WO1996038400A1 - Method for preparing a meta-dihydroxylated aromatic compound - Google Patents

Abstract

A method for preparing a meta-dihydroxylated aromatic compound, and more particularly for preparing resorcin or 1,3-diphenol is described. The preparation of a meta-dihydroxylated aromatic acid as an intermediate is also described. The method for preparing a meta-dihydroxylated aromatic compound includes the steps of successively or simultaneously hydroxylating and decarboxylating an aromatic compound bearing one or more carboxylic and/or carboxylate groups and, on either side, in the ortho position, a hydroxyl group and a hydrogen atom.

Description

 PROCESS FOR THE PREPARATION OF AN AROMATIC COMPOUND

META-DIHYDROXYLE.

The subject of the present invention is a process for the preparation of a meta-dihydroxy aromatic compound.

The invention relates more particularly to the preparation of resorcinol or 1, 3-diphenol.

The invention also relates to the preparation of a meta-dihydroxylated aromatic acid as an intermediate product.

Several methods for preparing resorcinol are described in the literature [KIRK-OTHMER - Encyclopedia of Chemical Technology 12, p 48, 3rd edition]. Thus, one can mention the preparation of resorcinol by disulfonation of benzene followed by an alkaline fusion. The disadvantage from which this process suffers is that it produces sodium sulphate in large quantities, which poses pollution problems, in particular those of aqueous effuents.

Another access route to resorcin is a hydroperoxidation process for m-diisopropylbenzene. The process comprises two stages: an air oxidation of the m-diisopropylbenzene to the corresponding dihydroperoxide then a separation of the m-diisopropylbenzene from the oxidation products and the excess of m-diisopropylbenzene is recycled. This process co-produces acetone in large quantities and the economic interest of the process is based on the market demand for acetone. Furthermore, it should be noted the presence of products secondary to oxidation.

The present invention provides a new method for overcoming the aforementioned drawbacks.

li has now been found and this is what constitutes the object of the present invention, a process for the preparation of a meta-dihydroxylated aromatic compound characterized in that it consists in subjecting an aromatic compound carrying at least a carboxylic and / or carboxylate group and, on either side, in the ortho position, a hydroxyl group and a hydrogen atom, at a hydroxylation and decarboxylation stage; said steps being able to take place successively or simultaneously. According to a first variant of the method of the invention, the two steps are carried out successively. Thus, the method of the invention consists in preparing a meta-dihydroxylated aromatic acid, by hydroxylation of an aromatic compound carrying at least one carboxylate group and of a hydroxyl group in the ortho position, then in carrying out the decarboxylation of the compound obtained thus leading to a meta-dihydroxy aromatic compound.

According to a second variant of the invention, the hydroxylation and the decarboxylation are carried out simultaneously starting from an aromatic compound carrying at least one carboxylic group in acid form and from a hydroxyl group in the ortho position.

The starting substrate involved in the process of the invention is any aromatic compound in which the aromatic nucleus carries at least one carboxylic and / or carboxylate group and having, on either side, in the ortho position, a hydroxyl group and a hydrogen atom. In the following description of the present invention, the term "aromatic compound" means the classic notion of aromaticity as defined in the literature, in particular by Jerry MARCH, Advanced Organic Chemistry, 4 ^th edition, John

Wiley and Sons, 1992, pp. 40 and following.

In accordance with the process of the invention, a first hydroxylation reaction of an aromatic compound is carried out which can be represented symbolically by the form

dans laquelle :

in which :

- Z represents one or more substituents, identical or different, - Y represents a hydrogen atom, a metal cation or the rest of a base,

- n is a number less than or equal to 3,

- the ortho position of the COOY group is a hydrogen atom.

The compounds of formula (I) are of salicylic type. The benzene ring can carry one or more substituents on the aromatic ring.

Examples of Z substituents are given below, but this list is not limiting. Any substituent can be present on the cycle as long as it does not interfere with the desired product. As regards the meaning of Y, it is preferably a hydrogen atom. In this case, the COOY group is designated "carboxylic group".

