Etherified lactate esters, method for the production thereof and use thereof for enhancing the effect of plant protecting agents

Abstract

The invention relates to etherified lactate esters of formula (I), in which R represents alkyl and RI an alkoxylated alkyl radical and to the use thereof for enhancing the effect of plant protecting agents.

Claims

1. An etherified lactate ester of the formula (I) ##STR00005## wherein R is 2-ethylhexyl or lauryl, and R.sup.1 is an alkoxylated alkyl radical of the formula -(-AO).sub.m—R′, where AO is an ethylene oxide radical (EO), a propylene oxide radial (PO), a butylene oxide radical (BO), or mixtures of ethylene oxide and propylene oxide radicals or mixtures of ethylene oxide and butylene oxide radicals, and m is a number from 2 to 20, R′ is hydrogen.

2. The etherified lactate ester as claimed in claim 1, wherein R is 2-ethylhexyl, or lauryl, R.sup.1 is an alkoxylated alkyl radical of the formula -(-AO).sub.m—R′, where AO is an ethylene oxide radical, a propylene oxide radical, a butylene oxide radical, or mixtures of ethylene oxide and propylene oxide radicals, and m is a number from 2 to 15, R′ is hydrogen.

3. The etherified lactate ester as claimed in claim 1, wherein R is lauryl, R.sup.1 is -(-AO).sub.m—R′, where R′ is hydrogen and -(-AO).sub.m is selected from the group consisting of the following alkoxylate radicals: -(EO).sub.5—(PO).sub.2, -(EO).sub.5—(PO).sub.5, -(EO).sub.8-(PO).sub.2, -(EO).sub.8-(PO).sub.5.

4. The etherified lactate ester as claimed in claim 1, wherein R is ethylhexyl, R.sup.1 is -(-AO).sub.m—R′, where R′ is hydrogen and -(-AO).sub.m is selected from the group consisting of the following alkoxylate radicals: -(EO).sub.2—(PO).sub.2, -(EO).sub.2—(PO).sub.5, -(EO).sub.2—(PO).sub.10, -(EO).sub.2, -(EO).sub.5, -(EO).sub.10, -(EO).sub.15.

5. An etherified lactate ester of the formula (I) ##STR00006## wherein R is 2-ethylhexyl, R.sup.1 is an alkoxylated alkyl radical of the formula -(-AO).sub.m—R′, where AO is an ethylene oxide radical, m is 10, and R′ is hydrogen.

Description

EXAMPLES

Preparation of Inventive Etherified Lactate Esters

(1) Raw Materials Used:

(2) Catalyst for the alkylene oxide addition reaction (DMCcatalyst): Double metal cyanide catalyst, containing zinc hexacyanocobaltate, tert-butanol, and polypropylene glycol with a number-average molecular weight of 1000 g/mol; described in WO-A 01/80994, example 6.

(3) 2-Ethylhexyl lactate, acquired from the company Galactic

(4) Lauryl lactate (PURASOLV LL®), acquired from the company PURAC IRGANOX® 1076: octadecyl 3-(3,5-di-tert-butyl-4-hydroxy-phenyl)propionate. (BASF SE)

Preparation of the Inventive Etherified Lactate Esters Based on Ethylhexyl Lactate

A) 2-ethylhexyl lactate 2PO/2EO

(5) A 2 l laboratory autoclave was charged at 100° C. under a nitrogen atmosphere with 160.0 g (0.792 mol) of 2-ethylhexyl lactate and 0.067 g of DMC catalyst. After 5-fold nitrogen/vacuum exchange between 0.1 and 3.0 bar (absolute), the initial charge was heated to 130° C. Then, at this temperature, with stirring, 91.88 g (1.584 mol) of PO were metered into the reactor over the course of 10 minutes, the pressure in the reactor rising from 0.21 bar (absolute) to 0.54 bar (absolute). After a subsequent reaction time of 25 minutes, the reactor pressure was first adjusted with nitrogen to 2.15 bar (absolute), and subsequently, with stirring at 130° C. 69.68 g (1.584 mol) of EO were metered into the reactor over the course of 10 minutes, the pressure rising from 2.15 bar (absolute) to 2.37 bar (absolute). After a subsequent reaction time of 45 minutes, volatile fractions were removed by heating under reduced pressure at 90° C. for 30 minutes, and the reaction mixture was then cooled to room temperature. The product, lastly, was admixed with 161 mg of IRGANOX® 1076.

