GB2144117A

GB2144117A - 7-Chloro-3,5,7-trimethyl-2,6-octadiene and method for preparing same

Info

Publication number: GB2144117A
Application number: GB08320206A
Authority: GB
Inventors: Koit Vladimirovich Leets; Kheino Antonovich Rang; Elvi Antonovna Mix; Sirie Ottovna Viitmaa; Malle Gabrielovna Poom
Original assignee: INST KHIM AKADEMII NAUK ESTONS; Institut Khimii Akademii Nauk Estonskoi SSR
Current assignee: INST KHIM AKADEMII NAUK ESTONS; Institut Khimii Akademii Nauk Estonskoi SSR
Priority date: 1983-07-22
Filing date: 1983-07-27
Publication date: 1985-02-27
Also published as: GB2144117B; DE3327305A1; GB8320206D0; FR2550784A1; CH655087A5; DE3327305C2; NL8302764A; FR2550784B1

Abstract

The novel title compound has the formula: CH3C(CH3) = CH-C(CH3)H-CH2-C(CH3) = C-CH2Cl. To prepare it, methylchloropentenes are reacted with isoprene in the presence of a catalyst at a temperature within the range from -50 to +50 DEG C, followed by isolation of the desired product. The compound is useful in organic synthesis and as an intermediate product for the synthesis of fragrances.

Description

SPECIFICATION 1 -chloro-3,5,7-trimethyl-2,6-octadiene and method for preparing same The present invention relates to a novel chemical compound, more specifically, to 1-chloro3,5,7-trimethyl-2,6-octadiene and a method for preparing same. This compound is useful in the organic synthesis and as an intermediate for the synthesis of fragrances such as 4-methylionone.

The present invention is directed to the provision of a novel compound serving as an intermediate for the synthesis of fragrances and making it possibie to enlarge the range of the latter.

The compound according to the present invention, viz. 1 -chloro-3, 5, 7-trimethyl-2, 6-octadiene has the following formula: CH3C(CH3) = CH-C(CH3)H-CH2-C(CH3) = CH-CH2CI The method for preparing this compound according to the present invention resides in that methylchloropentenes are reacted with isoprene at a temperature within the range of from - 50 to + 50,C, followed by isolation of the desired product.

It is desirable that the process be carried out in the presence of an organic solvent such as dichloroethane or white spirit. As a catalyst use is preferably made of zinc chloride tin tetrachloride or aluminium trichloride.

The compound according to the present invention comprises a colourless liquid soluble in organic solvents, b.p. 65"C/2 mm Hg, n2D0= 1.4742; d2D0= 0.9064.

Molecular mass: found 186.7 calculated 186.7.

Elemental analysis: found, %:C 70.7, H 10.2, Cl 18.9 calculated, %:C 70.75 H 10.26, CI 18.99.

The compound according to the present invention is prepared in the following manner.

To a mixture of methylchloropentene and isoprene a catalyst, preferably tin tetrachloride, zinc chloride, aluminium trichloride is added. The catalyst is added to a mixture of the starting compounds in an organic solvent (such as dichloroethane, white spirit and the like) or therewithout. At the end of the reaction the catalyst is removed from the reaction mixture as a complex with an amine (such as carbamide) or in a solution of a heterogeneous solvent, wherein the catalyst is dissolved (water, salt solution in water, glycol and the like). After distillation the unreacted starting compounds are again used in the process.

From the reaction mixture the desired product, i.e. 1-chloro-3,5,74rimethyl-2,6-octadiene, is then isolated. The resulting 1-chloro-3,5,7-trimethyl-2,6-octadiene is an intermediate product for the synthesis of fragrances. It permits an enlargement of the scope of the starting materials and assortment of fragrances and preparation of fragrame-4-methylionone having an iris odour which, due to its perfumery properties, can substitute a high-quality natural or synthetic fragrance-irone.

For a better understanding of the present invention the following examples illustrating the method for preparing the claimed compound are given hereinbelow.

Example 1 To a mixture of 59.3 g of methyichloropentene and 34 g of isoprene a 2% solution of tin tetrachloride in a solution of white spirit is added under stirring. During the reaction the temperature of the mixture is raised to 50,C. Then the mixture is cooled and 10 ml of a concentrated aqueous solution of calcium chloride is added thereto. The mixture is stirred, settled and the aqueous solution is separated. The unreacted components are distilled off from the reaction mixture to give 34.4 g of a product which contains 53.2% of 1-chloro-3,5,7trimethyl-2,6-octadiene. The fraction of C"-chlorides is distilled off from the product.The fraction of C"-chlorides in the amount of 9.3 g containing 65% of 1-chloro-3,5,7-trimethyl-2,6octadiene, 5.4g of dimethylaniline and 5.4 g of methanol are stirred and left overnight. Then 25 ml of a 50% methanol, 30 ml of petroleum ether are added thereto, intermixed, distilled and the layers are separated.

