DE2653446A1 - METHOD FOR PRODUCING PYROGALLOLIC COMPOUNDS - Google Patents

Description

PATENT LAWYERS

Dipl.-Ing. P. WiRTH Dr. V. SCHMIED-KOWARZIK

Dipl.-Ing. G. DANNENBERG Dr. P. WEINHOLD - Dr. D. GUDEL

281134 6 FBANKFURTAM MAIN

TELEPHONE (0611)

287014 GR. ESCHENHEIMER STRASSE 38

- Case BA 49 142/75 -

PISONS LIMITED

Fison House,

9 Grosvenor Street

L 0 Ν D 0 U / ENGLAND

for the production of pyrogallol -

connections "

- Bl. 1 a -

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The invention relates to a method for the production of pyrogallol, (1,2,3-trihydroxybenzene) and certain derivatives thereof.

Pyrogallol and its derivatives have different uses, for example as a photographic developer, in the dyeing of leather and wool, in the analysis of heavy metals and as intermediate products, for example in the production of the insecticide 2,2-dimethyl-1,3-benzodioxol-4-ylitiethylcarbamate. Currently, all commercially available pyrogallol is made by the decarboxylation of gallic acid, which is obtained from relatively rare plant sources. This is Pyrogallol expensive and difficult to obtain. Pyrogallol derivatives are similar expensive and difficult to obtain. There has now been a significantly improved process for the preparation of pyrogallol and certain derivatives thereof . found the process by which such rare plant sources were avoided and the product is easily synthesized.

Accordingly, the present invention relates to a method for Preparation of pyrogallol compounds of the general formula

, (D

12 3
in which R, R and R are identical or different and each denotes hydrogen or an alkyl group having 1 to 6 carbon atoms, and their salts, which consists in that a 2,2,6,6-tetrahalocyclohexanone compound of the general formula

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12 3
worm R, R and R have the above meaning and X always has the same meaning and represents chlorine or bromine, hydrolyzed.

By this method, the pyrogallol compounds and their Salts synthesized in very high yields and in a state of high fineness will.

The pyrogallol compounds form due to their phenolic OH groups Salts. The pyrogallol compounds produced by the process according to the invention can be in the form of salts. The salts are in particular alkali metal salts, for example sodium or potassium salts, in particular the sodium salt, and can be prepared from the pyrogallol compounds themselves in a manner known per se, for example by reaction with Alkali metal alkoxides are produced. The pyrogallol compound itself can be obtained from the salts in a manner known per se, for example by reaction with an acid, for example hydrochloric acid.

Usually, in the hydrolysis of the present invention, the pyrogallol compound is used rather than a salt thereof and this can be converted to a salt if desired, although this is not preferred.

12 3 X is preferably chlorine. The alkyl group R, R or R can

for example, methyl, ethyl or, preferably, tertiary butyl. the Hydrolysis is of particular interest when at least two of the groups R,

2 3 13

R and R, preferably at least R and R, each denote hydrogen.

1 2 Thus, according to a particular embodiment, R and R

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each represents hydrogen and R represents tertiary butyl. It is most preferred

12 3

however, that R, R and R each represent hydrogen, so that the pyrogallol compound or the salt thereof is pyrogallol itself or a salt The hydrolysis can be represented as follows:

H'

+ 4HX

It can be brought about directly or indirectly.

The direct hydrolysis consists in the reaction of the tetrahalocyclohexanone compound even with water. Indirect hydrolysis consists in the reaction of the tetrahalocyclohexanone compound to form a Derivative that is reacted with water in a separate step. The indirect hydrolysis can be carried out, for example, by reacting the tetrahalocyclohexanone compound with a metal alkoxide (e.g. sodium, potassium, Calcium or aluminum alkoxide, for example of an alkanol with 1 to 4 carbon atoms originating), preferably sodium methoxide, and subsequent ones Acid hydrolysis, for example with hydrochloric acid, can be carried out. However, direct hydrolysis enables the Overall reaction with a fewer number of steps and is preferred.

The yield of direct hydrolysis can be significantly improved by using a catalyst. It was found that a further Range of materials in this regard acts as catalysts. as Catalyst can be a base or an anion. An anion falls under some definitions of a base, but is used herein

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Case preferred to distinguish between these. The base can, for example Morpholine, triethanolamine, cyclohexylamine, di-n-butylamine or 2- (diethylamino) ethanol or an anion exchange resin.

