DE2825363A1 - 1-Acetyl-2,2-di:methyl-3-di:halovinyl-cyclopropane carboxylic ester - prepd. by UV irradiation of 2,4,4-tri:methyl-5-di:halovinyl-4,5-di:hydro-furan-3-carboxylic acid ester and used as insecticide precursor - Google Patents

Abstract

Prepn. of dihalovinylcyclopropane-carboxylic acid esters of formula (I) comprises conversion of a novel dihalovinyl-dihydrofuran of formula (II) by illumination pref. using UV or UV-contg. light of wavelength >200 nm in the liq. or gaseous phase: (where R1 are opt. branched alkyl (pref. 1-8C) and X is Cl or Br). 2,2,5-Trimethyl-3-carbalkoxy-4-(beta, beta-dihalovinyl)-4,5-dihydro-furans of formula (VII) are new: (I) are precursors for synthetic pyrethroid insecticides. (II) and (VII) are intermediates. Compared with known processes (DT2606635 and DT2649856), the present invention gives (I) in gold yields with only small amts. of undesirable monomer and polymer formation. The starting cpds. (II) are readily prepd. and (II) is obtd. by an industrially economic process.

Description

Process for the preparation of 2,4,4-trimethyl-3-carbalkoxy-

5- (ß, ß-dihalovinyl) -4,5-dohydrofurans (addendum to patent application P 27 40 479.1) The main application (P 27 40 479.1) relates to vinyl dihydrofurans of the general formula I in which R1 is a straight-chain or branched alkyl radical and X is chlorine or bromine atoms, and a process for the preparation of these compounds.

is is an alkyl radical with 1 to 18 carbon atoms, preferably with 1 to 8 carbon atoms, in particular with 1 or 2 carbon atoms.

According to the process of the main application P 27 40 479.1, the new compounds of the formula I are prepared by adding a 1β-alkoxycrotonic acid ester of the general formula in which R1 and R4 can be identical or different and represent straight-chain or branched alkyl radicals with a) a 1,1,1-trihalo-4-methyl-3-penten-2-ol of the general formula in which X is chlorine or bromine atoms, in the presence of an acidic catalyst and / or with b) a 1,1,1-trihalo-4-methyl-4-penten-2-ol of the general formula in which X is chlorine or bromine atoms, reacts in the presence of an acidic catalyst.

In a modification of the process of the main application, it has now been found that the new compounds of the general formula I are obtained if at least one 3,3-bisalkoxybutyric acid ester of the general formula is used optionally its mixtures with at least one ß-alkoxycrotonic acid ester of the general formula where R1, R2, R3 and R4 are identical or different, preferably identical, and represent straight-chain or branched alkyl radicals, with a) a trihalo-4-methyl-3-penten-2-ol of the general formula in which X is chlorine or bromine atoms and / or with b) a trihalo-4-methyl-4-penten-2-ol of the general formula i of the X chlorine or bromine atoms is reacted in the presence of an acidic catalyst.

The radicals R1, R2, R3 and R4 are alkyl radicals with 1 to 18, preferably 1 1 to 8, in particular 1 or 2 carbon atoms.

Examples of suitable catalysts are Lewis acids such as AlCl3, ZnC12, BF3, FeC13 and the like, protonic acids (Brönsted acids) such as H2S04, H3P04, p-toluenesulfonic acid, Trichloroacetic acid, acidic ion exchangers and the like. Also mixtures of the individual Acids can be used.

The catalysts or catalyst mixtures are used in amounts up to 20 mol%, preferably less than 10 mol%, in particular in amounts of 0.1 to 4 mol%, based on the general formula II or mixture II + III used, used.

In the process according to the invention, hydrogen halide and an alcohol of the formula R2-OH-free, provided that R3 and optionally R4 = R2. In the event of inequality appropriate alcohol mixtures are released. Both products are preferred removed during implementation.

The reaction is preferably carried out at normal pressure, if necessary

but also by applying a vacuum, e.g. for separation by distillation a higher alcohol formed during the reaction (higher boiling alcohol) E.g. an alcohol with a Kp760 mm of> 160 ° C.

