FR2509295A1 - DERIVATIVES OF 2,4-HEXADIENOIC ACID AND ITS USE AS HERBICIDE AND REGULATOR OF PLANT GROWTH - Google Patents

Abstract

THE PRESENT INVENTION RELATES TO COMPOUNDS OF THE GENERAL FORMULA: (CF DRAWING IN BOPI) IN THIS FORMULA: R IS A HYDROGEN ATOM OR A RADICAL METHYL; Y IS AN ATOM OF OXYGEN OR AN ATOM OF DIVALENT SULFUR; R IS AN OR, SR OR (R) GROUP; R IS AN ATOM OF HYDROGEN, OR A RADICAL ALKYL CONTAINING 1 TO 4ATOMS OF CARBON, CYCLOALKYL CONTAINING 3 TO 6ATOMS OF CARBON, ALKENYL CONTAINING 2 TO 4ATOMS OF CARBON, ALKYNYL CONSISTING OF 2 TO 4ATOMS OF CARBON, BENZYLE OR CARBON PHASE; AR IS A RADICAL PHENYL, PYRIDYL, NAPHTYL, QUINOLINE, PHENOXYPHENYL OR PYRIDYLOXY-PHENYL, THESE GROUPS BEING POSSIBLE SUBSTITUTED BY ONE OR MORE SUBSTITUTES CONSISTING OF HALOGEN ATOMS, INCLUDING 4 ALKBYL ALKOMEN, COMPRESSING 1 ALKBYLE 4, ALKOMEN 4 COMBINATION OF 1 A XOMEN 4 CARBON, NITRO, CYANO, TRIFLUOROMETHYL, ACETOXY, ACETAMIDO AND METHOXYCARBONYL. THE USE OF THESE COMPOUNDS AS REGULATORS OF PLANT GROWTH AND DESTRUCTION OF PEST PLANTS.

Description

DERIVATIVES OF 2,4-HEXADIENOIC ACID AND ITS EMPLOYMENT

  WHICH HERBICIDE AND REGULATOR OF PLANT GROWTH.

  The subject of the present invention is new destructive agents.

  weed, based on hexadienoates, and more particularly on derivatives of mono- or disubstituted 2,4-hexadienoic acid at position 6, with weed-killing activity and activity. growth regulator

Plant.

  The present invention furthermore relates to the use, for the purpose of

  protection of agricultural plants from infesting plants,

  mentioned above and their use as regulators of

plant growth.

  One of the products used to destroy weeds on

  most commonly used in agriculture is 2,4-dichloroacid

  Phenoxyacetic (Tradename Generic 2,4 D in commerce), whose herbicidal activity was first described by P W Zimmerman

  and A E Hitchcock in the review Contr Boyce Thompson Inst, 12, 321 (1942).

  This compound has excellent herbicidal properties, especially

  in post-emergence treatments.

  2,4 D, however, is a highly volatile compound and this is a serious disadvantage because, during use and after use, this compound can pass into nearby cultures and

damage irreparably.

  In addition, the large use of 2,4 D has facilitated the formation of infesting plants that can withstand its destructive activity

weeds.

  In order to avoid this disadvantage, a large number of chemical compounds

  which have been prepared by synthesis, compounds whose structure derives,

  directly or indirectly from that of 2,4-dichloroacid

  phenoxyacetic. By way of example, mention may be made of naphthoxyacetic derivatives (Belgian Patent No. 774,748, Stauffer), phenoxyphenoxyacetic derivatives.

  (Belgian Patent No. 864,632, Ciba Geigy) and the phenoxy-phenoxycro

  tonic (Belgian Patent No. 871,523, Kumiaii).

  2,4-Dichlorophenoxyacetic acid is also provided with a plant growth regulating activity, but its high phytotoxicity prevents its use in regulating the growth of plants.

plant growth.

