DE2104683C3 - Fungicidal mixture - Google Patents

Description

The present invention relates to fungicidal mixtures with improved stability based on Dithiocarbamates.

It is known that dithiocarbamates, for example the mixed precipitation from the zinc salt of 1,2-propylene-bis-dithiocarbamic acid and the N, N ^r -poly-1,2-propylenebis (thiocarbamoyl) disulfide, can be used as fungicides.

However, these dithiocarbamates are subject to a slow rate, especially at elevated temperatures Decomposition.

It has now been found that this decomposition occurs in the case of a fungicidal mixture containing a dithiocarbamate as an active ingredient and a finely divided, solid carrier, occurs less strongly when the carrier has a pK value of 3.3 to 6.8

For the following experiments, mixed precipitation from the ammonia complex of the zinc salt was used as the active ingredient the 1,2-propylene-bis-dithiocarbamic acid and the

N, N'-poly-1,2-propylene-bis (thiocarbamoyl) disulfide
used.
By a dithiocarbamate we mean a salt,

ίο in particular an alkali or metal salt, for example the sodium, potassium, copper, iron, manganese or zinc salt or an ammonium salt of a dithiocarbrmic acid, for example monomethyldithiocarbamic acid, dimethyldithiocarbamic acid, monoethyldithiocarbamic acid, ethylene-bis -dithiocarbamic acid, 1,2-propylene-bis-dithiocarbamic acid, 1,3-propylene-bis-dithiocarbamic acid or mixed precipitations of these salts with thiuram disulfides, for example Ν, Ν'-poly-1,2-propylene-bis- (thiocarbamoyl )-disulfide. The salts can be present as such or in complex form, for example in the form of an ammonia complex.

50% by weight mixtures of the active ingredient with carriers of different pK values were prepared and stored at room temperature, 30.degree. C., 40.degree. C. and 50.degree. The levels of detachable carbon disulfide were determined at intervals and the feo and 50 values (tgo = the time in weeks in which 80% of the initial active ingredient content is still present; feo = half-life in weeks) for the individual temperatures from the degradation curves determined The following table contains the results of these tests. The stability of the unmixed technical active ingredient used for these experiments was also included in the table.

Carrier stolT

pK value

of

Carry

stofies [Tg]

'so at
50 °

30 °
[Where]

RT
[Where]

'so at

50 °

[Tg]

40 °
[Where]

30 °
[Where]

RT

[Where]

Kaolin 0.4 i, 5 0.7

Tone 1.5 1.5 0.5

KSK flour *) 3.3 4 4

Silica gel B, wind sighted 6.8 4 -

Magnesium carbonate> 6.8 1 -

Active ingredient - 18 12

(without carrier)

*) S1O2 precipitated in a special process.

6.8
3

22.5

7.5
12th
39
18.5

5.5

16.5

3
3
8th
10
2.5

26th

1.4
1.3
10

16.5

36.5
4th

31

20th
> 60
> 60

Carrier material

Calibrite

iii sii

Sililin N
\ ttnpuluii

ρ Κ value
of

Carrier torrs

> 6.8
0.8

4.5
3.3

% Salary from AnTaRgS-

clialed

after 1 to 3 months

at 40 ° C and 5O ⁰

1 month
40 ° 50 °

3 months 40 ° 50 °

89

82
94
95

10
28
80
JT

75
89
HX

Calibrite is a calcite mineral, Silitin N is a naturally occurring silica, Hi S ^; ! is a synthetic silica gel in which pK values between

w) -0.1 and +0.8 depending on the sample. Attapulgite is a natural clay mineral.

The results show that only solid carriers with a pK value between 3.3 and 6.8 stabilize the active ingredient, while other carriers lead to a

μ lead to faster degradation. The undiluted active ingredient itself cannot be used in practice because the small amounts required for the Pil / bekiiiiipfiiiifi sk Ii nii hl 'JL-η lnmiBii' \ ι · Πι · ίΙι · ιι I.inni-ii IVr Wiikslnll

must therefore be diluted by adding carriers before use.

