DE19959066C1 - Preparation of ortho-chloromethyl-benzoyl chloride derivatives from phthalide and thionyl chloride, for use as pesticide intermediate, using boron trifluoride dihydrate and quaternary ammonium catalysts - Google Patents

Abstract

Preparation of o-chloromethyl-benzoyl chloride derivatives (I) by reaction of benzo-fused lactones (phthalides) (II) with thionyl chloride is catalyzed by boron trifluoride dihydrate and a quaternary ammonium salt. The preparation of o-chloromethyl-benzoyl chloride derivatives of formula (I) by reaction of benzo-fused lactones of formula (II) with thionyl chloride is carried out in presence of catalytic amounts of each of boron trifluoride dihydrate and a quaternary ammonium salt. R1-R4 = H, 1-4C alkyl, halo or CF3.

Description

The present invention relates to a process for the preparation of o-chloromethylbenzoic acid chlorides of the formula I,

in which R ¹ to R ^{4 can be the} same or different and stand for water, C ₁ -C ₄ alkyl, halogen or trifluoromethyl, by reacting benzocondensed lactones of the formula II,

in which R ¹ to R ^{4 have} the abovementioned meaning, with thionyl chloride.

o-Chloromethyl-substituted benzoyl chlorides are important intermediates Products for the production of, for example, pesticidal activity substances as described in the patent specifications EP-A 460 575, EP-A 463 488, WO-A 95/18789, WO-A 95/21154 and WO-A 97/15552 are.

For example, o-chloromethyl substituted benzoyl chlorides by reacting benzocondensed lactones with thionylchlo rid or phosgene can be produced. When using thio nylchloride simplifies the equipment technology and safely technical effort is reduced.

EP-A 676 389 describes the preparation of o-chloromethylbenzoic acid rechlorides from benzo-condensed lactones with thionyl chloride in Presence of a nitrogen compound described. To be to achieve peaceful sales, reaction temperatures of 160 to 170 ° C required, at which thionyl chloride is already partially decomposed and consequently disruptive by-products be formed. Furthermore, the addition of gaseous hydrochloric acid  required. After all, the yields are partly clear below 90%.

In WO-A 99/16743 the reaction with thionyl chloride is carried out in the presence of BF ₃ etherate and a quaternary ammonium salt at 90 to 100 ° C. It proves disadvantageous here that the BF ₃ etherate is very sensitive to moisture and can continue to release diethyl ether in the course of the reaction. Diethyl ether is low-boiling, highly flammable and tends to form peroxides.

The object of the present invention was therefore an economical ches and processable process for the production of o-chlorine to find thylbenzoic acid chlorides that are those listed above Does not have disadvantages and still provides high yields.

Accordingly, the above-mentioned method has been found, which is characterized in that the reaction in the presence ka talytic amounts of boron trifluoride dihydrate and catalytic Amounts of an ammonium salt.

The use of BF ₃ dihydrate in combination with thionyl chloride has not previously been described in the literature. It was surprising here that the reagent retains its Lewis acid activity and remains effective in catalytic amounts.

The boron trifluoride dihydrate is used in amounts of 0.1 to 20 mol% based on the amount of benzo-condensed lactone used (Phthalide), preferably in amounts of 0.5 to 10 mol%, added.

Benzo-condensed lactones (phthalides) of the general formula II are used

in which R ¹ to R ^{4 can be the} same or different and stand for What serstoff (H), C ₁ -C ₄ alkyl, halogen (fluorine, chlorine, bromine or iodine) or trifluoromethyl. Unsubstituted phthalide is preferably used.

Quaternary ammonium in particular comes as quaternary ammonium salts halides such as tetraalkylammonium chlorides or Benzyltrialkylammoniumchloride in question. Particularly suitable  are: tetramethylammonium chloride, tetraethylammonium chloride, Te trabutylammonium chloride, benzyltrimethylammonium chloride, benzyl triethylammonium chloride, benzyltributylammonium chloride, N, N-Dime thylpiperidininum chloride. Benzyltriethyl is particularly preferred ammonium chloride.

