CH122731A - Process for the manufacture of synthetic camphor. - Google Patents

Description

  

  Process for the manufacture of synthetic camphor. The main patent claim defines a process for the manufacture of synthetic camphor, wherein a mixture of turpentine, an organic acid and a liquid catalyst in the form of a non-metallic compound is heated to a temperature from 100 to 150 C to facilitate and accelerate the reaction of turpentine with the acid employed, after which the bornyl salt obtained is saponified and the separated borneol is transformed by oxidation into camphor.

   As a catalyst, halogenated carbides, in particular a tetrachlorinated hydro-, arbide, are proposed in the main patent.



  The present invention relates to an embodiment of this process, in which, instead of employing halogenated carbides, the catalyst of at least one non-substituted aromatic hydrocarbon such as benzene, toluene etc.



  Although the catalytic reactions obtained with an unsubstituted aromatic hydrocarbon such as benzene, toluene etc. have the drawbacks of being slower and giving a less pure borneol, the fact remains that the absence of chlorine in these carbides has a real advantage over the use of chlorinated carbides .

   The non-possibility of hydrochloric acid formation prevents the isomeration in dipentene of part of the turpentine covered, which is caused even by a trace of this acid, resulting in a higher yield by counting on the turpentine used. Finally, the absence of hydrochloric acid also presents an advantage from the point of view of the apparatus.

    However, the defects inherent in the use of unsubstituted aromatic hydrocarbons can be corrected by choosing their relative proportion in the mixture of compounds covered, sufficiently high to activate the reaction of the mixture. The greater the proportion of these hydrocarbons in the mixture, the more vigorously the reaction and the greater the quantity of turpentine which has entered into the reaction. It goes without saying that instead of a single unsubstituted aromatic hydrocarbon, a mixture of such hydrocarbons may be employed as the catalyst.

    The use of such a small mixture has advantages in keeping the reaction temperature constant.



       F,; rerrîpie: We heat together at <B> 110 </B> C, for (3 to 8 hours, 1 part of dry oxalic acid, 3 to 4 parts of turpentine and 8 parts of a toluérre-berrzene mixture .



       A. when cooking is complete, it is washed with weak soda to remove the uncombined oxalic acid.

   The remaining oil composed of a mixture of terpene carbide and bornyl oxalate is easily, by fractional rectification, separated into its constituents by virtue of the difference in their boiling points. Bornyl oxalate is saponified with sodium hydroxide in the usual manner and the borneol produced is recovered either by steam dragging or by filtration and washing. Oxalic acid can be recovered from saponification water.



  With the treatment indicated above, the yield is significantly improved and can exceed <B> 70 </B>%) of the turpentine used; oxalic acid not entered in the combination may be recovered intact.

 

Claims (1)

CLAIM Process for the manufacture of synthetic camphor according to the main patent claim, characterized in that at least one unsubstituted aromatic hydrocarbon is used as catalyst in a relative proportion high enough to activate the reaction of the mixture.