The compounds of the formula II, optionally in a mixture with compounds of the Formula III, are mixed with the compounds of the formulas IV and / or 1V in a molar ratio 1: 0.5 to 1:10 implemented. Preference is given to using an excess of IIV and / or V. Preference is given to setting the compounds of the formula II where j is in each case one of the compounds of the formula IV or V, where the radicals R1, R2 and R3 are preferably pale.

The reaction is carried out in a largely anhydrous medium.

It is therefore advisable to use starting materials that are as dry as possible and to work during the reaction with substantial exclusion of moisture.

The reaction can take place in the presence of an inert solvent be carried out to a large extent with no moisture. Inert solvents are e.g. those that provide the starting product and the catalyst for the implementation do not render them unusable and do not react chemically with the end product. Suitable Are solvents e.g. chlorobenzenes, alkylbenzenes such as xylenes, Dioxanes, dimethylformamide and the like.

In general, one works with solvent quantities, e.g. the folL The following weight ratios result in: Compound II, optionally in a mixture with III: solvent = 2 to 0.1. In principle, however, the ratio can also be greater than 2 or less than 0.1 be.

In principle, the reaction can also be carried out without the use of a solvent be performed.

The reaction is carried out at an elevated temperature. In general one works at temperatures of 800 to 2000C, preferably 120 to 616,000.

The reaction is preferably carried out at the temperature at which is the resulting alcohol R2-OH or the resulting alcohol mixture by distillation can be separated at normal pressure or possibly underpressure without the output and end products are thermally damaged.

During the reaction, the mixture is expediently constantly stirred.

The process is generally carried out as follows: The 3,3-bisalkoxybutyric acid ester (II) optionally in a mixture with III is mitIV and / or V with stirring in the presence of the Heated catalyst, the alcohol formed being dedistillative during the reaction Will get removed. Preferably II is added in portions or continuously while maintaining the reaction temperature added to IV or V or to a mixture of IV and V, The addition expediently extends over the entire reaction period, e.g. 2 to 12 hours. After completion of the implementation, the approach is through fractionated Worked up distillation in vacuo.

The starting compound used in excess is obtained in the 1st fraction IV and / or V, and in the 2nd fraction the dihydrofuran.

The compounds used in excess can after distillation Separation can be used again without further purification process.

The 3,3-bisalkoxybutyric acid alkyl esters are e.g. according to the in Beilstein, E III 3, page 1199 described method accessible.

To make the other connections, the main registration P 27 40 479.1 referenced.

The new 2,4,4-trimethyl-3-carbalkoxy-5- (ß, ß-dihalovinyl) -4,5-dihydrofurans are intermediate products for the synthesis of insecticides.

The invention is illustrated by the following examples.

Example 1 2,4,4-Trimethyl-3-carbethoxy-5- (β, β-dichlorovinyl) -4,5-dihydrofuran 6.1 g 1,1,1-trichloro-4-methyl-3-penten-2-ol are mixed with 0.1 g AlOl3 and heated to 145 ° C. With exclusion of moisture and stirring, 6.1 g of ethyl 3,3-bisethoxybutyrate are obtained added dropwise over a period of 7 hours while maintaining the temperature of 14500. The resulting low-boiling components are distilled off during the reaction.

After the reaction has ended, the approach is fractional Worked up distillation. The dihydrofuran goes over at Kp0.1mm: 108 - 7090C, Yield 6.7g (80%).

Example 2 6.3 g of 1,1,1-trichloro-4-methyl-4-penten-2-ol are mixed with 6.1 g of ethyl 3,3-bisethoxybutyrate and 0.1 g of AlOl3 were mixed and 6 hours heated to 1550C, the resulting low boilers being removed by distillation. The high-boiling components are fractionally distilled. 6.9 g are obtained (yield 83%) 2,4,4-trimethyl-3-carbethoxy-5- (β, β-dichlorovinyl) -4,5-dihydrofuran.

Example 3 2,4,4-Trimethyl-3-carbomethoxy-5- (β, β-dichlorovinyl) -4,5-dihydrofuran 6.1 g 1,1,1-trichloro-4-methyl-3-penten-2-ol are mixed with 0.2 g AlCl3 and heated to 1500C. With exclusion of moisture and stirring, 4.8 g of methyl 3,3-bis-methoxybutyrate are obtained added dropwise within 4 hours while maintaining the temperature of 1500C. The resulting low boilers are removed by distillation. After the reaction has ended, the mixture is fractionally distilled. You get 6.6 g (yield 83%) of dihydrofuran (bp 0.1 mm: 102-104 ° C).

