DE1040539B - Process for the production of new unsaturated ketones with special fragrance properties - Google Patents

Description

GERMAN

The invention relates to a process for the preparation of new unsaturated ketones with special Rieehstofre features, which is characterized is that in a known manner, a tertiary alcohol of the general formula:

OH

I.
R ₁ -C-CH = CH ₂ ι

in which R _{1 is} an alkyl radical with 2 to 5 carbon atoms or a phenyl group and R _{2 is} either the methyl radical or, together with the radical R _1, the pentamethylene radical, is reacted with diketene or acetoacetic ester and the acetoacetate formed is heated with rearrangement and decarboxylation. As starting alcohols, for. B. used: 3-methyl-pentene- (1) -oil (3), 3,5-dimethyl-hexene- (1) -oil (3), 3-phenyl-butene (1) -oil - (3) and 1 - vinyl-cyclohexanol- (l).

According to one embodiment of the invention, the starting alcohol is in the first reaction stage with Diketones, e.g. B. in an inert solvent such as petroleum ether, preferably with cooling, reacted. In the next reaction stage, the acetoacetate obtained is advantageously heated to above 120.degree. C., preferably heated to 130 to 160 ° C. A rearrangement and decarboxylation takes place, with new ones Form ketones with fragrance character, which have the following general formula:

R ₁ -C = CH-CH ₂ -CH ₂ -CO-CH ₃

II

wherein R ₁ and R _{2 have} the above meaning.

In a further embodiment of the invention, the ketones of the above formula II can by. Heat of the starting alcohols of the general formula I with acetoacetic ester, preferably without a solvent and in the presence of transesterification catalysts, such as. B. sodium methylate can be obtained.

The new ketones have hitherto unknown, new odor nuances and can be used for the production of fragrance mixtures and perfumes or as intermediate products in the synthesis of fragrances ¹ .

The odor notes of the ketones which can be prepared according to the invention are compared with those of the above United States Patent 2,638,484 known 2-methylhepten-2-one-6 surprisingly highly refined and improved. They are therefore very suitable for creating compositions that are interesting in terms of smell.

Method of manufacture

of new unsaturated ketones

with special fragrance properties

Applicant:

F. Hoffmann-La Roche & Co.
Aktiengesellschaft, Basel (Switzerland)

Representative: Dr. G. Schmitt, lawyer,
Loerrach (Bad.), Friedrichstr. 3

Claimed priority:

V. St. v. America December 7th, December 10th 1954,
August 19 and August 25, 1955

Walter Kiinel, Highland Park, NJ (V. St. A.),
has been named as the inventor

example 1

A three-necked flask with a volume of 2 liters, which is provided with a stirrer, a thermometer, a dropping funnel and a reflux condenser, is filled with 200.4 g of 3-methyl-pentene- (1) -ol- (3), 200 cm ^{3 of} petroleum ether ( Bp. 60 ° C), 4 cm ^{3 of} pyridine and 4 cm ^{3 of} acetic acid charged. 185 g of diketene are then added dropwise to this mixture with vigorous stirring over the course of 2 hours. At the same time, the temperature is kept at 25 to 30 ° C. by external cooling. The mixture is then stirred at a temperature of 25 to 30 ° C. for a further 4 hours. The reaction mixture is then washed in a separating funnel twice with 200 cm ^{3 of} 7% aqueous sulfuric acid ^{each, then with 200 cm 3 of} water, then three times with 200 cm ³ of saturated aqueous sodium carbonate solution each time and finally with water until it is neutral . The organic layer is dried over anhydrous calcium sulfate and the drying agent is removed by filtration. Then the solvent is distilled off in vacuo. The product consisting of 3-methyl-penten- (1) -yl- (3) -acetoacetate is distilled under reduced pressure, a water-colored liquid with a bp. 58 to 60 ° C / 0.9 mm being obtained. »» = 1.4426; Yield 359 g (97.4% of theory).

