SA95160148B1 - A fungicidal formulation and method for controlling fungal infections - Google Patents

Abstract

Abstract: It was found that when using the R-enantiomer R of any of the metalaxyl, furaJaxyl or benalaxyl, this leads to a significant increase in the ability of these botanical fungicides to perform biodegradation processes in the soil and a higher activity in the plant compared to the data on the active ingredients. racemic active ingredients. Those fungicidal formulations which exhibit such improved properties include any of these fungicides with an R-enantiomer by weight of more than 70% based on the total amount of active ingredient.

Description

M Y — fungicidal formulation and method for combating fungal infections Full description

Invention background

The present invention relates to a new method of plant protection against bacterial infection by fungal cells using

any of metalaxyl, furalaxyl, or benalaxyl; And cast

It will then be expressed as the active ingredient oI by weight of the coenomers — the R-enantiomer R

oo is greater in each dla than Ve. The invention also relates to compound pesticides used against fungicides

for this purpose.

Metalaxyl is the first commercially available formulation in this class of ingredients

Active compounds that were first called ethyl alanine, and then called acylalanine compounds.

Phenylamide, which has been used as an antimicrobial agent for fungi. 0 The bacterial cells of the fungus include all types of downy mildew which mainly attack

potato and tomato crops; cas Ss nig Ml sugar and tobacco;

vegetables; cabbage; also grapes; rubber; green lawns; and ornamental plants.

It is preferable to use the fungicide ethyl alanine, acylalanine, on plant leaves; where to treat

Leaves and plants germinated with the active ingredient of the pesticide. Some active ingredients Veo are absorbed by the plant; Others remain on the plant and are removed by means

rain or absorbed by the soil when leaves fall on it during maturity. And in use

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Creamy _ on the soil The active ingredient is placed directly on the soil in liquid form or - for example - in the form of granules. The soil is humus or a mixture of sandy and loamy 0 or adsorption 76 to a large degree (loan/clay) and in the case of extended treatment periods as in perennial crops (Jie vineyards from dual) and in crops Typical soils such as potatoes, sugar beets, or green meadows in terms of es AT, the soil may be exposed here to a cumulative load of the fungicide ethyl-alanine-6, and this in turn leads to environmental risks, specifically to groundwater risks. General description of the invention metalaxyl is defined as a methyl ester Jal of N-(2,6 -dimethylphenyl)-N-(methoxyacetyl)-DL-alanine and benalaxyl is defined as a methyl ester L-N N-(2,6-dimethylphenyl)-N-(phenylacetyl)-DL-alanine. 0 As for furalaxyl, sed furalaxyl is the methyl ester of N-(2, 6dimethylphenyl) )-N-(2-furanylcarbonyl)-DL-alanine It is known in specialized books and references that these compounds have varying data from Gan biotransformation. In the reference known as the “Guide to Pesticides” issued in its tenth edition in 1994 by the British Council for Crop Protection, the following information was given about the half-life periods of these products upon hydrolysis (DT) means disappearance period): YAN

Metalaxyl: pHy(”Y+) DT-50 more than yoo day ps: 111 pHs penaxyl: pH 9.25 DT-50 for yoo day Furalaxyl: (2Y+) DT-50: um more than You day pH ° more than as Yoo shows that data. An undesirably high degree of stability in the aqueous medium. Attempts have been made to accelerate the biodegradation behavior by suitable formulations; For example; Through additives that do not harm water, which prevent deeper penetration of the active ingredient in Ay il, which exposes it to sunlight at the surface and to high temperatures. Here, an attempt was made to stand 0 boldly on the other negative property of acylalanine fungicides; Specifically, its high volatility when exposed to sunlight and high temperature. that the volatility of the active ingredient at the soil surface is expected to be equally high; Although this is practically not noticed. All these attempts did not result in any convincing solutions. Once the active ingredient, Vo, is leached by the soil surface or at the top 7 cm layer of soil, the rate of degradation is greatly reduced; Which leads to negative results represented in the weak decomposition of the active ingredients; This is what experts know. Now, quite unexpectedly, he has found that the solution to this problem lies in the active compound acylalanine itself, a compound in which the R-enantiomer degrades faster than the 5-S-enantiomer or any other available active ingredient. In the market, it consists mainly of the 7 racemates mentioned. Since the year 15; It is the period in which this class was known from YAN

