DD202418A5 - PROCESS FOR THE PREPARATION OF 1,1 DICHLOR-4-METHYL-1,3-PENTADIENE - Google Patents

Abstract

The invention relates to a process for the preparation of a novel tetrachloro-pentene derivative, in particular of 1,1-dichloro-4-methyl-1,3-pentadiene. The object of the invention is to provide an improved economical process which provides the desired compound in quantitative yield. According to the invention, chloral and isobutylene are reacted, then the resulting 1,1,1-trichloro-2-hydroxy-4-methyl-3-pentene of the formula I with thionyl chloride advantageously in the presence of a catalyst without a solvent or in an inert solvent for reaction brought and finally reduces the resulting 1,1,1,4-tetrachloro-4-methyl-2-pentene.

Description

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Field of application of the invention

The invention relates to a process for the preparation and reduction of a novel tetrachloro-penten-Oerivats «In particular, the invention relates to a process for the preparation of!, L-dichloro-4-methyl-l, 3-pentadiene, which is used as starting compound for the preparation of cyclopropane carboxylic acid esters is used «

characteristics the known technical solutions

The l, l-dichloro-4-fnethyl _l-f 3-pentadiene is the Schlüsselintermediär the synthesis of cyclopropane-carbonsäureestern. According to a variant of the known method for the production thereof, it is removed from the resulting from the addition of 2-methyl-3-buten-2-ol, and chloroform l _i | V-trichloro-4-methyl-4-hydroxy-pentane by water, later hydrochloric acid elimination or, in reverse order by dehydrohalogenation and dehydration produced (DE-OS Nos. 2,536,503, 2,535,504 and 2,616,528) The disadvantage of the method is that the compound formed in the Chloroformtelofiierization in an amount of about 15 to 20 % is contaminated by the isomer which does not contain the trichloromethyl group at the chain end. This substance can not be separated by physical methods, and the resulting products lead to significant losses in the purification of the valuable cyclopropane carboxylic acid ester.

In recent years, some processes have been devised to produce 1, 1-oichloro-4 at a temperature of 400 to 500 C in a tubular reactor with continuous operation.

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methyl - !, 3-pentadiene can be prepared. In these processes, isobutylene is used as the starting material, which is reacted in the presence of peroxide catalysts either with trichlorethylene or with nitric 1,1-dichloro-ethylene (GS-PS No. 1 532 676; DE-OS No. 2 529 868). The main part of the method consists in the fact that the product mixtures thus produced contain the seiproduct only in an amount of about 5 to 10 % .

A technically simple and with regard to the basic materials the cheapest way of producing the target product is the FARK-AS process (3 »Farkas, P. Kohrim, F. Sorro: Coll. Czech Chem., Coramun., 24.2230, 1959; OS No. 2 616 681), wherein the l, l, l-trichloro-2-hydroxy-4-methyl-pentene-3 and -4 isomer mixture formed in the "Prins" reaction of isobutylene and chloral is the starting material. From this isomer mixture is prepared by O-acetylation, Zn-acetic reduction, elimination and finally isomerization 1, l-dichloro-4-methyl-l, 3-pentadiene. The main disadvantage of the process is that very much - and quite expensive - zinc is required for the reductive acetoxy elimination.

Object of the invention

The aim of the invention is to provide a simple and economical process for the preparation of 1, l-dichloro-4-methyl-l, 3-pentadiene, with which the desired product can be obtained in quantitative yield.

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Explanation of the essence of the invention

The invention has for its object to produce ljl-dichloro-4-methyl-1,3-pentadiene from readily available starting compounds.

According to the invention, chloral and isobutylene are reacted for the preparation of 1,1-dichloro-4-methyl-1,3-pentadiene, then the l, l, l-trichloro-2-hydroxy-4-methyl-3-pentene of the formula I obtained

Cl OH

Cl - C - CH - CH s C - CH

Cl CH ₃

reacted with thionyl chloride advantageously in the presence of a catalyst without solvent or in an inert solvent and finally the thus obtained l, l, l, 4-tetrachloro-4-methyl-2-pentene reduced *

The basis of the process according to the invention is the recognition that in the "prins" reaction in the thionyl chloride-occurring chlo- ration of 1,1,1-trichloro-2-hydroxy-4-methyl-3, which is readily preparable from simple basic materials. penten, the sulfur dioxide elimination of the intermediate product is accompanied by an alkyl rearrangement and in the reaction quantitatively 1,1, l, 4-tetrachloro-4-methyl-2-pentene is formed, which is prepared by conventional reduction methods with almost quantitative yield 1,1-dichloro-4- methyl-l, 3-pentadiene provides »

