Insecticidal Benzoyl Hydrazone Derivatives

The present invention relates to a new class of benzoyl hydrazone derivatives and insecticides containing same. More particularly, the invention relates to a benzoyl hydrazone derivative of the general formula [I] ##STR2## and an insecticide containing as its active ingredient said benzoyl hydrazone derivative.

Recently, a wide variety of synthetic chemicals including organo-phosphorus compounds, carbamates, synthetic pyrethroids, etc. have been developed as agents for controlling various noxions insects including those populating in farm and land (cultivated or non-cultivated) and forestry as well as in residential areas.

We synthesized a group of benzoyl hydrazone derivatives and with investigating their insecticidal activity. As its result, we have found that the benzoyl hydrazone derivatives of the general formula [I] have strong insecticidal activity against various insects as referred to above and they are surprisingly effective even against the insects of organo-phosphorus-susceptible strains. Furthermore, the benzoyl hydrazone derivatives are advantageous in their extremely low toxicity against mammels and fish.

The compounds of the invention are useful to control a variety of insects, specifically including mosquitos (Culex pipiens pallens, Culex pipiens molestus, Aedes aegypti, Aedes togoi, Anopheles sinensis, etc), house fly (Musca domestica), flesh flies, rice crane fly (Tipula aino), rice midge (Chironomus oryzae), soybean pod gall midge (Asphondylia sp.), oriental fruit fly (Dacus dorsalis), melon fly (Dacus cucurbitae), rice leafminer (Hydrellia griscola), rice whorl maggot (Hydrellia sasakii), rice stem maggot (Chlorops oryzae), stone leek leafminer (Liriomyza chinensis), onion maggot (Hylemya antiqua), secdcorn maggot (Hylemya platura), and so on.

Prior to the present invention there are known some compounds which are resembling to the compounds of the present invention. Such known compounds can be defined in reference to the general formula [I] wherein n is zero, R.sub.2 is acetyl, benzoyl, p-nitrobenzoyl or phenyl, and both of R.sub.3 and R.sub.4 are methyl, and they are described in J. Pharm. Soc., Japan 79, 103-104 (1959). However, the prior art literature does disclose merely the process for the production of the compounds, which were found insecticidally weak against mosquitoes and flies. The compounds of the present invention are those obtained first by introducing a particular substituent (R.sub.1).sub.n into the benzoyl portion of the above-referred prior art compounds, thereby to impart surprisingly high insecticidal activity to the parent non-substituted benzoyl compounds.

The compounds of this invention can be prepared in good yield according to any of the following reaction schemes (a), (b) and (c). ##STR3## in which R.sub.1, n, R.sub.2, R.sub.3 and R.sub.4 individually have the same meanings as defined hereinbefore; X is a halogen atom, an alkylsurfuric acid residue or an arylsulfonic acid residue; and Y is a halogen atom. Accordingly, the compounds of the formula [III] can be alkyl halides, acyl halides, dialkylsurfuric acid and arylsulfonic acid esters, which are readily obtainable by the processes which per se have been known in the art. The compounds of the formula [V] are substituted benzoyl halides.

The compounds of the formula [II] are readily obtainable from a nucleically substituted benzoyl hydrazine and an aldehyde or ketone having R.sub.3 and R.sub.4 substituents by hydrazonation in the manner known per se. The compounds of the formula [IV] are also readily obtainable by hydrazonating the hydrazine substituted with R.sub.2 in the same way.

In case of reacting a compound of the formula [II] with a compound of the formula [III] according to the reaction scheme (a) or in case of reacting a compound of the formula [IV] with a compound of the formula [V], a solvent may not be used though it is usually preferable to use an organic solvent. It is also preferable to use the compound of the formula [III] or formula [V] itself as the solvent as the case may be. Suitable solvents to be used include, for instance, hydrocarbons, halogen-substituted hydrocarbons, ethers, esters, ketones, acid amides, alcohols and dimethylsulfoxides. As acid binders, organic amines such as triethylamine and pyridine, or inorganic acid salts such as potassium carbonate are usable.

The reaction can be carried out at room temperature. However, it is preferable to use heating usually. After the reaction has completed, the acid binder salt which separates from the reaction mixture is filtered off and the filtrate is distilled to remove the solvent thereby to obtain the compound of the invention. The compound of the invention are also obtainable by adding an organic solvent such as benzene, chloroform, ether or tetrahydrofuran and water to the reaction mixture, recovering the resulting organic layer and thereafter distillating the solvent therefrom.