(6) The products with compositions of “2-ethylhexyl lactate 2PO/5EO” and “2-ethylhexyl lactate 2PO/10EO” from table 1 were prepared analogously.

B) 2-ethylhexyl lactate 2EO

(7) A 2 l laboratory autoclave was charged at 100° C. under a nitrogen atmosphere with 160.0 g (0.792 mol) of 2-ethylhexyl lactate and 0.007 g of DMC catalyst. After 5-fold nitrogen/vacuum exchange between 0.1 and 3.0 bar (absolute), the initial charge was heated to 130° C., and the reactor pressure was then adjusted with nitrogen to 2.19 bar (absolute). Subsequently with stirring at 130° C., 69.68 g (1.584 mol) of EO were metered into the reactor over the course of 30 minutes, the pressure in the reactor rising from 2.19 bar (absolute) to 2.61 bar (absolute). After a subsequent reaction time of 60 minutes, volatile fractions were removed by heating under reduced pressure at 90° C. for 30 minutes, and the reaction mixture was then cooled to room temperature. The product, lastly, was admixed with 115 mg of IRGANOX® 1076.

(8) The products with compositions of “2-ethylhexyl lactate 5EO”, and “2-ethylhexyl lactate 10EO”, and, “2-ethylhexyl lactate 15EO” from table 1 were prepared analogously.

Preparation of the Inventive Etherified Lactate Esters Based on Lauryl Lactate

C) Lauryl Lactate 5EO/2PO

(9) A 2 l laboratory autoclave was charged under a nitrogen atmosphere with 50 g of PURASOLV LL®. Following addition of 2 mg of 85% strength phosphoric acid, the contents of the reactor were stirred at room temperature for 20 minutes (200 rpm, propeller stirrer). Following addition of 12 mg of DMC catalyst, the contents of the autoclave were heated to 130° C. and subjected to stripping for 30 minutes at this temperature with stirring at 800 rpm under reduced pressure, with an absolute pressure of 100 to 120 Mbar, with introduction of 50 ml of nitrogen per minute via a distributor ring lying beneath the level of the liquid. This distributor ring was then used for metered introduction, likewise at 130° C. with stirring at 800 rpm, of a total of 39.4 g of ethylene oxide over a period of 58 minutes. Following a subsequent reaction time of 17 minutes, 20.8 g of propylene oxide were metered in over a period of 30 minutes at 130° C. with stirring at 800 rpm. After a subsequent reaction time of 22 minutes, the product was heated to remove volatiles for 30 minutes under an absolute pressure of 1 mbar, and then cooled to 80° C. The autoclave was let down with nitrogen to about 1 bar. 50 g of product were discharged from the autoclave and admixed with 30 mg of IRGANOX® 1076.

D) Lauryl Lactate 5EO/5PO

(10) The remaining autoclave content of the product from example C) was heated to 130° C. with stirring (800 rpm), after which a further 17.1 g of propylene oxide were metered in over a period of 34 minutes. After a subsequent reaction time of 30 minutes, the product was heated to remove volatiles for a further 30 minutes under an absolute pressure of 1 mbar. Thereafter the autoclave was let down with nitrogen to about 1 bar, and cooling to 80° C. took place. The product was discharged and admixed with 47 mg of IRGANOX® 1076.

E) Laurel Lactate 8EO/2PO

(11) A 2 l laboratory autoclave was charged under a nitrogen atmosphere with 152.0 g of PURASOLV LL®. Following addition of 11 mg of 85% strength phosphoric acid, the contents of the reactor was stirred at room temperature for 20 minutes (200 rpm, propeller stirrer). Following addition of 56 mg of DMC catalyst, the contents of the autoclave were heated to 130° C. and subjected to stripping for 30 minutes at this temperature with stirring at 800 rpm under reduced pressure, with an absolute pressure of 100 to 120 Mbar, with introduction of 50 ml of nitrogen per minute via a distributor ring lying beneath the level of the liquid. This distributor ring was then used for metered introduction, likewise at 130° C. with stirring at 800 rpm, of a total of 191.7 g of ethylene oxide over a period of 4.03 hours. Following a subsequent reaction time of 10 minutes, 63.2 g of propylene oxide were metered in over a period of 2.0 hours at 130° C. with stirring at 800 rpm. After a subsequent reaction time of 30 minutes, the product was heated to remove volatiles for 30 minutes under an absolute pressure of 1 mbar, and then cooled to 80° C. The autoclave was let down with nitrogen to about 1 bar. 76.9 g of product were discharged from the autoclave and admixed with 41 mg of IRGANOX® 1076.

