Aldehyde ferric chloride test

Basic Fraction Amalie Acid Test p-Dimethylaminobenz-aldehyde Ferric Chloride Formaldehyde-Sulphuric Acid... 

Some aldehydes and ketones, those that have a high enol content, give a positive ferric chloride test, as described for phenols in Experiment 52F. 

Cinnamon Bark Oil. Use 1 g for the determination of aldehydes. By experiment, the usually accepted ferric chloride test for absence of leaf oil was found to admit from 30 to 40 per cent adulteration. A determination of phenols should be made, not more than 10 per cent being present in bark oils. 

The preparation of this analytical reagent is described by Sawicki et al., who developed a sensitive test for formaldehyde and other water-soluble aliphatic aldehydes. Treatment of a drop of an aqueous solution of formaldehyde with excess basified reagent effects conversion to the azine (2). Ferric chloride then oxidizes (1) to (3). which condenses with the azine to form the brilliant blue cation (4. one of the resonance structures).. Spot plate, paper, silica gel. and column procedures described fur the detection and determination of aldehydes are particularly useful fur determination of formaldehyde In auto exhaust fbmes and polluted air. 

Only a very activated aromatic compound could react in the absence of this catalyst. Dilution also reduces the effectiveness of nitration. All this information plus the fact that this compound gives a positive ferric chloride (FeCls) test [phenols react with FeCl3 to give a colored complex] tells us tropolone is a phenol. Thus, we now know tropolone is aromatic and, in particular, is a phenol. In addition, we know that tropolone cannot contain a carbonyl group since it does not undergo the 2,4 dinitrophenylhydrazine addition reaction typical of ketones and aldehydes. 

Adulteration with cinnamon leaf oil is indicated by a higher percentage of eugenol, and the deep blue colour yielded with ferric chloride solution. Artificial cinnamic aldehyde is frequently used as an adulterant. The oil should be tested for traces of cUorine as described under oil of almonds, which, if present, is due to the artificial aldehyde. If this adulterant, free from chlorine, has been used, it will be indicated by a high specific gravity, refractive index, and aldehyde-content. 

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