However, the catalyst is preferably an anion. Suitable anions are

A) the anionic part of a cation exchange resin (for example a carboxylic acid cation exchange resin) in the hydrogen or salt form (for example the sodium, potassium, calcium or AimDnium form), e.g. Amber lite IEC 50 in the hydrogen or sodium form, or preferably

B) an anion of another salt (hereinafter referred to as simple salt to distinguish it from the ion exchange resin salt), for example citrate, dihydrogen citrate, hydrogen citrate, acetate, monochloroacetate, hydrogen malate, malate, hydrogen phthalate, hydrogen isophthalate, hydrogen tartrate, tartrate, oxalate ("OOCCOO "), o-nitrobenzoate, benzoate, lactate, propionate, glycolate, malonate (" OOGCH ^ COO "), formate, salicylate (HOC ₆ H ₄ COC) -), hydrogen adipate, adipate, hydrogen phosphate, dihydrogen phosphate, picolinate, furoate, dihydrogen pyrophosphate , Hydrogen succinate, sulfamate, hydrogen phosphite, gluconate, borate (H ₂ BO ₃ ) or fluoride.

The anion of a simple salt is preferably more in the form of a simple salt than used in the form of acid. The anion catalyst can be in the form of a water-soluble metal, Aimonium or amine salt or be a mixture of these. The amine salt can be that of a primary, secondary or tertiary amine. The amine can be aliphatic, aromatic or heterocyclic or an amine containing a mixture of such substituents on the amine nitrogen atom. It is generally preferred to use the sodium, potassium, ammonium or morpholine salt. The salt can be mixed as such or it can be generated in situ,

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for example by reacting the acid from which the salt is derived with Alkali. For example, the cation exchange resin in the salt form can be generated in situ by using the resin in hydrogen form and an alkali is present. On the other hand, the salt can be formed in situ by using an ester such as methyl oxalate in the presence of an alkali will.

Specific simple salts that are catalysts are trisodium citrate, Monomorpholine citrate, dimorpholine citrate, sodium dihydrogen citrate, Disodium hydrogen citrate, sodium acetate, sodium chloroacetate, sodium hydrogen malate, Disodium malate, sodium hydrogen phthalate, potassium hydrogen phthalate, Ammonium hydrogen phthalate, sodium hydrogen isophthalate, sodium hydrogen tartrate, Disodium tartrate, disodium oxalate, sodium o-nitrobenzoate, sodium benzoate, Sodium Lactate, Sodium Propionate, Sodium Glycolate, Dinatriuittnalonat, Sodium formate, monosodium salicylate, sodium hydrogen adipate, disodium adipate, Disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium picolinate, Sodium furoate, disodium dihydrogen pyrophosphate, sodium hydrogen succinate, Sodium sulfamate, sodium hydrogen phosphite, sodium gluconate, monosodium borate and "potassium fluoride.

In the case of a salt of a basic acid, a mixed one can be used Salt, for example a sodium-potassium salt, can be used.

The anion catalyst is preferably an anion of a carboxylic acid. The carboxylic acid can be an aliphatic, aromatic, heterocyclic or alicyclic carboxylic acid. The carboxylic acid can be one or more Contain carboxyl groups. If more than one carboxyl group is present, one is preferably neutralized and the others optionally may also be. If more than one carboxyl group is present, a mixed salt such as sodium-potassium salt can be used.

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The carboxylic acid preferably contains only carbon, hydrogen and oxygen atoms. In terms of practicality, availability and high Yield is a) a straight-chain alkanoic acid with 1 to 6 carbon atoms, optionally replaced by one or more carboxyl and hydroxyl groups is substituted, or b) benzoic acid which is substituted by one or more carboxyl and hydroxyl groups is preferred.

The pK of the acid whose anion can be used is

el

usually 2.0 to 6.5, preferably 2.8 to 5.7.

Particularly preferred specific salts are sodium acetate, disodium hydrogen citrate, Sodium hydrogen phthalate or sodium hydrogen adipate.

A mixture of catalysts can be used.

The direct hydrolysis takes place at a pH value of at least 2. For for a maximum yield, the pH is preferably 2.8 to 6.0. The hydrolysis gives hydrohalic acid HX, which has the pH below can lower these lower limits. For an optimal yield, it is preferred to keep the pH above this lower during the hydrolysis To keep boundaries. This can be done by using the catalyst in salt form, for example as the sodium salt, to adjust the pH to increase above the value it would otherwise have, or that alkali is added. The alkali can be any convenient alkali, for example Alkali metal hydroxide, carbonate or bicarbonate, e.g. sodium carbonate, but preferably sodium hydroxide. Preferably the pH is during the hydrolysis was maintained at 2.8 to 6.0.