The COOY group is then called "carboxylate group" when Y represents a metallic cation in particular of the group la, Ma or Ib of the periodic table of the elements, an ammonium radical or a primary, secondary or tertiary amino group.

For the definition of the elements, reference is made below to the Periodic Table of the Elements published in the Bulletin of the Chemical Society of France, n ° 1 (1966).

Among the metal cations, Y preferably represents a metal from group la of the periodic table, namely an alkali metal and, preferably, sodium and potassium; a metal of group IIa, that is to say an alkaline earth metal and more particularly, magnesium, calcium or barium; a group Ib metal, copper.

The process of the invention applies more particularly to aromatic compounds of formula (I) in which:

- n is a number less than or equal to 3, preferably equal to 0, 1 or 2,

- Y represents a hydrogen atom, sodium or potassium, - the radical (s) Z represent one of the following atoms or groups:

. a hydrogen atom,

. an alkyl radical, linear or branched, having from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl,. a linear or branched alkoxy radical having from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms such as the methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy radicals,

. a nitro group,

. a halogen atom, preferably a fluorine, chlorine or bromine atom,. a trifluoromethyl radical.

The process of the invention applies more particularly to aromatic compounds of formula (I) in which n is equal to 0 or 1, the group Z represents an alkyl or alkoxy radical having from 1 to 4 carbon atoms.

By way of illustration of compounds corresponding to formula (I), there may be mentioned:

- 2-hydroxybenzoic acid (salicylic acid)

- 3-methylsalicylic acid

- 4-methylsalicylic acid - 5-methylsalicylic acid

- 3-methoxysalicylic acid

- 4-methoxysalicylic acid

- 5-methoxysalicylic acid - 3-nitrosalicylic acid

- 3,5-diiodosalicylic acid.

The aromatic compound preferably chosen is salicylic acid. According to the first step of the process of the invention, the hydroxylation of the aromatic compound of formula (I) is carried out in acid form or in salified form. A first embodiment of the invention consists in reacting said compound with an oxidant which is a copper compound.

Another embodiment of the invention is to bring said compound of formula (I) into contact with molecular oxygen or a gas containing it, in the presence of an effective amount of copper and / or of a compound copper. In this case, the copper and / or the copper compound is used in catalytic amounts.

Copper compounds are known products. These are generally all the organic or inorganic compounds of copper I or copper II, but the copper II compounds are chosen when they are used, alone, as oxidants.

As a non-limiting example, copper compound, cuprous bromide, cupric bromide, cuprous iodide, cuprous chloride, cupric chloride, basic copper carbonate II, cuprous nitrate, cupric nitrate, cuprous sulfate, cupric sulfate, cuprous sulfite, cuprous oxide, cupric hydroxide, cuprous acetate, cupric acetate, cupric trifluoromethylsulfonate, copper salicylate I, copper salicylate II, p- copper hydroxybenzoate I, copper p-hydroxybenzoate II, copper benzoate I, copper benzoate II, copper methylate I, copper methylate II, chloro-copper methylate A mixture of copper compounds can be used.

Among said compounds, acetates, salicylates, copper benzoates and cupric chloride are preferred.

The amount of copper compound used in the process of the invention can vary widely, depending on the variant used. Thus, when the copper compound is used as a reagent, the compound to copper / compound molar ratio of formula (I) is from 100% to 500% and, preferably, around 200%. PCÏYFR96 / 00814

5

When using a copper catalyst, the molar ratio of catalyst to copper / compound of formula (I) is from 0.01% to 10% and preferably from 2% to 5%.

The hydroxylation reaction can be carried out in an aqueous medium or in an organic medium.

The solvent used must at least partially but preferably completely dissolve the starting substrate.

Examples of solvents which are entirely suitable for the present invention are given below: water,

- monalcohols or diols, preferably aliphatic or arylaliphatic and more preferably, methanol, ethanol, propanol, isopropanol, butanol, β-phenylethyl alcohol, ethylene glycol, diethylene glycol, propylene glycol , glycerol; - Aliphatic carboxylic acids, preferably acetic acid, propionic acid, butyric acid, isobutyric acid, pentanoic acid, 2-methylbutanoic acid, benzoic acid.

