DE2344925C3 - Process for the preparation of 3-halophenols and 3,5-dihalophenols - Google Patents

Description

in which

a) R is an OH group

X is a chlorine or bromine atom

R ', R ² .

R ³ , R ^4, independently of one another, denote a hydrogen, chlorine or bromine atom, an alkyl, aralkyl, aryl, alkoxy, aryloxy, alkylmercapto or dialkylaminomethyl radical, where at least one of the radicals R ¹ , R ² or R ^{4 is} a chlorine or bromine atom and where the radical R ^{3 can} also mean a hydroxyl group and, in the case of the preparation of 3,5-dihalophenols, represents exclusively a chlorine or bromine atom, or

b) R together with R ¹ the remainder

-0-CH ₂ -O-CH ₂ -

means,

where daii phenol-oxygen atom for

R stands, and

X, R ² ,

R ³ , R ⁴ independently of one another represent a hydrogen, chlorine or bromine atom or an alkyl radical and at least one of the radicals X or R ³ and at least one of the radicals R ² or R ^{4 represent} a chlorine or bromine atom,

Treated in the temperature range of about 100-350 ⁰ C at elevated pressure with hydrogen in the presence of a base and a catalyst, the noble metals of the eighth group of the periodic table and sulfur and / or an inorganic mono- or polysulphide, thiosulphate or rhodanide and / or contains an organic sulfur compound.

by the almost exclusively 3-halo-l-nitrobenzene delivering halogenation of nitrobenzene and subsequent catalytic hydrogenation is obtained (cf. BeUstein's Handbook of Organic Chemistry, 4th Edition, Volume VI, Page 185).

Also the alkaline saponification of corresponding di- and trihalogenobenzenes to the 3-halogen and 3,5-dihalophenols are known, but required the use of di- and tri-halogenobenzenes in one Purity that is difficult to obtain (see L Chemischer Informationsdienst, 1971.B-24-232).

It is also already known to halogenated phenols to hydrogenate catalytically. However, only phenol is obtained (cf. Houben-Weyl, Methods of Organic Chemistry, 4th Edition, Volume V / 4, page 772).

From DE-PS 11 09 701 it is known that alumina impregnated with copper (I) chloride can be obtained from chlorophenols ^{at 490 ° C. in the presence of hydrogen} can remove hydrogenolytically. There is no information about a particular selectivity of the process known

From FR-PS 21 61 861 it is even known that under very similar conditions on one with one Copper salt impregnated carrier in the presence of Hydrogen at 280 to 350 ° C, which is particularly stable for chlorine, which is meta to the hydroxyl group

There has now been a process for the preparation of 3-halophenols or 3,5-dihalophenols by partial

Dehalogenation correspondingly higher halogenated Compounds found by catalytic hydrogenation, which is characterized in that halogen compounds of the general formula

The invention relates to a method of manufacture of 3-halo- and 3,5-dihalophenols by partial enthalogenation of higher halogenated phenols by catalytic hydrogenation.

The previously known manufacturing processes for 3-halophenols and 3,5-dihalophenols are cumbersome and laborious to carry out on an industrial scale expensive.

For example, nan gets 3-halophenol through Diazotization and boiling of 3-halo-aniline, the

in which

a) R is an OH group

X is a chlorine or bromine atom

R ¹ , R ² ,

R ³ , R ^4, independently of one another, denote a hydrogen, chlorine or bromine atom, an alkyl, aralkyl, aryl, alkoxy, aryloxy, alkylmercapto or dialkylaminomethyl radical,

where at least one of the radicals R ¹ , R ² or R ^{4 is} a chlorine or bromine atom and where the radical R ^{3 can} also mean a hydroxyl group and, in the case of the production of 3,5-dihalophenols, represents exclusively a chlorine or bromine atom, or

b) R together with R ¹ the remainder

-0-CH ₂ -O-CH ₂ -

means,

where the phenol-oxygen atom for R

stands, and

X ₁ R ² ,

R ³ , R ^4, independently of one another, denote a hydrogen, chlorine or bromine atom or an alkyl radical and at least one of the radicals X

or R ³ and at least one of the radicals R ² or R ^{4 represent} a ChIo - or bromine atom,

in the temperature range from about 100 to 350 ° C at elevated pressure with hydrogen in the presence of a Base and a catalyst treated, the noble metals of the eighth group of the periodic table as well as sulfur and / or an inorganic mono- or polysulphide, thiosulphate or rhodanide and / or an organic one Contains sulfur compound

Halogens for the radicals X and R ¹ to R ⁴ are chlorine and bromine

As alkyl radicals R ¹ to R ⁴ , straight-chain or branched alkyl radicals with up to 12, preferably up to 6 carbon atoms, as well as cycloaliphatic radicals, preferably those with 5 and 6 carbon atoms in the ring, may be mentioned.

