FR2470109A1 - 3-Hydroxybenzoic acid derivs. prodn. - from cresol ester by chlorination and then hydrolysis, useful as herbicide intermediates - Google Patents

Abstract

Prodn. of 3-hydroxybenzoic acid derivs. (A) comprises first reacting cresol esters (I) with gaseous chlorine under free radical conditions to give prods. (II) which are then hydrolysed. X is at least one H or halo. Y is carbon or phosphorus. Z is chloro or trichloromethyl. n is 1-3; m is 0-1 and n+m is 2 (when Y is carbon) or 3 (when Y is phosphorus). Pref. radical conditions are provided by irradiation with light of wavelength 300-500, esp. 360-450, nm or by a labile azo cpd. or peroxide at 0.1-10 wt.% on (I). Pref. chlorination is at 20-200, esp. 80-150, deg.C at 1-5 atmos. chlorine pressure with chlorine:(I) mole ratio 0.1-2, esp. 0.2-0.8 per hr. (A) are intermediates for herbicides and can now be made without using heavy metal catalysts or accelerators.

Description

 The present invention relates to a process for the preparation of meta-hydroxybenzoic acids.

dans laquelle X représente au moins un substituant choisi parmi le groupe comprenant l'hydrogène et les halogènes.For the purposes of the present invention, the term “meta hydroxybenzoic acids” means the compounds of the following general formula

in which X represents at least one substituent chosen from the group comprising hydrogen and halogens.

A number of processes are known in the prior art allowing the preparation of meta-hydroxybenzoic acid of the formula

 Thus, the patent of United States of America 3,094,558 describes the reaction of metasulfobenzolque acid with sodium hydroxide in the presence of water at a temperature of approximately 220 ° C. is then isolated by acidification with a strong mineral acid.

 The yields obtained are of the order of 90% relative to the starting meta-sulfobenzolic acid.

The main drawbacks of such a process are that they use large quantities of sulfuric acid and sodium hydroxide, which gives rise to significant pollution problems and that involve an alkaline fusion, which is very difficult to implement on an industrial scale.
We also know the French patent application 6,931,971 published under the number 2,018,454 which describes a process for preparing m-hydroxybenzoic acid from m-cresol.

According to this process, the m-cresol is acylated with an acylating agent, the m-acyloxytoluene obtained is oxidized by bringing it into contact with molecular oxygen, in the presence of a heavy metal catalyst and an accelerator. suitable for such an oxidation, in a homogeneous liquid phase not exceeding 1300 ° C. and the m-acyloxybenzoic acid obtained is hydrolyzed by heating it with an aqueous solution of a mineral acid or of an alkali.

The main drawbacks of this type of process result from the use of heavy metal catalysts, which poses pollution problems. It is also necessary to use an accelerator in a non-negligible and non-recoverable quantity which will have to be eliminated in order to obtain a pure product. On the other hand, the use of large amounts of solvent affects productivity.

 The Applicant has now discovered a method which overcomes the drawbacks of the prior art.

dans laquelle ::
- X représente au moins un substituant choisi pari le groupe comprenant l'hydrogène et I es halogènes
- Y représente C ou P
-Z représente C1 ou CCl3
- n est un nombre entier égal a 1,2 ou 3
- m est un nombre entier égal ü O ou 1
- n + m étant égal à 2 quand Y représente C et égal à 3 quand Y représente P et en ce que, dans une deuxième étape, on hydrolyse le dérivé trichlorométhylé obtenu de formule

où X, Z, n et m ont la signification précédente pour obtenir l'acide de formule

The subject of the invention is therefore a process for the preparation of m-hydroxybenzoic acids, characterized in that, in a first step, the reaction is carried out, in the presence of a radical chloratiorl initiator capable of creating free radicals of the chlorine gas with a metacresol eStll 'of general formula

in which ::
- X represents at least one substituent chosen pari the group comprising hydrogen and I halogens
- Y represents C or P
-Z represents C1 or CCl3
- n is an integer equal to 1,2 or 3
- m is an integer equal to ü O or 1
- n + m being equal to 2 when Y represents C and equal to 3 when Y represents P and in that, in a second step, the trichloromethylated derivative obtained of formula is hydrolyzed

where X, Z, n and m have the previous meaning to obtain the acid of formula

According to a particular embodiment of the invention, the compounds of formula (I) are used in which
Y = C, n = 1, m = l, Z = Cl and X represents an element chosen from the group comprising H, F and Cl and more particularly H.