- aliphatic, cycloaliphatic or aromatic ketones preferably, acetone, methyl ethyl ketone, methylisobutyl ketone, - alkyl or arylalkyl esters of carboxylic, aliphatic, cycloaliphatic or aromatic acids, and more preferably, acetate d ethyl, butyl acetate, benzyl salicylate, methyl laurate, methyl benzoate, ethyl citrate,

- Aliphatic or aromatic halogenated hydrocarbons, and one can mention more particularly, perchlorinated hydrocarbons such as in particular tetrachlorethylene, Thexachloroethane; partially chlorinated hydrocarbons such as dichloromethane, chloroform, 1,2-dichloroethane, 1, 1, 1-trichloroethane, 1, 1, 2,2-tetrachloroethane, pentachloroethane, trichlorethylene, 1-chlorobutane, 1,2-dichlorobutane; monochlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2,4-trichlorobenzene or mixtures of different chlorobenzenes; bromoform, bromoethane or 1,2-dibromoethane; monobromobenzene or mixtures of monobromobenzene with one or more dibromobenzenes; 1- bromonaphthalene.

It is also possible to use a mixture of solvents. Among the various solvents, a carboxylic acid is advantageously chosen, preferably acetic acid and / or water. The concentration by weight of the aromatic compound of formula (I) in the medium is usually between 5% and 30%.

According to one of the embodiments of the invention, the reaction is carried out in the presence of molecular oxygen or of a gas containing it. This gas can be pure oxygen or oxygen diluted with an inert gas, for example nitrogen or a rare gas, preferably argon. We can therefore use air.

The amount of oxygen to be used is adapted as a function of the amount of the compound of formula (I), the speed of the reaction and the amount of committed copper catalyst.

The molar ratio between the oxygen to be consumed and the compound of formula (I) is preferably at least 0.5 but is advantageously chosen between 0.5 and 5.0.

The operation is carried out at atmospheric pressure, by bubbling oxygen through the reaction medium, but it is also possible, if necessary, to operate under pressure, preferably between 1 and 20 bar.

The preferred embodiments of the invention consist in carrying out the process of the invention under a stream of air or in bubbling oxygen.

Practically one way of carrying out the process consists in bringing the compound of formula (I) optionally in an organic solvent, with a copper compound or with molecular oxygen or a gas containing it, in the presence of a catalyst with copper in the proportions indicated above.

The mixture is then stirred at the desired temperature until consumption of an amount of oxygen corresponding to that necessary to fix a hydroxyl group.

The reaction temperature to be adopted varies according to the thermal stability of the products to be prepared.

Generally, the reaction is carried out in a temperature range from 100 ° C to 200 ° C, preferably from 100 ° C to 180 ° C.

At the end of the reaction, a meta-dihydroxylated aromatic acid is obtained if one starts from a substrate in salified form, that is to say an aromatic compound carrying at least one hydroxyl group and one carboxylate group.

dans ladite formule (II), Z, n et Y ont la signification donnée précédemment à l'exception de Y qui n'est pas un atome d'hydrogène.Thus, starting from an aromatic compound carrying at least one carboxylate group and a hydroxyl group represented by formula (I), the intermediate product obtained at the end of the hydroxylation step can be symbolized by formula (II ):

in said formula (II), Z, n and Y have the meaning given above with the exception of Y which is not a hydrogen atom.

It should be noted that the OH group which is added to the benzene nucleus is not always found in the OH form. It can also be in esterified form OR which can result from its reaction either with the starting aromatic compound (I) or from the reaction with the copper compound in the case where the latter is used in the form of a carboxylic ligand . The ester function, if existing, is hydrolyzed during the next decarboxylation step and we arrive at compound (II).

According to the first variant of the process of the invention, the hydroxylation step is therefore followed by a step in which a decarboxylation reaction is then carried out.

The intermediate products obtained preferably corresponding to formula (II) optionally having an OH group in esterified form, then undergo decarboxylation.