8 «657/462

A three-necked flask of 1 liter capacity, which is equipped with a thermometer, a stirrer and a reflux condenser, its upper end with a freezer trap provided with carbonic acid foam and acetone, which in turn is connected to a gasometer, is treated with 276.3 g of 3-methyl-penten- (1) -yl- (3) -acetoacetate charged and the flask heated to 155 ° C with the aid of a hot oil bath, whereupon vigorous evolution of carbon dioxide entry. The mixture is heated to 155 to 160 ° C until (after about 3 hours) the evolution of gas has stopped. The crude product is then removed by fractional distillation in vacuo cleaned. The 6-methyl-octen- (5) -one- (2) is obtained as a water-colored liquid; Bp. 85 to 86 ° C / 19 mm: »| f = 1.4406; Yield 139g (66%).

Example 2

In a solution of 512.8 g of 3,5-dimethyl-hexen- (l) -ol- (3) in 500 cm ^{3 of} petroleum ether (boiling point 30 to 60 ° C) in a three-necked flask of 3 liters, which with a ° a stirrer, a thermometer, a reflux condenser and a dropping funnel, 8 cm ^{3 of} pyridine and 8 cm ^{3 of} acetic acid are introduced. Then, using the dropping funnel, 370 g of diketene are added dropwise over the course of 3 hours. The reaction temperature is kept at 25 to 30 ° C. by external cooling. After 5 hours, no further heat of reaction is perceptible, which indicates that the reaction has ended. The reaction mixture is washed several times with dilute aqueous sulfuric acid in order to extract the pyridine, then with saturated aqueous sodium bicarbonate solution to remove the acids and finally washed with water until it is neutral. The solution is then dried over anhydrous calcium sulfate and the solvent is distilled off under reduced pressure, the product consisting of 3,5-dimethylhexen (1) -yl- (3) -aoetoacetate remaining in quantitative yield (850 g); nnf = 1.4448.

3,5-Dimethyl-hexen- (l) -yl- (3) -acetoacetate (850 g) is in a three-necked flask of 2 1 content, which is equipped with a stirrer, a thermometer and a reflux condenser, the upper end of which by means of a fixed Carbon dioxide-provided freezer trap is connected to a gasometer, is equipped, entered and pyrolyzed in it. The pyrolysis is carried out by heating the flask in a hot oil bath to 130 to 135 ° C, with the rapid evolution of coMed dioxide. After the initially vigorous reaction has subsided, the temperature is increased to 150 ° C. and the reaction is allowed to continue until the generation of carbon dioxide has ceased, which is the case after a total of 4 hours. The product is then isolated by fractional distillation. 6,8-Dimethylnonen- (5) -one- (2) is obtained in a yield of 471.5 g (70% of theory) in the form of a water-colored liquid with a bp. 55 to 56 ° C / l mm; n% = 1.4430.

60

Example 3

5 cm ^{3 of} pyridine and 5 cm ^{3 of} acetic acid are introduced into a solution of 365 g of 3-phenyl-buten-(1) -ol- (3) in 365 cm ^{3 of petroleum ether.} The mixture is stirred vigorously and 227.5 g of diketene are added dropwise over the course of 2 hours, a reaction temperature of 25 to 30 ° C. being maintained. Then the reaction is allowed to proceed further at the same temperature for 6 hours. The mixture is finally washed twice in a separating funnel with 100 cm ^{3 of} 15% aqueous sulfuric acid each time, four times with 100 cm ³ of saturated aqueous sodium bicarbonate solution each time and finally with water until it is neutral. The solution is then dried over anhydrous calcium sulfate and the solvent is removed in vacuo, the 3-phenyl-buten- (1) -yl- (3) -acetoacetate being obtained in quantitative yield; n "- 1.5120.

The ester is heated to 110 to 125 ° C, with a stormy evolution of carbon dioxide occurs. After the initially stormy reaction has subsided somewhat, the temperature continues to 130 to 140 ° C heated until the evolution of gas has ceased, which takes about 2V2 hours.