Examples include the methyl, ethyl, propyl, isopropyl and tert-butyl radicals

The benzyl radical and substituted benzyl radicals may be mentioned as aralkyl radicals R ¹ to R ⁴

Possible substituents of the arylalkyl radicals R ¹ to R ⁴ substituted in the aryl nucleus are halogen (fluorine, chlorine, bromine, iodine), preferably chlorine and bromine, the hydroxyl group, straight-chain or branched alkyl radicals with up to 12, preferably up to 6, carbon atoms, cycloaliphatic Residues, preferably with 5 and 6 carbon atoms in the ring, aryl radicals, in particular the phenyl radical

The phenyl radical and substituted phenyl radicals are preferred as aryl radicals R ¹ to R ⁴

Possible substituents on the aryl radicals R ¹ to R ⁴ are halogen (fluorine, chlorine, bromine, iodine), preferably chlorine and bromine, the hydroxyl group, straight-chain or branched alkyl radicals with up to 12, preferably up to 6 carbon atoms, cycloaliphatic radicals, preferably with 5 and 6 carbon atoms in the ring, aryl radicals, in particular the phenyl radical.

Alkoxy and alkyl mercapto radicals R ¹ to R ⁴ include straight-chain or branched radicals with up to 12, preferably up to 6 carbon atoms, as well as cycloaliphatic radicals, preferably those with 5 and 6 carbon atoms in the ring.

The phenoxy radical and substituted phenoxy radicals are preferred as aryloxy radicals

As substituents of the aryloxy radicals R ¹ to R ⁴ , halogen (fluorine, chlorine, bromine, iodine), preferably chlorine and bromine, the hydroxyl group, straight-chain or branched alkyl radicals with up to 12, preferably up to 6 carbon atoms, cycloaliphatic radicals, are preferred with 5 and 6 carbon atoms in the ring, aryl radicals, in particular the phenyl radical.

Dialkylamino-methyl radicals R ¹ to R ⁴ include radicals with straight-chain or branched alkyl groups with up to 12, preferably up to 6 carbon atoms, as well as cycloaliphatic radicals, preferably those with 5 and 6 carbon atoms in the ring, and the two alkyl groups also be part of a ring.

In the hydrogenation of polyhalophenols with dialkylaminomethyl radicals, in addition to the partial and selective dehalogenation also eliminates dialkylamine. One arrives at this Way to the corresponding methyl-m-halogen-phe- es nolen.

The compounds of the above general formula are known and easily accessible. as such compounds which can be used for the process according to the invention are, for example called:

23-, 23-, 3,4-dihalophenols; 2,3,4-, 23,6-, 2,4,5-, 2,3,5- and 3,4,5-trihalophenols; 23,4,6-, 23,4,5-, 23,5,6-tetrahalophenols, where "halogen" stands for

Chlorine or bromine, pentachlorophenol ^ -Bromo-S-chlorophenol, 3-bromo-4-chloro-phenol, 3-bromo-2-chloro-phenol, 2-bromo-5-chloro-phenol, 5-bromine- 2-chlorophenol, 4-bromo-3-chlorophenol, 4-bromo-2,5-dichlorophenol, 4-chloro-23,6-tribromophenol, 4,5,6-trichloro-o- cresol, 5,6-dichloro-o-cresol, 2,4,5,6-tetrachloro-m-cresol, 2,4,5,6-tetrabromo-m-cresol, 2,5-dibromo-p-cresol, 2,5-dichloro-p-cresol, 23,5,6-tetrachlor-p-cresol, 6-chloro-24-dibromo-p-cresol, 23,6-tribromo-p-cresol, 23,5,6- Tetrabromo-p-cresol, 2 £ -dichloro- [3,4] -xylenol, 2,5,6-tribromo- [3,4] -xylenol, 4-chloro 3-bromo- [2,6] -xylenol, 3,4-dibromo- [2,6] -xylenol, 3,5-dibromo-4-chloro- [2,6] -xylenol, 3,4,5-tribromo- [2,6] -xylenol, 3, 4,6-tribromo [2,5] -xylenol, 2,5-dichloro-4-ethyl-phenol, 2,5-dichloro-4-propyl-phenol, 2,5-dichloro-4-tert-butyl- phenol, tetrachloro-resorcinol, 3,4,6-trichloro-2-benzyl-phenol, 2,2'-dihydroxy-3,5 _> 63 ', 5', 6'-hexachlorodiphenylmethane,