Example 4 2,4,4-Trimethyl-3-carbethoxy-5- (β, β-dibromovinyl) -4,5-dihydrofuran 10.5 g of 1,1,1-tribromo-4-methyl-3-penten-2-ol are mixed with 0.1 g of KHSO4 and 6.1 g of ethyl 3,3-bisethoxybutyrate mixed and heated with stirring to 1450C for 12 hours, the resulting low boilers are separated by distillation. Obtained by fractional distillation of the batch 7.7 g (yield 70%) of dihydrofuran (boiling point 2.5 mm: 120 ° C)

Claims (11)

New patent claims 1. Modification of the process according to patent application P 27 40 479.1 for the production of 2,4,4-trimethyl-3-carbalkoxy-5- (ß, ß-dihalovinyl) -4,5-dihydrofurnans of the general formula in which R1 is a straight-chain or branched alkyl radical and X is chlorine or bromine atoms, by reaction of a β-alkoxycrotonic acid ester of the general formula in which R1 and R4 are the same or different and can represent straight-chain or branched alkyl radicals with a) a 1,1,1-trihalo-4-methyl-3-penten-2-ol of the general formula in which X is chlorine or bromine atoms, in the presence of an acidic catalyst and / or with b) a 1,1,1-trihalo-4-methyl-4-penten-2-ol of the general formyl in which X is chlorine or bromine atoms, in the presence of an acidic catalyst, characterized in that a 3,3-bisalkoxybutyric acid ester of the general formula III is used instead of a β-alkoxycrotonic acid ester of the general formula III optionally in a mixture with a ß-alkoxycrotonic acid ester of the general formula where R1, R2, R3 and R4 can be identical or different and represent straight-chain or branched alkyl radicals, with a) a 1,1,1-trihalo-4-methyl-3-penten-2-ol of the general formula in the X chlorine. or means bromine atoms, in the presence of an acidic catalyst and / or with b) a 1,1,1-trihalo-4-methyl-4-penten-2-ol of the general formula in which X is chlorine or bromine atoms, reacts in the presence of an acidic catalyst. 2. The method according to claim 1, d a d u r c h g e k e n n -æ e i c hn e t that R1, R², R³ and R4 are straight-chain or combined alkyl radicals with 1 to 8 carbon atoms and are preferably the same. 3. The method according to claim 1 or 2, d a d u r c h g e k e n n -æ E i c h n e t that the acidic catalyst used is a Lewis and / or Brönsted acid begins. 4. The method according to any one of claims 1 to 3, d a d u r c h g e k It is noted that the catalyst in amounts up to 20 mol%, preferably less than 10 mol%, in particular in amounts of 0.1 to 4 mol%, based on the used starting material of the general formula II, or the mixture II + III is used. 5. The method according to any one of claims 1 to 4, d a d u r c h g e k It is noted that the starting materials of the general formula II, optionally in Mixture with III, and the starting materials of the general formulas IV and / or V im Molar ratio 1: 0.5 to 1:10, preferably 1: greater than 1, can be used. 6. The method according to any one of claims 1 to 5, d a d u r c h g e k It is noted that the reaction was carried out at elevated temperatures will. 7 .. The method according to claim 6, d a d u r c h g e k e n n -z e i c Note that the reaction takes place at a temperature between 80-2000C, preferably 120 to 1600. 8. The method according to any one of claims 1 to 7; d a d u r c h g e k It is noted that the compound of the formula II, possibly in a mixture with III, the submitted catalyst-containing compound heated to the reaction temperature of formula IV and / or V continuously or in portions during the reaction is added. 9. The method according to any one of claims 1 to 8, d a d u r c h g e k It is noted that the reaction is carried out in the presence of an inert solvent is carried out. 10. The method according to any one of claims 1 to 9, d a d u r c h g e it is not stated that the low-boiling substances in the course of their formation are separated by distillation. 11. The method according to any one of claims 1 to 10, d a d u r c h g e no indication that one works in an anhydrous Iledium.