The quaternary ammonium salts are generally in amounts of 0.1 to 20 mol% based on the amount of benzokone used densified lactone, preferably in amounts of 0.5 to 10 mol% given.

Regarding phthalide II, 1 to 1.5 Equivalent thionyl chloride used.

The thionyl chloride can be used with the other reactants be placed (batch mode) or in the course of the reaction half of preferably 1 to 8 hours are added (semi batch mode). It is also possible to continue the reaction to be carried out.

Optionally, to accelerate the ring opening can be gaseous Hydrogen chloride are introduced. However, preference is given to renounce the introduction of hydrogen chloride during the synthesis tet.

The reaction temperature is generally 80 to 140 ° C and preferably 90 to 110 ° C.

The process is preferably carried out without a solvent. However, a solution which is inert to thionyl chloride is possible add funds. Inert solvents are e.g. B. aromatic Hydrocarbons such as toluene, o-, m- or p-xylene or their Ge mix, chlorinated aromatic hydrocarbons such as chlorobenzene or dichlorobenzenes or cyclic carbonates such as ethylene or Propylene carbonate. It is also possible to use thionyl chloride itself to use as a solvent, which is distilled at the end of the reaction tiv separated and reintroduced into the process can.

The reaction is generally carried out at normal pressure and at 1 to 10 bar pressure carried out.

The following examples are intended to explain the process further tern.  

Process examples General instructions for the preparation of o-chloromethylbenzoyl chloride

In an agitator consisting of a 1.6 l double jacket reactors with an attached intensive cooling cascade were each X mole of phthalide together with the respective catalyst system sets. 1.3 equivalents of thionyl chloride based on phthalide were either submitted with the other components or during the Dropped from 1 to 8 hours. Then left 1 to Stir at reaction temperature for 15 hours. The value of the Raw mixture was determined by GC. In selected examples the product was fractionated at 0.5 mbar and 75 to 85 ° C Distillation isolated.

example 1

268 g (2 mol) of phthalide, 9.45 g (0.06 mol, 3 mol%) of BF ₃ dihydrate and 13.5 g (0.06 mol, 3 mol%) of benzyltriethylammonium chloride were placed in the stirred vessel and brought to 100 ° C warmed. 310 g (2.6 mol) of thio nyl chloride were added dropwise to this melt in the course of 5 hours. The mixture was then stirred at 100 ° C for 10 hours. The reaction discharge contained 95 GC area% o-chloromethylbenzoyl chloride and 3.7% unreacted phthalide. After distillation of the reaction product, 323 g (85% from booty) of o-chloromethylbenzoyl chloride were obtained in a purity of 98.5% (GC).

Example 2

536 g (4 mol) phthalide, 18.9 g (0.12 mol, 3 mol%) BF ₃ dihydrate and 27 g (0.12 mol, 3 mol%) benzyltriethylammonium chloride as well as 620 g (5.2 mol) thionyl chloride were placed in the stirred tank and heated to 100 ° C. The mixture was then stirred at 100 ° C for 15 hours. The reaction discharge contained 95.4 GC area% o-chloromethylbenzoyl chloride and 1.3% unreacted phthalide.

Claims (3)

1. Process for the preparation of o-chloromethylbenzoic acid chlorides of the formula I,
in which R ¹ to R ^{4 can be the} same or different and represent hydrogen, C ₁ -C ₄ alkyl, halogen or trifluoromethyl, by reacting benzofused lactones of the formula II,
in which R ¹ to R ^{4 have} the abovementioned meaning, with thio nyl chloride, characterized in that the reaction is carried out in the presence of catalytic amounts of boron trifluoride dihydrate and catalytic amounts of a quaternary ammonium salt. 2. The method according to claim 1, characterized in that the Boron trifluoride dihydrate in a concentration of 0.1 to 20 mol% based on the lactone II is used. 3. The method according to any one of claims 1 or 2, characterized records that 0.1 to 20 mol% of the quaternary ammonium salt be used based on the lactone II.