M - cal gall It has become common to use the 17 enantiomer R-enantiomer which is the most effective in terms of fungicide (eg 581 500 63-1). As a solution for practical use, specialized journals did not propose from the beginning and during the period of 14 years of research to use the ~ R-enantiomer R of the fungicide ethyl-acylalanine. On the other hand, the difficulties (A) facing Preparation of enantiomers - 8-88 07 in pure form from active substance rich in enantiomers 7 1 R-enantiomer (such as fractional crystallization of the racemate stereospecific synthesis) with no driver or A technical necessity for the oY practitioner to follow this method.However, the deciding factor was that it could not be assumed that dispensing with Lis Vo or partially removing a proportion of the 5-S-enantiomer in the racemates would result in So far, none of the racemates rich in the 2-18 enantiomer or the 5-S-enantiomer of the fungicide ethyl alanine have been marketed. Lady.acylalanine relates to the general environmental situation to find another effective control avalanche against the villous mold fungus (vo fungus germ cells) using the fungicide ethyl acylalanine OT ¢ specifically Jr uC metalalaxy]; The solution to the biodegradation problem proposed here is of fundamental technical importance in agriculture worldwide. It is a standard requirement in crop protection to obtain the optimal effect of an active ingredient at the lowest possible chemical rate while maintaining the lowest level of contamination available. VAN

+ In the field of fungicides ethyl alanine «acylalanine», specifically using metalaxyl, which is the basic material for this pesticide; We can say that the problem of pollution has been eliminated. A better degree of soil biodegradation can be obtained when the content of the enantiomer — R-enantiomer R in the active ingredient is greater than 01/ by weight. © Shar z A summary of the graphics Fig. 1: Shows the degradation rate curves of racemic metalaxyl WR for R-metalaxyl in fresh field soil (loam-clay) iad under laboratory conditions. appearance ? : shows the degradation rate curves of racemic metalaxyl and 1-1-R-metalaxyl in fresh field soil (Je) under laboratory conditions. Detailed Description The present invention presents a pathologically preferred method for the control and prevention of infection with fungal bacterium cells of ell) using the R-enantiomer R of metalaxyl or benalaxyl : 3 CH, Cpls C —COOCH, / N wa / CH, CH, . \ R Vo . VAY

R-metalaxyl JS¥Us—R) OCH; = R ( CHs = R (8-benalaxyl) or using the 7 R-enantiomer R of furalaxyl H to CH; 4 C—COOCH ; J \ 1 lm CH, © 0 In both cases, there is at least 70 7 (percentage by weight) of a certain quantity relative to the total active ingredient.In this text, as will be shown later, the racemates The racemates of the three active ingredients metalaxyl, benalaxyl, and furalaxyl are expressed as the active ingredient 1. With the increase of the contents of the 1607 R-enantiomer in the active ingredient, the properties of the soil with respect to lead oy degradation are improved. bacteriophage, a method in which the active ingredient used contains the R-enantiomer R in a proportion greater than #8 on a weight basis, namely a proportion of 797 and preferably greater than 757 on a total quantity of active ingredient. The manner in which active ingredient 1,10 mainly contains the coenimers — R-enantiomers R and is completely free of the covalents — 86 S-enantiomers (which is no more than (7) YAN

M - In addition, the present invention deals with a formulation to combat fungus bacterial cells in which the content of R-enantiomers R in active ingredient 1 exceeds 970 on the basis of weight. amount of active ingredient. Specifically, the present invention is characterized by a composition in which the content of the -R Reenantiomer © in the active ingredient is greater than 79517 on a weight basis; The present invention also has a formulation in which the active ingredient is essentially devoid of the -5 S-enantiomer (less than 7 on a weight basis). In the aforementioned proportions, it is not taken into account that the technically produced active ingredient contains - in addition to that - small amounts of by-products and intermediates (their ratio ranges approximately from 7-75 on the basis of weight).

0 This invention presents a composition capable of controlling fungal pests from among the bacterial cells of the fungus; It is a lil belonging to the Peronosporales group, especially the plasmopara viticola, in addition to the types of << << phytophthora such as ———— Pythium ¢P infestans, = pathogens and the Qatari species Prima bremia; And fungal species --- Pseudoperonospora and other fungal species.