Without being bound by this theory, it appears that if a Anion is used as a catalyst, the hydrolysis is carried out in such a way that a catalyst anion of each halogen atom X on the 2,2,6,6-tetrahalocyclohexanone compound of formula (II) and then each catalyst

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anion itself is displaced by a HO ion of water, i.e. a Addition takes place, which leads to the pyrogallol compound of the formula (I) leads. It can be seen that this is analogous to the aforementioned indirect hydrolysis, in which the tetrahalocyclohexanone compound with a Metal alkoxide is converted and the product is acid hydrolyzed; an alkoxide ion is the anion that displaces every X atom and the displacement of the alkoxide ion takes place in a separate stage.

When an anion is used as a catalyst and the anion is the one of a simple salt, the amount of catalyst is preferably at least four anions per molecule of tetrahalocyclohexanone. In general better yields are achieved by using 6 to 10 catalyst anions obtained instead of 4 catalyst anions per molecule of tetrahalocyclohexanone. In general, there is no better yield using 16 Catalyst anions instead of 8 catalyst anions per molecule of tetra. obtained halocyclohexanone.

When an anion is used as a catalyst and the anion that of a cation exchange resin, the amount of catalyst is preferably at least 4 equivalents, in particular 6 to 10 equivalents Anion per mole of tetrahalocyclohexanone, with generally no better Yield by using 16 instead of 8 equivalents of anion per mole Tetrahalocyclohexanone is achieved.

If a base is used as a catalyst, it is assumed without to be bound by this theory that one equivalent of base with one equivalent of hydrohalic acid, which is formed during hydrolysis, reacted. When a base is used as a catalyst, the amount is Catalyst preferably at least four equivalents of base per mole of tetrahalocyclohexanone.

.7 0 9 8 2 37 1 0 2 7

When direct hydrolysis is used, an organic liquid such as methanol or ethanol can be used in the reaction mixture to obtain a system that initially consists of one phase rather than two phases.

The hydrolysis according to the invention is preferably carried out in solution. At least the theoretical amount of water must be used to effect the hydrolysis and, if direct hydrolysis is used, is the solvent is preferably water in excess of the amount required for hydrolysis. When direct hydrolysis is applied, it is preferably the total amount of the catalysts in solution.

When the above-mentioned alkoxide route is used, the reaction with the alkoxide generally in the presence of the alkanol of which the alkoxide originates, carried out as a solvent and the subsequent acid hydrolysis can be carried out in the presence of water as a solvent, which is in excess of the amount required for hydrolysis.

Preferably 0.3 ml to 1 liter of water per g of tetrahalocyclohexanone compound are used in the hydrolysis.

The hydrolysis may, for example, at a temperature from 0 to 250 ⁰ C, for example, 0 to 12O ° C is performed. The reaction mixture is usually heated. According to a preferred embodiment, particularly if direct hydrolysis is employed, the temperature is 60 to 140 ⁰ C. Preferably, the direct hydrolysis is performed under reflux.

The hydrolysis can take place under pressure which is above, at or below atmospheric pressure. The pressure can be 0.1 to 15, for example atm and is preferably atmospheric pressure.

The pyrogallol compound and its salts absorb in the heat

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Oxygen and the salts absorb oxygen even at ambient temperature.

Accordingly, excessive heating of the same should be avoided, and in some cases it may be desirable to carry out the hydrolysis under an inert atmosphere, for example in an atmosphere of nitrogen or carbon dioxide.

The product can be isolated and purified in a manner known per se will.

The starting material of the formula (II) of the process according to the invention can be prepared in a manner known per se or by methods that for the preparation of analogous compounds are known. When the starting material is 2,2,6,6-tetrachlorocyclohexanone or 2,2,6,6-tetrabromocyclohexanone, can it can be made by chlorinating or brominating cyclohexanone. On the other hand, 2,2,6,6-tetrachlorocyclohexanone can be obtained by chlorinating Cyclohexanol can be produced. 2,2,6,6-tetrachlorocyclohexanone or 2,2,6,6-Tetrabromocyclohexanone is preferably made, but after a method which is new in itself and to which the present invention per se also relates. This procedure is a procedure for Production of 2,2,6,6-tetrachlorocyclohexanone or 2,2,6,6-tetrabromocyclohexanone, where in the case of the production of 2,2,6,6-tetrachlorocyclohexanone chlorine or in the case of the production of 2,2,6,6-tetrabromocyclohexanone Bromine in the liquid phase with a cyclohexanone compound of the general formula

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Il

' ^(ΙΙΙ)

H H

wherein each group Y is the same or different and in the case of manufacture of 2,2,6,6-tetrachlorocyclohexanone a hydrogen or chlorine atom and im Case of the production of 2,2,6,6-tetraborticyclohexanone a hydrogen or Bromine atom represents, in the presence of a catalyst from the group of thionyl chloride, selenium oxychloride, potassium fluoride, sulfuryl chloride or Tributylphosphine is implemented.