 According to another particular mode of the invention, the compounds of formula (I) are used in which Y = C, n = 1, m = 1 1, Z = CC13 and X represents an element chosen from the group comprising H , F and C1 and more particularly H.

où X représente un élément choisi parmi le groupe comprenant
H, F, Cl et plus particulièrement H.According to another particular mode of the invention, the compounds of formula (I) are used in which
Y = C, n = 2, m = 0 i.e. the compounds of formula

where X represents an element chosen from the group comprising
H, F, Cl and more particularly H.

où X représente un élément choisi parmi le groupe comprenant
H, F, C1 et plus particulièrement H.According to another particular embodiment of the invention, the compounds of formula I are used, in which
Y = P, n = 3, m = O i.e. the compounds of formula

where X represents an element chosen from the group comprising
H, F, C1 and more particularly H.

 According to a variant of the invention, the chlorination initiator used in the first step is light of wavelength between about 300 and about 500 nanometers and preferably between 360 and 450 nanometers.

 According to another variant of the invention, the radical chlorination initiator is chosen from the group comprising labile azole compounds and peroxides, and preferably used in an amount of between approximately 0.1 and approximately 10% by weight relative to the metacresol ester of formula (I) used; even more preferably, between 0.1 and 5% by weight are used.

Mention may be made, as an example of a labile azole compound, of azobisisobutyronitrile (AIBN) and as examples of peroxides, benzoyl and lauroyl peroxides.

 The first set'api is preferably carried out at a temperature between approximately 200 C and approximately 2000 C. It is more particularly preferred to operate at a temperature between approximately 800 C and approximately 1500 C.

For a good implementation of the invention, chlorine gas is used at a pressure between about 1 and 5 atmospheres. Chlorine is preferably used in an amount such that the number of moles of chlorine per mole of product loaded per hour is between approximately 0.1 and 2 and more preferably between approximately 0.2 and 0.8.

 The chlorination reaction can be carried out in the presence or in the absence of solvent. In the first case, it is clear that the solvent must be inert under the conditions of the reaction, that is to say non-chlorinable. One can, for example, use as solvent: CCl4. The reaction temperature is then limited by the boiling point of the solvent.

Light of wavelength between 300 nanometers and 500 nanometers can be supplied by high pressure ultraviolet mercury lamps or by fluorescent tubes.

des produits lourds formés lors de la réaction.The mixture obtained at the end of the chlorination step is subjected to conventional distillation to separate the trichloromethylated derivative of formula:

heavy products formed during the reaction.

 This distillation is not imperative, but it is clear to one skilled in the art that it ensures good purity of the final product.

 The second stage, the hydrolysis stage of the trichloromethylated derivative, is preferably carried out at a temperature of between approximately 800 ° C. and approximately 1100 ° C. under atmospheric pressure.

 For a good implementation of the process according to the invention, the amount of water used is preferably between approximately 1 and approximately 5 liters / mole of trichloromethylated derivative.

More preferably, about 2 liters of water / mole is used.

 The water which is used can either be pure water or mother water from the hydrolysis of a previous operation which contains HCl and dissolved m-hydroxybonzoic acid resulting from this hydrolysis, IIICl catalyzing the hydrolysis reaction.

The acid is recovered at the end of the reaction by filtration, washing and drying.

sont préparés selon des procédés bien connus de l'homme de l'art à partir de meta cresol par réaction avec un chlorure d'acide du type

où Y et m ont lasignification précédente.
On peut mettre en oeuvre les composés suivants COC12,

ou POC13. The starting compounds of formula

are prepared according to methods well known to those skilled in the art from meta cresol by reaction with an acid chloride of the type

where Y and m have the previous meaning.
The following compounds can be used COC12,

or POC13.