To do this, the resulting medium is acidified by adding a protonic acid of mineral origin, preferably hydrochloric acid or sulfuric acid or an organic acid such as, for example, acetic acid, trifluromethanesulfonic acid or methanesulfonic acid until a pH less than or equal to 5 is obtained.

The reaction medium is heated to a temperature varying for example between 100 ° C and 220 ° C and, preferably, from 100 ° C to 180 ° C.

The process is preferably carried out under the autogenous pressure of the reactants.

At the end of the reaction, the reaction medium is cooled to between 20 ° C and 80 ° C. An essentially homogeneous medium is obtained consisting of an organic or aqueous phase comprising on the one hand, optionally the starting substrate of formula (I) and on the other hand, the aromatic meta-dihydroxylated compound obtained, preferably corresponding to the formula (III):

dans ladite formule (III), Z et n ont la signification donnée précédemment. On sépare le substrat de départ de formule (I) par extraction à pH contrôlé dans un solvant organique qui peut être choisi parmi ceux qui ont été précités.

in said formula (III), Z and n have the meaning given above. The starting substrate of formula (I) is separated by extraction at a controlled pH in an organic solvent which can be chosen from those which have been mentioned above.

The pH is brought to between 6 and 8 by adding a base, preferably sodium hydroxide, carbonate or sodium bicarbonate. An aqueous phase is obtained comprising the compound of formula (I) in salified form and an organic phase comprising the aromatic meta-dihydroxylated compound preferably corresponding to formula (III).

There is possibly the presence, as a secondary product, of a compound which results from the decarboxylation of the compound of formula (I), which can optionally be used to prepare the aromatic starting compound of formula (I).

The organic and aqueous phases are separated and the aromatic meta-dihydroxylated compound is recovered from the organic phase, according to conventional separation techniques, preferably by distillation or by crystallization. According to the second variant of the process of the invention, there is direct access to the meta-dihydroxylated aromatic compound, in the case where the starting substrate is in acid form (then Y = H).

One then obtains a final product corresponding more particularly to formula (III). It is recovered as previously described.

The process of the invention is particularly well suited for the preparation of resorcinol from salicylic acid.

Examples of the invention are given below. These examples are given by way of illustration and without limitation.

In the examples, the yields mentioned correspond to the following definition: number of moles of salicylic acid transformed Conversion: TTAS =% number of moles of salicylic acid introduced

number of moles of resorcinol formed Yield: RRRESORCIN = ^0o number of moles of salicylic acid introduced Example 1:

0.203 g (1.46 mmol) of salicylic acid, 0.5084 g (2.79 mmol) of copper diacetate, 2.53 g (140 mmol) of water are charged into a 100 ml stirred reactor. and 7.5 g of acetic acid.

The reaction mixture is brought to reflux for 30 hours.

The reaction medium is then cooled and assayed by high performance liquid chromatography and by gas chromatography.

The conversion of salicylic acid is 23% and the yield of resorcinol 12%.

Example 2:

0.1201 g (1.46 mmol) of salicylic acid, 0.0127 g (0.07 mmol) of copper diacetate, 2.5 g of water and 7.5 g are charged into a 100 ml stirred autoclave. acetic acid. The reaction medium is heated to 120 ° C. under a pressure of 20 bar of air, with an air flow rate of 1 l / h for 30 hours.

After being brought back to atmospheric pressure and cooled, the reaction medium is analyzed by high performance liquid chromatography and by gas chromatography. The conversion of salicylic acid is 21%, and the yield of resorcinol 11%.