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In the method according to the invention is advantageously carried out such that the mixture of 1, l _/ l-trichloro-2-hydroxy-4-methyl-3-pentene and in excess of 15 to 80 mol% applied thionyl chloride and advantageous 1 wt -.% dimethylformamide as a catalyst without solvent or in an inert organic solvent - advantageously in aromatic hydrocarbons or aliphatic chlorinated hydrocarbons - heated at a temperature from 40 to 130 Cy advantageous in SO to 90 C to the setting of the gas evolution, then the upper weft to Thionyl chloride or the organic. The crude product obtained can be used in the reduction without purification or - if necessary - (before the catalytic hydrogenation) are purified by distillation under reduced pressure. The reduction is carried out by known methods, advantageously with araalgamated iron, aluminum or zinc powder in an alkanol (methanol-> ethanol, isopropanol) solvent at a temperature of 40 to 70 ⁰ C by catalytic Hydrogsnierung (with a bone coal palladium catalyst in Alkanol, acetone or acetic acid at 20 to 50 C or »with a Raney Ni catalyst in alkanol solvent in the presence of an equivalent with the resulting hydrochloric acid base, preferably triethylamine or potassium carbonate) or with sodium dithionite, in methanol, with the resulting hydrochloric acid Equivalent sodium hydroxide, carried out at 60 C, the product is separated after filtration and liberation from the solvent of the reaction mixture under reduced pressure by distillation. ,

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Ausführunpsbeispiel

Further details, the erfindungsgeraäßen process are illustrated by the following examples _t without thereby limit the present process to "

example 1

The mixture of 90.0 g (0.44 mol) of 1,1,1-trichloro-2-hydroxy-4-methyl-3-pentene, 350 cm solvent (aromatic hydrocarbon or aliphatic chlorinated hydrocarbon - advantageously 1,2-dichloro -ethane or benzene), further.59.5 g (0.5 mol) of thionyl chloride and 1.0 cm ° dimethylformamide is heated to 60 to 80 ⁰ C, then it is stirred to adjust the gas evolution at this temperature * The reaction mixture is in my

400 cm " ^{3 of} water, neutralized with NaHCO ³ , the organic phase is isolated, dried, then the solvent is distilled off The amount of residual product obtained is 91.0 to 95.8 g (93 to 98 %) For further purification, the product is fractionated at a pressure of 26 mbar.

Yield: 86.0 to 88.9 g of 1,1,1,4-tetrachloro-4-methyl-2-pentene (88 to 91 %), boiling point: 115 to 120/26 mbar

IR (film): 3000, 1460, 1380, 1285, 1250, 1120, 1085, 960,

840, 775, 730 cm ^{"1 1} H NMR _(CDCl3), <fC ppm" f: Me: 1.73 s (64); CH = CH-: 6.27d (14)

6,43d (14)

¹³ C NMR (CDCl3 ), ≤ ppm: 7: Me: 32.2, Me ^ CCl: 65.3, CCl: 9.40

CH = CH: 132.4, 137.8

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Example 2

The mixture of 90.0 g of 1,1,1-trichloro-hydroxy-methyl-3-pentene, 89.3 g of thionyl chloride and 1.0 cm of dimethylformamide is heated to boiling, then the mixture is heated to Setting the gas evolution boiled. The thionyl chloride overhead is distilled off, the residue is fractionated under reduced pressure. Yield: 88.0 g (90%) l, l, l _i 4-tetrachloroethane ~ 4-methyl-2-pentene ₁

Example 3

The mixture of 22.2 g (0.1 mol) of 1,1,1,4-tetrachloro-4-ethyl-2-pentene, 150 cnt of ethanol, 4 g (0.15 gram atom) of Al powder and 0.27 g (0.001 mol) of mercury II) chloride is boiled for 2.5 to 3 hours, then the solid is filtered off, washed with ethanol »The alcoholic solutions are combined, the solvent is distilled off, the residue is fractionated under reduced pressure.

Yield: 13.8 g (91 %) of 1,1-dichloro-4-methyl-1,3-pentadiene (boiling point: 62 to 64 ° C./26 mbar).