The compounds used as starting materials in the above process of formula (III) are either known compounds or can be prepared by methods which are known to those skilled in the art organic chemical synthesis for the production of analogous compounds are known.

These catalysts for the production of 2,2,6,6-tetrachlorocyclohexanone or 2,2,6,6-tetrabromocyclohexanone allow the reaction to occur in is carried out expediently and with high yield. The catalysts are particularly useful when the desired product is then too Pyrogallol is said to be hydrolyzed. Thionyl chloride, potassium fluoride and sulfuryl chloride are advantageous because they are relatively easily available and therefore are relatively cheap. Thionyl chloride is the most preferred catalyst.

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A catalytic amount of the catalyst must be used. in the in general, the weight of the catalyst is at least 0.1%, preferably 0.5 to 12%, based on the weight of the cyclohexanone compound.

The process is of particular interest for the production of 2,2,6,6-tetrachlorocyclohexanone, so that the halogen used is more likely to be chlorine than bromine and Y represents a hydrogen or chlorine atom rather than a hydrogen or bromine atom.

The cyclohexanone compound is preferably cyclohexanone itself, although a halogenated intermediate compound can be used. For example, 2,2,6,6-tetrachlorocyclohexanone can be used as a starting point for the production of 2,2,6-trichlorocyclohexanone.

The reaction is preferably carried out in the presence of a solvent carried out. Suitable solvents are saturated chlorinated hydrocarbons (e.g. aliphatic hydrocarbons with 1 or 2 carbon atoms and 2 to 4 chlorine atoms, such as carbon tetrachloride, methylene dichloride or tetrachloroethanes), saturated hydrocarbons (e.g. those with 5 to 10 carbon atoms, such as pentane, hexane, cyclohexane, octane or decane) or saturated carboxylic acids (e.g. saturated aliphatic carboxylic acids with 2 to 5 carbon atoms, such as acetic acid, propionic acid or butanoic acid). at the production of 2 / 2,6,6-tetrachlorocyclohexanone can be 2,2,6-trichlorocyclohexanone be used as a solvent, preferably that is Solvent but the melted desired product (e.g. 2,2,6,6-tetrachlorocyclohexanone) itself. A mixture of solvents can be used, but this is not preferred.

According to a preferred procedure, the halogen and the cyclohexanone compound are a reaction zone, which is a solvent and the

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- .Λ

Contains catalyst, supplied. The reaction is usually conducted at a temperature in the range of 60 to 160 ⁰ C, preferably 75 to 11O ° C, for example up to 110 C, performed 80th The reaction temperature is preferably below the boiling point of the solvent, if one is used. When molten 2,2,6,6-tetrachlorocyclohexanone is used as the solvent, the reaction temperature is its melting point as changed by the other materials present. The melting point of pure 2,2,6,6- ^J tetrachlorocyclohexanone is 82 to 83 ° C.

Preferably the reaction is carried out under essentially anhydrous conditions, i.e. less than 1% by weight, preferably less than 0.5% by weight of water, based on the weight of the cyclohexanone compound, available.

The total amount of chlorine or bromine used is usually sufficient to convert all of the cyclohexanone compound into the desired product. If the reaction occurs by the halogen and the Cyclohexanone compound are fed to a reaction zone containing a solvent and the catalyst, it is preferred to Side reactions to a minimum, reduce that with the cyclohexanone amount of halogen in contact in the reaction zone at all times at least corresponds to the stoichiometric amount required to convert the cyclohexanone compound into the desired product. For example, starting from cyclohexanone, preferably at least moles of halogen per mole of cyclohexanone are added; expediently 4 to 6 moles of halogen supplied per mole of chlorhexanone supplied.

When the reaction is carried out by the halogen and the cyclohexanone compound fed to a reaction zone containing a solvent

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and contains a catalyst, the hourly feed rate is Cyclohexane compound to the zone generally never more than that Half, for example more than a third, of the weight of the respective Solvent. If one assumes an assaulted weight W of the solvent. runs out, therefore, the initial hourly feed rate of the Cyclohexanone compound W / 2. As the reaction proceeds and the desired product formed acts as an additional solvent, that becomes Total weight of solvent increased and thus the hourly The rate of supply of the cyclohexanone compound can be increased while still being no more than half the weight of the solvent. However, a constant feed rate is expediently used.