3,4 ^ -Trichlor-2-hydroxy-diphenyl, 4,4'-dihydroxy-octachlor-diphenyl, 3,4-dichloro-guaiacol, 3,6-dichloro-guaiacol, 4,5-dichloro-guaiacol, 5, 6-dichloro-guaiacol, 3,4,6-trichloro-guaiacol, 3,4,5-trichloro-guaiacol, 3,4,5,6-tetrachloro-guaiacol, 44-dichloro-3-methoxyphenol, S. ö-dichloro-S-methoxyphenol, 2,5-dichloro-3-methoxyphenol, 4,5,6-trichloro-3-methoxyphenol, 2,4,5,6-tetrachloro-3-methoxy- phenol, 23-dichloro-4-methoxyphenol, 2 ^ -dichloro-4-methoxyphenol, 23,6-trichloro-4-methoxyphenol, 23> 5-trichloro-4-methoxyphenol, 23.5.6 -Tetrachlor-4-methoxyphenol, 4,5-dichloro-2-phenoxyphenol _> S ^ Äö-tetrachlor ^ -phenoxyphenol, 2,4,5,6-TetΓachloΓ-3-phenoxyphenol _> 2, 5-dichloro-4-phenoxyphenol, 2,3,5,6-tetrachlor-4-phenoxyphenol, ^ S-dichlorom-methylmercapto-phenol, 2,4,5,6-tetrachlor-4-methylmercapto-phenol ₎ 2- (dimethylamino-methyl) -3,6-dichloro-phenol, 4- (dimethylamino-methyl) -2,5-dichloro-phenol, 2- (dimethylamino-methyl) -3,4,6-trichloro-phenol , 2,4-bis (dimethylamino-methyl) -3,6-dichlorophenol,

2,4-bis (dipiperidylamino-methyl) -

3,6-dichlorophenol, 5,6-dichloro-1,3-benzodioxane, S ^ -Dichlor-l ^ -benzodioxane, S ^ .e-TricWor-l ^ -benzodioxane, S.e-dichloro-e-methyl-benzodioxane, S. e-dichloro-e-methyl-benzodioxane.

The catalysts that can be used for the process according to the invention consist of as Hydrogenation catalysts known noble metals of Group VIII of the Periodic Table of the Elements (See L. K. A. Hoffmann and U. R. Hoffmann, Inorganic Chemie, 12th edition, Braunschweig 1948, page 380) in the form of their metals, oxides and sulfides and sulfur and / or sulfur compounds. As Group VIII noble metals, which are in the form of their metals, oxides and Sulfides that can be used include, for example, ruthenium, rhodium, palladium, osmium, and iridium Called platinum; palladium and platinum are preferably used

Both inorganic sulfur compounds, namely mono- and Polysulfides, thiosulfates and rhodanides, as well as organic sulfur compounds in question. You can be both soluble and sparingly soluble or insoluble in water and solvents. In general however, sparingly soluble or insoluble sulfur compounds are preferred

Preferred inorganic sulfur compounds are mono- and polysulfides, for example water-soluble such as sodium sulphide and potassium sulphide and poorly soluble ones such as calcium sulphide, manganese sulphide, iron sulphide, cobalt sulphide, nickel sulphide, copper sulphide, silver sulphide, cadmium sulphide, antimony sulphide, lead sulphide.

As organic sulfur compounds are, for example, thioalcohols, thiophenols, thioaldehydes and Called thioketones; Of course, the corresponding anions or salts such as sodium thioethylate and silver thioethylate can also be used. Likewise is the use of organic sulfur compounds not falling under the aforementioned groups such as Carbon disulfide, thiourea, possible.

The ratio of sulfur and / or sulfur compound to Group VIII noble metal is im generally 0.5 to 30, preferably 1 to 15, in particular 2 to 5 mol of sulfur and / or sulfur compound each Moles of precious metal, oxide or sulfide.

The catalysts used according to the invention can of course also be applied to support materials. All carrier materials known per se are suitable for this, provided they are inert to bases and water. Examples of these are BaSO ₄ , Ca ₃ (PO ₄ ^, coal.