In Examples 4 and 5, the procedure is as in Example 3, except that iron or zinc powder is used as the reducing agent.

example Reduction 1, 1-dichloro-4-methyl-1-medium g iron powder 13.2 , 3-pentadiene rv / 0 4 8.2 g zinc powder 13.5 · S7 5 8.6 g 89

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Example 6

The mixture of 22.2 g (0.1 mol) of 1, 1, 1, 4-tetrachloro-4-methyl-2-pentene, 200 cm of isopropanol, 1.0 g of soluble Pd / C catalyst hydrogenated at room temperature and atmospheric pressure. After receiving an equimolar amount of hydrogen, the catalyst is filtered off, the solvent is distilled off, the residue is fractionated under reduced pressure. Yield: 14.0 g (92 %) of 1,1-dichloro-4-methyl-1,3-pentadiene

In Examples 7 and 8, the procedure is as in Example 6, except that acetic acid or acetone is used as the solvent.

Example solvent terape 1, 1-dichloro-4-methyl-1, 3

pentadiene

acetic acid ⁰ C G /O 7 acetone 60 12.6 83 8th 30-35 13.0 86

Example 9

The mixture of 22.2 g (0.1 mol) of 1, 1, i, 4-tetrachloro-4-methyl-2-pentene, 200 cm " ^{3 of} ethanol and 20.2 g (0.2 mol) of triethylamine and 0 4 g of Raney nickel are hydrogenated under intense shaking at room temperature and atmospheric pressure, and after receiving an equimolar amount of hydrogen, the catalyst is filtered, the filtrate is sealed to 40 ml, then 200 ml of water are added.

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set. The mixture is extracted with 2 × 70 ml of dichloromethane, the resulting dichloroethane-containing solution is dried, the solvent is removed and the residue is distilled off under reduced pressure (26 mbar). Yield: 12.5 g (83 %) of 1-chloro-o-methyl-1,3-pentadiene.

Sedspiel 10

The procedure is as in Example 9, except that instead of triethylamine 0.2 'mol of potassium carbonate used. Yield: 12.7 g (84 %) !, 1-oichloro-4-methyl-1,3-pentadiene.

Example 11

In the mixture of 22.2 g (0.1 mol) of 1,1,1,4-tetrachloro-4-methyl-2-pentene, 100 cm of methanol and 12.0 g of sodium dithionite is prepared from 8 g of sodium hydroxide 30% dripped aqueous solution, then the mixture is stirred at 60 ⁰ C for 3 to 4 hours. The mixture is evaporated to a quarter, 200 cm of water are added, then extracted with 2 χ 100 ml of dichloromethane. The extract is dried, the solvent is distilled off and the residue is fractionated under reduced pressure

Yield: 12.8 g (84 %) of 1, 1-dichloro-4-methyl-1,3-pentadiene *

Claims (3)

E rf induncjs entitlement 1. A process for the preparation of 2., l ~ dichloro-4-? Ethyl-I ₁ 3-pentadiene-, characterized in that .Calchloro and isobutylene are reacted, then the obtained 1> 1,1-trichloro-2-hydroxy 4-methyl-3-pentene of the formula I Cl OH Cl C ·-CH-CH = C-CH, Cl^ .CH₃ reacted with thionyl chloride advantageously in the presence of a catalyst without solvent or in an inert solvent and finally the resulting 1,1 ", 1,4-tetrachloro-4-methyl-2-pentene is reduced, 2. The method according to item 1, characterized in that * Penten of the formula I is reacted with molar in excess of 15 to 80 % thionyl chloride used » 3. Process according to items 1 and 2, characterized in that pentene of the formula I in the presence of 1 part by volume of dimethyl-formamide catalyst with thionyl chloride at a temperature of 40 to 130 C, advantageously 60 to 90 C, implemented. 13.AU (H9 $ 2 * 028954 23 8 5 2 2 5 io.8 AP C 07 C / 233 522/5 10
- 3? - 60 589/11 4. The method according to item 1, characterized in that the reductive dehydrohalogenation of 1,1,1,4-tetrachloro-4-methyl-2-pentene with amalgamated rietall (zinc ~, iron, aluminum) powder in alkanol-type solvents at a temperature of SO to 90 ⁰ C is performed. 5. The method according to item 1, characterized in that the reductive dehydrohalogenation of 1,1,1,4-tetrachloro-4-methyl-2-pentene is carried out with basic sodium dithionite. 6. The method according to item 1, characterized in that the reductive dehydrohalogenation of 1,1,1,4-tetrachloro-4-methyl-2-pentene with catalytic hydrogenation tion, in acetic acid, in acetone or in alcoholic solvents
is carried out· Solvents at a temperature of 20 to 60 C. A method according to item 6, characterized in that in the reduction a 5 to 10 % metal-containing bone char carrier palladium catalyst is used. 3 ". Process according to item 6, characterized in that a Raney nickel framework catalyst and organic or inorganic bases, advantageously trimethylamine or potassium carbonate, are used in the reduction.