DE1930024B - Process for the production of dithio phosphoric acid esters - Google Patents

Description

> before R is alkyl with 1 to 5 carbon atoms and R 'denotes phenyl or carba'thoxymethyl, with low toxicity to warm-blooded animals. characterized in that the technical esters present undiluted or in solution are treated with an aliphatic or aromatic acid bromide or iodide and then the volatile substances are distilled off in vacuo or in a steam countercurrent.

The present invention relates to a process for the production of di-phosphoric acid esters general formula

CH ₃ O

P-S

/ I!

CH ₃ OS

CH COOR

R '

wherein R is alkyl having 1 to 5 carbon atoms and R 'is phenyl or carbethoxymethyl, with low toxicity to warm-blooded animals, which is characterized by this. that you can use them undiluted or in solution present technical esters with an aliphatic or aromatic acid bromide or iodide treated and then the volatile substances are distilled off in vacuo or in a steam countercurrent.

The inventive method brings with it a considerable technical advance, since It is well known that the value of a pesticide does not only depend on an activity against pests, but To the same extent due to its toxicity against warm-blooded animals, which occur during the application of the pesticide or, for example, after its deposition Vegetable substances could come into contact with it, so that the degradation of the Toxicity of a pesticide against warm-blooded animals while maintaining activity against pests is extremely advantageous.

The result achieved according to the invention, which is only possible when using aliphatic and The occurrence of aromatic acyl bromides and iodides was in no way predictable, since the corresponding chlorides have no effect.

When carrying out the process according to the invention, which comprises the treatment of technical products, the reaction mixture is stirred for various periods of time, depending on the temperature, and at the end the excess acyl halides and volatile substances are removed. There is practically no loss of product and no reduction in content.

In the French patent specification 1507 651 is a method to reduce the toxicity for warm-blooded animals of technical dithioplicosphoric acid esters described that. essentially a treatment with adsorbing agents and the removal of

containment of volatile substances. This The method is disadvantageous compared to the method according to the invention, since the treatment with the absorbent means is technically complex. while the method according to the invention directly in

is the final stage of the pesticide manufacturing process can be carried out.

The compounds of the above general formula are known as pesticides and some are in use, for example O, O - dimethyl - S - (carboxyethyl - phe-

nyl - methyl) - dithiophosphate and O, O - dimethyl-S- (1 ^ -dicarbäthoxyäthyU-dithiophosphat.

The toxicity of the compounds of the present class to warm blooded animals varies considerably with the manufacturing process, in some cases

² S even with the same procedure.

This is due to the fact that extremely small amounts of special substances are present, which door the toxicity of warm-blooded animals raise.

The technical O, O-dimethyl-S- (carboxyäthylphenyl-methyl) -dithiophosphat (compound I) has an average toxicity between 200 and 1000 mg / kg:

CH ₃ O

PS-CH-COOC ₂ H ₅

/ I! I.

CH ₃ OSC ₆ H ₅

Technical products of OO-Dimethyl-S- (1.2-dicarbäthoxyäthylj-dithiophosphats (compound II) have a toxicity for warm-blooded animals in the range of about 1000 to 2500 mg / kg:

CH ₃ O

\
PS-CH-COOC ₂ H ₅ (II)

/ Il ^]

CH ₁ OS CH ₂ - COOC ₂ H ₅

OO-Dimethyl-S-fcarboxyisoprops l-phenyl-methyl) - dithiophosphate (compound III) has a toxicity between 210 and 1100 mg / kg for warm-blooded animals:

CH ₃ O

> - S - CH - COO - iso-C, H ₇ (III)

/ Il I

CH ₃ OS QH ₅

The method according to the invention also applies to products with the lowest toxicity values

possible. Products with a toxicity above 2000 mg / kg 7ii received.

If the product to be treated has a very high toxicity level for warm-blooded animals, «, N it is best to treat with the said Acyl bromides or iodides on that in a solvent Make dissolved product and in the end ilas solvent and volatile substances to be removed by distillation in a steam countercurrent.

The temperature is not very critical. The duration of the treatment depends on the temperature and decreases when the latter increases.

The amounts used in the treatments at 5 acyl halides are not significant, an average of amounts in the range between 0.5 and 2 'O ¹ sufficiently.

