IE51875B1 - Acaricide compounds - Google Patents

Abstract

Hydroquinone diethers possessing prolonged acaricide activity, particularly against mite eggs, of the general formula: in which R represents a C8-11 alkyl group, R<1> represents a hydrogen atom or a group, and R<2> represents a C1-4 alkyl group, a C3-6 cycloalkyl group or a phenyl group.

Description

Price 90p This invention relates to acaricide compounds and in particular to hydroquinone diethers, their preparation, their use as acaricides and to acaricide compositions containing them.

Many products are known to be endowed with an acaricide 5 activity, some being active on the acari eggs, others being effective against neanides or adult acari (mites). The known acaricides belong to various different chemical classes, e.g. organo-phosphoric compounds, halo-aromatic compounds, carbamates and metal-organic compounds. Many of the known acaricide compounds are disclosed in Basis for Selectivity of Acaricides, J C Street, Chapter VIII, page 155, and in Pesticide Selectivity, Dekker Inc., New York (1975) Recently acaricide compounds belonging to the class of alkoxydiphenyl ethers have been disclosed in United States Specification No 4,061,683 and acaricide compounds which are cyclopropancarboxylates have been disclosed in United States Patent Specification No 3,995,054 In spite of the great variety of known acaricide compounds, the acari pest still remains a serious problem because of the damage they inflict upon plants since control of the pests is hampered by the fact that in the course of one season they reproduce several generations, thus facilitating the evolution of acari resistant to the acaricide products used.

According to the present invention there is provided a compound of the general formula: R-0· in which - 2 S1875 R represents an alkyl group having from 8 to 11 carbon atoms, 2 R represents a hydrogen atom or a -C-R group, and R represents an alkyl group having from 1 to 4 carbon atoms, a cycloalkyl having from 3 to 6 carbon atoms or a phenyl group.

The compounds of formula (I) are endowed with a high acaricide activity and are particularly effective against mite eggs in preventing hatching.

The compounds of formula (I) may be prepared according to reactions analogous to those known in the standard procedures of organic chemistry.

A suitable starting material for the synthesis is a monoalkyl ether of hydroquinone of the formula: which may be prepared from hydroquinone, as described, for example, in Journal of Pharmaceuitcal Society of Japan, No 74, page 875 (1954) (Chemical Abstracts 59, 9543 d).

It is possible to prepare the ethers of formula (I) from the compounds of formula (II) by various routes employing reactions common to the standard procedures of organic chemistry. According to one scheme the monoether (II) is converted to the corresponding alkali metal salt (III) by treatment with alkali metal bases: The alkali metal salt (III) is then reacted with an alkynyl halide or tosylate (p-toluene-solphonate) of formula: - 3 51875 Z-(CH2)3-C=CH (IV) in which Z represents Cl, Br or tosyl, to yield a compound of formula: which is then salified on the triple bond utilizing a strong base, e.g. butyl-lithium, The compounds of formula (I) in which iJ is a hydrogen atom are then obtained by condensing the salt (VI) with formaldehyde. The 1 2 compounds of formula (I) in which R is a -C-R group are readily obtained by condensing the compounds of formula (I) in which R1 is a hydrogen atom with an acyl-halide of the formula: Z^C-R2 (VII) I in which Z^ is Cl or Br.

An alternative procedure for the preparation of the intermediates of formula (VI) comprises reacting the alkali-metal salt (III) with 1,1,1,5-tetrachloropentane (CC13-CH2-CH2-CH2-CH2C1) in an inert solvent and in the presence of an excess of a strong base to yield a compound of the formula: R-0· O-CH2-CH2-CH2-C=C-C1 (VIII) - 4 51878 which is then salified by treatment with butyl-lithium in an inert solvent at low temperature.

The above described reaction scheme is one of a number of possible synthesis methods for preparing compounds of formula (I). In an alternative method, the compounds of the formula: are prepared, e.g. using similar techniques to those described above.

The compounds of formula (IX) are treated with alkali metal bases to yield the corresponding alkaline salts which are then condensed with halo derivatives or tosylates of the formula: R - Ζ (X) in which 7 represents halogen or tosyl.

The compounds of formula (I) are endowed with a high acaricide activity and are especially active against mite eggs and also possess a certain activity against adult mites. Moreover, the compounds of formula (I) are endowed with a high residual activity, which is particularly desirable for ovicide compounds, and a very low toxicity for warm-blooded animals and fish, and are characterised by the absence of phytotoxicity.