The pK value is a measure of the acidity of solid surfaces or their ability to release protons (LP. Hammett, A. J. Deyrup: J. Am. Chem. Soc, 54, 2721 [1932], J. Am. Chem. Soc, 56,827 [1934], Chem. Rev, 16, [1935]). It is described by H a m m e 11 as follows Are defined

_H _ - iog Qu ⁺ -Sh

Carrier or mixture

pK value

10

15th

20th

25th

30th

35

40

Here a _H + means the activity of the proton and / the activity coefficient of the neutral base or its conjugate acid. It is determined by dotting suspensions of the carrier in isooctane with solutions of different color bases, the different dissociation constants and the acidic forms of which must have a different color than the neutral forms (K. U11 rich: Chem. Techn., 16, 263 [1964]) .

The surface acidity results for most of the carrier substances completely different values than the usual ones Characterization by measuring the pH value in an aqueous suspension. According to Ullrich z. B. the pH of an attapulgite mineral 8.1 to 9.5 (measured in a suspension of 20 g of carrier in 80 ml of water), while the pK value is -5.3, which corresponds to the acidity of a 70% sulfuric acid. From the -cited reference also shows that the damaging effect of the mineral carrier substances to active ingredients is due to their surface acidity, in the sense that a low pK value or a negative pK value of the carrier material is synonymous with damage of the active ingredient, while higher pK values show no adverse effect. As a limit for that Damage is given a pK value of +1.5. Lower values indicate damage to the active substance fear and must be compensated by adding a deactivator, while higher pK values are safe. In contrast, it was found that in the present case, pK values of 1.5 are no longer permissible for the carrier material and there is also an upper limit insofar as pK values above 6.8 are also no longer permissible.

The solid carrier present in the fungicide mixture according to the invention should be in finely divided form. By this we mean particles with a size from 10 ^ to 10 'mm, in particular from 10' to 10 ² mm.

The finely divided, solid carrier material used is preferably silica gel whose pK value is within of the range mentioned above. The stability of the mixtures is extremely good. The contained therein finely divided, solid carrier material with a pK value of 3.3 to 6.8 can be used as the only solid carrier Carrier as well as in a mixture with various other mineral carriers, wherein the pK value of this mixture must again be between 3.3 and 6.8. In this way you can use carriers with a pK value less than 3.3 or greater than 6.8, which are not per se for the inventive Mixtures are suitable, by mixing with carriers, a suitable pK value to a pK value of the mixture

iI 3,3 and 6.8 set as the following ¹ /eit'1.11

50

e> o

Kaolin 0.4

Tone 0.4 to 1.5

Silica gel K 322 3.3

Silica gel B, wind sighted 6.8

BLP / 3 (calcium carbonates> 6.8

Clay silica gel B, wind sighted 3.3

(1: 1)

Kaolin silica gel K 322 (1: 1) 1.5 to 3.3

Kaolin silica gel B, wind sighted 3.3

BLP / 3 silica gel K 322 (1: 1) 4.5

Mixtures containing fungicidal dithiocarbamates which have a solid carrier or a solid carrier mixture with a pK value between 3.3 and 6.8 are stable. They are suitable for combating of mushrooms, especially in crop protection. It is used in the usual way, for example by dusting, spraying or spraying. It is used prophylactically, i.e. to avoid a Infection of plants by fungal spores.

The ratio of dithiocarbamate to total solid carrier can be in the range from 5 to 90 Parts by weight of dithiocarbamate vary from 95 to 10 parts by weight of carrier. Preferably contains the fungicidal mixture 70 to 80 parts by weight of dithiocarbamate mixed with 30 to 20 parts by weight of solid Carrier, wherein, as stated above, this solid carrier is a mixture of customary mineral Can be carriers with silica gel.

A fungicidal mixture with increased stability for unfavorable storage conditions is obtained if this in addition to the finely divided solid carrier substance with a pK value of 3.3 to 6.8, it also contains urotropin. This urotropin content in the fungicidal mixture sent can vary from 0.5 to 10% by weight. Such a mixture preferably contains 1 to 5% by weight of urotropine.

In addition to the substances mentioned above, the stable fungicidal mixtures according to the invention can also contain customary wetting agents or dispersants. They can also contain other active ingredients, for example substances with a fungicidal, insecticidal or herbicidal action. The mixtures according to the invention are prepared by adding the mixture components dithiocarbamate and solid carrier substance or solid carrier substance mixture with a pK value of 3.3 to 6.8 and optionally other mixture components such as urotropine, other active ingredients, wetting agents and dispersants, advantageously in finely divided form Form, mixed intensively with each other and optionally finely ground. The mixture can be carried out in conventional mixing devices, for example a ribbon mixer. It is advisable to avoid heating the mixture for about 6O ⁰ C at a mixing and eventual grinding process. Depending on the amount and intensity, the mixture components are mixed with one another in the mixing device for about 30 minutes to 3 hours and are then suitable for longer storage.