Activated carbon is preferably used as the carrier material

The catalysts used according to the invention can be prepared in various ways:

In general it is not necessary to use the noble metal, oxide or sulfide and the sulfur and / or the sulfur compound even before its use as a catalyst in the invention To live together process, you can do them in each case of the reaction mixture before the start of the reaction to add. It can be particularly useful for continuous implementation of the process according to the invention It may be advantageous to arrange the noble metal, oxide or sulfide optionally on an inert support in the reaction space as a fixed bed or fluidized bed catalyst and with sulfur and / or sulfur compound to continuously add to the starting material and / or hydrogen or separately. However, it can also be expedient to add sulfur and / or sulfur compounds to the noble metal or oxide or to add sulfide before use and, if necessary, to mix the components intimately. However, this can also be used advantageously

ίο Precious metal or oxide already applied to a carrier slurry or sulfide in the aqueous solution of a corresponding water-soluble metal salt and by adding sulfide or polysulfide ions, for example by introducing hydrogen sulfide or adding a water-soluble sulfide, or by Addition of an organic compound containing the mercapto group the sulfur compound, e.g. B. the metal sulfide, polysulfide or mercaptide, on the metal sulfide, possibly already applied to a carrier

Precipitate precious metal oxide or sulphide.

In general, all water-soluble metal salts are suitable for this type of preparation, e.g. B. halides, Nitrates, sulfates, salts, organic acids such as oxalates, acetates; however, readily available salts such as

Chlorides, nitrates, sulfates preferred

As the mercapto group-containing organic compounds are, for. B. thio alcohols such as thioethanol, Called thiophenols and thio- and dithiocarboxylic acids; of course, their water-soluble borrowed salts such as alkali salts can be used.

In general, it is useful to prepare the catalyst used according to the invention, non-volatile and / or insoluble sulfur compounds, in particular to use insoluble sulfides. the keep catalysts used according to the invention then also with repeated repeated use in the method according to the invention and when the method according to the invention is carried out continuously over a long period of time their activity and selectivity and result in consistently high yields of 3-halogen and 3,5-dihalophenol.

When using volatile and / or soluble sulfur compounds for the production of the invention The catalyst used can be the catalyst Reuse in a new approach or at continuous implementation of the process according to the invention after some time a decrease in its Show activity and selectivity. It can therefore be advantageous to use a catalyst that has already been used

so before using again sulfur and / or To add sulfur compound. When the process according to the invention is carried out continuously, it is in this case, advantageously small amounts of sulfur and / or sulfur compound as described above ben continuously inflicting.

The amount of the catalyst used according to the invention is not a critical variable for the process according to the invention. It can be varied within wide limits will. In general it is 0.1-2% by weight, based on the raw material used. at Use of a supported catalyst is a correspondingly larger amount Supported catalyst generally uses about 1-20% by weight, based on the starting material used material.

The process according to the invention is generally carried out at temperatures from about 100 to about 350 ° C, preferably between about 180 and 330 ° C carried out.

Because of the vapor pressure of the compounds to be hydrogenated and the solvent used, if any, at these temperatures, one works at increased pressure. In general, a hydrogen pressure between 20 and 250 atmospheres, preferably between 40 and 220, in particular between 50 and 200 atmospheres. The response time generally depends on the Reaction temperature in such a way that with increased reaction temperature and speed for the same Sales a shorter reaction time is necessary. Because of this dependency, the response time not generally stated, however, exceeding the necessary reaction time does not affect

10

the selectivity of the dehalogenation nor the yield as a result of further undesired dehalogenation.

In general, the process according to the invention is carried out in solution. Come as a solvent all solvents which are inert under the reaction conditions are suitable. Preference is given to water, and polyhydric alcohols and mixtures of the aforementioned solvents.

The process according to the invention can be carried out using the following reaction equation for the dehalogenation of 2,4,5-trichlorophenol to 3-chlorophenol are explained:

2H ₂

(Catalyst)

2 HCl

Since hydrogen halide is formed in the reaction according to the invention, the is already before the reaction A base is added to the starting mixture as hydrogen halide acceptor Bases suitable for hydrogen halide acceptors are used. Preference is given to tertiary amines, anilines, Pyridine, as well as the hydroxides, carbonates, hydrogen carbonates and acetates of the alkali metals, especially des Sodium and potassium and the alkaline earth metals, especially calcium hydroxide, are used The amount of base used is generally chosen so that per halogen atom of the starting compound, that is not in the 3 or 5 position to the OH group one equivalent of base is used. It can however, an excess of base beyond this ratio can also be used.