F) Laurel Lactate 8EO/5PO

(12) The remaining autoclave content of the product from example E) was heated to 130° C. with stirring (800 rpm), after which a further 77.2 g of propylene oxide were metered in over a period of 1.02 hours. After a subsequent reaction time of 26 minutes, the product was heated to remove volatiles for a further 30 minutes under an absolute pressure of 1 mbar. Thereafter the autoclave was let down with nitrogen to about 1 bar, and cooling to 80° C. took place. The product was discharged and admixed with 204 mg of IRGANOX® 1076.

(13) Use

(14) The etherified lactate esters possess very good properties as surfactants. Surfactants find use in sectors including crop protection, as wetters and stickers and also as emulsifiers. Their suitability as wetters is characterized, for example, by the static surface tension; their suitability as stickers by the dynamic surface tension (see Adamson A W 1990. Physical Chemistry of Surfaces. London, Wiley/Berger P D & Berger C H, 1993. Effect of Surfactant Type and Order of Addition on Droplet Size and Dynamic Interfacial Properties. Pesticide formulations and application systems, 13th Vol., Berger, P D, Debisetty, B N, Hall, F R, Eds., American Society for testing and Materials/Knowles, D A 1998. Chemistry and Technology of Agrochemical Formulations, Kluwer Academic Publishers, Dordrecht).

(15) 1) Static Surface Tension in Aqueous Systems

(16) The surface tension value achievable in equilibrium was determined via the Pending Drop Method using a Goniometer (DSA10 Goniometer, Krüss), The table shows the results of the measurements on the etherified lactate esters at 0.3 and 3 g/l at room temperature (20° C.) in comparison to literature values for two frequently used surfactants.

(17) TABLE-US-00001 TABLE 1 Static surface tension (mN/m) Test substance 0.3 g/l 3 g/l Lauryl lactate 5EO/2PO 31.63 31.34 Lauryl lactate 5EO/5PO 31.65 30.14 Lauryl lactate 8EO/2PO 30.76 30.71 Lauryl lactate 8EO/5PO 31.38 31.51 2-Ethylhexyl lactate 2PO/2EO 40.40 29.47 2-Ethylhexyl lactate 2PO/5EO 43.35 28.48 2-Ethylhexyl lactate 2PO/10EO 47.43 36.0 2-Ethylhexyl lactate 2EO 45.34 28.19 2-Ethylhexyl lactate 5EO 48.65 32.61 2-Ethylhexyl lactate 10EO 52.99 35.18 2-Ethylhexyl lactate 15EO 54.33 42.23 Comparative (commercial) Frigate* — 39.6 (tallowamine ethoxylate) Tanemul HOT** 35.2 29.7 (ethylhexyl alkoxylate) *ISK Biosciences, Diegem (Belgium), **Tanatex, Leverkusen (Germany) Here, for example, lauryl lactate 5EO/2PO means that for this etherified lactate ester, in the notation of formula (I), R is lauryl and R1 is —(—AO).sub.m—R′, where AO is a mixture of ethylene oxide (EO) radicals and propylene oxide (PO) radicals, the first EO fraction bonding to the lactate ester group, and the subsequent PO fraction bonding to the EO radicals, m is 5 + 2 = 7, and R′ is hydrogen.
2) Dynamic Surface Tension (Interfacial Activity)

