DE138141C - - Google Patents

Description

IMPERIAL

PATENT OFFICE.

A process for converting compounds is described in patent specification 75062 of the citral series into isomers. This is done with the help of acids or analogous condensation agents. To the citral itself, which is converted into cymene by the elimination of water into its cyclic To convert isomers, one must, as in patents 73089, 108335, 123747 etc. is shown the aldehyde group of the citral in a suitable manner prior to the action of the condensing agent protection.

The situation with geraniol is very similar to that of citral. This also works do not transform directly into cyclogeraniol, since under the influence of acids it turns into terpine hydrate, Terpineol, terpinen and other derivatives pass over.

It has now been found that the geraniol can be converted into cyclogeraniol by the means given in patent specification 75062 if the CU ₂ - OH group is protected from attack by the acids and from the rearranged ones in the same way as with citral Derivatives of geraniol split off the cyclogeraniol. The esters of geraniol are particularly suitable for conversion into cyclic isomers using the process described in patent 75062. They are then used to give cyclogeraniol by saponification.

Erdmann has shown (Journal f. Pract. Chemie 56 (1897) p. 24) that geraniolphthalic acid can be found Benzyl dissolves in concentrated sulfuric acid with an intense orange-yellow color. But he does not intend to attempt this still undertaken with the success of the preparation of cyclogeraniol.

The cyclogeraniol also consists, like the other compounds of Cyclocitralreihe which are by rearrangement of the corresponding \ ^r onnectivity the Citralreihe emerged of two isomers of a mixture. The ratio of these (α-cyclogeraniol and β-cyclogeraniol) to one another varies depending on the mode of presentation, in such a way that when phosphoric acid is used mainly α-cyclogeraniol is formed, but when rearrangement with sulfuric acid, on the other hand, more β-cyclogeraniol is present in the product seems to be.

Example: 100 parts of geranyl acetate are converted into 300 parts of phosphoric acid (spec. Wt. 1.7 to 1.75) allowed to run in; the crowd will then warmed to about 50 ° for a short time and poured into water. The product is

*) Previous additional patents: 123747; 124228; 126960.

known manner and isolated by exaggeration with steam and fractional distillation cleaned. In the meantime, the raw product, freed from the resins, can also be further processed directly to process.

Or: One carries that from 100 parts each of geraniol and 100 parts of acetic anhydride Raw product obtained by brief boiling directly, with good cooling, in 300 parts Phosphoric acid and proceed as indicated above.

Instead of the ethyl acetate, other esters of geraniol can also be used with the same success, such as butyric acid esters, isovaleric acid esters, benzoic acid esters, etc. They are produced in a known way by the action of the chlorides or anhydrides of the acids on geraniol, or with the acids below Use of mineral acids. The esters are washed with soda solution, then dried and incorporated into the concentrated acid without further purification. The inverted ones Esters do not require any further purification either, but can be saponified directly.

Instead of phosphoric acid, sulfuric acid of various concentrations can also be used (e.g. from 60 to 98 pct.).

The ester of cyclogeraniol obtained is (e.g. by heating with a little excess Alkali in a diluted alcoholic solution) saponified and the alcohol that can be obtained from it in a known manner, e.g. B. by conversion into an acidic or non-volatile Ester, purification of the same and saponification freed from impurities.

If there is still some geraniol in the product, this can be done before the Purification of the cyclogeraniol by heating with concentrated formic acid or benzoyl chloride destroy by known methods (Bertram and Gildemeister, Journal für pract. Chemie (2) 49, 1894, p. 194 and Barbier and Bouveault, Compt. rend. 122, p. 530, Walbaum and Stephan, Ber. d. D. eh. Ges. 33 (1900) p. 2307).

The pure cyclogeraniol boils at about 95 to 100 ° (corr.) Under 12 mm pressure, has a spec. Wt. From 0.935 to 0.995 at 20 ⁰ refraction η d = about 1.48. The cyclogeraniol should, among other things, also serve to represent its industrially usable esters.

The esters of cyclogeraniol have a very pleasant odor, which is clearly different from that of the geraniol esters. The cyclogeranyl formate shows the following data: Sp. 20 mm 102 to 10 8 °, spec. Wt. 0.907 at 18 °. The cyclogeranyl acetate: Sp. 30 mm about 130 to 132 ⁰ spec. Weight at 18 ° about 0.96 refraction nd = 1.46 to 1.47. The Cyclogeranylvalerianat boils under 20 mm pressure at 145 to 15 5 °. These data are subject to slight fluctuations, depending on whether the cyclogeraniol contains more of the α-compound or more of the ß-compound.

The esters of cyclogeraniol can also be obtained directly by rearrangement of the esters of Geraniols prepared by the method of patent 75062 and by fractional distillation getting cleaned; however, the esters produced by way of the pure cyclogeraniol are purer and therefore finer in weight Odor.

The cyclogeraniol is also used to prepare cyclocitral. The latter takes place according to known methods, e.g. B. by oxidation with chromic acid and sulfuric acid etc.

Almost pure α-cyclocitral is obtained from the cyclogeraniol prepared with phosphoric acid, while the cyclocitral to be obtained from cyclogeraniol obtained with sulfuric acid, in addition to α-cyclocitral (semicarbazone melting point 204 °), more or less also β-cyclocitral (semicarbazone melting point 1660 ⁰ ). contains.

Claims (1)

Patent claim:
Embodiment of the process protected by patent 75062 in its application to the conversion of geraniol into cyclogeraniol, consisting in subjecting the esters of geraniol to the action of concentrated acids and splitting off the cyclogeraniol from the cyclic reaction products.