The crude product is taken up in an equal volume of diethyl ether and washed several times with a saturated aqueous sodium bicarbonate solution and then with water. The solution is dried over anhydrous calcium sulfate and the resulting product, namely 6-phenyl-hepten- (5) -one- (2), isolated by fractional distillation in vacuo; Bp 98-99 ° C / 0.4mm; <= 1.5389; d ₂₅ = 0.9898. This compound has a pleasant, fresh smell, which is reminiscent of that of wild strawberries. It has this characteristic fragrance both in high concentrations and in strong dilutions. In addition, it has excellent and excellent adhesiveness. As a result of its unusual odor properties and its physical and chemical properties, it can be used with advantage for perfumes and cosmetics, e.g. B. for lipsticks, and for flavoring essences, gastric liqueurs and other liqueurs.

Example 4

A flask equipped with a stirrer, thermometer, dropping funnel and reflux condenser, three-necked flask of 3 1 Inihalt is with 504.8 g l-Vimyl-cyclohexanoHl), 500 cm ³ of petroleum ether (bp. 3O ⁰ C), 8 cm ³ of pyridine and 8 cm ³ of acetic acid loaded. With rapid stirring of the solution, 370 g of diketene are allowed to flow in from the dropping funnel over the course of 3 hours. The reaction temperature is kept at 20 to 30 ° C. by external cooling and stirring is continued until no further development of heat can be perceived. The solution is then extracted twice with dilute aqueous sulfuric acid to remove the pyridine and then extracted several times with aqueous sodium bicarbonate to remove the free acids. Finally, the organic layer is washed neutral with water and dried with anhydrous calcium sulfate. The latter is removed by filtration and the solvent is distilled off in vacuo, 1-vinylcyclohexyl (l) acetoacetate remaining as a light oil; »Ff = 1.4706; Yield 842 g (100% of the theoretical value). This product is sufficiently pure to be used for the next stage.

In a three-necked flask with a capacity of 21, which with a stirrer, thermometer and a reflux condenser, the latter above by intermediary a freezer trap containing solid carbon dioxide is connected to a gasometer one 842g of l-vinyl-cyclohexyl- (l) -acetoacetate. The flask is heated to 145 ° C by means of an oil bath, a vigorous stream of carbon dioxide is developed, which is measured with the aid of the gasometer will. After the initially stormy reaction

has subsided somewhat, the mixture is heated to 155 ° C. until the evolution of gas has ceased (total heating time approx. 4V ₂ hours). The residue is purified by fractional distillation in vacuo. The product obtained, namely 5-cyclohexylidenepentanone- (2), is a colorless liquid with a melting point of 75 to 77 ° C / 2.5 mm; «« = 1.4763; Yield 536 g (80% of theory). This product can be used as an odor-imparting agent in perfume manufacture and in the manufacture of other fragrances.

Claims (3)

Patent claims: 1. Process for the production of new unsaturated substances which have special Rieehiststoffverbindungen Ketones of the general formula: R ₁ -C = CH-CH ₂ -CH ₂ -CO-CH ₃ in which R _{1 is} an alkyl radical with 2 to 5 carbon atoms or a phenyl group and R _{2 is} either the methyl radical or, together with the radical R _1, the pentamethylene radical, characterized in that a tertiary alcohol of the general formula is used in a manner known per se: OH R ₁ -C-CH = CH ₂ wherein R ₁ and R ₂ are as defined above, are reacted with diketene or acetoacetic ester and the acetoacetate formed is heated with rearrangement and decarboxylation. 2. The method according to claim 1, characterized in that one uses diketene and that Acetoacetate obtained is heated to above 120.degree. C., preferably to 130 to 160.degree. 3. The method according to claim! 1, characterized in that the alcohol with acetoacetic ester heated without solvent in the presence of a transesterification catalyst. Considered publications:
U.S. Patent No. 2,638,484;
British Patent No. 695 313. © «09 657/462 9.58,