0 The rate of addition of the composition (by spraying, fogging, or mixing with the soil and the like) ranges between pl ae = 10 of the active substance per lia, based on the weight of the pure assorters - 1 061-8. The active substance used may be furalaxyl or benalaxyl; But it is preferable to be a mit laxel legs 0161. Preferably -R combinations

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R-metalaxyl is highly concentrated (more than 710/7 by weight of the active ingredient)”; As this leads to saving transportation expenses and storage places. In addition, the presence of pathogens on live plants means that the activity shown by the 107 R-enantiomer of active ingredient 1 is many times greater than that of the racemates © and not twice as much activity as expected. The activity may be higher by YoY times, and in certain cases this activity is 100 times higher than the activity of the racemate. Confirmation studies have shown that in the type of active ingredient mentioned for ethyl alanine compounds with the general formula above, the right half of the molecule ( see above) is stable in an upright position relative to the plane of 6,7 = 2,6-dimethylphenyl dimethylphenyl in the crystalline state; Its color is in 0 | solutions when . It is possible to overcome this barrier that prevents rotation around the phenyl-N-axis N = by means of energy, the methylene group to which the substituent group 18 is attached is here at an angle towards de sane this methylene group As shown above in the general formula: (R.

Nyfeler, P.

Huxley, Monograph No. 31, British Crop Protection Conference Publication, Croydon 1985, p. 45 et seq.). \o This means that the remaining substituents in the molecule can change their position relative to the carbon atom © in the alanine methyl ester responsible for the absolute formation. This applies in the same way to the furalaxyl compound to which the ?-furanyl moiety is attached instead of the CHp-R substituent shown by Adle YAN.

S1 Recently, a group of biological studies confirmed in principle the result that the R-enantiomer R isomer is more active as a fungicide compared to the activity of the 5-S-enantiomer isomer. In PHYTOPHTHORA PALMIVORA plants, the two scientists found Fisher. times in the case of the -5 S-enantiomer of the metalaxyl compared to the 7-isomer (R-enantiomer R), while the corresponding EDs for the R-enantiomer R and racemic 8 were in the ratio of about FY : 0, 1 An experienced person can expect here that the activity of a given amount of enantiomers - the R enantiomer - is about twice as much as the amount of 0 racemates; ols concludes that the much lower activity of the 5 S-enantiomer In racemates, it contributes to the role of the -8 S-enantiomer as an inert substance with a non-ionotropic existence.Therefore, separating the racemates from the active component T and using the -R-enantiomer was not an option for the two workers. In this area; Even if only because of the high level of performance of the racemates; Hence, this has not been proposed in specialized references throughout the last nineteen years as a solution to the problem of practical use. Thus, it was hypothesized that in the ready-to-use mode of racemic active ingredient 1 the contribution of the R-enantiomer to activity is correspondingly reduced through the 5-S-enantiomer and through other conformations of the molecule. For example we can imagine YAY here

11- The large number of biochemical receptors are temporarily occupied by the inactive components of the racemates, but are not permanently blocked. Moreover, since the active ingredients 1; specifically metalaxyl and furalaxyl; It has become known for its ability to penetrate the plant; There are other negative effects of these isomers.” These are effects 01 that impeded the rapid penetration of the R-enantiomer R into the plant; which led to increased losses due to volatilization; Which could also play a role. The 18-R-enantiomers of general formula I can be obtained by fractional crystallization of the salt prepared from 7<-(7,>-dimethylphenyl) » -aminopropionic acid (N-(2,6- dimethylphenyl)- © -aminopropionic acid and a light-active base substance containing 0 [2] with subsequent liberation of the light-active conjugate and with esterification with methanol and from the amalgamation of the light-active base substance » - phenyl J Amisen -phenylethylamine His (10 14488) (GRP). In addition, the R-enantiomers R of the active ingredients can also be obtained by activating the evening group as a leaving group in the in situ 10 (+)-1 of lactic acid L(+) lactic acid; or its esters or salts; with a substitution of 1am, Y-methylalanine 2,6-dimethylaniline by terrain recovery. The use of the acid or its salts imposes Here, a subsequent esterification process is performed with methanol, while the use of a lactic acid ester other than the methyl ester requires here a subsequent transesterification process using methanol YAN.

The point of lle 18-metalaxyl R-metalaxyl ranges between a VE0 - a VEY under a pressure of 0.1 "mbar aqtd. The composition of the aforementioned active ingredient is made in the known way to obtain pesticide formulations according to It was described - for example - in 581 500 68311.