The table below shows results obtained from toxicity reduction tests ίο have been received.

"o active
substance Initial
oral LD ₅₁₁ at Weight percent Treatment "Tem. Oral LD ₅₁ , % more active Priukukt (± 1%) of the rat, mg kg Ac \! Halide length of time component
after coming down (+) setting the ° C mg / kg ToMzilat 92.9 625 Acetyl bromide, 1% 2 hours. 80 2650 (± 1%) 92.9 625 the same 4h 80 3400 92.80 92.9 625 the same 7h 80 2150 92.80 92.9 625 Acetyl bromide, 0.5% 4h 80 2040 92.80 92.9 625 Propionyl bromide, 1% 4h 80 2280 92.90 92.9 625 Butyryl bromide, 1% 4h W. 2000 92.70 92.9 625 Benzoyl bromide, 1% 4h 80 2370 92.85 Vcr- J 92.9 625 2-bromopropionyl 4h 80 2580 92.50 binding I bromide, 1% 92.90 92.9 625 Lauroyl bromide, 1% 4h 80 2600 92.9 625 Stearoyl bromide, 1% 4h 80 2530 93.00 92.9 625 Acetyl iodide, 1% 4h 80 2360 92.60 92.9 625 Acetyl chloride, 1% 4h 80 400 92.90 92.30

product

Compound I
comparison

% active
substance Initial
oral LD ₅₀
in the rat (± I%) mg / kg (+) 92.9 625 92.8 400 92.0 1020 92.0 1020 92.0 1020 92.0 1020 92 1020 92 1020 92 1020 92.1 500 92.1 500 92.1 500 92.1 800 92.1 . 800 92.1 800 92.1 800

Weight percent acetyl halide Working time

Acetyl chloride,

1% acetyl bromide.

2% acetyl bromide,

1%

the same

the same

also acetyl bromide.

2%

the same

also acetyl bromide,

1%

the same

the same

the same

like. like. like.

2 hours. 5 days 24 hours

48 hours 5 days 4 hours "> 4 hours

48 hours b days 10 days

17 days 30 days 30 min.

1 hour 2 hours 4 hours

Oral LD _5n
in the rat % more active Solution
medium component Tcmp. mg / kg after coming down
setting the 400 toxicity - C. 1730 (± 1%) - 80 1980 92.30 - 20-22 2300 92.50 - 25th 2850 91.20 - 25th 3500 92.00 - 25th 2600 91.40 - ■ 80 3000 - 25th 2080 91.10 - 25th 2900 92.80 - 25th 2350 91.60 - 50 2600 92.10 - 50 1880 91.80 Dichloro 50 91.70 ethane 90-95 2370 92.00 the same 2000 the same 90-95 1800 92.00 the same 90-95 91.70 90 95 91.50

Vcrhiiidu "

on/ "») 1 ! 1 1 "η active You are I · ■ I 02 02, 02 02.

Initial

oral ID _S "

hot the rat

mg kg
80Ü

800
800
800

(iewichlspro / enl Ac> I ha lied id

Acetyl bromide. 1% like the like the like

Treatment ^

il.lllL-l

7 sid.

1 H.

2 mercenaries 4Sid.

Temp

00 05

SI)
SI)
■ SO

product

Compound II

product

Compound II

(Comparison)

Compound III

'ο active
substance

t 1.5% I.

83.60

83.60
83.60
83.60
93.60
83.60
83.60
83.60

83.60
83.60
83.60
83.60
83.60
83.60
90

90
90

Initial

oral LD ₅₁ ,

hot the rat

mg / kg (+)

1170

1170 1170 1170 1170 1170 1.170 1170

1170 1170 1170 1170 1170 1170 1340

1340 1340

Weight percent AcWhalide

Acetyl bromide,

1%

the same

the same

the same

the same

the same

also acetyl bromide.

2%

the same

the same

the same

the same

the same

also acetyl bromide.

1%

the same

the same

Treatment · »duuer

30 min.

