DE1618145B2 - Process for the preparation of 2,3-dehydronorbornyl (5) ketones by reacting cyclopentadiene and vinyl ketones - Google Patents

Description

It is from the Bulletin de l'Academie des Sciences de r.URSS, Classe des Sciences Chimiques 1947, P. 219ff. (ref. in Chemical Abstracts, Vol. 42 [1948], Col. 5440 a to 5440 c) known, 2,3-dehydronorbornyl methyl ketone by reacting cyclopentadiene with methyl vinyl ketone. Cyclopentadiene is produced by distillation of dicyclopentadiene or by pyrolysis of hydrocarbons (Ullmann's Encyclopedia of Industrial Chemistry, 3rd ed., Vol. 5, p. 701). Methyl vinyl ketone is obtained by water attachment to monovinylacetylene (Johnson, the Acetylenic alcohols, 1946, p. 56) or by condensation of acetone and paraformaldehyde (Journal of the Chemical Society, 1943, P. 30). The German patent specification 1008 281 describes the production of endomethylenetetrahydroacetophenone described by the reaction of methyl vinyl ketone with cyclopentadiene in benzene at room temperature.

It has now been found that 2,3-dehydronorbornyl (5) ketones can be obtained by reacting cyclopentadiene and vinyl ketones are advantageously obtained at elevated temperature if the vinyl ketone is used in the course the reaction to be carried out at 100 to 300 ° C from the corresponding / i-hydroxy-alkyl-ketone through Dehydration and, if appropriate, at the same time also the cyclopentadiene from dicyclopentadiene, tricyclopentadiene and / or tetracyclopentadiene can arise. You can do the process in the presence of Perform dehydration catalysts.

The reaction can be carried out if dicyclopentadiene and 3-oxobutanol are used reproduce the following formulas:

OH

+ 2CH, -CH, -C-CH ₁

55

60

-CH

³ + 2H ₂ O

Compared to the known method, the method according to the invention is more accessible Starting materials and supplies numerous 2,3-dehydronorbornyl ketones in a 1-step process in good yield. The easy implementation of the dicyclopentadiene is surprising, since this Starting material at elevated temperature for polymerization and formation of polycyclopentadienes inclines (Liebigs Annalen der Chemie, Vol. 447, p. 99 [1926]).

Cyclopentadiene or, under the reaction conditions, cyclopentadiene are used as starting materials Substances such as tricyclopentadiene, tetracyclopentadiene or preferably dicyclopentadiene, and / f-Hydroxy-alkyl-ketones used. That as a starting material used or resulting from the starting material cyclopentadiene is usually with the Starting ketone in a molar ratio of 1 to 10: 1, preferably 2: 1, implemented. The final products that can be produced Depending on the starting material and the reaction conditions, exo, endo compounds or mixtures can be used of the two configurations.

Preferred end products are those of the general formula

CH

CH

Il

CH

CH,

₂ \

CH,

CH

in R an aliphatic, araliphatic, cycloaliphatic or an aromatic radical. Preferred / i-hydroxy-alkyl-ketones are those of the general formula

OH

CH,

CH ₂ -CR

(H)

in which R has the aforementioned meaning.

Particularly preferred starting materials 11 and accordingly particularly preferred end products I are those in whose formula II R is an alkyl radical with 1 to 8 carbon atoms, an aralkyl group with 7 to 12 carbon atoms, a cycloalkyl group with 6 to 10 carbon atoms or an aryl radical with 6 to 10 carbon atoms.

So z. B. the following / ϊ-hydroxy-alkyl ketones The following are used as starting materials: 3-oxo-butanol, -pentanol, -n-decyl alcohol, 3-oxo-4,4-dimethylpentanol, 3-Oxo-4-phenyl-butanol, S-Oxo-S-phenylpropyl alcohol, 3-oxo-12-phenyl-lauryl alcohol, 3-oxo-4-naphthylbutanoI, 3-oxo-3-toluyl propyl alcohol.

The reaction is conducted at a temperature between 100 and 300 ⁰ C, preferably between 150 and 220 °, carried out C; it takes place at normal pressure or at elevated pressure and can be carried out continuously or batchwise. It is advantageous to use dehydration catalysts such as aluminum oxide, silica gel, kaolin, fuller's earth or bauxite in the reaction; they are generally used in an amount of up to 5 percent by weight, based on the amount by weight of 3-oxo alcohol.

The reaction can be carried out as follows: A mixture of the starting materials and, if appropriate, a dehydration catalyst is kept at the aforementioned temperature for _{a period of 2 to 4 hours.} The water formed is left during the reaction, usually in a mixture with fractions

of cyclopentadiene, distill off and condense into a receiver. The condensate is separated from the Cyclopentadiene layer formed from the aqueous layer and thus continuously discharges cyclopentadiene to react again. After the reaction has ended, the reaction mixture is subjected to a fractional distillation and separates excess dicyclopentadiene that can be reused and the dehydronorbornyl ketone.

The connections that can be made by the method ι ο genes are valuable solvents for dyes and serve as stabilizers for dye solutions in Hydrocarbons.

The parts given in the examples are parts by weight.

example 1

A mixture of 800 parts of dicyclopentadiene, 350 parts of 3-oxo-butanol- (l) and 10 parts of neutral aluminum oxide (in 4 mm extrudates) is kept in a stirred apparatus for 30 minutes at 170 ^° C., the water formed being continuously lets distill off. Cyclopentadiene components exiting with the water in the mixture are fed back into the reaction after separation from the water. The end product is now separated from the reaction mixture by fractional distillation. 481 parts of 2,3-Dehydronorbornyl- obtained when Kp. ₁₃ 79 to 8I ⁰ C (5) methylketone (corresponds to 89% of theory, based on 3-oxo-butanol used).

Example 2

A mixture of 264 parts of dicyclopentadiene and 176 parts of 3-oxobutanol- (l) is brought to reaction at 200.degree. C. in a stirred apparatus. The reaction has ended after 4 hours. The reaction product is discharged and worked up as in Example 1. In addition to unreacted dicyclopentadiene 189 parts of a mixture of endo- and exo-2,3-Dehydronorbornyl- (5) methylketone from the Kp obtained ₁₅ 80 to 82 ° C and n'S 1.4828.. (69.9% of theory, based on 3-oxobutanol used).

Example 3

300 parts of phenyl-2-hydroxyethyl ketone and 450 parts of dicyclopentadiene are reacted in the presence of 15 parts of aluminum oxide at 200 ° C. as in Example 1 and the reaction mixture is worked up accordingly. 184.5 parts of 2,3-dehydronorbornyl (5) phenyl ketone with a boiling point of ₇ 112 to 114 ° C. and ni ° 1.5677 are obtained (corresponds to 93.5% of theory, based on the phenyl hydroxyethyl ketone used).

Claims (2)

Patent claims: 1. A process for the preparation of 2,3-dehydronorbornyl (5) ketones by reacting cyclopentadiene and vinyl ketones at elevated temperature, characterized in that the vinyl ketone is converted from the corresponding / V ^{in the course of the reaction to be carried out at 100 to 300 0 C} -Hydroxy-alkyl-ketone by dehydration and optionally at the same time also the cyclopentadiene can be formed from dicyclopentadiene, tricyclopentadiene and / or tetracyclopentadiene. 2. The method according to claim 1, characterized in that it is in the presence of dehydration catalysts performs.