In order to ensure maximum conversion into the desired product (in particular 2,2,6,6-tetrachlorocyclohexanone), it is preferred to continue the Halpgen feed at the end of the cyclohexanone compound feed. The supply of halogen is preferably continued until the weight of the 2,2,6-trihalocyclohexanone (in particular the 2,2,6-trichlorocyclohexanone) is less than 5%, in particular less than 1% of the total weight of 2,2,6- ^j rrihalocyclohexanone and 2,2,6,6-tetrahalocyclohexanone. The supply of halogen is preferably continued for at least a quarter of an hour, for example 1 / 4-3 hours, for example 1 / 2-3 hours, after the end of the cyclohexanone compound supply.

The desired product can be separated off in a manner known per se.

The following examples are intended to further enhance the present invention explain, but without this being limited to this. All parts and percentages are based on weight.

Example 1: A mixture of 1CX) parts of 2,2,6,6-Tetrachlorcyclohexanon and 532 parts of water was heated to 60 ⁰ C and 149 parts

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Morpholine were added dropwise over a period of 14 minutes added. The mixture was held at 60 ° C. for an additional 4 minutes, then cooled and filtered. The filtrate was made by adding 21 parts concentrated hydrochloric acid solution and then extracted continuously with ether. After drying over MgSO. the extract was evaporated, whereby 21 parts of tar were obtained which, as gas-liquid chromatography showed, after acetylation contained 6 parts (11.2% yield) pyrogallol. Example 2: 1CXD parts of 2,2,6,6-tetrachlorocyclohexanone, 424 parts of sodium acetate and 1059 parts of water were mixed and the mixture was refluxed for 10 minutes. Then it got to 50C cooled and when 318 parts of sodium bicarbonate were added, there was profuse foaming. The mixture was then extracted continuously with ether and the extract was dried over magnesium sulfate and evaporated to give 39 parts of residue. This residue was 39 parts Triturated chloroform, with 15.2 parts after filtering and drying in air (28.5% yield) pyrogallol were obtained as a yellow-brown solid, M.p. 130-133.5 ° C.

Example 3: 100 parts of 2,2,6,6-tetrachlorocyclohexanone, 456 parts of disodium oxalate and 1064 parts of water were mixed and the mixture was refluxed for 2 hours. Then it became continuous extracted with ether and dried over sodium sulfate. After filtering, the extract was evaporated, leaving 52.2 parts of a residue which gas-liquid chromatography showed converted into the triacetate contained 24.5 parts (46% yield) pyrogallol. Example 4: 2.36 g (0.01 mol) of 2,2,6,6-tetrachlorocyclohexanone was added to 35 ml (0.17 mol) of a stirred 27% sodium methoxide solution added under nitrogen at 24 ° C. The temperature of the mixture rose

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and was kept at 45 ° C by external cooling. When the heat development ceased, the mixture was cooled in ice and 17 ml of concentrated hydrochloric acid and 28 ml of water were added. The methanol was distilled off from the reaction mixture under nitrogen and the aqueous solution obtained was continuously extracted with ether. The ether extract was _{dried over MgSO 4} and the ether removed in vacuo, 0.85 g g of a residue being obtained which, when analyzed, consisted of 18% pyrogallol. This corresponds to a pyrogallol yield of 12.2%. Example 5: 4.72 g (0.02 mol) of 2,2,6,6-tetrachlorocyclohexanone were added to a solution of 0.16 mol of disodium hydrogen citrate, which was prepared by adding 12.8 g of sodium hydroxide to a solution of 33.6 g of citric acid monohydrate in 50 ml of water with cooling. The mixture was stirred and heated to reflux. The reaction mixture was sampled at intervals and analyzed for free chloride until the samples indicated that the reaction was complete. The total time at reflux was 4 hours. The reaction mixture was continuously extracted with ether. The ether extract was _{dried over MgSO 4} , filtered and the ether removed, 2.74 g of a residue being obtained which, on analysis, consisted of 77.5% pyrogallol. The pyrogallol yield is 84.4%.

