Hydroquinone Ethers Having Juvenile Hormone Activity

U.S. Pat. No. 4,061,683 describes compounds of general formula: ##STR1## in which R.sub.1 is hydrogen, halogen, alkyl, vinyl or ethynyl;

R.sub.2 is hydrogen, halogen, methyl or ethyl;

R.sub.3 is hydrogen, methyl or alkoxyl;

R.sub.4 is hydrogen, halogen or methyl;

R.sub.5 is hydrogen or R.sub.3 and R.sub.5 form a carbon-carbon bond or an oxygen bridge;

R.sub.6 is hydrogen or methyl;

R.sub.7 is cyclohexyl or a variously substituted phenyl group;

Y is either a methylene or an oxymethylene bridge; and

m and n are either 0 or 1,

as showing insecticide activity against Orthoptera, Isoptera, Hemiptera, Coleoptera, Lepidoptera, Diptera and Acarina.

Among other compounds (col. 17, No. 30 and col. 19, No. 46) the compound ##STR2## is disclosed.

In U.S. Pat. No. 4,153,731, there are disclosed compounds of the general formula: ##STR3## in which n is 0 or 1;

Z represents oxygen or sulphur;

R.sub.1 represents a substituted phenyl group;

R.sub.2 represents hydrogen, methyl or ethyl; and

R.sub.3 and R.sub.4 each represents hydrogen, methyl, ethyl, methoxy, ethoxy, nitro or halogen.

Such compounds are described as able to control a large number of insects, including Acarididae, Tenebrionidae, etc.

U.S. Pat. No. 4,000,312 and U.S. Pat. No. 4,140,794 describe aliphatic compounds having juvenile hormonal activity and a dichloro- or trichloro-substituted end vinyl group bound to a phenyl or substituted phenyl group. Among them, only those having a trichloromethyl terminal group exhibit acaricidal activity.

One object of the present invention is to provide two new hydroquinone diethers having an acetylenic and halosubstituted terminal group which exhibit both juvenile hormonal and acaricidal activity and unexpectedly high activity against Tenebrio molitor, Aedes Aegypti and Musca domestica.

Another object of the invention is to provide an improved method for fighting infestations due to noxious insects.

Still another object of the invention is that of providing two methods for obtaining such compounds.

These and other objects are achieved by this invention which provides two new hydroquinone diethers of formulae: ##STR4## and which, besides exhibiting acaricide activity, exhibit a complete activity on Tribolium confusum, at 2 p.p.m., Aedes aegypti at 0.02 p.p.m.; on Musca domestica at 20 p.p.m.; and on Tenebrio at doses of 0.02 .gamma. (micrograms, 1.sub./10.spsb.6 g) per insect.

The two new compounds II and III show the following .sup.1 Hnmr spectrum (in CDCl.sub.3).

and may be prepared by reacting the sodium salt of hydroquinone or of phenoxy-phenol with 1,5-dichloro-1-pentine.

Instead of reacting the 1,5-dichloro-1-pentine with the hydroquinone alkali metal salt or with the alkali metal salt of phenoxy-phenol, the hydroquinone alkali metal salt or the alkali metal salt of phenoxy-phenol may be reacted with 1,1,1,5-tetrachloropentane, following by dehydrohalogenation of the reaction product at temperatures of 50.degree.-100.degree. C., preferably at 80.degree. C., in dimethylsulphoxide.

The activity of the compounds of this invention, in comparison with the activity of the compound of formula I hereinabove, has been determined as described in Example 3, infra. The results are summarized in the following Table.

As appears from Table I, the compounds of the present invention are far more active than compound I, the activity of which latter is recognizable only at 20 ppm on Tribolium confusum; at 0.2 ppm on Aedes aegypti; at 100 ppm on Musca domestica and at 0.2 .gamma./ins. on Tenebrio molitor. It is surprising that the substitution of a terminal H atom by a Cl atom can improve the hormonal juvenile activity 10 times or more.

The following examples are given to illustrate the invention in more detail and are not intended to be limiting:

In 100 ml of DMF (dimethylformamide) were dissolved 5 g of hydroquinone and 4.5 g of NaOH and the solution was stirred for 1 hour at room temperature. 14 grams of 1,5-dichloro-1-pentine were dripped into the solution and the mixture was then heated to 60.degree. C. for 6 hours.

At the end, the reaction mixture was cooled down, poured into water and extracted with ethyl ether. The ether extract was then neutralized with diluted HCl, washed with water, anhydrified with Na.sub.2 SO.sub.4, and finally concentrated. The residue was chromatographed on a silica gel colum; by eluting with ether and petroleum ether 95:5, 6 g 1,4-di(5-chloro-4-pentinyloxy)-benzene were obtained having the following characteristics:

m.p.=62.degree. C.; .sup.1 Hn.m.r. spectrum (in CDCl.sub.3); .delta.=1.7-2.7 (8H, complex); 3.97 (4H, t); 6.8 (4H, s).

Two gms of 4-phenyloxy-phenol were dissolved in 10 ml of dimethylsulphoxide and 1.6 g of milled NaOH were added to the solution. The mixture was then stirred for one hour at room temperature, after which 2.5 g. of 1,1,1,5-tetrachloropentane were dripped into the mixture. The mixture was then heated to 60.degree. C. and kept at that temperature for 6 hours.

After 6 hours, the mixture was poured into water, then extracted with ethyl ether. The residue thus obtained, by concentration of the etheric phase, was purified on the chromatographic column as in Example 1. Thereby were obtained 2.1 g. of a compound showing the following .sup.1 Hn.m.r. characteristics (in CDCl.sub.3): .delta.1.7-2.6 (4H, complex): 3.97 (2H, t); 6.7-7.5 (9H, complex).

5 g of wheat meal were uniformly treated with an acetone solution of the product. 24 hours after the treatment, the meal or flour was infested with 22 days old larvae. Survey of the results was made about 45 days later when the insects of the witness group had completed emergence from the cocoons.

5 g of maize meal were uniformly treated with an acetone solution of the product. 24 hours after the treatment, the meal or flour was infested with 21 days old larvae. The survey of the results was made every 3-4 days starting from the first appearance of the adult insects until the end of the emergence from the cocoons in the witness group.

3 cc of an acetone solution of the product were added to 297 cc of tap water into which were successively transferred 25 larvae, four days old, supplying them the suitable food.

Surveyings of the results were made every 2-3 days until the end of the emergence from the cocoons in the witness group.

250 g of artificial nutrient medium were mixed with 5 ml of an acetone solution of the product and then infested with 100 larvae, 2 days old. After 6 days, the pupae in the nutrient medium were collected and kept apart waiting for adults. The results were calculated when all the pupae of the control test (without the substances having juvenile hormonal activity) developed into adults.

0-24 hours aged pupae were treated by topical application on the antepenultimate urosternite with an acetone solution of the products (2 micro liters). A survey of the results was taken after about 9 days when the insects of the witness group completed their emergence from the cocoons.

Eggs--Bean leaves discoids were infested with acari eggs and were then treated by sprinkling on them an aqueous dispersion having a concentration of 1% of the compound under examination. The percent mortality was evaluated as 0 in the untreated leaves discoids.

Adults--Bean leaves discoids were infested with acari adults and successively treated with an aqueous dispersion of 0.1% of the product being tested. The percent mortality was valued 0 for the untreated leaves discoids.

As activity index there was adopted the percentual ratio of dead individuals, misshaped and abnormal individuals with respect to the number of treated individuals, as may be deduced from the following formula: ##EQU1##

The results for hormonal juvenile activity are summarized in Table I; the activity on Tetranychus urticae at 1% dose is the following.