Ionone pseudo

Enone formation-aromatization has been used for the synthesis of 7-hydro-xyalkavinone (716)[456]. The isotlavone 717 was prepared by the elimina-tion[457]. The unsaturated 5-keto allyl esters 718 and 719, obtained in two steps from myreene. were subjected to enone formation. The reaction can be carried out even at room temperature using dinitriles such as adiponitrile (720) or 1,6-dicyanohexane as a solvent and a weak ligand to give the pseudo-ionone isomers 721 and 722 without giving an allylated product(458]. 

Woker has apparently overlooked the classic example of the icon-version of pseudo-ionone to ionone. 

In order to attempt to synthesise irone, experiments were made which finally led to the condensation of citral with acetone, in the presence of alkalis. Irone was not obtained, but an isomer, which Tiemann called pseudo-ionone, as follows —... 

If pseudo-ionone be heated with dilute sulphuric acid and a little glycerine, it is converted into another isomeric ketone, and now well-known ionone, CjgHo O. 

It has been proved that whilst concentrated sulphuric acid at a low temperature caused isomerisation of pseudo-ionone, so that the resulting product consists chiefly of j8-ionone, the use of phosphoric, hydrochloric, and hydrobromic acids at low temperatures yields chiefly -ionone. 

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 product of condensation remaining in the distilling apparatus is purified by the fractional distillation in vacuo. Under a pressure of 12 mm. a liquid distils off at a temperature of from 143° to 145° C. This product of condensation which I term Pseudo-ionone, is a ketone readily decomposable by the action of alkalis. Its... 

The pseudo-ionone has a peculiar but not very pronounced odour it docs not oombine with bisulphite of sodium as most of the ketones of the higher series, but, in other respects, it possesses the ordinary characteristic properties of the ketones, forming, in particular, products of condensation with phenylhydrazine, hydroxyl-amine and other substituted ammonias. 

The ketone derivatives of the pseudo-ionone are converted under similar conditions into ketone-derivatives of the ionone. The pure ionone corresponds to the formula CjjHjjO, it boils under a pressure of 12 mm. at a temperature of about 128° 0., its specific weight is 0-935, and its index of refraction mD = 1-507. 

Although the odour of the pseudo-ionone does not appear to render it of great importance for its direct use in perfumery, it is capable of serving as raw material lor the production of perfumes, the pseudo-ionone being converted by the action of dilute acids into an isomeric ketone, which I term lonone, and which has most valuable properties for perfumery purposes. This conversion may be effected, for example, by heating for several hours in an oil-bath 20 parts of pseudo-ionone with 100 parts of water, 2-5 parts of sulphuric acid, and 100 parts of glycerine, to the boiling-point of the mixture. 

A new chemical product termed pseudo-ionone obtained by the reaction of citral upon acetone in the presence of alkaline agents and subsequent treatment of the products, substantially as described. 

A new article of manufacture termed ionone suitable for perfumery and the like and having the characteristics hereinbefore set forth, obtained from pseudo-ionone referred to in the preceding claim, substantially as described. 

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. 

They also claim that large quantities of iso-pseudo-ionone are formed in the process of Tiemann s patent, and which can be separated by distillation, coming over at a higher temperature than the ordinary pseudo-ionone. 

For the preparation of a-ionone, citral and acetone are reacted in an aldol condensation catalysed by a base to form so-called pseudo-ionone (Scheme 13.2). The pseudo-ionone can be cyclised to form a-ionone catalysed by an acid. 

Citral and acetone give pseudo-ionone. (B., 27, R., 768 see Reaction XVIII. (iv.).)... 

Pseudo-ionone is the first prodnct, and this is then converted to a mixture of a- and /3-ionone by boiling with dilute sulphuric acid ... 

Geraniol is a constituent of rose and geranium oils and citral is in lemon and orange oils and lemon-grass oil. When citral condenses with acetone, with loss of water, a product known as pseudo-ionone is obtained. 

Ionone is an important chemical in the synthesis of vitamin A. It is prepared by the reaction of pseudo-ionone with sulfuric acid, d, il-a-ionone... 

---