DE1925195A1 - Process for the production of aromatic hydroxyaldehydes - Google Patents

Description

1Q0C1QC Badisohe Anilin- & Soda-Fabrik AG ^{| g4J} ' ^ΰνί

Our reference: O.Z. 26 194 ste / km

67ΟΟ Ludwigshafen, May 16, 1969 Process for the production of aromatic hydroxyaldehydes

The present invention relates to a new process for the preparation of aromatic hydroxyaldehydes by chlorination of certain aromatic methyl compounds and hydrolysis of the obtained aromatic dichloromethyl compounds.

It is known from Houben-Weyl, Methods of Organic Chemistry, Volume 7/1 (1954), page 36, to produce aromatic hydroxyaldehydes according to the Reimer and Tiemann method by reacting phenols with chloroform and sodium hydroxide solution. However, this process is extremely dependent on the constitution and gives yields which, as a rule, are only between 20 and 30 % of theory. The Reimer and Tiemann method is therefore no longer of any technical importance. It is also known from the above-mentioned Houben-Weyl volume, page 214, a process for the preparation of salicylaldehyde, in which one converts o-cresol into the di-o-tolyl carbonate, this is then chlorinated and finally the chlorination product obtained under pressure of 5 atmospheres saponified. This process has the disadvantage that the yields are already unsatisfactory in the conversion to the dicarbonate and the vacuum distillation of the dicarbonate as well as the vacuum distillation of the tetrachlorinated product is very expensive because of the high boiling and melting points of the compounds. Furthermore, during the saponification of the tetrachlorinated product, a certain amount of resinification occurs, which results in a further reduction in yield.

It has now been found that aromatic hydroxyaldehydes of the general formula

CHO

OH

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Can be advantageously prepared if you first of all aromatic methylchlorocarbonic acid esters of the general formula

II, OCOCl

to aromatic dichloromethylchlorocarbonic acid esters of the general formula

CHCl ₂

III, OCOCl

chlorinated and the dichloromethylchlorocarbonic acid ester III obtained is hydrolyzed to the aromatic hydroxyaldehydes I.

According to the new process, the aromatic hydroxyaldehydes I are obtained in excellent yield and in high purity. Leave the aromatic dichloromethyl chlorocarbonic acid esters III hydrolyze themselves at atmospheric pressure in an aqueous reaction medium without the addition of basic or acidic agents, without the formation of resinous by-products being observed. The distillation of the aromatic methylchlorocarbonic acid ester II, or the aromatic dichloromethyl chlorocarbonic acid ester III can be carried out in a relatively simple manner because of the relatively low boiling point of the compound, fertilize.

On the benzene ring of the aromatic hydroxyaldehydes I and accordingly the methylchlorocarbonic acid ester II and dichloromethylchlorocarbonic acid ester III can also fused a benzene ring be. The rings mentioned can also be replaced by groups and / or atoms which are inert under the reaction conditions, e.g. chlorine atoms, Bromine atoms, nitro groups, lower alkoxy groups may be substituted.

The production of the aromatic to be used as starting materials

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Methylchlorocarbonic acid ester II is known per se (cf.Houben-Weyl, Methods of Organic Chemistry, Volume VIII (1952), pages 101 to 104). You will, for example, by implementing the * appropriate Methylphenols obtained with phosgene, expediently in the presence of acid-binding agents. Suitable acid-binding Means are, for example, hydroxides, carbonates of the alkali or alkaline earth metals and especially tert. Amines. In detail are for example, called potassium, sodium, calcium hydroxide, potassium, sodium carbonate, triethylamine, dimethyl aniline, pyridine. The phosgenation in inert organic solvents, such as ethers, optionally nitrated or halogenated, is expedient aromatic or aliphatic hydrocarbons.

Suitable solvents are, for example, benzene, toluene, cumene, Xylene, chlorobenzene, o-dichlorobenzene, nitrobenzene, carbon tetrachloride, Ligroin. In general, the phosgenation is carried out in the cold, expediently at temperatures between 0 and 50 C, by. The reaction mixture can, for example, be worked up in such a way that it is mixed with after the reaction has ended Washes water and separates the solvent from the organic phase by distillation. Depending on the degree of purity, the chlorocarbonic acid esters remaining in the distillation of the solvent are used as such or after vacuum distillation will.

Suitable starting materials II are, for example, the chlorocarbonic acid ester of o-cresol »p-cresol, m-cresol, nitro-hydroxy toluene, 1-methyl-naphthol- (2), 2-methyl-naphthol- (1), 6-methyl-naphthol- (2), the cresols being preferred.