  It has been found that certain derivatives of 2,4-hexadienoic acid are provided with a very destructive activity towards plants.

  selective approach to many agrarian cultures as well as an activity

  The present invention relates to compounds of the general formula: ## STR1 ## wherein: R is a hydrogen atom or a methyl radical; Y is an oxygen atom or a divalent sulfur atom; RI is OR 2, SR 2 or N (R 2) 2; R 2 is a hydrogen atom, or an alkyl radical comprising 1 to 4 carbon atoms, cycloalkyl comprises 3 to 6 carbon atoms, alkenyl comprises 2 to 4 carbon atoms, alkynyl comprises 2 to 4 carbon atoms, phenyl or benzyl; Ar is phenyl, pyridyl, naphthyl, quinoline, or phenoxy-phenyl or pyridyloxyphenyl, these groups being

  optionally substituted with one or more substituents selected

  in the group consisting of halogen atoms, alkyl groups having 1 to 4 carbon atoms or alkoxyl having 1 to 4 carbon atoms, nitro, cyano, trifluoromethyl, acetoxy-, acetamido and methoxycarbonyl

  The compounds of the general formula (I) have a character des-

  tractor (herbicide) and a growth regulator activity.

  plants and are used with great advantage in agriculture.

  The preparation of the aforementioned compounds is carried out with

  commonly used in organic chemistry One possible method of synthesis is to condense an alkaline salt of the formula: Ar YM (M (II) (wherein MO is the cation of an alkali metal, and Ar and Y have the meanings indicated in FIG. part of formula (I) above) with an alkyl ester of formula R

1

CH = CH CH = CH C OR 2 (III)

He O

  (wherein R 2 is a lower alkyl radical, R is a hydrogen atom,

  or a methyl radical and X is a chlorine, bromine or

diode).

  The aforementioned reaction leads to the production of the compounds of formula

  (1) wherein R 1 is a group OR 2, and R 2 is an alkyl radical

(residue of an ester).

  From the compounds thus prepared, according to the conventional method, it is possible to prepare other compounds of formula (I). For example, by hydrolysis, it is possible to prepare the carboxylic acids (RI = OH), which can be converted to the corresponding acyl halides

  and reacted with the appropriate alcohols, thiols or amines,

  to lead to compounds of formula (I) in which R 1 = OR 2, Sr 2

or N (R 2) 2 respectively.

  The condensation between salt (II) and ester (III) is generally

  carried out under an atmosphere of an inert gas and in a polar solvent.

  After stirring for a few hours at a temperature between room temperature and the boiling point of the solvent,

  the reaction is complete and the product is isolated according to standard methods.

used for this purpose.

  The compounds of formula (I) are in the form of solids or liquids having a high boiling point. The alkaline salts of

  (II) are generally known or readily

  from known compounds using conventional techniques.

  Similarly, the compounds of formula (III) in which R = H, are

  known compounds which may be prepared, for example, according to the

  the method described in Helvetica Chimica Acta 29, 1191 (1946) or the

  Journal of Chemical Society, page 866 (1946).

  As far as is known, compounds of formula (III) in

  which R = CH 3, are new compounds.

  Thus, the subject of the present invention is also the compounds of formula: CH 3 I

X CH CH CH CH = CH C OR 2 (IV)

  where X is an atom atom of chlorine, bromine or iodine and,

  R 2 is an alkyl radical comprising 1 to 4 carbon atoms.

  Such compounds are prepared by halogenation and dehydrohalogenation.

  generation of 2,5-heptadienate alkyl, known compound, according to the following reaction scheme:

  CH 3 -CH = CH-CH 2 -CH = CH-COOR 2 + X 2> CH 3 -CH-CH-CH 2 -CH = CH-COOR 2

  The preparation of a compound of formula (IV) is described in the following example: ## STR2 ## ## STR2 ##

  As briefly mentioned above, the compounds of

  mule (I) have a strong herbicidal activity (that is, destructive to

weeds).

  In this class, a number of compounds have an

  more effective against dicotyledonous weeds, while others against monocotyledonous weeds, while giving rise in all cases to high selectivity

useful cultures.

  In addition, these compounds are active both in pre-emergence treatments (i.e., when the infesting plant does not yet have

  emerged from the soil) and for post-emergence treatments.

  The best results are obtained when operating in

post-emergence.

  With regard to the destructive activity of the weeds (herbicide), the most interesting compounds are those having the formula (I) in which R is a hydrogen atom and Ar is a radical

  substituted phenyl, where R is a methyl radical and Ar is a phenoxy radical;

  optionally substituted phenyl or pyridinoxy-phenyl.

  From the point of view of their use in agriculture, the compounds of

  formula (I) are usable as they are or in the form of a suitable composition.

  These compositions contain, in addition to one or more of the compounds

  of the above-mentioned formula (I) acting as active substances and

  vehicles or diluents, solid or liquid, and possibly

  surfactants, emulsifiers and other additives

suitable.