01 The compositions are prepared in a known way, i.e.; for example; by close mixing and/or rubbing of active ingredients with diluents such as solvents; carrier materials; And if necessary, active compounds at the surface (surfactant), and the carrier materials and appropriate additives can be in a solid or liquid state, identical to the materials used in the formula work technology (Jie), natural or generated mineral materials.

substances 0 « or solvents; or dispersants » or wetting agents » or tackifiers » or thickeners; Or binders or fertilizers One of the preferred methods of using enantiomers - R-enantiomer R is the one in which this substance is placed on the aerial parts of the cabal) and specifically J for the leafy parts (use by leaves ).

The number of treatment times and the rate of use depend on the biological and climatic conditions of the sick organism. Alternatively, the R-enantiomer R can reach the plant via the soil through the root system (general verb); or by wounding a specific site of the plant with a liquid formula; Or by combining the materials with the soil in a solid form such as granules (using by soil). ‎VAN

1 pm

The compound is used in the form of a pure active ingredient; or preferably as an addition to materials traditionally used in formulations; Then the treatment is carried out in the well-known way to obtain; for example; on emulsion concentrates, ALB spreadable pastes 8, or solutions that can be sprayed or diluted directly; or dilute emulsions or ALG wettable powders or soluble powders or dusts; or granules; Or by containing the composition, for example, in polymeric materials, and the method of use is tested by spraying, atomizing, dusting ¢, scattering, or using a brush; or casting; And also the quality of the fixtures and that

To suit the purposes for which they are intended and also to suit the prevailing circumstances.

0 As a general rule, agricultural chemical formulations include a percentage of active ingredient 1 ranging from 1 to 7194, specifically between + 730 and a percentage of solid or liquid additive ranging from 99.5 to 1, specifically between 99 ,1 to 0 with a percentage of the surfactant ranging from zero to 75, specifically between 1.1 to aXe. Although concentrated formulations are the most preferred as commercially available materials, the consumer

Jello is used, as a general rule, in diluted formulations. Such agrochemical formulations form part of this present invention. The following examples illustrate the invention; As the active substance which; preferably metalaxyl, duralaxyl, or benalaxyl; It better has a high proportion of the enantiomer = mY ( R-enantiomer R (2) by weight in its composition:

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A: M61

Wettable powders Active ingredient Metalaxyl yYo | 741) active ingredient metalaxyl | prevent yvo | Isomorphs - (R-enantiomer R) sodium lignosulfonate [ae] sodium lignosulfonate a sodium lauryl sulfate Jays! 11 mol mol A=V) octylphenol polyethylene glycol ether (ethylene oxide highly-disperse silica dispersion dle silica EE om i The active ingredient is mixed well with the additives; then the mixture is ground well In a suitable mill, dilute it with water to obtain a suspension with (Say and this is JL} and thus obtain powders capable of the required concentration.

DAG \ — Emulsion concentrate 0 Active ingredient mit laxyl Active ingredient metalaxyl 15 coenomers — 710 R (R-enantiomer octylphenol polyethylene glycol ¥ 7 mol © — % ether of ethylene oxide (ethylene oxide Calcium dodecylbenzenesulfonate ether polyglycol of castor oil mol Y'©) Castor oil polyglycol ether of 7.8 ethylene oxide Cyclohexanone Xylene mixture and emulsions that can be used in various concentrations in crop protection can be prepared from this concentrate by diluting it with water. 1.1 R-enantiomer with a ratio of more than 85/) n (con l aaa aa aa) and the ready-to-use dust is obtained by mixing the active ingredient with a carrier, then crushing the mixture in a suitable mill z no

Granules resulting from the extruder granules » M Active ingredient 1 ingredient I 80076 (condenser - R-enantiomer R solution by more than 737) Sodium lignosulfonate Carboxymethylcellulose Kaolin Kaolin The active ingredient is mixed with the additives, then the mixture is ground, wetted with water ¢, after which it is centrifuged and then dried in a stream of air. At i - am I the El! The tet isomer of 7 polyethylene glycol (molecular weight = (V+) for kaolin Qom 7 0 In a blender, the active ingredient that was finely ground is placed on kaolin regularly after wetting the kaolin with polyethylene glycol polyethylene glycol In this way fine granules free from dust are obtained.