The starting materials II are converted into the dichloromethylchlorocarbonic acid ester III in a manner known per se by the action of chlorine. The chlorination is generally carried out at temperatures between 50 and ^100.degree. C., preferably 120 and 150.degree. The chlorination is preferably carried out under irradiation with ultraviolet light. In general, chlorination is carried out at atmospheric pressure. However, it is also possible at slightly increased pressure, for example 3 atmospheres, or under different

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chlorinated under reduced pressure, e.g. 600 Torr.

The chlorination can be carried out in the presence of inert solvents, e.g. nitrated or chlorinated aromatic or aliphatic hydrocarbons such as carbon tetrachloride, trichlorobenzene. However, the chlorination is preferably carried out without Solvent off.

The chlorination can be carried out in such a way that the gaseous chlorine is allowed to act on the starting material as long as until the theoretical amount of 2 moles of chlorine per mole of starting material has been absorbed. As we have found, the substitution occurs of the hydrogen atoms of the methyl group not gradually, but the second or third hydrogen atom of the methyl group substituted before all first or second hydrogen atoms of the methyl group are substituted are. It is therefore advantageous to only allow the chlorine to act as long as there is still no large amount of it have formed trichlorinated reaction product. The chlorination is therefore preferably carried out in such a way that only about 1.2 to about 1.6 moles of chlorine can react with 1 mole of starting material and the chlorination then stops. The reaction product is expediently separated by rectification, with the monochlorine compound obtained is expediently recycled to the chlorination, while the dichloro compound to the aldehyde is hydrolyzed. In this procedure, practically no trichloro compound is obtained, and the dichloromethyl chlorocarbonic acid ester III has a high purity.

The hydrolysis of the dichloromethylchlorocarbonic acid ester III to the hydroxyaldehyde I can be carried out in an acidic, neutral or basic aqueous medium. Mixtures of water with an organic solvent, in particular a water-miscible organic solvent, can be used for the hydrolysis. Suitable organic solvents are, for example, ethers, alcohols, ketones, lower aliphatic carboxylic acids, lower; Ari.de, ix'ialkylamin "In particular, for example • i-uint methanol, propanol, but & nol, dioxane, tetrahydrofuran,

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Glacial acetic acid, triethylamine, acetone ,. Dimethylformamide. Preferably however, water alone is used as the hydrolysis medium. The weight ratio of dichloromethylchlorocarbonic acid ester III to the aqueous solvent is generally 5: 1 to 1: 10, preferably 1: 2 to 1: 5

Is advantageously used in the hydrolysis temperatures between 30 and 150 ⁰ C, preferably between 70 and 10O ⁰ C, to. If the boiling point or boiling range of the hydrolysis mixture is above the reaction temperature, or if the hydrolysis is carried out under reflux, it is expedient to use atmospheric pressure. However, the hydrolysis can also be carried out at elevated pressure, for example at the pressure which is established in the closed reaction vessel as the sum of the partial pressures of the reactants. However, it is also possible to carry out the hydrolysis under reduced pressure, for example 600 torr.

If the hydrolysis is carried out in a basic medium, use as basic agents, preferably hydroxides or carbonates of the alkali or alkaline earth metals. Suitable basic Agents are, for example, sodium, potassium, calcium hydroxide and potassium carbonate. In general, the amount of basic is Average 1 to 4 equivalents, preferably 2 to 3 equivalents per mole of chlorocarbonic acid ester. In case of hydrolysis in acidic medium are generally organic as acidic agents Acids and preferably mineral acids are used. Suitable acids are, for example, hydrochloric acid, hydrobromic acid, sulfuric acid, Phosphoric acid, acetic acid, chloroacetic acid. The acidic agents are generally used in a concentration of 1 to 20 wt. preferably 5 to 15% by weight, based on the aqueous medium.

Ea is a particular advantage of the present method "that the hydrolysis of the compounds III can also be carried out in an aqueous medium without the use of basic or acidic agents admittedly v / ground.

With de "- ³ hydrolysis in the basic reactionaniödiuiii the hydro-

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Appropriately acidified before working up, preferably the lysis mixture by adding mineral acids. The extraction of the 'aromatic Hydroxyaldehyde I from the hydrolysis mixture can be carried out, for example, in such a way that, if appropriate, after acidification, the organic phase is filtered off or an azeotrope of the aldehyde is distilled over with water and then rectifies the organic layer.

The aromatic hydroxyaldehydes I are important intermediate products for the production of e.g. dyes, fragrances and antioxidants.