1 Hours. Hours. Min 2 Hours. 5 days Hours. 4th Hours. 30th Hours. 24 hours 1 Hours. 48 2 Hours. 4th Hours. 24 rage 48 Hours. 5- Hours. 1 Hours. 1 4th

Oral Ι.Π ₅ ιι
at the hat

mg / kg

1800

25 (K)
3600
3000

'! Ό more active
component
after degradation, the
Toxicilul
(1 1%)

91.70

92.00
91.90
91.90

Oral LD ₅₁ , Bes I'emp. in the rat Her; C. mg / k « I. 80 2630 80 2530 80 2300 80 2200 25th 2600 25th 2100 25th 2540 80 3200 80 3100 80 2670 80 2380 25th 3200 25th 3800 25th 3750 80 2870 80 2380 80 2040

i exercise means

Dichlnratshaii desul desgl

"o active part n ;: hset / ιιημ ι ι oxizitiii

i l.5 "., i

83.10

83.30 83.50 82.50 83.00 83.60 83.30 83.00

82.60 83.30 82.40 83.90 83.90 83.70

% active
substance

l ± 1.5%)

90

90
90

90
90

(± 1%)
92.3

92.3
92.3
92.3

Initial

oral LD ₅₀

in the rat

mg / kg *) 1340

1340 1340

1340 1340

650

650 650 650

C ic weight percentage Treatment Acyl halide permanently Acetyl bromide. 7 hours 1% the same 24 SId. Acelyl bromide, 7 hours 2% the same 24 hours Acetyl chloride. 2 hours. 2% Acetyl bromide. 5 days 1% the same 2 hours. the same 4 hours the same 7 hours

Tcmp.

25th

25th
25th

25th
25th

25th

80
80
80

Oral LD _5n
at the RaIIc

jrng / kg
2100

2300
2700

3100
1400

2670

2200
2200
2000

% active ingredient after reducing the

Toxicity

92.10

91.40 92.00 92.50

• | The LD _5n values, "c ^r dcn, are obtained by administering the product undiluted via a gastric tube to a mixed population (1/2": 1/2 ") of adult albino rats weighing 100 g.

The following examples illustrate the invention. Example I.

A suitable reaction vessel with a capacity of 40 l is charged with 29 kg of UO-dimethyl-S- (carboxyethyl-phenyl-methyl) -dithiophosphate (oral LD _{J0 for} the rat = 435 mg / kg), which contains 88% of the active ingredient . Ice is heated to about 55X '. 310 g of acetylbrotnide are added with stirring. The temperature rises to 8O ⁰ C and held for 3 hours and 45 minutes at this value. Stirring is then continued for 15 minutes at a vacuum of 2 torr. Finally, it is cooled to room temperature. The product obtained without weight loss had an oral toxicity to the rat of 2700 mg / kg and a content of 88%.

. B e i s ρ i e 1-2

105 kg of technical O, O-dimethyl-S- (carboxyethylphenyl-methyD-dithiophosphate) are dissolved in 160 kg of dichloroethane. This solution is heated to 55 ° C. and 1.05 kg of acetyl bromide are added. The mass is heated to 80 ° C. and Maintained at this temperature for 2 hours with stirring. The solution is then distilled in a steam countercurrent. The ester is decanted off and then, after the aqueous phase has been separated off, dried in vacuo at 50 to 60 ° C. 102 kg of product with 92% activity are obtained ingredient and an oral LD _5n mg receive / kg in the rat of 2500. It is found that a sample of the product obtained from the dichloroethane solution by vacuum evaporation at 40 "C before the addition of acetyl bromide. 91.8% active ingredient at an oral LD _5n in the rat contains 800 mg / kg.

Example 3

A flask with a capacity of I 1 is dissolved in 294 g of 0,0-dimethyl-S- (carboxyethyl-phenylmethyl) -dithiophosphate with 88.5% active ingredient (oral LDj ₀ in the rat = 250 g / kg) 445 g dichloroethane, charged. 3 g of acetyl bromide are added. The temperature is increased to 80 ^° C. and the mass is stirred for 2 hours. Finally, the solvent and volatiles are removed by distillation in a countercurrent of steam.

274 g of product with an oral LD ₅₀ in rats of 2500 mg / kg and an active ingredient content of 94.5% are obtained.

J09 517/337

Claims (1)

Claim: Process for obtaining dithiophosphoric acids the general formula CH ₁ O P - S - CH - COOR
CHjO S R '