. Heat so that it boils in approximately 4 minutes and boil for 2 minutes. Collect the precipitated cuprous oxide in a tared filtering crucible previously washed with hot water, alcohol, and ether, and then dried at 105 C for 30 minutes. Wash the cuprous oxide on the filter Avith hot water, then with 10 mL of alcohol, and then 10 mL of ether. Dry at 105 C for 30 minutes. The weight of the cuprous oxide should not exceed 50 mg. 

A basic copper chlorate is formed when soln. of potassium chlorate acidified with sulphuric acid are electrolyzed with an alternating current between copper electrodes (L. Rossi) 83 when the hydrate is heated above 100° (A. Wachter) when a soln. of copper chlorate be mixed with pieces of marble or urea, and heated in a sealed tube to 130° (L. Bourgeois) when the hydroxides of the alkalies or alkaline earths act on cupric chlorate soln., or copper hydroxide acts on soln. of potassium chlorate (A. Brochet) when hydrated cupric oxide or cupric hydroxide acts on cupric chlorate soln. (P. Sabatier) or when potassium chlorate acts on cupric acetate soln. (A. Casselmann), basic cupric chlorate is obtained. The basic chlorate forms bluish-green monoclinic prisms of sp. gr. 3 55 and composition 4Cu0.C1205.3H20, that is, Cu(C103)2.3Cu(0H)2, which A. Werner considers to be hexahydroxyl cupric chlorate ... 

When metallic copper is heated in the air it becomes coated with a layer of oxide, which, according to conditions, may be cuprous or cupric oxide, or a mixture of the two. Pure cuprous oxide is most conveniently prepared in the wet way by treating an alkaline cupric salt solution with a reducing agent, whereby the red cuprous oxide is precipitated. 

A. Add 5 mL of sulfuric acid TS to 10 mL of a 2% aqueous suspension of sample, heat in a boiling water bath for 30 min, and cool. Neutralize the mixture with barium carbonate, and centrifuge it at 900 g for 10 min. Add 1 mL of the supernatant to 5 mL of hot alkaline cupric tartrate TS. A copious red precipitate of cuprous oxide forms. 

Identification Add a few drops of a 1 20 aqueous solution to 5 mL of hot alkaline cupric tartrate TS. A copious red precipitate of cuprous oxide forms. 

Identification Add 5 mL of 1 N sodium hydroxide to 5 mL of a hot, saturated solution of sample, and gently warm the mixture. The liquid turns yellow and, finally, brown-red. Cool to room temperature, and add a few drops of alkaline cupric tartrate TS. A red precipitate of cuprous oxide forms. 

Cuprous oxide is produced in the form of an orange-yellow, amorphous gel containing water by the reduction of an alkaline cupric solution with sodium hyposulphite 7... 

Other methods of formation are the addition of sodium carbonate to a solution of cupric sulphate and sodium chloride reduced with sulphurous acid,9 and that of an alkaline solution of sodium potassium tartrate to a solution of cuprous chloride and sodium chloride.10 At temperatures below 350° C. copper reacts with nitrous oxide to form cuprous oxide above this temperature the product is cupric oxide.u Cuprous oxide is also formed at the anode in the electrolysis of a solution of cupric sulphate,12 and by heating cupric oxide in steam. 

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