 The products obtained according to the process of the invention are useful, in particular, as intermediates for the synthesis of compounds having herbicidal activity.

 Other characteristics and advantages of the invention will appear more clearly on reading the examples which follow. These examples should in no way be considered as limiting the invention.

Example ia) Preparation of methyl-3 phenyl chloroformate
540 g (5 moles) of meta are charged into a glass reactor equipped with central stirring, a dropping funnel, a straight condenser connected to a water slaughter column and a dip tube distilled cresol and 2 liters of toluene. Using the dip tube, 5.7 moles (564.3 g) of phosgene are introduced while maintaining the temperature at 309 C. Then 5.4 moles (545.4 g) of triethylamine are introduced over 45 minutes while controlling the temperature around 300 C. After elimination of the toluene and distillation under reduced pressure (Eh18 = 940 C), 3-methylphenyl chloroformate is obtained with a yield of 84% b) Preparation of m-hydroxybenzolque acid
In a glass photochlorination reactor, 941 g (5.52 moles) of 3-methylphenyl chloroformate of formula

 The reaction medium is illuminated using a 75 watt high-pressure mercury vapor lamp, the mixture is heated to 140-1500 ° C. and chlorine gas is added under a pressure of 2 atmospheres at a speed of 0.5 mol. / mole of methyl-3 phenyl chloroformate / h.

The progress of the reaction is monitored by assaying the hydrochloric acid released. When the acid evolution stops after 7 h, the mixture obtained is distilled under reduced pressure (Eb = 1080 C); 1097 g of trichloromethyl-3 phenyl chloroformate of formula is obtained

 The conversion rate of 3-methyl phenyl chloroformate is 100, the yield of 3-chlorophenyl phenyl formate is 72.5%.

 2 liters of distilled water are introduced into a reactor fitted with stirring and surmounted by a straight condenser and a dropping funnel.

 It is brought to the boil and poured in one hour 1 mole (274 g) of 3-trichloromethyl-phenyl chloroformate. It is left for 1 hour under reflux. It is cooled, filtered, washed with 2 times 250 ml of water and dried at 800 ° C. under reduced pressure.

 125 g of 99% pure benzolque bydroxy-3 acd are obtained.

 The yield of> 3-ydroxy benzolic acid is 90.6%.

 In the same reactor, 2 liters of mother liquors from the previous step are introduced. It is brought to the boil and poured in 1 hour 1 mole (274 g) of 3-trichloromethyl-phenyl chloroformate. It is left for 1 hour under reflux, then the procedure is carried out as above. 138 g of 3-hydroxy-benzolic acid at 99 O, ol of purity are then obtained. The yield is 100%.

Example 2 a) Preparation of meta tolyl carbonate
6 moles (648 g) of distilled meta cresol, 888 g of water and 6 moles (240 g) of sodium hydroxide pellets are charged into the reactor used in Example 1a). The mixture is heated to reflux for 30 minutes with stirring.

 After cooling, 1.2 liters of perchlorethylene are added. While maintaining the temperature at 250 ° C., 3 moles (297 9) of phosgene are introduced over 3 hours via a dip tube. At the end of the addition, the reaction mass is bright red, then the mixture is heated at 800 ° C. for 2 hours. After cooling and decanting, the organic phase is washed with 250 ml of cold 2N sodium hydroxide then with water until pH- 7. By cooling to -20 C, 552 g of metatolyl carbonate is recovered which has crystallized (yield ~ 76 %).

et 3,5 litres de tétrachlorure de carbone. On chauffe à reflux eton éclaire la réaction à l'aide d'une lampe à vapeur de mercure haute pression de 75 watts. On ajoute du chlore gazeux sous une pression de 2 atmosphères à une vitesse de 1 mole/mole de carbonate de meta tolyle/h. On suit l'avancement de la réactison par dosage de l'acide chlorhydrique libéré.Lorsque le dégagement d'acide s'arrète au bout de 16 h, on élimine le tetrachlorure de carbone par distillation et on récupère un produit pateux qui correspond à la formule

