Process for the preparation of ketals
AssigneeHuls Aktiengesellschaft
InventorsKlaus-Dieter Steffen, Josef Metz
Life of this patent
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Abstract
Ketals of longer-chain or branched alcohols are prepared from dimethyl ketals or their ketones by reaction of the dimethyl ketals and the alcohols at high temperatures of 150.degree. to 180.degree. C. in the presence of acid catalysts. The enol ethers and mixed ketals which are separated by distillation are added to the next reaction batch and also react to form the target product. The starting material, dimethyl ketal, may also be formed during the reaction from the ketone and trimethyl orthoformate.
Claims8
In the method of preparing a ketal by transketalizing a dimethyl ketal with an alcohol of the formula R.sup.2 OH in the presence of an acid catalyst and distilling off the methanol released by the reaction, the improvement which comprises reacting said dimethyl ketal with said alcohol of the formula R.sup.2 OH to more than 90% completion by bringing the reaction temperature to 150.degree. to 180.degree. C. pursuant to the reaction sequence ##STR2## wherein R and R.sup.1 are each independently alkyl of 1 to 8 carbon atoms or aryl, or
- R and R.sup.1 together with each other are --(CH.sub.2).sub.4 -- or --(CH.sub.2).sub.5 --, and
- R.sup.2 is linear or branched alkyl of 2 to 8 carbon atoms,
- and separating the ketal of the formula II by distillation without a solvent.
Dependencies are inferred from the claim text.