Oxidizing agents specific reagents

Phenols are rather easily oxidized despite the absence of a hydrogen atom on the hydroxylbearing carbon. Among the coloured products from the oxidation of phenol by chromic acid is the dicarbonyl compound p-benzoquinone (also known as 1,4-benzoquinone or simply quinone). Dihydroxybenzenes, hydroquinone (7.30) and catechol (7.32) are oxidized to p-benzoquinone (7.31) and o-benzoquinone (7.33), respectively, by milder oxidants such as Jones reagent. Fremy s radical (7.34) is an excellent and very specific oxidizing agent for the oxidation of phenols to o- or p-benzoquinones. (m-Quinones do not exist.)... 

A more long term goal is to explore the use of OMS and OL systems for other selective oxidations. Conventional manganese oxide reagents are typically used as oxidizing agents for stoichiometric oxidations on a laboratory scale. 51 Specific examples include oxidation of primary and secondary alcohols,10 transformation of vitamin A to retinene, l02 overoxidation of aldehydes to acids and esters, 03 etc. Radical intermediates and specific stereochemistries are important in these systems. We expect that these reactions can be carried out catalyticaiiy using our OMS and OL materials. 

This method is not specific and generally refers to oxidation agents. It has already been described in detail in determining chlorine so that it need only be mentioned briefly here. An ozone disc is to be used. If potassium iodide is added before the reagent, or potassium iodide and DPD reagent are added simultaneously, the colour reaction corresponding to the ozone equivalents is the result. Ozone apparently reacts first with iodide to iodine, which then quantitatively forms a red dye with DPD. The DPD reagent should be present in excess of the quantity of iodine for the colour reaction so that the reaction can proceed quantitatively in the way described. 

Like DPD, indigo trisulphonate is not a specific reagent to ozone. How ever, it is only decolourized by such reactive oxidation agents as chlorine, chlorine dioxide and ozone. Other substances contained in the water, such as chlorite, chlorate and hydrogen peroxide do not interfere. Chlorine can be masked by adding malonic acid. 

A number of oxidizing agents are used to identify functional groups of carbohydrates, in elucidating their structures, and for syntheses. The most important are (1) Benedicts or Tollens reagents, (2) bromine water, (3) nitric acid, and (4) periodic acid. Each of these reagents produces a different and usually specific effect when it is allowed to react with a monosaccharide. We shall now examine what these effects are. 

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