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AAM Concentrated components of the suspension Suspension concentrate Active ingredient 1 Active ingredient (Coordinator - Ee R- R dua enantiomer more than 97/) Propylene glycol Propylene glycol Ether Nonylphenol Polyethylene glycol Nonylphenol polyethylene 1 J se©) glycol ether ethylene oxide Sodium lignosulfonate Carboxymethylcellulose Silicone oil (A aqueous emulsion) 7Ye emulsion What is the need and the active ingredient is mixed after grinding it into fine parts with additives, which leads to obtaining a concentrated suspension from which any diluted solution can be prepared as desired by diluting with water.These dilutions can be used to treat live plants and plant propagation materials by spraying or 0 watering or asl) or to protect these plants from infection with microorganisms. diameter (y sal) 5 = 1 cm); With spraying the plant with a mani liquid prepared from the concentrated suspension, either in the two-leaf stage or the three-leaf stage. The following concentrations of the active ingredient are used per dc jana of £ plants in Yoo Kit Kat Compounding 6 mg of the active ingredient / YAY

- 18 liters. These groups are prepared from the rate of dilution in non-mineral water, just before use, to be sprayed on the leaves. In order to prevent the effect of the gaseous phase of the active ingredient on neighboring plants, all plants are separated from each other on the side using plastic sheets kept in the dark for one day at a temperature ranging between 71-7? m with a relative humidity of approx. Then the plants are kept for V days in a photoperiod of debi using artificial daylight under a temperature range of 0-71-77 C and a relative humidity of about 100, followed by an assessment of the degree of infection. Separate the sprays of the two-leaf stage and the three-leaf stage. The following tables show average; Parallel sprinkles at each stage. A- Sprayings in the two-leaf stage (PL. viticola on vines)

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- 18 racemic metalaxyl level of effect 7- metalaxyl and metalaxyl

Level of action of R-metalaxyl and racemic metalaxyl. Leaf injury ge Active Ingredient Dose mg 1 Active Ingredient Per Liter Zero Yoo R-metalaxyl —-R Zero “6 A Zero Zero 1 ¢ Y

VA ON ay oY 97 a 7 meee zero Yoo racemic metalaxyl racemic metaxyl F “zero

Ya Xe

Y.A. 3

A.Y

Ve "4 av OY 47 Cet does not play an effective role in racemic infection with racemic metalaxyl, although metalaxyl is mg of active ingredient / liter and does not play any role in 10 foliar purposes at a concentration of less than 0 ‎

- No process at a concentration of less than 710 mg of active ingredient / liter, the activity of enantiomeric R-metalaxy!l *-metalaxy!l is better than concentrations diluted to “mg of active ingredient per liter.” In the case of spraying with the SON leaf stage the differences here are more pronounced as shown in Table-B. B- Sprays in the ternary leaf stage against B. 1.108 on vines: Level of effect – R-metalaxyl and racemic metalaxyl Active ingredient Dosage mg of | Foliar infestation Active ingredient per / 1 liter ~R metalaxyl You R-metalaxyl zero “woo” zero Y 0 zero 1 zero Y zero “0 zero YA oY a” q 7 1 Se adsorbed group Yoo racemic metalaxyl zero 0 1 zero 1 of Ao 1 An X 1 11 Y and 0 5 AY Ce YAN

Y \ — — although no bacterial activity was shown with racemic metalaxyl at a concentration of 1 mg active ingredient per liter (or lower) and only at a concentration of 0 " mg of active ingredient / liter ', the activity of YR asylase 1 of the two isomers of R-metalaxyl 056 is about 100 times a at a concentration in the range of aa.. in mg ms active ingredient / liter.. = decomposition Soil active ingredients: EXAMPLE - 1 Degradation behavior of racemic metalacyl and ©1-metalaxyl R-metalaxyl in moderately ALE soil: two JS groups were treated including A samples from biologically active soil ( silt, loam, Joam ¢ 0 loam: eV, loam: 94.7 ; sand: YY A; organic carbon: 771: ¢ ¢ V,V=pH biomass : patio) of microbial carbon per 1,001 g of soil; Origin: (Valais, Switzerland “Les Evouettes”) This treatment was carried out in parallel using racemic metalaxyl or ~R Rometalaxyl metallaxyl, respectively, in each case inside an acetonic solution. \o The rate of addition was 0 + mg / kg of the soil sample, which is a rate corresponding to 0 + kg / ha (mg/kg). Evaluation of results in repeated treatment after zero 1015 oY "day. YAN

