| abstract |
In a process for producing dehydroacetic acid (I) (an intermediate, e.g. for therapeutically valuable heterocyclic cpds.) by dimerisation of diketene in an inert anhydrous org. medium in the presence of trimethylamine and/or 1,4-diazabicyclo(2,2,2)-octane as catalyst, one or more di- or polyhydric phenols (pref. pyrocatechol) are added continuously or portionwise to the reaction mixture in an amt. of 0.1-10 (pref. 0.5-3)% of the wt. of diketene before and/or simultaneously with the addn. of the diketene. When using 85-95% diketene, the addn. of di- or polyhydric phenols increases yields of (I) from 75-80% to >90% and improves the purity of the product from 85-90% to 98-100%. |