Example 6: 4.72 g (0.02 mole) 2,2,6,6-tetrachlorocyclohexanone became a mixture of 26.5 g (0.16 mol) of phthalic acid in 75 ml of water added to which 6.4 g (0.16 mol) of sodium hydroxide had been added. the The mixture was refluxed for 11/2 hours. 5 ml of 5N sodium hydroxide solution was added over 5 minutes and the mixture an additional 2 1/2 Heated at reflux for hours. A sample was analyzed for free chloride and this indicated that the reaction was complete. 13 ml concentrated

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Hydrochloric acid was added at 90 ° C. The reaction mixture was cooled to 5 ° C. and the phthalic acid was filtered off. The pH of the filtrate was adjusted to 3.5 and extracted continuously with ether. The ether extract was _{dried over Na 5} SO ₄ , filtered and the ether removed, 3.04 g of a crude product containing 2.02 g of pyrogallol being obtained. This corresponds to a pyrogallol yield of 80%. Example 7: 9.6 g (0.16 mol) of glacial acetic acid were dissolved in distilled water and the pH was adjusted to 4.7 with 1ON sodium hydroxide solution. The volume of the solution was adjusted to 55 ml by diluting it with distilled water. 4.72 g (0.02 mol) of 2,2,6,6 ^ etrachlorocyclohexanone were added and the mixture was heated to reflux. The pH of the reaction mixture was kept at 4.7 by adding 5N sodium hydroxide solution. Samples were taken intermittently and analyzed for free chloride to determine the end of the reaction. The aqueous solution obtained was continuously extracted with ether. The ether extract was obtained via Na “SO. dried, filtered and the ether removed, 3.5 g of a crude product were obtained which contained 1.46 g of pyrogallol. The pyrogallol yield is 58%.

Example 8: 16.8 g (dry) Amberlite IRC 50 ion exchange resin in the sodium form was suspended in 50 ml of distilled water. 4.72 g (0.02 mol) of 2,2,6,6-tetrachlorocyclohexanone were added and the Mixture heated to reflux for 11/2 hours, during which time the pH value had fallen from 6.2 to 1.7. The pH was adjusted to 3.8 and refluxing continued for an additional 4 hours during which Time the pH was maintained between 2 and 4 by adding 5N sodium hydroxide solution. Chloride analysis indicated 92% hydrolysis. The resin was filtered off and the reaction mixture continuously with

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- ΛΑ

Ether extracted. The ether extract was dried, filtered and the Ether removed, yielding 1.2 g of a brown oil. When analyzed, this contained 19.6% pyrogallol, which corresponds to a yield of 9.3% Corresponds to pyrogallol.

Example 9: 4.72 g (0.02 mol) of 2,2,6,6-tetrachlorocyclohexanone were added to 50 ml of distilled water and the pH was adjusted to 5.0 with 5N sodium hydroxide solution. The mixture was stirred and heated to reflux and the pH was maintained at 5.0 by adding sodium hydroxide solution. The mixture was sampled at intervals and analyzed for free chloride until the reaction was complete. The reaction mixture was extracted with ether and the ether extract was dried over Na ₃ SO ₄ , filtered and the ether was distilled off, 1.3 g of a brown oil being obtained. This contained 0.03 g of pyrogallol, which corresponds to a yield of 1.2%.

Example 10: As in Example 9, but with the pH at 3.0 was maintained, a 3.7% yield of pyrogallol was achieved. Example 11: As in Example 5, but using 0.02 mol of 2,2,6,6-tetrabromocyclohexanone instead of tetrachlorocyclohexanone, a yield of 44% pyrogallol was achieved.

Examples 12 to 52: A suspension of 4.72 g (0.02 mol) of 2,2,6,6-tetrachlorocyclohexanone was refluxed with an aqueous Solution / suspension of the catalyst compound given below (0.16 mol; in the case of Amber lite IRC 50, 16.0 g of dry resin used) heated in 50 ml of water. The mixture was sampled at intervals and analyzed for free chloride to determine the endpoint of the Determine reaction. The aqueous reaction mixture was then filtered, if necessary, and continuously extracted with ether. The ether

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The extract was _{dried over Na 3} SO ₄ , filtered and the ether removed to give the crude pyrogallol. This was analyzed to determine the yield.
Example catalyst compound yield pyrogallol%

12th Trisodium citrate 25.5 13th Sodium dihydrogen citrate 31.0 14th Sodium chloroacetate 31.0 15th Sodium hydrogen malate 71.0 16 Disodium malate 52.0 17th Potash Hydrogen Phthalate 75.0 18th Atonium hydrogen phthalate 52.0 19th Sodium hydrogen isophthalate 59.8 20th Sodium hydrogen tartrate 58.0 21 Disodium tartrate 60.5 22nd Disodium oxalate 44.0 23 Sodium o-nitrobenzoate 35.1 24 Sodium benzoate 49.5 25th Sodium lactate 68.5 26th Sodium propionate 42.9 27 Sodium glycolate 57.0 28 Disodium malonate 27.0 29 Sodium formate 20.8 30th Sodium salicylate 29.0

