Ketones, detection paper chromatography

Br-Butanone-Pi. An aqueous solution (10 ml) containing 179 mg (0.025 M) of the triscyclohexylammonium salt of the diethyl ketal is swirled with 2 g of Dowex 50 (H ) to remove cyclohexylammonium ions and then filtered. The resulting acidic solution is incubated at 40 for 3 hr. At this time paper chromatography (same system as above) followed by visualization with the spray for phosphate esters" revealed an essentially complete conversion of the ketal Rf = 0.53) to the ketone (Rf = 0.23). The latter component gave an immediate positive response with a silver nitrate dip," whereas the ketal was not detected. Solutions of... 

Hydroxamic acid gives a strong color with ferric chloride. This reaction is suitable for the detection of aldehydes in the presence of ketones. Aromatic / -hydroxyaldehydes, / -aminobenzaldehyde, vanillin, / -dimethyl-aminobenzaldehyde, salicylaldehyde, and aliphatic aldehydes with a hydroxy group in the y-position do not react. A positive reaction is observed with benzyl ketones in strongly alkaline media. It is necessary, therefore, to keep the mixture distinctly but not excessively alkaline. This reaction can be utilized for the separation of aldehydes from their mixture with ketones by converting the acid to its insoluble copper salt. Paper chromatography can be used for the identification of aldehydes in mixtures (41). 

Diphenylacetyl-l,3-indandione-l-hydrazone, first prepared by Braun and Mosher [143], reacts readily with carbonyl compounds such as aldehydes and ketones in weakly acidic media. The derivatives are separated by paper or thin-layer chromatography [144]. The derivatives are excited at 400-415 nm and emit at ca. 525 nm. The limit of detection is 2 ng per spot. 

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