  If necessary, it is possible to add to other compositions

  selected active substances among those belonging to groups of

  greases, plant growth regulators and other herbicides or herbicides. The herbicidal compositions may be in any form

  suitable for use in the agricultural sector

  such as granules, powders, moisturizing powders, concentrates

emulsifiable and the like.

  Depending on the type of composition and the specific use for which they are intended, the active substance may be contained in

  proportions of the order of 1 to 99% by weight.

  The amount of composition or formulation to be distributed in the area to be protected from weeds varies according to a large number

  factors, such as the type of composition or formulation and the effectiveness

  respective active substance it contains, the rate and type of infestation, the type of crop and the factors

climate and environment.

  In all cases, the amount of active substance to be distributed in order to obtain a satisfactory crop protection against the bad

  herbs is between 0.3 and 6 kg / ha.

  The compounds of general formula (I) have, and furthermore, of interest

  important regulating properties of plant growth in many

many areas of application.

  For example, they help the development of flowers, that is to say the development of parthenocarpic fruits without

  no pollution has occurred. Such capacity is generally

  used to promote development in greenhouses

  tomatoes and peppers or the like.

  Another use of plant growth regulators is

  that of stimulating root growth in grafts.

  Another use in which the products of formula (I) are suitable

  is to reduce the fall of the fruits, before the harvest,

  especially for those which produce apple trees.

  The regulating action of plant growth due to the compounds of formula (I) may vary in importance depending on the compound and the type

  However, depending on their class, different

  These plants have been shown to exhibit plant growth regulator activity comparable to that of commercially available plant growth regulators of different classes, and a number of compounds have been shown to be even more potent than the

  commercially known compounds for this particular type of use.

  In the field of application of plant growth regulators, the compounds of formula (I) are employable in the form of emulsifiable concentrates, other formulations being of low interest to the point of

  practical view because of their particular use.

  Emulsifiable concentrates contain, in addition to one or more

  compounds of formula (I) as active substance, also sol-

  Suitable surfactants and surfactants A certain amount of water

  can even be present in concentrates.

  When the treatment is carried out, the concentrate is diluted in water until the required concentration of active substance is obtained, which during treatment is about 10 to 200 mg / l, preferably 100 mg / l, whereas for treatments intended to prevent

  the fall of the fruit, it is about 1 to 10 g / hl, preferably

dre of 3 g / hl.

  Other objects and advantages of the present invention will become apparent

  reading the description given for illustrative but not limited

tative.

EXAMPLE 1

  Preparation of methyl 6-bromo-hepta-2,4-dienoate

  A solution of 50.9 g (0.318 mol) of bromine in 100 ml of CC 14 is added dropwise, in about 2 hours, to a solution of 44, 6 g (0.318 moles) of 2,5-methylheptadienoate (prepared according to the method described by GB Chiusoli in the journal "La Chimica e l'Industria" 41,

  506 (1959) in 50 ml of CC 14 kept under stirring at -15 C.

  Once the reaction is complete, the temperature is allowed to rise spontaneously to room temperature. The reaction mixture is then distilled under vacuum and the fraction whose boiling point is of the order of 100 to 105 ° C.

  under a pressure of 0.1 mm Hg is collected.

  There is thus obtained 65.72 g of methyl 5,6-di-bromo-hept-2-enoate of formula:

CH 3 CH CH CH 2 CH = CH COOCH 3

I I

  Br Br 63.4 g (0.21 moles) of said ester are then dissolved in 200 ml of methyl-ethyl ketone, and 29 g (0.21 moles) of anhydrous potassium carbonate are added to the solution thus obtained. reaction

  is then heated to reflux temperature for about 30 hours.

  The solvent is then removed cold by evaporation under reduced pressure.

  The crude product obtained is diluted again in ethyl ether and then

  washed with water until a neutral pH is obtained.

  It is then made anhydrous and the solvent is removed by evaporation.

  under reduced pressure The crude product is then distilled under high vacuum.

  and the fraction whose boiling point is of the order of 80 ° C. under a pressure of 0.1 mm of mercury is collected. Thus 26.9 g of the desired product are obtained, the result of elemental analyzes and infrared analyzes. are in accordance with the planned structure:

1 H NMR (CD C 13, TMS)

Br

  W 1 CH 3 -CHA-CHB = CH-CHD = CHE-COOCH 3

  6 (ppm): 1.82 (d, 3H, CH 3 -CH) 3.76 (s, 3H, COOCH 3) 4.77 (m, 1H, HA) 5.7-6.8 ( m, 3H, HB + HC + HD) 7.0 -7.7 (m, 1H, HD) (s = singlet, d = doublet, m = multiplet)

EXAMPLE 2

  Preparation of 6- (3 ', 5'-dichloro-2'-pyridinoxy-phenoxy-hepta-2,4-

methyl dienoate.