The parts given in the examples are parts by weight. Parts by weight relate to parts by volume like kg to 1.

example 1

In a reaction vessel, 836 parts o-Kresolchlorkohlensäureester at 120 to I ¹ IO C under irradiation with ultraviolet Lieht be as long as gassed with chlorine, with stirring, to about 272 'parts of chlorine have been added. Rectification of the reaction mixture in a Püllkörperäule filled with glass Raschig rings in vacuo gives iJOO parts of monochlorochlorocarbonic acid ester with a boiling point of ₁₂ 125 ° C and 700 parts of dichloro-occresol-chlorocarbonic acid ester of boiling point ₁ -, 13 ^ ⁰ C. The monochlorochlorocarbonic acid ester is again in the chlorination recycled. The yield of dichlorocresol chlorocarbonate is 98 % of theory.

For hydrolysis, 700 parts of dichlorocresolchlorocarbonate in 2,800 parts of water at room temperature are allowed to run in with stirring, the mixture also heating. Subsequently, keeping the hydrolysis mixture a further 2 hours under stirring Bol 90 ⁰ C, the port passage of the hydrolysis by titration of the resulting chloride anions is controlled. It is then heated to boiling, an azeotrope of saicylaldehyde / waaaer distilling off, and separates the organic layer which separates out as the lower, dry layer

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In an organic layer with anhydrous calcium chloride, 330 parts (92.5 % of theory) of salicylaldehyde at 196 ^° C. are obtained.

The chlorocarbonic acid o-cresol used as starting material is prepared as follows: 56O parts of phosgene are introduced into a mixture of 2,000 parts by volume of toluene and 540 parts of o-cresol in a stirred tank with a capacity of 4,000 parts by volume. 640 parts of dimethylaniline are then added to the reaction mixture at temperatures between 10 and 25 ° C. with cooling. After completion of the addition, the reaction mixture is maintained for 1 hour at ¹ IO ⁰ C and then the excess phosgene is blown with nitrogen. The reaction mixture obtained is washed twice with 500 parts of water each time. Sodium hydroxide solution is added to the washing water until it has an alkaline reaction and the dimethylaniline is recovered, which can be used for further reactions. The toluene is first distilled off from the organic layer and the residue is then distilled in vacuo. Is obtained (98% of theory) of o-cresol chlorkohlensäureester, bp ₁₁ 84 ° C 836 parts.

Example 2

In 830 parts of p-cresol-chlorocarbonic acid ester, which has been prepared according to the manner described in paragraph 3 of this example, chlorine is passed in at 135 ° C. under irradiation with ultraviolet light until 270 parts of chlorine have been absorbed. After rectification under vacuum, as a flow of 365 parts of p-cresol Monochlorchlorkohlensäureester, bp ₁ - 144 ⁰ C and 56 ⁰ C and Fp as the main fraction, 700 parts of dichloro-p-kresolchlorkohlensäureester.. The monochlorochlorocarbonic acid ester is returned to the chlorination. The yield of dichlorochlorocarbonic acid ester is 9-7 % of theory.

For hydrolysis, 700 parts of dichloro-p-cresolchlorocarbonic acid ester are run into 2350 parts of 20% strength by weight aqueous sodium hydroxide solution at room temperature with stirring. The reaction mixture is heated to 90 to 100 ^° C. for 2 hours and about 20 parts are filtered

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Polymer products. The piltrate is then acidified to a pH of 6.8 and, after cooling, the precipitated p-hydroxybenzaldehyde is separated off from the aqueous layer by filtration. 330 parts (92.5 % of theory) of very pure, p-hydroxybenzaldehyde with a mp. 116 ° C. are obtained. Further acidification to a pH of 4 results in 5 parts of p-hydroxybenzoic acid.

560 parts of phosgene are passed in to a mixture of 2,000 parts by volume of toluene and 450 parts of p-cresol in a 4,000 parts by volume stirred tank and 640 parts of dimethyl aniline are then run in at 25 ° C. with cooling. The reaction mixture is then kept at 40 ° C. for 2 hours and the excess phosgene is blown out with the aid of nitrogen. It is washed twice with 500 parts of water each time. Sodium hydroxide solution is added to the washing water until it has an alkaline reaction, and the dimethyl aniline is recovered. By rectification of the organic layer to obtain 830 parts of p-cresol chlorkohlensäureester from Kp _1-92 C, corresponding to a yield of 97.4% of theory.

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Claims (1)

- 9 - O.Z. 26th Claim Process for the production of aromatic hydroxyaldehydes the general formula HO OH characterized in that aromatic methylchlorocarbonic acid esters of the general formula are first used CH ₃ II OCOCl to aromatic dichloromethylchlorocarbonic acid esters of the general Pormel HCl ₂ III COCOCl chlorinated and the dichloromethylchlorocarbonic acid ester obtained III hydrolyzed to the aromatic Hydroxyalelehyden I. Badische Anilin- & Soda-Fabrik AG 009847/1892