— Y Y - : results 1

R-metalaxyl and racemic metalaxyl decomposition rate of racemic metalaxyl, Y = table. New soil (silt/loam) in laboratory conditions ie in R-metalaxyl 1-racemic additive R-metalaxyl racemic time 1 7 (metalaxyl additive)

Tn a ees | Uncle 1 to TT Tem ae vey LL var v.14 th Decomposition Equations 0

Metalaxyl racemate: C¢ = 86.66%. (-0.0644%%t)

DT-50 = 1n2/0.0644; DT-90 = 1n10/0.0644

R-metalaxyl: Cc. = 95.9% o (= 0.1776%*t)

DT-50 = 1n2/0.01776; DT-9 0 = 1nl10/0.1776 (Appendix). 1- The decomposition curves are shown in Figure 0.

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—YY-

These results allowed the calculation of decomposition times:

Meet Laxel Racemic | 1-Metalaxyl R-metalaxyl metalaxyl

DT-50 (70 hydrolysis) 0 A day 85 day Dro (142 0) Example Y

Degradation behavior of racemic metalaxyl and 18-R-metalaxyl in soil

0 sandy:

Two groups were treated, each with 01 samples of biologically active soil (ro) sible 711 Ei ah; sand: m8; Organic carbon: 1.,6? = Ph 4; Biomass: 1*mg of microbial carbon per 100g of soil; Origin: (Valais, Switzerland «Collombey] Processing was carried out in parallel with racemic metalaxyl or ©-metalaxyl

R-metalaxyl \ respectively in each case inside a 0 acetone solution, and the rate of addition was mg/kg of the Ay ill sample, which is a rate corresponding to 0 2 kg/ha “mg/kg,” and here an evaluation was made. The results are in repeated treatment after 0 1/2 ya day. YAY

p -

Results :

Schedule ? Degradation rate of racemic metalaxyl and R-metalaxyl in a fresh soil sample (sandy soil) under laboratory conditions.

time metalaxyl racemic UR racemic laxyl R-metalaxyl additive metalaxyl additive (7) (7) |e ha em TT Te a ssa ee A a aa ssk a a |sama ae © fst YAN decomposition equations

— Y c rac. Metalaxyl: Ct = *3.67 and . (-0.05006*t) ; DT-30 = 1n 2/0.05006; DT-90 = In 10/0.5006 R-Metalaxyl: Ct = 98.53% 0 (-0.08548*t) ; DT-50 = In 2/0.08548; DT-90 = 1n 10/0.08548 The decomposition curves are shown in the form -? (Appendix). These results allowed the calculation of degradation times. 5 Racemic metalaxyl | 8-Metalaxyl

R-metalaxyl racemic metalaxyl oo (solved) 121) D5 dissolved) 4 0( 0

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Claims (1)

71 - Elements of protection 1 1 - Fungicide formulation that degrades better in soil; It mainly includes the pesticide “_ fungal metalaxyl, which combats infection with fungal bacterial cells, in which un V has the enantiomer content = R-enantiomer R in the active ingredient § 701 on the basis of weight » in association with a carrier Carrier material suitable for this © Active ingredient .active ingredient R; In which the content of isomers increases -1 — 7? - Composition 0 in claimant 1 based on weight. 7Ae for active ingredient in active ingredient R-enantiomer ~~ Y 1? - The composition ht in the protection element - ? ; In which the content of the R-enantiomer RY in the active ingredient is more than 797 on a weight basis. R and in which the content of the isomers increases - “FF - protection element 3 composition ? - Composition 1 for 997 based on weight. active ingredient in the active ingredient R-enantiomer ¥ and in which the active ingredient is cE - A composition A composition - > 1 . The S-enantiomer is largely free of isomers -? active ingredient ¥ Except 1 - - 1 1 - the composition in the claim = 10 where the content of active ingredient Y in the composition is greater than 771 by weight. 1 “a - Compound which is largely devoid of the -5 S-enantiomer and selects from Tris CH, Tttumn 32 / \ C—O 7 CH rd . 1 % R 8 where R is OCH; YAN