CH 3

C 1 O CH CH: CH CH = CH COOCH 3

  In a 100 cm 3 flask equipped with a magnetic stirrer and

  held under a nitrogen atmosphere, 3.2 g (0.0125 moles) of sodium 4- (3 ', 5'-dichloro-2'-pyridinoxy) -phenate are introduced; 3.2 g (0.0146 moles) of methyl 6-bromo-2,4-heptadienoate;

cm 3 of methanol.

  The reaction mixture is then stirred for 2 hours at a temperature of

  The methanol is then evaporated at room temperature and the residue is diluted again in ethyl ether. The ethereal solution is washed with a dilute aqueous solution of sodium hydroxide and then with water until the reaction is complete. to obtain a neutral pH By evaporation of the solvent, it is possible to obtain 3.4 g of the desired product which is crystallized

  in petroleum ether (melting point = 100 ° C.).

  The physical properties that are determined on the product obtained are as follows:

1 H NMR (CDCl 3, TMS)

ci CH 3

  C 1 O O CH CH = CHC CHD = CHE COOCH 3

  8 (ppm): 1.45 (d, 3H, CH CH) 3.72 (s, 3H, COOCH 3) 4.85 (m, 1H, HA) 5.64-6.62 (m, 3H, HC + HD + HE) 6.7 -8 (m, 7H, aromatic protons + HB) {s = singlet, d = doublet, m = multiplet}

EXAMPLE 3

  Preparation of Methyl 6- (3-trifluoromethylphenoxy) -hexa-2,4-dienoate In a 100 ml flask provided with a reflux condenser and a magnetic stirrer, and maintained under a nitrogen atmosphere, 3.6 g (0.02 mol) of sodium trifluoromethyl-phenate; 4.2 g (0.02 moles) of methyl 6-bromo-hexa-2,4-dienoate;

ml of methanol.

  The reaction mixture is stirred under a nitrogen atmosphere during

  3 hours at a temperature of 35 C.

  The methanol is then evaporated and the residue is diluted again in ethyl ether. The ethereal solution is washed with water and then rendered

TABLE i

Compounds of formula (I) R

Ar y CH -

CH = CH CH = CH

  C Omss Ar Jy R RI Physical state at ambient temperature i c O HC OCH 3 solid (PF <(2) = 1151 C) 2 Cl OH OCH 3 solid PF = 67-680 C) 3 H 3 COH OCH-3 solid PF 61-630 C) 4 Br O c HO CH 3 solid (P 72-740 C) Cl OCH 3 solid (P 1000 C) 6 Cl H OCH 3 solid (P 1000 C)

________ CH 3

  7 02 N 05 H OCH 3 solid P 1420 C) C R il o) LM. "I) 1 TABLE 1 (cont.) 8 (3) O H OCH 3 liquid (P Eb = 900 ° C at 0.05 mm Hg)

C F 3 _ _ _ _ _ __ _ _ _

Solid (P = 110-1150 ° C)

  _________ 1: CH 3 F__ _ _ __ _ __ _ _

  : 0 H OH solid = 140-150 C with decomposition

  HSC OH OCH 3 solid (mp = 75-80 ° C.) 12 C 11 SH OCH 3 liquid (P Eb = 150-1550 ° C. under 0.1 mm of mercury) 13 H 3 CS HOCH 3 liquid (P B = 1401450 C at 0, 1 mm Hg) 14 F 3 COH OCH 3 solid (mp = 62-640 ° C) OH OCH 3 solid (mp = 74-76 ° C.) CD I 'A% O' 16 H 3 COCOH OCH solid (P = 100, C) II- <DF 1 7 OH OCH 3 so 1 i of (PF = 114, C) 18 O OH OH OCH 3 solid (P = 50-55, C)

N F

  H 3 C-O OH OCP 3 sol (mp = 78 ° C) HCl OH -VCH 3 solid (P = 55 ° C) F 21 H 3 c OH OH solid (P = 155-160 ° C) - < : OB-r F 22 H 3 C NN OH OCH 3 solid (mp = 155, C) Ln solid FOH OCH 3 CD (P = 48-520 ° C)% OF TABLEA-U 1 (cont.) Ci 24 OH OCH 3 solid (PF 100-103-C)

