Alcohols, secondary, oxidation with potassium dichromate

By the oxidation of secondary alcohols with potassium dichromate and dilute sulphuric acid, for example ... 

Aldehydes. Primary alcohols (in CH2CI2) can be oxidized to aldehydes with potassium dichromate in 9 A/ sulfuric acid in the presence of tetra-n-butylr ammonium bisulfate as a phase-transfer catalyst. It is generally advantageous to use a slight excess of oxidant. The oxidation is complete in a few seconds at room temperature. Yields are generally high except for water-soluble aliphatic alcohols and ,/3-unsaturated alcohols (the double bonds appear to be oxidized). Of course, secondary alcohols can also be oxidized to ketones in the same way. ... 

Primary and secondary alcohols undergo oxidation when reacted with a mixture of acidified potassium dichromate (VI) and dilute sulphuric acid. Primary alcohols are oxidised in the sequence... 

Solution Ketones can be prepared by oxidation of secondary alcohols with a variety of reagents, such as CrOa (chromium trioxide) or KaCraO (potassium dichromate) with acid. The compound that is formed by oxidation of an alcohol depends upon the number of hydrogens attached to the carbon bearing the -OH group, that is upon whether the alcohol is primary, secondary or tertiary. For example, in the first problem, to synthesize the product, methyl ethyl ketone, a secondary alcohol is used that has the same number of carbon atoms as the product. In this case sec-butyl alcohol is used as the precursor. 

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