(18) The dynamic surface tension was determined via the bubble pressure method (BP2100, tensiometer, Krüss). With a time span relevant for the spray application of agrochemicals in aqueous dilution (referred to as the surface age in the bubble pressure method) of 200 milliseconds, the value of the dynamic surface tension in [mN/m] correlates with the adherence on difficult-to-wet plants such as barley (cereal). A value of 50 mN/m (at 20-21° C.) produces, relative to water (72.8 mN/m), an improvement in the adherence from “zero adherence” to about 50% (Baur P, Pontzen R 2007. Basic features of plant surface wettability and deposit formation and the impact of adjuvants. In: R E Gaskin ed. Proceeding of the 8th International Symposium on Adjuvants for Agrochemicals. Publisher: International Society for Agrochemical Adjuvants (ISAA), Columbus, Ohio, USA). Table 2 shows that this value is attained by many etherified lactate esters even at the low test concentration in water, and that all of them fall below this value clearly at 3 g/l. The etherified lactate esters are therefore outstandingly suitable for promoting the accommodation of agrochemicals by cereals (with maize, rice, millet), banana, cabbage/oil seed rape, soybean, and other difficult-to-wet crop plants and weed plants. The positive wetting and sticking effects also apply, of course, for other organisms and artificial surfaces and/or technical applications, for the purpose, for instance, of achieving thin coatings on, or cleaning, surfaces.

(19) TABLE-US-00002 TABLE 2 Dynamic surface tension (mN/m) Test substance 0.3 g/l 3 g/l Lauryl lactate 5EO/2PO 51.9 37.4 Lauryl lactate 5EO/5PO 52.7 36.5 Lauryl lactate 8EO/2PO 54.3 37.7 Lauryl lactate 8EO/5PO 50.9 36.2 2-Ethylhexyl lactate 2PO/2EO 47.8 30.7 2-Ethylhexyl lactate 2PO/5EO 50.7 29.6 2-Ethylhexyl lactate 2PO/10EO 54.2 37.4 2-Ethylhexyl lactate 2EO 50.9 26.8 2-Ethylhexyl lactate 5EO 54.4 35.3 2-Ethylhexyl lactate 10EO 56.6 46.6 2-Ethylhexyl lactate 15EO 58.6 48.1 Comparative (commercial) Frigate* — 50.9 (tallowamine ethoxylate) Tanemul HOT** 44.3 31.5 (ethylhexyl alkoxylate) *ISK Biosciences, Diegem (Belgium), **Tanatex, Leverkusen (Germany)
3) Promotion of Penetration of Exemplarily Selected Active Ingredients

(20) Surfactants may also promote the uptake of (active) ingredients through membranes such as skin, films, or the plant cuticle. In the form of what is called “finite dose” application, it is known, for the single administration or application of a solution, cream, gel, etc. to a membrane, that the uptake of active ingredient can be influenced, even after wetting has taken place, by certain adjuvants such as surfactants. This effect is independent of the surfactant activity, is often highly concentration-dependent, and to a very large extent occurs following volatilization of water and any solvents present, as a consequence of interaction with, for example, active ingredient, membrane, and environmental factors. For various surfactants it is observed, following addition onto active ingredient preparations, that the penetration of a particular active ingredient is massively promoted by some surfactants, while others are completely inactive (Cronfeld, P, Lader, K. Baur, P. (2001). Classification of Adjuvants and Adjuvant Blends by Effects on Cuticular Penetration, Pesticide Formulations and Application Systems: Twentieth Volume, ASTM STP 1400, A. K. Viets, R. S. Tann, J. C. Mueninghoff, Edsl, American Society for Testing and Materials, West Conshohocken, Pa. 2001).