Claims

1 - Process for the preparation of a meta-dihydroxy aromatic compound characterized in that it consists in subjecting an aromatic compound carrying at least one carboxylic and / or carboxylate group and on both sides, in the ortho position, a hydroxyl group and a hydrogen atom, in a hydroxylation and decarboxylation step; said steps being able to take place successively or simultaneously. 2 - Process according to claim 1 characterized in that one prepares a meta-dihydroxylated aromatic acid, by hydroxylation of an aromatic compound carrying at least one carboxylate group and a hydroxyl group in ortho position, then l the decarboxylation of the compound obtained is carried out, thus leading to a meta-dihydroxy aromatic compound. 3 - Process according to claim 1 characterized in that the hydroxylation and decarboxylation are carried out simultaneously starting from an aromatic compound carrying at least one carboxylic group in acid form and from a hydroxyl group, in position ortho. 4 - Method according to one of claims 1 to 3 characterized in that the starting aromatic compound corresponds to the general formula (I):

in which: - Z represents one or more substituents, identical or different, - Y represents a hydrogen atom, a metal cation or the rest of a base, - n is a number less than or equal to 3, - the ortho position of the COOY group is a hydrogen atom. 5 - Process according to claim 4 characterized in that the aromatic compound corresponds to formula (I) in which the remainder Y represents a hydrogen atom or a metal cation in particular of the group la, lia or Ib of the periodic classification of elements, an ammonium radical or a primary, secondary or tertiary amino group and more particularly a metal of group la, preferably sodium and potassium; a metal from group IIa, preferably magnesium, calcium or barium; a group Ib metal, preferably copper. 6 - Process according to claim 4 characterized in that the aromatic compound corresponds to formula (I) in which: - n is a number less than or equal to 3, preferably equal to 0, 1 or 2, - Y represents a hydrogen atom, sodium or potassium, - the radical (s) Z represent one of the following atoms or groups:. a hydrogen atom, . an alkyl radical, linear or branched, having from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, . a linear or branched alkoxy radical having from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms such as the methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy radicals, . a nitro group, . a halogen atom, preferably a fluorine, chlorine or bromine atom, . a trifluoromethyl radical. 7 - Process according to claim 6 characterized in that the aromatic compound corresponds to formula (I) in which n is equal to 0 or 1, the group Z represents an alkyl or alkoxy radical having from 1 to 4 carbon atoms. 8 - Method according to one of claims 1 to 7 characterized in that the aromatic compound is chosen from: - 2-hydroxybenzoic acid (salicylic acid) - 3-methylsalicylic acid - 4-methylsalicylic acid - 5-methylsalicylic acid - 3-methoxysalicylic acid - 4-methoxysalicylic acid - 5-methoxysalicylic acid - 3-nitrosalicylic acid - 3,5-diiodosalicylic acid. 9 - Method according to one of claims 1 to 8 characterized in that one carries out the hydroxylation of the aromatic compound of formula (I) in acid form or in salified form by reacting it with an oxidant which is a copper compound. 10 - Method according to one of claims 1 to 8 characterized in that one carries out the hydroxylation of the aromatic compound of formula (I) in acid form or in salified form by bringing it into contact with oxygen molecular or a gas containing it, in the presence of an effective amount of copper and / or a copper compound. 11 - Method according to one of claims 9 and 10 characterized in that the copper compound is any organic or inorganic compound of copper I or copper II but we choose a copper II compound when used, as oxidant. 12 - Method according to one of claims 9 to 11 characterized in that the copper compound is chosen from: cuprous bromide, cupric bromide, cuprous iodide, cuprous chloride, cupric chloride, copper carbonate Basic II, cuprous nitrate, cupric nitrate, cuprous sulfate, cupric sulfate, cuprous sulfite, cuprous oxide, cupric hydroxide, cuprous acetate, cupric acetate, cupric trifluoromethylsulfonate copper I, copper salicylate II, copper p-hydroxybenzoate I, copper p-hydroxybenzoate II, copper benzoate I, copper benzoate II, copper methylate I, copper methyl methylate, chlorocultural methylate. 13 - Method according to one of claims 9 to 12 characterized in that the copper compound is chosen from: acetates, salicylates, copper benzoates and cupric chloride. 14 - Method according to one of claims 9, 11 to 13 characterized in that the molar ratio of compound to copper / compound of formula (I) is from 100% to 500% and, preferably, around 200%. 15 - Method according to one of claims 10, 11 to 13 characterized in that the molar ratio of catalyst to copper / compound of formula (I) is from 0.01% to 10% and, preferably, from 2% to 5%. 16 - Method according to one of claims 1 to 15 characterized in that the hydroxylation reaction is carried out in an aqueous medium or in an organic medium. 17 - Process according to claim 16 characterized in that the solvent is water and / or an organic solvent chosen from: - monalcohols or diols, - aliphatic carboxylic acids, - aliphatic, cycloaliphatic or aromatic ketones, - alkyl or arylalkyl esters of carboxylic, aliphatic, cycloaliphatic or aromatic acids, - halogenated aliphatic or aromatic hydrocarbons. 18 - Process according to claim 17 characterized in that the solvent is acetic acid and / or water. 19 - Method according to one of claims 1 to 18 characterized in that one operates at atmospheric pressure, by bubbling oxygen in the reaction medium or by operating under pressure, preferably between 1 and 20 bar. 20 - Method according to one of claims 1 to 19 characterized in that the temperature of the hydroxylation reaction is carried out in a temperature range from 100 ° C to 200 ° C, preferably from 100 ° C to 180 ° C. 21 - Method according to one of claims 1 and 2 characterized in that one prepares a meta-dihydroxylated aromatic acid, by hydroxylation of an aromatic compound carrying at least one carboxylate group and a hydroxyl group in ortho position, according to the method described in one of claims 4 to 20, then the decarboxylation of the compound obtained is carried out thus leading to a meta-dihydroxylated aromatic compound preferably corresponding to the formula