The main mite-pests of a considerable economical importance due to the damage they inflict upon plants and because of their wide diffusion in all cultivated areas, belong mainly to the Tetranychidae family, genera: Tetranychus (T. urtieae, T. telarlus, T. pacificus, etc.), Panonyehus (P. ulmi, P. ci tri, etc.), Bryobia (B. preatiosa) and Oligonychus. Other species harmful to cultivations are present for instance in the Eriophydae families (genera: Aceria, Eriophyes, Phyllocoptes, Phyllocoptruta, Vasates, etc.), Tarsonemidae (genus: - 5 518 7 5 Hemitarsonemus) and Tenuipalpidae.

The acaricide compounds of fonnula (I) may usefully be used to combat mites alone or in the form of suitable compositions or formulations. In the compositions or formulations, in addition to one or more compounds of formula (I) as an active ingredient, suitable vehicles, solid or liquid, and additives such as surfactants, wetting agents, fixing agents and dispersants may be present.

The compounds may be formulated either as granules or powders, wettable powders, pastes, emulsions, emulsifiable concentrates or solutions according to techniques well known in the preparation of formulations.

It is possible, if required by particular purposes, e.g. the necessity to expand the range of action of the compounds or parti15 cular environment conditions, to include other active substances, e.g. insecticides and/or acaricides, in the compositions. Examples of active ingredients which may be included in such compositions include organo-phosphorous compounds, pyrethroids, nitrophenols, formamidines, ureic derivatives, carbamates, chlorinated hydrocarbons and organo-metal compounds.

The active ingredient in the acaricide composition of the invention may be present in quantities in the range 0.5 to 90% by weight, depending on the type of composition and on the particular treatment for which it is used. The dosage rate of the compositions in the area to be protected against mite infestation, depends on various factors, e.g. the type of composition of formulation, the type of application, the nature and degree of the infestation, the type of cultivation to be protected, the climatic and environmental conditions. Generally, the active ingredient must be distributed - 6 51875 in amounts of from 0.1 and 3 Kg/ha.

The invention will now be illustrated by the following Examples.

Example 1 Preparation of 6-(4-decyloxy-phenoxy)-2-hexinyl alcohol Compound No 1) C10H21° O-CH2-CH2-CH2-CSC-CH2-OH A) Preparation of 5-(4-decyloxy-phenoxy)-l-pentyne C10H21° CH2-CH2-CH2-CSCH A solution of 5g of 4-decyloxy-phenol in 10 ml of dimethylformamide (DMF) was dripped into a suspension of 1.28 g of finely divided KOH in 50 ml of DMF, maintaining the temperature at about 10°C. The reaction mixture was maintained under constant stirring at this temperature for 1 hour, and was then cooled to 0°C. 4.4 g of tosylate (£-toluene-sulphonate) of 4-pentinyl alcohol (CH=C-CH2-CH2-CH2-0H) in 10 ml of DMF were then added to the reaction mixture. On completion of the addition, the temperature was allowed to spontaneously rise to room temperature and the reaction mixture was maintained under stirring overnight, after which it was poured into water and ice and, finally, extracted with ethyl ether. The ethereal phase, after separation, was washed with a 5% NaOH solution and then with water until attaining a neutral pH. After drying the - 7 solvent was eliminated under reduced pressure to yield 5.5 g of the desired product.

]H NMR (CDClg, TMS) δ (ppm) : 0.9 (t, 3H, CHg) 1.1- 2.5 (m, 23H) 3.7- 4.1 (m,4H, CH^-O-CgH^O-CHg) 6.7 (s, 4H, aromatic protons) (s = singlet; t = triplet; m = multiplet or an unresolved complex signal).

B) 9 g of the alkyne obtained as described above were dissolved in 40 ml of anhydrous tetrahydrofurane (THF). The solution was cooled to between -5 and 0°C and then additioned with 17.5 ml of a 1.6 M solution of lithium-butyl in hexane, under stirring and in a nitrogen atmosphere. After a few minutes the solution was additioned with 0.9 g of finely ground anhydrous formaldehyde.

The reaction mixture was heated to 60°C for 3 hours, then poured into water and ice and extracted with ethyl ether. After drying the solvent was removed by distillation under reduced pressure.

The raw product thus obtained was purified by chromatography on a silica gel column (eluent: petroleum ether/ethyi ether in the ratio 2:1). g of 6-(4-decyloxy-phenoxy)-2-hexynyl alcohol were obtained exhibiting a melting point of 66°C.