(21) The potential, independent of the surfactant activity, to promote the leaf uptake of active agrochemical ingredients was determined in membrane penetration experiments with leaf cuticles of apple. The principle of the method has been published (e.g., WO-A-2005/194844), and only the specifics and methodological deviations are explained below. The leaf cuticles were isolated enzymatically in the manner described from apple leaves from field trees in a commercial pome fruit orchard at Kriftel, to the west of Frankfurt, in 2010. After they had been dried in air, the cuticles were installed into stainless steel diffusion cells. After application to the original top leaf face and evaporation of the test fluid, i.e., of the aqueous preparations of the active ingredients without or with the etherified lactate esters, the diffusion cells were transferred to thermostated blocks and were filled with aqueous liquid. The water used to prepare the aqueous test liquids was local tap water (known composition). At regular intervals, samples were taken and the penetrated fraction of active ingredient was determined, depending on the test system, either by HPLC or by scintillation measurement. In the system with radiolabeled active ingredient (thiacloprid and fluoxastrobin), the aqueous liquid was a phospholipid suspension and the entire quantity was replaced. In the case of the HPLC variant (tebuconazole SC430), only an aliquot was removed. During the experiment, the temperature in the system (block, diffusion cells, liquids, etc.) and the atmospheric humidity over the spray coating on the cuticle was precisely known and monitored. In each of the experiments, the relative humidity was kept consistently at a constant 60%, but the temperature was increased after one day by 10° C., specifically from 20° C. to 30° C. for thiacloprid and tebuconazole, and from 15° C. to 25° C. for fluoxastrobin. Depending on variant (active ingredient x, etherified lactate ester), 7-8 repetitions were set up.

(22) Set out by way of example below is the promotion of uptake by the etherified lactate esters on tank-mix addition to

(23) 1) a solution of the insecticide thiacloprid with 0.5 g/l and 3 g/l etherified lactate ester

(24) 2) to a suspension concentrate of the fungicide tebuconazole with 0.5 g/l and 2 g/l etherified lactate ester

(25) 3) a solution of fungicide fluoxastrobin with 0.5 g/l and 2 g/l etherified lactate ester

(26) in each case in comparison to the systems without addition of the etherified lactate esters.

(27) TABLE-US-00003 TABLE 3 Mean penetration of thiacloprid* in % (n = 4-8) 0.5 g/l 3 g/l Etherified lactate ester 24 h** 48 h*** 24 h** 48 h*** Thiacloprid in solution in <3 <5 <3 <5 acetone/water without etherified lactate ester Lauryl lactate 5EO/2PO 13.6 17.4 63.9 74.5 Lauryl lactate 5EO/5PO 18.6 24.0 67.4 76.3 Lauryl lactate 8EO/2PO 14.5 18.8 73.3 80.4 Lauryl lactate 8EO/5PO 20.5 27.3 72.0 82.9 2-Ethylhexyl lactate 2PO/2EO 11.5 15.1 20.3 23.4 2-Ethylhexyl lactate 2PO/5EO 10.2 12.1 43.2 49.2 2-Ethylhexyl lactate 2PO/10EO 8.1 10.0 36.9 47.2 2-Ethylhexyl lactate 2EO 5.6 6.5 35.5 43.0 2-Ethylhexyl lactate 5EO 12.1 14.1 31.4 39.9 2-Ethylhexyl lactate 10EO 11.0 12.4 39.6 46.2 2-Ethylhexyl lactate 15EO 10.5 14.0 29.9 41.9 *0.2 g/l thiacloprid; **20° C./60% relative humidity (RH); ***30° C./60% RH

(28) TABLE-US-00004 TABLE 4 Mean penetration of tevuconazole* in % (n = 4-8) 0.5 g/l 2 g/l Etherified lactate ester 24 h** 48 h*** 24 h** 48 h*** Tebuconazole SC 430 2.2 20.5 2.2 20.5 without etherified lactate ester Lauryl lactate 5EO/2PO 27.6 75.1 57.1 68.3 Lauryl lactate 5EO/5PO 36.9 36.9 59.0 74.0 Lauryl lactate 8EO/2PO 25.4 62.9 62.9 73.3 Lauryl lactate 8EO/5PO 45.6 75.9 41.0 56.9 2-Ethylhexyl lactate 2PO/2EO 23.2 58.1 27.0 36.5 2-Ethylhexyl lactate 2PO/5EO 31.7 74.8 53.9 71.1 2-Ethylhexyl lactate 2PO/10EO — — 52.2 79.3 2-Ethylhexyl lactate 2EO — — 42.1 42.1 2-Ethylhexyl lactate 5EO — — 45.0 63.8 2-Ethylhexyl lactate 10EO — — 42.3 78.1 2-Ethylhexyl lactate 15EO — — 30.5 53.6 *0.5 g/l tebuconazole; **20° C./60% RH; ***30° C./60% RH