The aqueous-methanolic solution is twice washed with petroleum ether. Then methanol is distilled off under moderate vacuum. Toluene is added to the remaining mixture and then azeotropic water is distilled off from tie mixture under moderate vacuum. The remaining toluene are distilled off from the dry residue. The mixture is heated to a temperature of 120"C and the dimethylaniline and 1-chloro-3,5,7-trimethyl-2,6-octadiene formed in pyrolysis are distilled in vacuum.The latter product is washed with a 10% acetic-acid aqueous solution to remove dimethylaniline and then with an aqueous solution of calcium chloride and dried over sodium sulphate to give 3.2 g of 1-chloro-3,5,7-trimethyl-2,6-octadiene C,lH19Cl, b.p. 65"C/2 mm Hg, n2D0= 1.4742, d240= 0.9064; product purity is 99%. yield of the product-30.6% of methylchloropentane.

Molecular mass: found: 186.7 calculated: 186.7 Elemental analysis: %C 70.7, H 10.2, Cl 18.9 calculated, % C 70.75, H 10.26, Cm.18.99 Chemical shifts in the 13C NMR-spectrum

C-i C-2 C-3 C-4 C-S C-6 C-7 C-8 C-9 C-10 C-11 40.5 122.1 141.0 47.7 30.9 130.8 129.8 25.7 16.1 20.8 17.8 Example 2 To 10.8 g of methylchloropentene and 11.2 g of isoprene 0.02 g of zinc chloride is added under stirring. The reaction temperature is maintained at 23"C. At the end of the reaction the mixture is added with 4 ml of glycol, stirred, settled and the glycolic solution is separated.The unreacted components are distilled off by fractionation in vacuum to give, from the residue, 15,5 g of a fraction containing 78.0% of 1-chloro-3,5,7-trimethyl-2,6-octadiene. Then the process of isolation of the desired product is carried out in a manner similar to that described in Example 1. The yield of the desired product is equal to 36% of methylchloropentene.

Example 3 To a mixture of 3.3 kg of methylchloropentene (85.1% of hydrochlorides, 14.9% of lightweight hydrocarbons) and 3.7 kg of isoprene a 2.2% solution of tin tetrachloride in dichloroethane is added. During the reaction the temperature rises from 15 to 33"C. At the end of the reaction the mixture is cooled and carbamide is added, intermixed and filtered through cotton wool. The unreacted components are distilled off from the reaction mixture. The residue amounting to 4.4 kg contains 45.3% of 1-chloro-3,5,7-trimethyl-2.6-octadiene. The fraction of 1-chloro-3,5,7-trimethyl-2,6-octadiene is distilled off from the residue to give 2.5 kg at 58-65"C/2 mm Hg; the content of 1-chloro-3,5,7-trimethyl-2,6-octadiene is 71%.From 100 9 of the resulting fraction after rectification in a film-rotary column 45 g of a fraction of pure 1 chloro-3,5, 7-trimethyl-2,6-octadiene (98%, b.p. 65"C/2 mm Hg, n2D0= 1.4741, d2D0= 0.906) is obtained. The yield, as calculated for methylchloropentene, is 25.7%.

Example 4 A mixture of 31 g of isoprene, 23.7 g of methylchloropentene and 50 ml of dichloroethane is cooled down to the temperature of - 50"C and then added with 0.5 g of anhydrous aluminium chloride. Under vigorous stirring the temperature rises up to - 1 0'C. The reaction is completed by the addition of a 30% aqueous solution of calcium chloride in the amount of 10 ml to the mixture. After stirring and separation of an aqueous layer, the organic layer is dried over anhydrous calcium chloride. Under moderate vacuum the unreacted starting compounds are distilled off and then reused in the reaction. From the residue 17.9 g of fraction Ca1HrgC1 which contains 71.8% of 1-chloro-3,5,7-trimethyl-2,6-octadiene is distilled off at a temperature of 58-62"C (2 mm Hg). The yield is 51.1% (theoretical as calculated for 1 7 g of the reacted methyl-chloropentenes). The further stages of the process of isolation of the desired product are carried out as described in Example 1 hereinbefore. The yield of the desired product is 33.2% as calculated for methylchloropentene.

Example 5 A mixture of 23.7 g of methylchloropentene, 54.4 g is isoprene and 0.5 9 of anhydrous zinc chloride is vigorously stirred upon boiling. Then 30 ml of a 20% aqueous solution of sodium chloride is added to the reaction mixture. The mixture is cooled under stirring, then settled, the aqueous layer is separated and the organic layer is dried over anhydrous calcium chloride.

Then the process of isolation of the desired product is carried out following the procedure described in Example 1 hereinbefore.

The product yield is 33.0% as calculated for methyl-chloropentene.

Claims

1. 1-chloro-3,5,7-trimethyl-2,6-octadiene of the following formula: CH3C(CH3) = CH-C(CH3)H-CH2-C(CH3) = CH-CH2CI

2. A method for preparing 1-chloro-3,5,7-trimethyl-2,6-octadiene according to Claim 1, comprising reacting methylchloropentenes with isoprene in the presence of a catalyst at a temperature of - 50 to + 50"C, followed by isolation of the desired product.

3. A method according to Claim 2 comprising carrying out the process in the presence of an organic solvent - dichloroethane, white spirit.

4. A method according to Claims 2 and 3, comprising the use of zinc chloride, tin tetrachloride, aluminium trichloride as a catalyst.

5. A method according to the foregoing Claims 1 to 4, substantially as described in the Specification and Examples given hereinbefore.