IR (cm'1): 3350 (v OH), 2240 (v -C5C-); ]H NMR (CDClg, TMS) δ (ppm): 0.9 (t, 3H, CHg) 1.1- 2.6 (m, 20H) 3.7- 4.3 (m, 7H) 6.8 (s, 4H, aromatic protons) - 8 51875 (s = singlet, t = triplet, m = multiplet or an unresolved complex signal).

Example 2 Preparation of 6-(4-decyloxy-phenoxy)-2-hexynyl cyclopropanecarboxylate Compound No 2 g of 6-(4-decyloxy-phenoxy)-2-hexynyl alcohol (obtained as described in Example 1) was dissolved in 10 ml of anhydrous benzene containing 0.4 ml of pyridine. 0.3 g of cyclopropanecarboxylic acid chloride was added to the solution and the reaction mixture was subjected to stirring for 4 hours at room temperature, after which it was poured into water and ice.

The organic phase was separated, washed with water, diluted with hydrochloric acid and saturated bicarbonate solution and finally dried over anhydrous NagSO^. The solvent was removed by distillation at reduced pressure and the residue purified by chromatography on a silica gel column, thereby yielding 1 g of the desired product as a thick oil.

]H NMR (CDC13, TMS) δ (ppm): 0.7-2.6 (m, 28H) 3.7-4.4 (ro, 4H) 4.6 (t, 2H, sC-CH2-0) 6.7 (s, 4H, aromatic protons) (s = singlet, t = triplet, m = multiplet or unresolved complex signal).

Example 3 Adopting an analgous procedure to Example 2, and using the alcohol of Example 1 and acetyl chloride or isobutyryl chloride the following compounds were prepared respectively: 6-(4-decyloxy-phenoxy)-2-henynyl acetate (Compound No 3) ΊΗ NMR (cdci3, TMS 0.9 (t, 3H, CH3) 1.1-2.6 (m, 20H) 2.0 (s, 3H, CH2-C00) 3.7-4.0 (m, 4H, OTg-O-CgH^O-CHg) 4.55 (t, 2H, sc-CH2-0-C0) 6.7 (s, 4H, aromatic protons) 6-(4-decyloxy-phenoxy)-2-hexynyl isobutyrate (Compound No 4) ί (ppm) : 0.9 (t, 3H, CH3) 1.1 (d, 6H, CiTj-CH-CHg) 1.1-2.7 (m, 21H) 3.7-4.0 (m, 4H, Cf^-O-CgH^O-CHg) 4.55 (t, 2H, =C-CH2-0 CO) 25 6.7 (s, 4H, atomatic protons) - 10 51875 (s = singlet, d = doublet, t = triplet, m = multiplet or unresolved complex signal).

Compound Nos 3 and 4 are thick oils at room temperature.

Example 4 Determination of the acaricide activity For the evaluation of the acaricide activity two species of 5 mites (Tetranychus urticae and Panonychus ulmi) were considered as being particularly representative and significant for the extent of damage inflicted to cultivations and for their wide diffusion. (1) Determination of the activity against Tetranychus urticae (eggs) Foliar discs obtained from bean leaves were infested with mite 10 eggs and subsequently treated by besprinkling with a water-acetone solution of the product under examination. The percentage of unhatched eggs was evaluated after 7 days from the day of treatment in comparison with the percentage of unhatched untreated eggs in a control sample. (2) Determination of activity against Panonychus ulmi (eggs) Foliar discs, obtained from apple leaves, were infested with summer eggs of mites, and subsequently treated by besprinkling with a water-acetone solution of the product under examination. The percentage of unhatched eggs was evaluated after 10 days from the date of treatment in comparison with the percentage of unhatched untreated eggs in a control sample.

For comparative purposes the acaricide activity of the following compounds was evaluated: - 11 51875 disclosed in United States Patent Specification No 4,061,683. 5 Compound B: hexadecyl-cyclopropanecarboxylate of the formula: /CH2 disclosed in United States Patent Specification No 3,995,054.