(29) TABLE-US-00005 TABLE 5 Mean penetration of fluoxastrobin* in % (n = 4-8) 0.5 g/l 2 g/l Etherified lactate ester 24 h** 48 h*** 24 h** 48 h*** Fluoxastrobin in solution in 2.6 6.9 2.6 6.9 acetone/water without etherified lactate ester Commercial fluoxastrobin 1.8 7.3 1.8 7.3 EC formulation 3 g/l Lauryl lactate 5EO/2PO 3.3 7.5 12.7 25.6 Lauryl lactate 5EO/5PO 4.7 10.0 12.2 23.1 Lauryl lactate 8EO/2PO 4.0 7.8 11.5 20.4 Lauryl lactate 8EO/5PO 3.9 9.6 6.8 19.8 2-Ethylhexyl lactate 2PO/2EO 12.1 18.6 16.1 26.0 2-Ethylhexyl lactate 2PO/5EO 9.9 16.2 14.4 24.2 2-Ethylhexyl lactate 2PO/10EO 8.9 17.5 13.1 22.1 2-Ethylhexyl lactate 2EO 10.6 35.2 11.4 18.9 2-Ethylhexyl lactate 5EO 8.7 13.9 13.0 21.4 2-Ethylhexyl lactate 10EO 9.7 15.9 16.8 26.9 2-Ethylhexyl lactate 15EO 9.5 14.1 13.4 25.8 *0.3 g/l fluoxastrobin; **15° C./60% RH; ***25° C./60% RH;

(30) Tables 3 to 5 show the outstanding suitability of the etherified lactate esters of the invention, as a function of concentration, for greatly promoting leaf penetration for a variety of active ingredients, active ingredient preparations (solutions in the case of thiacloprid and fluoxastrobin; suspension concentrate in the case of tebuconazole), and environmental factors. The relative independence from the degree of ethoxylation or alkoxylation and from the capacity to promote penetration, and the difference in interfacial activity at the same time, means that the etherified lactate esters are also components of interest for incorporation into agrochemical formulations.

(31) 4) Foam Behavior

(32) The important properties of interface-active substances include the foam behavior, particularly in aqueous systems. Virtually all surfactants foam, and the time to collapse of the foam has to be shortened in the case of critical (highly foaming) surfactants through addition of defoamers to formulation or to aqueous use preparation. The foam behavior of certain of the substances of the invention was characterized, using aqueous solutions at a concentration of 3 g/l, by the foam test of CIPAC Method MT47. The values in the table show the percentage filling with foam in a cylinder over a period of 12 minutes. A value of 100(%), therefore, denotes maximum foam and is obtained, for example, over the entire 12-minute period with lauryl ether sulfates (such as Genapol LRO).

(33) Using the etherified ethylhexyl lactate esters of the invention as an example, the table below shows that the foam behavior of the substances can be classed as very favorable. At the concentration of 3 g/l, which is relatively high, for example, for use in agrochemical aqueous spray mixtures, collapse of the foam is very quick. It is surprising also in the case of the ethoxylated ethylhexyl lactate esters of the invention that only the 5 EO degree of ethoxylation exhibits an initially relatively great foam behavior, whereas higher and lower degrees of ethoxylation produced virtually no foam or none. The comparative is the result with the alkoxylated ethylhexyl lactate esters (mixed EO/PO) of the invention, despite the fact that these are also stronger surfactants (see tables 1 and 2).

(34) TABLE-US-00006 TABLE Percentage foam volume* Etherified lactate ester 10 s 60 s 3 min 12 min Ethylhexyl lactate 2PO/2EO 2 2 0 0 Ethylhexyl lactate 2PO/5EO 25 10 10 10 Ethylhexyl lactate 2PO/10EO 50 10 0 0 2-Ethylhexyl lactate 2EO 5 5 5 5 2-Ethylhexyl lactate 5EO 50 40 20 10 2-Ethylhexyl lactate 10EO 10 5 5 0 2-Ethylhexyl lactate 15EO 0 0 0 0 *CIPAC MT47 foam test with CIPAC D water (342 ppm); concentration of 3 g/l
5) Crop Tolerance

(35) At the concentrations where the significantly promoting effects on wetting and uptake of agrochemicals were found, the tolerance by crops of the etherified lactate esters (lactate ester ethoxylates) was very good.