(P 105-110-C).

  c-OE 7 cl F 26 O H OCH 3 solid (P 60-65-C) F

H 3 C-C-NH

  Solid OCH 3 (mp 162-166-C) liquid (4) 1 N-NMR (5) (Spp) 28 Cl (CH 3 OCH 3 O.D. 1.52 (d, 3H); 3.84 (s) , 3H), 4.97 (m, 1H), 9-6.68 (m, 3H), 6.78-7.98 (m, 9H) liquid (4) 29H 3 C - OCH 3 = 1.42 (d, 3H), 2.23 (s, 3H), 3.65 (s, 3H), 4.95 (m, 1H NMR (CDCl3):? 1H); 5.66-6.3 (m, 3H); 6.5-7.4 (m, 9H) TABLE 1 (cont'd) ## STR1 ## % O Ln TABLE 1 (cont'd) liquid (4) O CH 3 OCH 3 1 H NMR (6 ppm) F 3 CO 1.47 (d, 3H) 3.7 (s, 3H); , 8 (m, 1H), 55-6.42 (m, 3H), 6.68-7.78 (m, 9H) liquid (4) 1H-NMR (S, ppm) 31 <T 3 H (CH 3 OCH 3) 1.48 (d, 3H) 3.76 (s 3H) 4.91 (m, 1H) / <5.77-6.66 (m, 3H) 6.77-7.66 (m, 9H) CF 3 liquid (4) 1 H-NMR (6 ppm) 32 Cl -O 3 OCH 3 OCH 3 1.42 (d, 3H) 2.2 (s 3H), 3.68 (s 3H), 4.76 (m, 1H), 5.64-6.37 (m, 3H), CH 3 6.52-7; , 53 (m, 8 H) Cl 33 (6) C- 4 O CH, OCH 3 solid (mp = 100-103 C) Legend for Table 1 (1) The data resulting from the elemental analysis and the spe analysis infrared ctroscopic and NMR

  compound are in agreement with the planned structures.

  (2) The melting points mentioned in Table 1 are not corrected.

  (3) The preparation of compound No. 8 is described in Example 3.

  (4) This compound decomposes during heating preceding distillation.

  (5) The 1H-NMR spectrum provided in Table 1 was obtained using as a C 13 CD solvent.

  as internal reference TMS; S = singlet, d = doublet, m = multiplet.

  (6) The preparation of compound 33 is described in Example 2.

  for each and as anhydrous Na 2 SO 4 is then evaporated. The solvent is then evaporated. The residue is distilled under a high vacuum and the fraction whose boiling point is

  of the order of 90 at a pressure of 0.05 mm Hg is collected.

  3.4 g of the desired product are thus obtained. This product has the following physical properties:

1 H NMR (CD C 13, TMS)

  3 (ppmn): 3.8 (s, 3H, CH 3) 4.8 (d, 2H, CH 2), 9- (CH 3) 6.8 (m, 3H, HB + HC + HD) 7-7.8 (mni, 5H, HA + aromatic protons) {s = singlet, d = doublet, mni = multiplet}

EXAMPLE 4

  A number of representative compounds of the general formula

  (I) are shown in Table 1.

  The compounds shown in Table 1 are prepared according to a method similar to that described by Examples 2 and 3 The compounds mentioned in Table 1, in which R 1 = OH are prepared from the corresponding compounds in which R 1 = OCH 3, using

  hydrolysis according to conventional techniques.

EXAMPLE 5

  Determination of the herbicide activity (destructive of weeds) Pots are prepared with an upper diameter of 10 cm and a height of 10 cm containing a sandy soil in which one of the following plants is planted in each pot: Monocotyledons Echinocloa crusgalli (A ) Avena fatua (B) Alopecurus myosuroides (C) Sorghum spp (D) Setaria glauca (E) Digitaria sanguinalis (F) Panichum dichotomiflorum (L) Festuca pratensis (L) Bromus sterilis (L) Lolium italicum (L) Dactilis glomerata (K) ) Dicotyledons: Stellaria media (L) Ipomea purpurea (M) Vigna sinensis (N) Convolvolus sepium (0) Solanumn nigrum (P) Amaranthus retroflexus (Q) Chenopodium album (R) Rumex acetosella (S) Veronica persica (T) In each pot, is brought water in sufficient quantity to ensure good germination of plants The pots are divided into three