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Sodium hydrogen adipate 82.0 2653446 31 Dinatriuit adipate 46.0 32 Amberlite IRC 50 H ⁺ form 17.0 33 Dinatriuiti hydrogen phosphate 22.6 34 Sodium dihydrogen phosphate 32.5 35 Mononatriur riborate 7.0 36 Potassium fluoride 16.0 37 Ethylenediaminetetraacetic acid
dinatriuiti salt. 49.0 38 Sodium hydrogen fumarate 53 39 Disodium fumarate 58 40 Sodium hydrogen 1,2,3,6-tetra-
hydrophthalate 62 41 Sodium Hydrogenite Bleat 34 42 Sodium pivalate 11 43 Dipotassium oxalate 71 44 Sodium picolinate 6th 45 Sodium furoate 19th 46 Disodium dihydrogen pyrophosphate 47 47 Sodium hydrogen succinate 76 48 Sodium sulfamate 13th 49 Sodium hydrogen phosphite 18th 50 Dimethyl oxalate 25th 51 Sodium Fluconate 67 52

Example 53: 4.72 g (0.02 mol) 2,2,6,6-tetrachlorocyclohexanone were added to a solution of morpholine citrate obtained by adding 24.6 ml (0.283 mol) of morpholine to a solution of 33.6 g (0.16 mol) Citric acid monohydrate in 50 ml of water with cooling.

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The mixture was stirred and heated to reflux. The reaction mixture samples were taken at intervals and analyzed for free chloride until the samples indicated that the reaction was complete. The total time on The reflux was 3 hours. The reaction mixture was continuously extracted with ether. The ether extract was over MgSO. dried, filtered and the ether removed to yield 5.4 g of a residue which, when analyzed, contained 33.6% pyrogallol. The pyrogallol yield is 71.9%.

Example 54: 5g (0.02 mole) 2,2,6,6 ^ etrachloro-4-methylcyclohexanone were to a solution of 30.1 g (0.16 mol) of sodium hydrogen phthalate in 50 ml of water added. The mixture was heated to reflux and samples were taken at intervals to storm free chloride. as the reaction was complete, the mixture was cooled, filtered, extracted with ether and the ether removed, with 3.8 g of a crude product were obtained, the 1.26 g of 1,2,3-trihydroxy-ynethylbenzene (methylpyrogalol) contained. This corresponds to a yield of 45%.

Example 55: 45 g of 2,2,6,6-TeUTaChIOrCyClOhCXaTiOn and 5 g of thionyl chloride were placed in a 500 ml flask fitted with a mechanical stirrer, thermometer, water condenser, and a chlorine inlet tube with a sinter outlet to the bottom of the flask . The flask was heated and the melt was ^{flushed with nitrogen at 85 to 90 °} C. for 10 minutes. At 95 to 105 ^° C., 276 g of chlorine and 66 g of cyclohexanone were added continuously to the flask over 6.7 hours. The molar ratio of chlorine to cyclohexanone was kept at 5.8 during the addition. Chlorine was then added continuously over 11/2 hours at the same rate as before while maintaining the same temperature. 375 ml of η-hexane were added to the reaction mixture

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.ar

then heated to give a clear solution. Gas-liquid chronatography analysis a 464.1 g sample of the solution indicated it contained 143.4 g (90.2% theoretical yield) of freshly formed 2,2,6,6-tetrachlorocyclohexanone contained.

When the solution was cooled to 5 ° C., crystals of 2,2,6,6-tetrachlorocyclohexanone fell from which, after filtration and drying, contained 122.4 g (77.3% yield) of freshly formed 2,2,6,6-tetrachlorocyclohexanone (i.e. the 2,2,6,6-tetrachlorocyclohexanone, which in addition to the originally supplied to the flask). The analysis showed that the 2,2,6,6-tetrachlorocyclohexanone obtained was 99% pure. Example 56: The procedure of Example 55 was repeated, wherein however, 5 g of selenium oxychloride was used in place of the thionyl chloride. The yield of freshly formed 2,2,6,6-tetrachlorocyclohexanone was 89.4%.

Example 57: The process of Example 55 was repeated, except that 5 g of potassium fluoride were used instead of the thionyl chloride, the reaction ^{temperature was 80 to 108 °} C., 42 g of cyclohexanone and 177 g of chlorine were fed in over 4.3 hours, and the molar ratio of Chlorine to cyclohexanone was 4.6. The yield of freshly formed 2,2,6,6-tetrachlorocyclohexanone was 118.7 g (72.7%).

