DE566156C - Process for the preparation of cyclic ketones - Google Patents

Description

GERMAN EMPIRE

ISSUED ON
DECEMBER 15, 1932

REICH PATENT OFFICE

PATENT LETTERING

CLASS 12 ο GROUP

Schering-Kahlbaum A. G. in Berlin *) Process for the production of cyclic ketones

Patented in the German Empire on October 18, 1930

As is well known, the by action z. B. of peracids, such as peracetic acid or perbenzoic acid, ethylene oxides obtainable from ethyls by heating or under the influence of dilute acids in Rearrange ketones or aldehydes. It is also known that one can do this from 3-menthene 3-Menthenoxide obtainable in benzoic acid by heating with alkalis or acids in. the 3-menthone can rearrange. The temperatures are here in accordance with the

CH.,

CH

CH ₃ CH ₃

by simply heating to 250 ⁰ the 3-menthone of the formula II, which is a convenient starting material for the production of the technically valuable 3-menthol. Likewise, z. B. the oxide of i-menthen, cyclohexene, methylcyclohexene, camphene, etc. It has also been found that the manure of aqueous or alcoholic solutions of acids or alkalis is only relatively low, so that a long reaction time is required for a complete rearrangement.

It has now been found that the from cycloolefins z. B. with the help of peracids easily accessible cyclic oxides by heating to about 250 ⁰ C can be converted into the corresponding ketones. So you get z. B. from the 3-menthenoxide of the formula I.

CH,

II

S = O

CH

CH ₃ CH ₃

in individual cases only slowly taking place transition of the oxides into the ketones by the Use of catalysts can accelerate. Surface catalysts are suitable as such, such as pumice stone, silica gel, asbestos, kieselguhr and the like, or the metals of the 1st, 2nd, 3rd and 8th group of the periodic

Devi patent seekers have named the following as the inventors:

Dr. Walter Schoeller, Dr. Erwin Schwenk in Berlin-Charlottenburg and Dr. Erich Borgwardt in Berlin-Pankow.

Systems, their neutral and acidic salts, which may be deposited on a carrier are.

The oxides can also be passed over the catalyst in vapor form, whereby the possibility is given to carry out the process in a continuous process. Another benefit of the present Process versus heating ίο the cycloolefin oxides with acids or alkalis is that the rearrangement is not carried out in the presence of water, which leads to the formation of glycols is avoided by water accumulation.

Example ι

io parts of 3-Menthenoxyd two hours are heated at 250 ⁰ in a closed vessel with 0.5 parts of silica gel. The ketone is distilled off from the pale yellow reaction product with steam and purified by distillation. One obtains 8 parts menthone, boiling at 204-208 ^0th

₂ _ Example2

ι S parts of cyclohexene oxide are slowly ^{distilled over a catalyst heated to 230 to 250 0} , which consists of magnesium sulfate '- applied to pumice stone; the outgoing vapors are condensed. The cyclohexanone obtained in a yield of 90% is purified by distillation. It boils at 154 to 156 ⁰ .

Example

When using i-Menthenoxyd and Cupripyrophosphat as a catalyst at a temperature of 250-280 ⁰ is obtained at ₀ to 222 ° Carvomenthon boiling in a yield of 9O ° /.

Example4

10 parts of 3-menthenoxide are heated ^{to 250 to 260 0} in a closed vessel for 3 to 4 hours. When the slightly colored reaction product was fractionated, in addition to unchanged oxide, 6 parts of menthone with a boiling point of 206 to 208 ° were obtained.

Claims (1)

Claim: Process for the preparation of cyclic ketones, characterized in that oxides of cyclic olefins by themselves or in the presence of surface catalysts, such as pumice stone, silica gel, asbestos, kieselguhr or metals of the 1st, 2nd, 3rd and 8th group of the periodic table, its neutral or acid salts, which are optionally deposited on a support, heated to about 250 ⁰ C. Werlin. printed in the ReichsdruckehK