The processes for preparing the compounds of the invention by the reaction schemes (a) and (b) are shown in Example 1 and Example 2, respectively. ##STR4## In the above, R.sub.1, n, R.sub.3 and R.sub.4 individually have the same meanings as defined hereinbefore. Therefore, the process of the reaction scheme (c) is applicable to the case where R in the general formula [I] is a lower alkylcarbomoyl group. In the reaction scheme (c), when a compound of the formula [II] is reacted with a compound of the formula [VI], a solvent may not be used; however, it is usually preferable to use a solvent non-reactive with the compound of the formula [VI], for example, an organic solvent such as hydrocarbons, halogen-substituted hydrocarbons, ethers, esters and ketones. Occasionally, the compound of the formula [VI] may be used as a solvent. The reaction can proceed very smoothly by the addition of an organic amine such as triethylamine and pyridine in small amount as a catalyst.

Although the reaction can be carried out satisfactorily at room temperature, heating may be used if necessary. The compound of the invention is obtainable by filtering off the crystals isolated in the reaction mixture or by distilling the solvent used.

Example 3 is to illustrate the preparation of the compound of the invention in accordance with the reaction scheme (c).

10.5 g of 1-p-chlorobenzoyl-2-isopropylidene hydrazine, 5.3 g of triethylamine and 100 ml of tetrahydrofuran were placed in a 200 ml round-bottom flask, and while stirring with ice-water cooling, 3.9 of acetylchloride was dropped gradually. After dropping, the mixture was heated at reflux for one hour so as to complete the reaction. The reaction mixture was cooled to room temperature and the separated salts were filtered off, and then the filtrate was concentrated to obtain yellow brown crystals, which were then recrystallized from a mixed solvent of hexane/acetone to yield 10.4 g (82%) of yellow crystalline 1-p-chlorobenzoyl-1-acetyl-2-isopropylidene hydrazine having a melting point of 73.degree.-74.degree. C.

6.5 g of 1-methoxycarbonyl-2-isopropylidene hydrazine (prepared from methoxycarbonyl hydrazine and acetone), 5.3 g of triethylamine and 100 ml of acetone were placed in a 200 ml round-bottom flask, and while stirring with ice-water cooling, 11.0 g of p-bromobenzoyl chloride was added dropwise. Thereafter, the resulting mixture was stirred at room temperature for one hour to complete the reaction. The reaction mixture was added with 50 ml each of benzene and water. The separated organic layer was taken out by fractionation, dried with anhydrous sodium carbonate and then distilled to remove the solvent. The white crystalline mass thus obtained was recrystallized from a mixed solvent of hexane/acetone to yield 13.6 g (87%) of 1-p-bromobenzoyl-1-methoxycarbonyl-2-isopropylidene hydrazine as white crystals having a melting point of 103.degree.-104.degree. C.

10.5 g of 1-p-chlorobenzoyl-2-isopropylidene hydrazine, 2.9 g of methyl isocyanate and 100 ml of acetone were placed in a 200 ml round-bottom flask, and 3 drops of trimethylamine were added thereto. The mixture was stirred at room temperature for one hour. The separated crystalline mass was recovered to obtain 12.7 g (95%) of 1-p-chlorobenzoyl-1-methylcarbamoyl-2-isopropylidene hydrazine as white crystals having a melting point of 119.degree.-123.degree. C.

Typical compounds of the formula [I] which were prepared in the same manner as in the preceding examples are shown in Table 1. The compound number assigned therein will be referred to in the later-mentioned tests and examples.

In order to use the compounds according to the invention as insecticides, the compounds may be used as they are or may be diluted with a suitable carrier such as water or a solid powder, to which an adjuvant is added. If necessary, adjuvants such as a wetting agent, a spreader, a dispersing agent, an emulsifier, a binder and the like may be added to the mixture for use as various types of preparations such as wettable powders, solutions, emulsions, sols (flowable), dusts, DL(driftless)-type dusts, granules, and fine granules.

In preparing these chemicals, there are used as a liquid carrier water, aromatic hydrocarbons, aliphatic hydrocarbons, alcohols, esters, ketones, acid amides, and highly polar solvents such as dimethylformamide, dimethylsulfoxide and the like; as a solid carrier mineral powders such as clay, talc, kaolin, bentonite, diatomaceous earth, calcium carbonate, silicic acid and the like, and organic powders such as wood meal; and as an adjuvant nonionic, anionic, cationic and amphoteric surface active agents, ligninsulfonic acid or its salts, gums, fatty acid salts, pastes such as of methyl cellulose, and the like.