in said formula (III), Z and n have the meaning given in claims 4, 6 and 7. 22 - Process according to claim 21 characterized in that one carries out the decarboxylation of the aromatic meta-dihydroxylated acid obtained, by addition of a protonic acid, of mineral origin, preferably hydrochloric acid or sulfuric acid or an organic acid preferably, acetic acid, trifluromethanesulfonic acid or methanesulfonic acid until a pH less than or equal to 5 is obtained. 23 - Method according to one of claims 21 and 22 characterized in that the reaction medium is heated to a temperature varying between 100 ° C and 220 ° C and, preferably, from 100 ° C and 180 ° C and after cooling, the meta-dihydroxylated compound preferably separating from formula (III) is separated. 24 - Method according to one of claims 1 and 3 characterized in that one carries out the hydroxylation of an aromatic compound carrying at least one carboxylic group and a hydroxyl group in the ortho position, according to the method described in one of claims 4 to 20 and the simultaneous decarboxylation leading directly to a meta-dihydroxylated aromatic compound preferentially corresponding to formula (III):

in said formula (III), Z and n have the meaning given in claims 4, 6 and 7. 25 - Process for the preparation of a meta-dihydroxylated aromatic acid characterized in that it is obtained by hydroxylation of an aromatic compound carrying at least one carboxylate group and of a hydroxyl group in the ortho position. 26 - Process according to claim 25 characterized in that the aromatic meta-dihydroxylated acid obtained corresponds to formula (II):

in said formula (II): - Z represents one or more substituents, identical or different, - Y represents a metal cation or the rest of a base, - n is a number less than or equal to 3. 27 - Method according to one of claims 25 and 26 characterized in that the aromatic meta-dihydroxylated acid obtained corresponds to formula (II) in which - n is a number less than or equal to 3, preferably equal to 0, 1 or 2, - Y represents sodium or potassium, - the radical (s) Z represent one of the following atoms or groups: . a hydrogen atom, . an alkyl radical, linear or branched, having from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl,. a linear or branched alkoxy radical having from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms such as the methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy radicals, . a nitro group, . a halogen atom, preferably a fluorine, chlorine or bromine atom,. a trifluoromethyl radical. 28 - Method according to one of claims 25 to 27 characterized in that the hydroxylation is carried out according to the method described in one of claims 4 to 20. 29 - Hydroxylation catalyst of an aromatic compound carrying at least one carboxylic and / or carboxylate group and of a hydroxyl group in ortho position, based on copper and / or a copper compound. 30 - Use of the method described in one of claims 1 to 24, in the preparation of resorcinol, from salicylic acid.