L'hexachloro α, α, α, α', α', α' carbonate de méta tolyle n'est pas purifié et est utilisé tel quel pour la réaction d'hydrolyse.b) Preparation of 3-hydroxy benzoic acid
419 g (1.73 mole) of meta tolyl carbonate of the formula are introduced into a glass photochlorination reactor

and 3.5 liters of carbon tetrachloride. The mixture is heated to reflux and the reaction is lit using a 75 watt high pressure mercury vapor lamp. Chlorine gas is added under a pressure of 2 atmospheres at a rate of 1 mole / mole of meta tolyl carbonate / h. The progress of the reaction is monitored by assaying the hydrochloric acid released. When the evolution of acid stops after 16 h, the carbon tetrachloride is removed by distillation and a pasty product is obtained which corresponds to the formula

Hexachloro α,α,α,α',α',α' meta tolyl carbonate is not purified and is used as such for the hydrolysis reaction.

 300 ml of a 20% by weight sulfuric acid solution are introduced into a reactor fitted with stirring and surmounted by a straight condenser. 48 g of hexachloro α, α, α, eG, (, C, meta tolyl carbonate are added and the mixture is refluxed for 3 hours. The mixture is cooled, filtered and washed with twice 250 ml of water. water and dried at 800 C under reduced pressure.

 18 g of 99% pure 3-hydroxy benzoic acid are obtained.

Example 3 a) Preparation of 3-methylphenyl trichloroacetate
324 g (3 moles) of distilled metacresol are charged into a glass reactor fitted with a stirrer, a straight condenser and a dropping funnel. The mixture is heated to 1500 ° C. and 582% (3.2 moles) of trichloroacetyl chloride are introduced over 3 hours. Then left for 1 hour at 1500 C. By distillation under reduced pressure (Eb = 1060 C), the trichlora is obtained
3 3-methylphenyl acetate with a yield of 82.7%.

b) Preparation of 3-hydroxybenzoic acid
629 g (2.47 moles) of 3-methylphenyl trichloroacetate of formula

The reaction is illuminated using a 75 watt high pressure mercury vapor lamp, heated to 130 - 1400 C and chlorine gas is added at a pressure of 2 atmospheres at a rate of 0.8 moleXmole of 3-methylphenyl trichloroacetate / h. The progress of the reaction is monitored by assaying the hydrochloric acid released. When the release of hydrochloric acid stops after 6 hours, the mixture obtained is distilled under reduced pressure (Eblo = 1700 C), 698 g of 3-trichloromethylphenyl trichloracetate of formula

The conversion rate of 3-methylphenyl trichloracetate is 100%; the yield of 3-trichloromethyl-phenyl trichloracetate is 79.2%.

 700 ml of distilled water and 178.5 g (0.5 mol) of trichloromethyl-3-phenyl trichloracetate are charged into a reactor fitted with stirring and surmounted by a straight refrigerant.

It is brought to the boil for 2 hours and after cooling, the precipitate obtained is filtered, washed with 2 times 250 ml of water and dried at 800 C under reduced pressure.

 52.5 g of 3-hydroxy benzoic acid with 98% purity are obtained.

The yield of 3-hydroxy benzoic acid is 76%.

Example 4 a) Preparation of tri-meta cresyl phosphate
3 moles (324 g) of distilled metacresol, 3.3 moles (260 g) of pyridine and 275 ml of carbonate are charged into a glass reactor fitted with a stirrer, a straight condenser and a dropping funnel. benzene. While maintaining the temperature between 15 and 200 ° C., l mole (153 D) of phosphorus oxychloride is introduced over 2 hours. Then heated for 1 hour under reflux.