In general, the process is carried out in such a way that the starting material, solvent and hydrogen halide acceptor are placed in an autoclave, the catalyst is added and, after the autoclave has been closed, the air is flushed out with nitrogen and the reaction is carried out at the selected temperature. After the reaction has ended, the 3-halogen or 3,5-dihalo-phenol is dissolved or kept in solution as phenolate by adding alkali metal hydroxide and the catalyst, e.g. B. by ritration, separated. The work-up of the catalyst-free solution is carried out in a manner known per se, for. B. by acidification with a mineral acid, e.g. B. concentrated hydrochloric acid, shaking out the 3-halo or 3,5-dihalo-phenol with an organic solvent, for. B. methylene chloride, and subsequent work-up of the organic phase, for example by ₆₀ fractional distillation.

The process according to the invention can be carried out either batchwise or continuously will. The continuous implementation of the process according to the invention can be particularly advantageous. The necessary equipment configuration as Fixed bed or fluidized bed catalyst process is necessary as is the continuous feed the starting and auxiliary materials and the continuous isolation of the reaction product from the Reaction mixture according to the prior art is possible and known per se (cf., for example, DE-PS 9 48 784).

The surprising advantage of the process according to the invention is that it allows the selective dehalogenation of corresponding more highly halogenated phenols Makes 3-halo- or 3,5-dihalophenol possible in a simple manner by catalytic hydrogenation

Another advantage of the process according to the invention is that mixtures can also be used as the starting material can be used which, in addition to the compounds of general formula I, further halogen or Contain polyhalophenols in which no halogen is in the 3- or 5-position to the OH group In the process according to the invention, compounds are dehalogenated to phenol, which is easily distilled On the other hand, the separation of the corresponding halophenols from the compounds of the general formula I where R is OH cumbersome and tedious (see e.g. DE-AS 15 43 367).

The 3-halo and 3,5-dihalo-phenols, which according to can be prepared by the process according to the invention, correspond to the general formula II

(Π)

OH

in which

X represents chlorine or bromine

R ⁵ , R ⁶ ,

R ⁷ and R ⁸ independently represent hydrogen, an alkyl, aralkyl, aryl, alkoxy, aryloxy or alkylmercapto radical, at least one of the radicals R ^s , R ⁶ and R ^{8 being} hydrogen and where the Remainder R ⁷

can also stand for a hydroxyl group and in the case of 3,5-dihalophenols represents exclusively a chlorine or bromine atom.

Examples of halophenols that can be obtained by the process according to the invention are:

3-bromo-phenol, 3-chloro-phenol, 3,5-dichloro-phenoUi-chloro-o-cresol, S-chlorine-m-cresol, S-bromo-p-cresol, 3-chloro-p-cresol, 3,5 dichloro-p-cresol, 3-bromo-p-cresol, 3.5 "dibromo-p-cresol,

S-Brom- ^ S-xylenoi.ci-ChloM-äthyl-phenoi, S-ChloM-propyl-phenol, 3-chloro-4-tert-butylphenol, 5-chloro-resorcinol, 3-chloro-2-benzyl-phenol, 2 ^ '- dihydroxy-6,6'-dichloro-diphenylmethane, 4-chloro-2-hydroxy-diphenyl, 4,4'-dihydroxy-2,6,2 ', 6'-tetrachlorodiphenyl, S-chlorine-guajacoLS-chlorine-guajacol, S.S-dichloro-guaiacol, S-chloro-S-methoxy-phenol, S-ChloM-methoxy-p-henol, 3,5-dichloro-4-methoxyphenol, 3-chloro-2-phenoxy-p: ienol, 5-chloro-2-phenoxyphenol, 3,5-dichloro-2-phenoj: y-phenol, S-chloro-S-phenoxy-phenol, 3-chloro-4-phenoxy-phenol, ilh

3,5-dichloro-4-methyl mercapto-phenol.

3-halophenols and 3,5-dihalophenols are known Intermediate products and are used in particular for the production of pesticides (DE-PS 9 21 870, 16 656.8 14 152) use.