  The first group is not treated with a herbicide and is

  read as a control The second group is treated a day later

  planting, using a hydro-acetonic dispersion (20% in volume / vol-

  lume) compounds according to the present invention, in order to evaluate the ac-

  The third group is treated 15 days after planting (that is, when the plants, depending on the species, have

  height between 5 and 10 cm) using a hydrofluoric dispersion

  acetone (20% by volume / volume) of the compounds according to the invention, in order to evaluate the herbicidal activity in post-emergence treatment. All the pots are kept under observation in an enclosure conditioned at temperatures between 15 and 24, under 70% relative humidity, 12 hour photoperiod, 2,000 lux light intensity All

  two days, the pots are uniformly sprayed with water first.

  careful to moisten only the soil so as to ensure a humi-

  sufficient for the good development of the plants 28 days after the treatment, the vegetative state of the plants is determined and the corresponding evaluations are expressed according to a scale of values between 0 (growth equal to that of the control) and 4 (full stop of growth or destruction of the plant) The results obtained are

  recorded in Tables 2 and 3.

EXAMPLE 6

  Selectivity vis-à-vis useful cultures in post-emergence The compounds according to the invention are tested to determine their phyto-toxicity vis-à-vis agricultural crops is carried out according to a similar method to that described in Example 5 in operating in post-emergence, the damage due to phyto-toxicity is evaluated on the following useful plants: wheat (A ') beet (B') cucumber (C ') parsley (D') celery (E ') fennel (F') pea (G ') tomato (H') carrot (I ') The damage due to phyto-toxicity is expressed using the same scale of values as that used in Example 5 for

  herbicidal activity, the values being between O (growth equivalent

  to that of the witness) and 4 (complete cessation of growth or

  truction of the plant) The results obtained are recorded in the table.

next 4.

TABLE 2

  Herbicide activity during pre-emergence at the indicated doses.

TABLE 4

Phytotoxicity on culture

useful at the indicated doses.

  Compound dose of weed substance

No active -

  (see tab 1) (kg / ha) A C D E F H I J M N

2 6 3

8 6 4 3

9 6 4

6 4

2 3 4 3 3 4 4 3 3

  Compound dose of useful plant substance NO active (cf tab 1) (kg / ha) A 'B' C 'D' E 'F' G'l H 'I'

* 28 4 O O O 00 O

4 1 O 1 0 1

TABLE 3

  Herbicide activity in post-emergence at the indicated doses.

  Compounds no Dose in substance Weeds (see Table 1) active (kg / ha) A B C D E F G H I J K L M N O P Q R S T

I 6 2 4 4

I 4 44 4

2 6 3 4 4

1 4 _________ 3 4 4 4 4

4 6 4 4

i 3 42 4 4

6 6 4 3 4 4

1 3 43 3 3

8 6 3 4 4 4

i 4 42 44

9 6 4 4 4 4

2 4 3 4 4 4

6 4 4 4

2 3 4 4 4 3

18 6 3 4

28 2 4 4 43 4 4

44 41 4

  F- = ru 4-q "O o rd i Oo L. 4 4 4 1 3

4 4 4

EXAMPLE 7

  Test carried out on tomatoes Marmande tomato plants, grown in greenhouses at a temperature of 18 to 21 ° C, are

  transplanted into pots with a diameter of 35 mm.

  plant growth, the suckers are continuously removed so that the plants have only a central stem When the first bud

  gave three or four flowers, we sprayed the

  hydro-acetonic solution (20% by volume of acetone) containing a hu-

  the product is tested at a concentration of 100 ppm.

  is repeated again 7 days after this first treatment Twelve

  days after this second treatment, the fruits are picked and weighed.

  For verification purposes, a group of tomato plants is cultivated

  similar and is only treated with the hydro-acetonic solution without

  a plant growth regulating agent is added.

  The results of the tests, expressed as average weight, of fruits, are recorded in Table 5 below. These results given below

  unequivocally show that the products of the general formula

  (1) are provided with a development activity (setting) Moreover, their activity is comparable, or even in some cases

  greater than that of naphthoxyacetic acid, a growth regulator

  commercially available plants used for the development of

tomatoes in greenhouses.

TABLE 5

  Developpment of tomato flowers.