After cooling and decanting, the benzene is removed under reduced pressure. 342 g of tri-metacresyS phosphate are thus recovered.

b) Preparation of 3-hydroxybenzoic acid
342 g (0.93 mole) of tri-metacresylphosphate of formula is introduced into a glass photochlorination reactor

The reaction is illuminated using a 75 watt high pressure mercury vapor lamp, heated to 130 - 1400 ° C and chlorine gas is added at a pressure of 2 atmospheres at a rate of 0.8 mole / mole of tri-meta cresyl phosphate / h. The progress of the reaction is monitored by assaying the hydrochloric acid released. When the evolution of hydrochloric acid stops after 10 hours, 570 g of tris phosphate (3-trichloromethyl-phenyl) of formula

500 ml of distilled water and 67.5 g (0.1 mole) of tris phosphate (3-trichloromethyl-phenyl) are charged into a stirred reactor topped with a straight condenser. It is brought to the boil for 10 hours and after cooling, the precipitate obtained is filtered, washed with water and dried under reduced pressure. 2 g of 3-hydroxybenzoic acid are obtained.

Claims (22)

 1) Process for the preparation of m-hydroxybenzoic diacids, characterized in that, in a first step, reacting in the presence of a radical chlorination initiator, capable of creating free radicals, chlorine gas with an ester of metacresol of formula general

 in which X represents at least one substituent chosen from the group comprising hydrogen and halogens, Y represents C or P, Z represents Cl or CCl3, n is an integer equal to 1, 2 or 3, m is an integer equal to O or 1, n + m being equal to 2 when Y represents C and equal to 3 when Y represents P and in that in a second step, the trichloromethylated derivative obtained of formula is hydrolyzed

 or X, Y, Z, n and m have the previous meaning to get  the acid of formula

 2) Method according to claim 1 characterized in that a compound of formula I is used in which Y = C, n = l, m = 1, Z = Cl and X is chosen from the group comprising H, F and Cl.  3) Method according to claim 2 characterized in that X represents H.  4) Process according to claim 1 characterized in that a compound of formula I is used in which Y = C, n = 1, m = 1, Z = CCl3 and X is chosen from the group comprising H, F and Cl.  5) Method according to claim 4 characterized in that X represents 11. 6) Process according to claim 1 characterized in that a compound of formula I is used in which Y = C, n = 2, m = O and X is chosen from the group comprising H, F and Cl.  7) Method according to claim 6 characterized in that X represents H.  8) Process according to claim 1 characterized in that a compound of formula I is used in which Y = P, n = 3, m = O and X is chosen from the group comprising H, F and Cl.  9) Method according to claim 8 characterized in that X represents He.  10) Method according to claim 1 characterized in that the radical chlorination initiator used in the first step is light of wavelength between about 300 and about 500 nanometers.  11) Method according to claim 10 characterized in that the wavelength is between about 360 and about 450 nanometers.  12) Process according to claim 1 characterized in that the radical chlorination initiator used in the first step is a peroxide chosen from the group comprising labile azole compounds and peroxides. 13) A method according to claim 12 characterized in that the peroxide is used in an amount between about 0.1 and about 10% by weight relative to the ester of formula I engaged.  14) Method according to claim 1 characterized in that the first step is carried out at a temperature between about 200 C and about 2000 C  15) Method according to claim 14 characterized in that the temperature is between about 800 C and about 1500 C.  16) A method according to claim l characterized in that the chlorine gas is under a pressure between about l and 5 atmospheres.  17) A method according to claim l characterized in that chlorine is used in an amount such that the number of moles of chlorine per mole of meta cresol ester and per hour is between about 0.1 and about 2.  18) A method according to claim 17 characterized in that the number of moles of chlorine per mole of meta cresol ester per hour is between about 0.2 and about 0.8.  19) Process according to any one of claims 1 to 18 characterized in that a solvent is used in the first step.  20) Process according to claim 19 characterized in that the solvent is carbon tetrachloride.  21) Method according to claim l characterized in that the second step, the step of hydrolysis of the trichloromethylated derivative is carried out at a temperature between about 800 C and about 1100 C under atmospheric pressure.  22) Method according to claim l characterized in that the amount of water used in the second step is between about l and about 5 liters of water per mole of trichloromethylated derivative.