Example 58: The process of Example 55 was repeated, except that 5 g of sulfuryl chloride were used instead of the thionyl chloride, the reaction ^{temperature was 84 to 104 °} C., 255 g of chlorine and 73 g of cyclohexanone were fed in over 6.2 hours and the molar ratio of chlorine to cyclohexanone was 4.8. The yield of freshly formed 2,2,6,6-tetrachlorocycldhexanone was 122.1 g (69.5%). Example 59: The procedure of Example 55 was repeated, wherein

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however, 5 g of tributylphosphine was used in place of the thionyl chloride. The yield of freshly formed 2,2,6,6-tetrachlorocyclohexanone was 86.5%.

Example 60: 45 g of 2,2,6,6-tetrachlorocyclohexanone and 5 g of thionyl chloride were placed in a 500 ml flask fitted with a mechanical stirrer, thermometer, water condenser, and a chlorine inlet tube with a sinter outlet to the bottom of the flask . The flask was heated and the melt was ^{flushed with nitrogen at 85 to 90 °} C. for 10 minutes. At 95 to 105 ^° C., 276 g of chlorine and 66 g of cyclohexanone were continuously added to the flask over the course of 6.7 hours. The molar ratio of chlorine to cyclohexanone was maintained at 5.8 during the addition. Chlorine was then added continuously at the same rate as before over one and a half hours while maintaining the same temperature. It solidified as the reaction mixture cooled. Gas-liquid chromatographic analysis showed that it was 93% pure 2,2,6,6-tetrachlorocyclohexanone. The yield of freshly formed 2,2,6,6-tetrachlorocyclohexanone was 92%.

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Claims (15)

Patent claims: 1. Process for the preparation of pyrogallol compounds of the general formula DH 12 3
in which R, R and R are identical or different and each represent hydrogen or an alkyl group having 1 to 6 carbon atoms, and their salts, characterized in that a 2,2,6,6-tetrahalocyclohexanone compound of the general formula , (ID 1 2 wherein each group X is the same and is chlorine or bromine and R, R and 3
R have the meaning given above, hydrolyzed. 2. The method according to claim 1, characterized in that starting compounds are used in which X is chlorine. 3. The method according to claim 1 or 2, characterized in that one 2,2,6,6-tetrachlorocyclohexanone hydrolyzed. 709823/1027 ORIGINAL 4. The method according to any one of the preceding claims, characterized in that that direct hydrolysis is used. 5. The method according to claim 4, characterized in that the hydrolysis is carried out in the presence of a catalyst which is a base. 6. The method according to claim 4, characterized in that the hydrolysis is carried out in the presence of a catalyst which is an anion. 7. The method according to claim 6, characterized in that as a catalyst the anionic part of a cation exchange resin in hydrogen or Salt form is used. 8. The method according to claim 6, characterized in that as a catalyst an anion of a simple salt is used. 9. The method according to claim 8, characterized in that the catalyst in the form of sodium acetate, disodium hydrogen citratej sodium hydrogen phthalate or sodium hydrogen adipate is used. 10. The method according to any one of claims 4 to 9, characterized in that that the pH is kept at 2.8 to 6.0 during the hydrolysis. 11. Process for the preparation of 2,2,6,6-tetrachlorocyclohexanone or 2,2,6,6-Tetrabroncyclohexanone, characterized in that in the case of Production of 2,2,6,6-tetrachlorocyclohexanone and chlorine in the case of Production of 2,2,6,6-tetrabromoyclohexanone in the liquid phase with bromine a cyclohexanone compound of the general formula O
[t H J, I H H wherein each group Y is the same or different and in the case of H 709823/1027 of ^^, e ^ -Tetrachlorocyclohexanone represents a hydrogen or chlorine atom and in the case of the production of 2,2,6,6- ^j retrabromocyclohexanone represents a hydrogen or bromine atom, in the presence of a catalyst from the group of thionyl chloride, selenium oxychloride, potassium fluoride, sulfuryl chloride or tributylphosphine is implemented. 12. The method according to claim 11, characterized in that the cyclohexanone compound Cyclohexanone itself is used. 13. The method according to claim 11 or 12, characterized in that as Catalyst thionyl chloride is used. 14. The method according to any one of claims 11 to 13, characterized in that 2,2,6,6- ^J tetrachlorocyclohexanone is prepared. 15. The method according to any one of claims 1 to 10, characterized in, that the 2,2,6,6-tetrahalocyclohexanone compound is 2,2,6,6-tetrachlorocyclohexanone or 2,2,6, G-tetrabroncyclohexanone, which compound according to the The method of any one of claims 11 to 14 has been produced. 709823/1027