Typical for inventionsjjeni.ilk · mixtures are about iIr · iniiTiuk ¹ !! Misi hinii'rii Du · I Ii ιΜιΉιιι · .In ·. ■ ·!

Mixing was carried out in such a way that 70% by weight of active ingredient and 13.5% by weight of conventional dispersing agents and Wetting agents and, as the remainder, various carriers or carrier mixtures after intensive mixing be ground in a pin mill. The experiments were carried out with kaolin (a carrier with a pK value of 0.4), silica gel B wind-sighted (a carrier material with a pK value of 6.8), Silica gel K 322 (a carrier with a μΚ value of 3.3), BLP / 3 (a carrier with a pK value greater than 6.8) and with Urotropin (an additive that is also used in mixtures according to the invention may exist). The result of the tests is shown in the following table, with in cases where the value for iso and fso it has not yet been possible to determine which Carbon disulfide content in% by weight of the initial value after 30 weeks of storage is given in brackets is

The active ingredient was mixed precipitation from the ammonia complex of the zinc salt of 1,2-propylenebis-dithiocarbamic acid and the N, N'-poly-1,2-propylene-bis (thiocarbamoyl) disulfide used

70% active ingredient + 11.5% dispersion pK value of + stabilizer / ₈₀ [weeks] / ₅₀ [weeks]

and power supply carrier mixture [% urotropine] 50 ° 40 ° 50 ° 40 °

+ Carrier I + carrier II

18.5% B 22 - 0.4 - *) 12.5% B 22 6.0% Kg.B.w. 3.3 - 10.5% 5.0% 3.3 3 9.0% 4.5% 3.3 5 7.5% 3.5% 3.3 7.5 6.5% B 22 12.0% Kg.B.w. 4.5-6.8 - 5.5% 10.0% 4.5-6.8 3 4.5% 9.0% 4.5-6.8 5 3.5% 7.5% 4.5-6.8 7.5 6.5% B 22 12.0% K 322 3.3 - 5.5% 10.0% 3.3 3 4.5% 9.0% 3.3 5 3.5% 7.5% 3.3 7.5 18.5% BLP / 3 - > 6.8 - *) 12.5% BLP / 3 6.0% K 322 4.5-6.8 - 10.5% 5.0% 4.5-6.8 3 9.0% 4.5% 4.5-6.8 5 7.5% 3.5% 4.5-6.8 7.5 6.5% BLP / 3 12.0% K 322 4.5 - 5.5% 10.0% 4.5 3 4.5% 9.0% 4.5 5 3.5% 7.5% 4.5 7.5

0.25

0.75

20th

B 22 = kaolin B 22.

Kg.B.w. = Silica gel B, wind sighted.

K 322 = silica gel K 322.

*) Examples are not according to the invention. You serve

1.25 15th 2.25 25th 14th (83%) (63%) (83%) 13th (82%) 22nd (82%) 14th (84%) 25th (84%) 1.25 15th 2.25 30th 12th (84%) (60%) (84%) 19th (84%) (65%) (84%) 10 (85%) 29 (85%) 1.25 17th 2.0 (73%) 13th (84%) (70%) (84%) 16 (84%) (68%) (85%) 8th (79%) 23 (79%) 0.25 8th 0.75 18th 0.5 16 1.5 25th 13th 30th (64%) (80%) 9 (84%) 22nd (84%) 18th (91%) 24 (91%) 0.75 13th 1.75 26th 15th 30th (76%) (81%) 11th (86%) 30th (86%) 17th (90%) 27 (90%)

only to illustrate the invention.

Claims (3)

Patent claims: 1. Fungicidal mixture containing a dithiocarbonate as active ingredient and a finely divided, solid Carrier, characterized in that the carrier has a pK value of 3.3 to 6.8 having 2. Mixture according to claim 1, containing silica gel as a carrier. 3. modification of the mixture according to claim 1, characterized in that it has a finely divided, solid carrier with a pK value less than 3.3 or greater than 6.8 and a finely divided, solid Contains carrier with a pK value of 3.3 to 6.8, the pK value of the mixture between 3.3 and 6.8.