  Compound No. Average weight of fruit (see Table 1) (g)

1 40.42

2 52.86

9 48.02

18 41.87

23 50.19

26 41, -53

  e-NOA (1) 45.37 control 17.68 (2) Legend for Table 5:

  (1) S-NOA = e-naphthoxyacetic acid, phyto-growth regulator

  sold in the shops; (2) 17.68 g = average fruit weight of untreated plants

  using plant growth regulators.

EXAMPLE 8

  Fruit drop prevention tests Potted potato plants grown in greenhouses are sprayed with hydro-acetone dispersions (20% acetone by volume) containing the test product at a concentration of 30 ppm Three days after treatment, 20 leaves of each of the trees are cut, each of the stems remaining attached to the branches After an additional 11 days since treatment, the percentage of stems that come off is determined by the exercise of a slight manual pressure. of a witness, an anal-

  logue is performed on apple trees treated only with solutions

  hydro-acetonetics without the addition of plant growth regulators.

  The results of the tests, expressed as a percentage of fallen stems, are

  recorded in the following table 6.

TABLE 6

  Action on preventing the fall of apple leaves.

  Of course, the invention is not limited to the modes of

  described and represented and it is likely to have many variations

  accessible to the person skilled in the art, without leaving the mind

of the invention -

  Composite N O Percentage of stems of fallen leaves (cf Table 1) (%)

1 O

6 6.4

9 25.6

23 14.3

witness 67.5

Claims (9)

CLAIM $   1. As new industrial products, the compounds of   general mule: R I Ar Y CH CH = CH CH = CH C RI (I) I O   wherein: R is a hydrogen atom or a methyl radical; Y is an oxygen atom or a divalent sulfur atom; R 1 is OR 2, SR 2 or N (R 2) 2; R 2 is a hydrogen atom, or an alkyl radical comprising 1 to 4 carbon atoms, cycloalkyl comprising 3 to 6 carbon atoms, alkenyl comprising 2 to 4 carbon atoms, alkynyl comprising 2 to 4 carbon atoms, phenyl or benzyl;   Ar is phenyl, pyridyl, naphthyl, quinoline, phenoxy-   phenyl or pyridyloxy-phenyl, these groups being optionally substituted by one or more substituents consisting of halogen atoms, alkyl groups comprising 1 to 4 carbon atoms,   alkoxyl having 1 to 4 carbon atoms, nitro, cyano, tri-   fluoromethyl, acetoxy, acetamido and methoxycarbonyl.   2. Compounds according to claim 1, characterized in that RI   is a group OR 2 and R 2 is a hydrogen atom or a methyl group.   3. Process for the preparation of the compounds according to claim 1, in which R 1 is a group OR 2 and R 2 is a hydrogen atom or an alkyl group comprising 1 to 4 carbon atoms, characterized in that an alkaline salt of formula: Ar YM (II) (in which M G is a cation of an alkali metal, Ar and Y have the same meanings as above).   is reacted under an atmosphere of an inert gas, in a polar solvent and at temperatures between room temperature and the boiling point of the solvent, with an ester of the formula: R CH = CH CH = CH C OR 2 (III)   Wherein X is a chlorine, bromine or iodine atom; R 2 is an alkyl radical having 1 to 4 carbon atoms; R is a hydrogen atom or a methyl radical; in order to obtain the compounds of formula (I) in which R 2 is an alkyl radical comprising 1 to 4 carbon atoms, then, from these compounds, by hydrolysis, to obtain compounds of formula (I) in the   which R 2 is a hydrogen atom.   4. A method for controlling infestations of mono and di   cotyledons, in pre-emergence or post-emergence, consisting of   in the area to be protected, an effective quantity of one or more of the   poses of the formula (I) either as such or in the form of suitable compositions. 5. Destructive plant composition containing as a   active substance, one or more of the compounds according to the claims   1 to 3, in proportions of between 1 and 99% by weight.   6 Process for promoting the development and training of   useful plant roots or to increase the fruit crop,   whether to treat the plants or a part of these plants by a quantity   effective one or more of the compounds according to any one of the   1 to 3, either as such or in the form of compositions Suitable.   7. Process according to claim 6, applied to the treatment of   development of tomatoes, peppers or the like in greenhouses.   8. The method of claim 6, applied to the treatment against   the fall of the fruits before their harvest.   9 Plant growth regulating compositions containing as active substance one or more of the compounds according to one of   any of claims 1 to 3.