The acaricide activity data of compounds according to the present invention and of the comparison compounds A and B at various dosage rates have been reported in the following Table 1 according to the following scale: = 100% of unhatched mite eggs = 80-99% of unhatched mite eggs 3 = 60-79% of unhatched mite eggs 2 = 40-59% of unhatched mite eggs 1 = 20-39% of unhatched mite eggs 0 = 0-19% of unhatched mite eggs. - 12 51875 Table 1 Acaricide activity Compound No. (Example No) Dose (% a.i.) T. urticae eggs P. ulmi eggs 1 0.1 5 5 (Example 1) 0.01 5 5 0.001 5 4 2 0.1 5 5 (Example 2) 0.01 5 5 0.001 4 4 3 0.1 5 5 (Example 3) 0.01 5 5 0.001 4 4 0.1 5 5 (Example 3) 0.01 5 5 0.001 4 4 A 0.1 5 - (Comparative) 0.01 3 - 0.001 0 B 0.1 5 5 (Comparative) 0.01 4 4 0.001 1 0 - 13 51873 Example 5 Determination of the persistence of acaricide activity The compounds of the present invention possess prolonged acaricide activity which is a particularly desirable property for ovicide compounds. Mite reproduce with several generations during the growing season and the high persistence of activity of the compounds of the invention reduces the number of acaricide treatments required for effective control.

The persistence of acaricide activity has been determined according to the following procedure.

Potted apple trees, 3 years old, were uniformly sprayed with water-acetone dispersions (containing a wetting agent) of the products under test (3 plants each formulation). After drying, the plants were transferred into a greenhouse and maintained there for the period of the test. At time intervals from the treatment, three leaves were picked from each plant and from every leaf a disc (25 mm diameter) was cut off, corresponding to nine discs per treatment. The foliar discs were infested for egg-laying with adult mites deriving from a field-collected resistant strain.

After 24 hours the adult mites were removed and the foliar discs, infested with about a hundred eggs each, were kept in a conditioned room at 24 - 1°C and 65 ί 5% relative humidity for about 10 days (still hatching).

A set of plants was treated with a water-acetone solution and a wetting agent, without any active compound, as a control, and subjected to the above described test. Table 2 reports the data relative to compounds of the invention and to the comparison compounds A and B (see Example 4). - 14 51875 The acaricide activity is expressed in Table 2 according to the same scale used for the data in Table 1.

Table 2 Persistence of acaricide activity against £. ulnti eggs Compound No. (Example No) Dose (% a.i.) Acaricide activity after 3 days (a) 13 days (a) 1 (Example 1) 0.05 5 5 4 (Example 3) 0.05 5 5 A (Comparative) 0.05 3 0 6 (Comparative) 0.05 4 0 (a) Days elapsed from the treatment to infestation. - 15 S1875

Claims (11)

1. A compound of the general formula: R-0 0-CH 2 -CH 2 -CH 2 -CSC-CH 2 -0-R 1 (I) in which R represents an alkyl group having from 8 to il carbon atoms, 1 Z 5 R represents a hydrogen atom or a -C-R group, and R represents an alkyl group having from 1 to 4 carbon atoms, a cycloalkyl having from 3 to 6 carbon atoms or a phenyl group.

2. 6-(4-decyloxy-phenoxy)-2-hexynyl alcohol.

3. 6-(4-decyloxy-phenoxy)-2-hexynyl cyclopropancarboxylate.

4. 6-(4-decy1oxy-phenoxy)-2-hexynyl acetate.

5. 6-(4-decyloxy-phenoxy)-2-hexynyl isobutyrate.

6. A compound as claimed in Claim 1 substantially as herein described with reference to any one of the Examples.

7. A process for the preparation of a compound of the general 1 2 formula (I) in which R, R and R are as defined in Claim 1, in which a compound of the formula: R-0 0-CH 2 -CH 2 -CH 2 -C5CH (V) in which R is as defined in Claim 1, is salified on the terminal triple bond by treatment with a strong 20 base and the salt is condensed with formaldehyde, in order to yield a compound of formula (I), in which R^ is a hydrogen atom, and - 16 51875 optionally the latter is condensed with an acyl chloride of the formula: ι o in which Z is Cl or Br and R is as defined in Claim 1, 1 2 5 to yield a compound of formula (I) in which R is -C-R .

8. A process as claimed in Claim 7 substantially as herein described with reference to any one of the Examples.

9. A method for combatting infestations of mites, which comprises spreading over the infested area an effective amount of 10. One or more of the compounds as claimed in any one of Claims 1 to 6, either alone or in a suitable composition.

10. A method as claimed in Claim 9, in which the active ingredient is applied at a rate of 0.1 to 3Kg/ha.

11. An acaricide composition having as active ingredient one 15 or more compounds as claimed in any one of Claims 1 to 6, together with an inert carrier and optionally a surfactant.