DE1140933B - Process for the preparation of derivatives of aromatic phosphonic acids - Google Patents

Description

Process for the preparation of derivatives of aromatic phosphonic acids The German patent specification 954 244 already discloses a process for the preparation of derivatives of aromatic phosphonic acids of the general formula known, in which Ar stands for an optionally substituted aromatic radical and X stands for the radicals - OR, - SR or stands, where R, Rl and R2 mean any optionally substituted alkyl radicals. The process is characterized in that chloral is reacted with esters, ester amides or ester thiol esters of aromatic phosphonous acids - expediently in the presence of an inert solvent - at elevated temperature.

The phosphonic acid derivatives mentioned are said to be insecticidal because of their properties Properties as a pesticide, especially in crop protection, use Find.

It has now been found that derivatives of aromatic phosphonic acids of the general formula can be used in which Ar is an aryl radical optionally substituted by halogen, the nitro group or lower alkyl or alkoxy radicals, by reacting the corresponding aryl phosphonous acid-B-chloroethyl ester with chloral, preferably at temperatures of 40 to 120 ° C. and expediently in the presence of an inert one Solvent, such as benzene or toluene, is obtained.

The compounds obtainable according to the invention are distinguished from one another the phosphonic acid derivatives mentioned in German Patent 954244 better insecticidal effectiveness with relatively low warm-blooded toxicity and should therefore preferably be used as a pesticide especially in crop protection.

The technical superiority of the process products compared to the compounds of analogous composition known from the aforementioned prior publication can be seen from the table below: Comparative tests biological effect Active substance killing Serial No constitution Use against concentration of pests inO / o in ovo 0 1 <2 \ aphids aphids 0.01 100 OCH = CC12 flies | 0.01 100 (according to the invention example 1) Comparative tests biological effect I killing of active ingredients Serial No. Constitution Use against I concentration of pests in Olo I in O / o 0 2 P / N (CH3) 2 aphids 0.1 1 60 ½y- Cm12 flies 0.1 1 100 (known from German patent specification 954 244, Example 2) 0 } 7O-CH2-C112-Cl 3 P 4 ~ p CH CCl2 spider mites 0.1 100 0 - CH = CQB (according to the invention, example 2) 0 / OC, H, 4 Cl / P \ spider mites 0.1 0 OCH 0-CH = CCl2 (known from German patent specification 954 244, Example 4) The following examples give an overview of the process for the preparation of the compounds according to the invention: Example 1 37 g of chloral are added dropwise to 67 g (0.25 mol) of phenylphosphonous acid O, O-ß-chloroethyl ester (boiling point 0.01-110.degree. C.) with stirring, the temperature rising to about 100 to 110.degree. The mixture is allowed to stir for a further 1 hour at 100 ° C. and the reaction product is then poured into 200 com of ice water. The oil which has separated out is taken up in 200 cc of benzene, washed neutral with water and dried with sodium sulfate.

After the solvent has been distilled off in vacuo, 69 g of des are obtained above ester as a colorless, water-insoluble oil. Yield 88% of theory.

Analysis for mole 316: Calculated. . Cl 33.9%, P 9.8%; found ... Cl 32.4 0 / o, P 9.40 / 0.

The compound shows a DL50 of 25 mg / kg in the rat per os.

Example 2 76 g (0.25 mol) of p-chlorophenyl-phosphonous acid O, O-ß-chloroethyl ester are dissolved in 100 cc of benzene. 37 g of chloral are added dropwise to this solution at 50 ° C. and appropriate external cooling ensures that this temperature is not significantly exceeded. The reaction mixture is then kept at 50 ° C. for a further hour and then worked up as described in Example 1. In this way, 70 g of the new ester are obtained as a colorless, sparingly water-soluble oil. Yield 80% of theory.

Analysis for mole 350: Calculated ... Cl 40.5 0 / o, P 8.9 0 / o; found ... Cl 39.4%, P 9.0%, DL50 rat orally 50 mg / kg.

Example 3 70 g (0.25 mol) of 4-methylphenyl-phosphonous acid O, O-ß-chloroethyl ester are dissolved in 100 cc of benzene and 37 g of chloral are added to the resulting solution at 70 ° C. with stirring. The reaction mixture is then kept at 700 ° C. for a further hour and then worked up as in Example 1. 74 g of the new ester are obtained as a colorless, sparingly water-soluble oil.

Yield 90% of theory.

Analysis for mole 330: Calculated. P 9.4%, Cl 32.5%; found . . P 9.4 0 / o, Cl 32.2 0 / o.

DL50 rat orally 50 mg / kg. Example 4 79 g (0.25 mol) of 2-chloro-4-methylphenyl-phosphonous acid O, O-fl-chloroethyl ester are dissolved in 100 cc of benzene. 37 g of chloral are added to this solution at 70 ° C. with stirring. It is held at 70 ° C. for a further hour and then worked up as described in Example 1. 75 g of the new ester are obtained as a colorless, sparingly water-soluble oil. Yield 820 / o of the Theons.

Analysis for mole 364: Calculated ... P 8.50 / o, Cl 39.1 0 / o; found . . P 8.7%, Cl 38.2%.

DL50 rat orally 250 mg / kg.

Claims (1)

PATENT CLAIM: Process for the preparation of derivatives of aromatic phosphonic acids, characterized in that chloral with aryl-phosphonous acid-chloroethyl esters, expediently in the presence of an inert solvent and preferably at temperatures of 40 to 120 ° C., to give compounds of the general formula converts, where Ar is optionally replaced by halogen, the nitro group or lower alkyl or. Alkoxy radical substituted aryl radical. Documents considered: German Patent No. 954244.