Citral Subject

I have found that a mixture of citral and acetone, if it is subjected, in the presence of water, for a suffieiently long time to the action of hydrates of alkaline earths or of hydrates of alkali metals, or of other alkaline agents, is eondensed to a ketone of the formula CjjH pO. This substanee, which I term Pseudo-ionone," may be produced lor instance in shaking together for several days equal parts of citral and acetone with a solution of hydrate of barium, and in dissolving the products of this reaction in ether. 

The process for the production of the pseudo-ionone referred to in the first claim, consisting in the subjection of a mixture of citral and acetone to the action of an alkaline agent, and in purifying the product of this reaction, extracted by means of ether, by fractional distillation, substantially as described. 

Note 5). The layers are separated (Note 6) the aqueous layer is returned to the separatory funnel and covered with 200 cc. of ether. After 100 cc. of 10 per cent sodium hydroxide has been added, the mixture is vigorously shaken, and then the aqueous layer is removed and extracted with another 200-cc. portion of ether. The two ether extractions, one with addition of sodium hydroxide and one without, are repeated. The second half of the bisulfite solution is subjected to the same treatment as the first half, and all the ether extracts are combined (Note 7) and dried over anhydrous sodium sulfate. The ether is removed on the water bath, and the residual yellow-green oil is distilled under reduced pressure, yielding 120-130 g. (45-49 per cent of the theoretical amount, based upon 210 g. of pure citral) of pale yellow pseudoionone, boiling at 114-116°/2 mm. (124-126°/4 mm.). 

The remaining half of the sulfite solution is subjected to the same treatment, and the total ether extract, after drying, is evaporated on a water bath. The residue is then distilled under reduced pressure, yielding 200-215 g. of almost colorless citral which boils at 84-85°/2 mm. (93-95°/5 mm.). 

In functional products, citral is subject to both acid and base reactions and to oxidation by air or by other components, such as hypochlorite bleach. Consequently, a great deal of research has been invested in the search for materials with the odor of citral, but with much better stability. 

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