The preparations such as wettable powders, solutions and emulsions may contain the active ingredient(s) in the amount of 1-95% by weight, usually 2-75% by weight. These preparations are diluted with water to a concentration of 0.0001-10% by weight. Dusts and granules usually contain 0.1-10% by weight of the active ingredient(s). The liquid concentrates such as emulsions and sols (flowable agent) can be used as they are, without dilution.

In using the compound of the invention for insecticidal purposes, it is possible to broaden its applicability by mixing with other insecticides, fungicides, herbicides and plant growth regulants, and is also possible to realize synergistic effects as the case may be. The insecticidial effect of the compound of the invention can be greatly improved by the addition of a synergist such as propenyl butoxide (P.B.), octachlorodipropylether, N-octyl bicycloheptene dicarboximide.

The present invention will be particularly described by way of examples, which should not be construed as limiting the invention thereto. The parts as given in examples are parts by weight.

20 parts of the compound No. 1, 30 parts of dimethyl formamide, 35 parts of xylene and 15 parts of polyoxyethylene alkylarylether were mixed uniformly to obtain an emulsion containing 20% of the active ingredient.

20 parts of the compound No. 2, 5 parts of polyoxyethylene alkylarylether, 3 parts of calcium lignin sulfonate and 72 parts of diatomaceous earth were mixed uniformly to obtain a wettable powder containing 20% of the active ingredient.

3 parts of the compound No. 10, 0.5 part of anhydrous silicic acid, 50 parts of clay and 46.5 parts of talc were mixed uniformly to obtain a dust containing 3% of the active ingredient.

The following experiments are to explain the usefulness of the insecticides which contain the active ingredients according to the present invention.

250 ml of a test liquid of the determined concentration of an emulsion prepared according to the Example 4 was placed in a Petri dish of 9 cm in diameter and 6 cm in height, in which 20 4th-instar-larvae were set free. After allowing stand for 24 hours under the constant temperature of 25.degree. C., the mortality (%) was determined. This experiment was performed three times and the average mortality was calculated. The results were tabulated in Table 2.

In the foregoing table, the comparative chemicals A-D are the compounds described in "J. Pharm. Soc., Japan 79, 103-104 (1959) and, in chemical names, "A" is 1,1-dibenzoyl-2-isopropylidene hydrazine, "B" is 1-benzoyl-1-p-nitrobenzoyl-2-isopropylidene hydrazine, "C" is 1-benzoyl-1-acetyl-2-isopropylidene hydrazine and "D" is 1-benzoyl-1-phenyl-2-isopropylidene hydrazine. "E" is a fungicidal preparation containing 0,0-dimethyl-0-(3-methyl-4-nitrophenyl)phosphorothioate, available from the market under the common name of MEP.

A filter paper was placed on the bottom of a glass Petri-dish having a diameter of 9 cm, to which 1 ml of a test liquid of the determined concentration of an emulsion prepared according to Example 4 was dropped. In this Petri-dish 10 house flies of the Takatsuki strain (Organo-phosphorus-susceptible strain) or of the 3rd Yumenoshima strain (multi-resistant strain) were set free. After allowing to stand for 48 hours under a constant temperature of 25.degree. C., the number of knock down insects was determined to obtain the mortality (%). This experiment was performed three times for one concentration. Average mortality was calculated and the results were tabulated in Table 3.

In the foregoing table, the comparative chemicals A-E are the same compounds as explained hereinbefore, and the comparative chemical F is an insecticide containing 0,0-dimethyl S-(1,2-dicarbethoxyethyl)phosphorothiolo-thioate (Malathon).

A 60 cm-wideditch in a test field was incorporated with fish dregs and then allowed to stand for 22 days, so that egg-laying of Hylemya platura was induced. The fish dregs were covered with soil, and the soil was mixed with a test agent of the determined amount of the emulsion prepared according to Example 4. The soil thus treated was sown with kindey beans (New Edogawa species) and covered with soil. On the 20th day after the treatment, the number of germination and the degree of injury were examined to obtain the control value (%) from the injury index described hereinbelow. The results were tabulated in Table 4.

In the foregoing table, comparative chemicals A-D are the same as those described hereinbefore, and "G" is an insecticide containing 0,0-diethyl-0-(2,4-dichlorophenyl)phosphorothionate (ECP).