Oxidation alcohols, “green

Oliveira, R.L., Kiyohara, P.K. and Rossi, L.M. (2010) High performance magnetic separation of gold nanoparticles for catalytic oxidation of alcohols. Green Chemistry, 12 (1), 144-149. 

Green Oxidation of Alcohols using Biominetic Cu Complexes and Cu Enzymes as Catalysts Isabel W.C.E Arends, Patrick Gamez and Roger A. Sheldon... 

Green Oxidation of Alcohols using Biominetic Cu Complexes and Cu Enzymes as Catalysts... 

Dichromate test Add 10 drops of the alcohol to be tested to a mixture of 1 ml of 1% Na CX, and 5 drops of concentrated H2S04. A blue-green solution is a positive test for a 1 or 2° alcohol. Three degree alcohols do not react, and therefore, the solution stays orange (detection limit, 20 pg compounds tested, C, to C8). Slight heating may be necessary for water-immiscible alcohols. Extensive heat gives a positive test also for tertiary alcohols, which is due to the water elimination of the alcohol and oxidation of the formed alkene. 

Chromic acid test. This test is able to distinguish primary and secondary alcohols from tertiary alcohols. Using acidified dichromate solution, primary alcohols are oxidized to carboxylic acids secondary alcohols are oxidized to ketones tertiary alcohols are not oxidized. (Note that in those alcohols which are oxidized, the carbon that has the hydroxyl group loses a hydrogen.) In the oxidation, the brown-red color of the chromic acid changes to a blue-green solution. Phenols are oxidized to nondescript brown tarry masses. (Aldehydes are also oxidized under these conditions to carboxylic acids, but ketones remain intact see Experiment 31 for further discussion.)... 

The chromic acid test for primary and secondary alcohols exploits the resistance of tertiary alcohols to oxidation. When a primary or secondary alcohol is added to the chromic acid reagent, the orange color changes to green or blue. When a nonoxidizable substance (such as a tertiary alcohol, a ketone, or an alkane) is added to the reagent, no immediate color change occurs. 

Experiment 183. — Add to a few cubic centimeters of potassium dichromate solution a little concentrated hydrochloric acid and a few drops of alcohol. Warm gently. Two important changes occur. The chromate is reduced to chromic chloride which colors the solution green the alcohol is oxidized to aldehyde, which is detected by its peculiar odor. (See Exp. in ( ).) The equation is —... 

Of the compounds we have dealt with so far, alcohols also dissolve in sulfuric acid. Alcohols can be distinguished from alkenes, however, by the fact that alcohols give a negative test with bromine in carbon tetrachloride and a negative Baeyer test—so long as we are not misled by impurities. Primary and secondary alcohols are oxidized by chromic anhydride, CrOa, in aqueous sulfuric acid within two seconds, the clear orange solution turns blue-green and becomes opaque. 

M. Guo, Quaternary ammonium decatungstate catalyst for oxidation of alcohol. Green Ghent. 6 (2004) 271. 

Ramakrishna D, Bhat BR, Karvembu R (2010) Catalytic oxidation of alcohols by nickel (11) Shiff base complexes containing triphenylphosphine in ionic hquid an attempt towards green oxidation process. Catal Commun 11 498-501... 

Arts. The color change from orange to green indicates that dichromate has oxidized the unknown and has itself been converted to the green-colored Cr . However, this test does not distinguish hexene from hexanol since alkenes as well as primary and secondary alcohols are oxidized by dichromate. 

GREEN OXIDATION OF ALCOHOLS USING BIOMIMETIC Cu COMPLEXES AND Cu ENZYMES AS CATALYSTS... 

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