Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
  • C07C45/61—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups
  • C07C45/67—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
  • C07C45/61—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups
  • C07C45/67—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton
  • C07C45/673—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton by change of size of the carbon skeleton
  • C07C45/676—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton by change of size of the carbon skeleton by elimination of carboxyl groups

Definitions

• a Carroll reaction is the chain extension of an allyl or propargyl alcohol with acetoacetate or diketene to form ⁇ , ⁇ -unsaturated ketones. For example, it can proceed according to the following reaction scheme:
• the new acetoacetic ester of the unsaturated alcohol which is primarily formed from the allyl or propargyl alcohol and the acetoacetic acid ester or diketene, is rearranged in a Claisen rearrangement to give ⁇ -keto acid, which then spontaneously decarboxylates.
• the terpenes required as essential precursors for vitamin A and vitamin E are 2-methyl-2-hepten-6-one, 6, 10-dimethyl-5, 9-undecadien-2-one (geranylacetone) and 6, 10 , 14-Trimethyl-5, 9, 13-pentadecatrien-2-one (farnesylacetone), produced on an industrial scale by the Carroll reaction.
• aluminum alcoholates in particular the aluminum isopropylate of the formula AI (0-CH (CH 3 ) 2 ) 3 , were used as catalysts for Carroll reactions in amounts of 0.8 to 2.5 mol% on the alcohol used as the starting material.
• aluminum complexes with acetylacetone or acetoacetic esters such as aluminum tri (acetylacetonate), aluminum tri (methyl acetoacetate) or aluminum tri (ethyl acetoacetate), were used as catalysts for Carroll reactions.
• the invention relates to a process for the preparation of ⁇ , ⁇ -unsaturated ketones of the general formula I
• an acetoacetic acid alkyl ester at temperatures of 150 to 45 220 ° C in an optionally modified Carroll reaction in the presence of an aluminum catalyst and distilling off the alkanol which is formed, which is characterized in that an acetoacetic acid ester of the general formula III as the acetoacetic acid alkyl ester
• R 2 represents an alkyl group having 1 to 4 carbon atoms.
• n stands for an integer from 1 to 5 and x and y either stand for H, or x stands for methoxy and y stands for H or x and y together for an additional bond between the C and X bearing y Atoms are, such as 3, 7-dimethyl-1,6-octadien-3-ol (linalool),
• R 4 is branched or unbranched alkyl or alkoxy groups with 1 to 4 C atoms, preferably methyl or ethyl groups
• R 5 and R 5 is branched or unbranched alkyl or alkoxy groups with 1 to 5 C atoms, preferably one Are methyl or a 2-butyl group
• R 7 is a branched or unbranched alkyl group having 1 to 4 carbon atoms and m and n can be an integer from 0 to 3, where n + m 3 3, and Aluminum triaryloxylates into consideration.
• Liquid aluminum compounds, in particular aluminum compounds, in which R 5 is a methyl radical, R 6 is a butyl radical and the sum of n + m ⁇ 3 and the ratio n / m> 0.3 are particularly preferred.
• radicals R 1 , R 2 and R 3 are H, methyl or ethyl, preferably H or methyl and R 4 is H, methyl, ethyl, isopropyl, phenyl or methoxymethyl, preferably H or methyl , as a solvent.
• Particularly suitable 5-ring lactones of the general formula VII are v-butyrolactone and 3-methyl- ⁇ -butyrolactone, in particular ⁇ -butyrolactone. 15
• ⁇ -butyrolactones of the general formula VII used according to the invention can also be prepared on an industrial scale by dehydrogenation of the corresponding butanediols.
• the alkanol formed in the reaction surprisingly attacks the cyclic carbonates or lactones under the reaction conditions so little that, for example, when using propylene carbonate, the solvent can be reused for up to 10 reaction cycles without any purification
• the 5-ring carbonates and 5-ring lactones are generally used in amounts of 50 to 1000% by weight, preferably 100 to 500% by weight, based on the ⁇ , ⁇ -unsaturated ketone formed.
• the Carroll reaction can advantageously also be carried out without the addition of substantial amounts of a solvent. This has advantages when working up the reaction mixture.
• the process according to the invention can be carried out batchwise and continuously.
• the procedure is advantageously such that the starting compounds and the catalyst are combined with a
• reaction vessel with attached condensation device for the alcohol released and for the discharge of Pumped carbon dioxide and pumps the reaction product with the help of an overflow.
• the wished ⁇ , ⁇ -unsaturated ketones of the general formula I can be obtained in a simple manner with surprisingly high yields.
• the tertiary alcohols released from the acetoacetic acid ester can be recovered almost completely.
• a mixture of a mixture of 50 ml (45 g) 1, 2-propylene carbonate and 2.8 g of a separately (according to GB 886 353) aluminum tri-methylacetoacetate catalyst was made at 170 ° C within 2 hours 25.7 g of a 92% 2-methyl-3-butene-2-ol and 39.8 g of acetoacetic acid tert. -butyl ester added dropwise.
• the mixture was stirred for a further 10 minutes (min) until the evolution of gas had ended and then cooled.
• reaction discharge was distilled under a pressure reduced to 0.1 mbar.
• a total of 139.7 g of 6, 10-dimethyl-5, 9-undecadien-2-one (geranylacetone) was obtained in two fractions, which corresponds to a yield of 96% of theory.
• Example 2a 5.6 g of the aluminum catalyst described there were introduced as in Example 2a) and a mixture of 115.4 g of linalool and 94 g of methyl acetoacetate was pumped in at an internal temperature of 180 ° C. This spontaneously formed C0 2 and methanol, which was condensed. As in Example 2a), the reaction mixture was stirred for a further 20 min until the CO 2 evolution had ceased and then cooled. It was distilled under reduced pressure and 133 g of geranyl acetone were obtained. The yield was 91.5% of theory. As a side pro Products had formed 1.6 g of 6, 10-dimethyl-5, 9-undecadien-2-ol, which were not detectable in Example 2a).
• E E-geranyllinalool. This solution was pumped evenly into the horizontal reactor vessel described in Example 3a). The pumping rate was matched to the available reaction volume so that there was an average residence time of 10 ⁇ 0.5 min. At 190-200 ° C 35 internal temperature, the mixture reacted continuously to geranylgeranylacetone. After the feed had ended, the contents of the reactor were heated for a further 10 minutes and then added to the cooled reaction discharge. It was distilled at 0.3 mbar and 84.2 g of geranylgeranylacetone with a purity of 40 97.1% were obtained in the main fraction. This corresponds to a yield of 85% of theory.
• Example 6a A comparison of Example 6a with Comparative Example 6b clearly shows that the reaction with the acetoacetic acid tert. - Butyl ester runs much faster (3 to 10 times faster) than that with the methyl acetoacetate previously used for Carroll reactions.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

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• 1998
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