Examples

A) Preparation of the catalyst Examples 1 to 12

g of about 5gewichtsprozentigen noble metal charcoal (= 0.005 mole of metal) are added to the solution of a 3fsch ir.ciarcrs amount of a water-soluble metal salt, based on the amount of noble metal, in ml of water and heated with stirring at 8O ⁰ C under a protective gas atmosphere (nitrogen) will g Na ₂ S -3 H ₂ O (= 0.015 Mo mol S), dissolved in 30 ml water, slowly added dropwise

After the addition has ended, the mixture is ^{stirred at 80 °} C. for a further 30 minutes. The catalyst is then filtered off with suction and washed thoroughly with distilled water until free from sulfide. The following table gives individual examples for the preparation of the catalyst according to the above general procedure; the example number is in column 1, the noble metal of the noble metal activated carbon in column 2 and in column Amount and type of the metal salt mentioned above called:

Table I. example

Eidelmetall metal salt

1 Pd 4.2 g FeSO ₄ -7 H ₂ O

2 Pd 4.2 g CoSO ₄ -7 H ₂ O

3 Pd 3.6 g NiCl ₂ -6 H ₂ O

4 Pd 3.0 g MnCl ₂ -4 H ₂ O

5 Pd 5.7 g Pb (CH ₃ COO) ₂ • 3 H ₂ O

6 Pd 2.56 g AgNO ₃

7 Pd 3.75 g CuSO ₄ · 5 H ₂ O

8 Pd 3 g CdCl ₂ H ₂ O

9 Pt 4.2 g FeSO ₄ -7 H ₂ O

10 Pt 2.56gAgNO ₃

11 Ru 4.2 g FeSO ₄ -7 H ₂ O

12 Rh 4.2 g FeSO ₄ -7 H ₂ O

Example 13

Analogously to Example 1, 10 g of an approximately 5 percent by weight palladium-activated carbon (= 0.005 mol of palladium) are added to the solution of 4.2 g of FeSO ₄ · 7 H ₂ O in 200 ml Added water and heated with stirring at 8O ⁰ C under a protective gas atmosphere (nitrogen), 2.14 g of Na ₂ S 3, dissolved in 30 ml of water was slowly added dropwise Upon complete addition, for another 30 minutes at 80 ° C. Then the catalyst is filtered off with suction and washed well with distilled water free of sulfide.

Examples 14-21

The following examples indicate the preparation of catalysts, which is carried out by simply adding together noble metal and sulfur or sulfur compound, the two components being both before addition to the hydrogenating substance or its solution as well as only in this combined can be. 10 g of an approximately 5 percent by weight precious metal activated carbon (= 0.005 Mol of metal), the amount of sulfur or sulfur compound indicated in Table II below (corresponding to 0.015 mol of sulfur) was added.

In the table are example no, precious metal the Precious metal activated carbon, amount and type of sulfur compound specified.

Example 22

In a solution of 4.2 g FeSO ₄ · 7 H ₂ O in 200 ml of water, 10 g of an approximately 5 weight percent palladium sulfide activated carbon are added and heated to 80 ° C. with stirring. Under a protective gas atmosphere (nitrogen), a solution of 2 g of Na ₂ S ■ 3 H ₂ O in

Table II Precious metal G Sulfur or H
■ j 50 example -link No. Pd 2.6 Sb ₂ S ₃ 14th Pd 1.0 Na ₂ S • 3 H ₂ O i 15th Pd 1.08 CaS 1 ⁵⁵ 16 Pd 0.5 S. I. 17th Pd 1.15 CS ₂ I. 18th Pd 1.25 NaS ■ C ₂ H ₅ I. 19th Pd 2.53 AgS · C ₂ H ₅ 20th Pt 1.0 Na ₂ S · 3 H ₂ O 60 ₂₁

30 ml of water were slowly added dropwise. After the addition has ended, the mixture is ^{stirred at 80 °} C. for a further 30 minutes. The catalyst is then filtered off with suction and washed thoroughly free of sulfide with distilled water.

example

In a solution of 4.2 FeSO ₄ · 7 H ₂ O g, 10 g of about 5gewichtsprozentigen platinum sulfide-carbon was added and heated with stirring to 80 ⁰ C in 200 ml of water. _{A solution of 2 g of Na 2} S · 3 H ₂ O in 30 ml of water is slowly added dropwise under a protective gas atmosphere (nitrogen). Upon complete addition, stirring is continued for 30 minutes at 8O ⁰ C. The catalyst is then filtered off with suction and washed thoroughly free of sulfide with distilled water.

example

In a solution of 4.2 FeSO ₄ · 7 H ₂ O g, 10 g of about 5gewichtsprozentigen palladium-activated carbon was added and heated with stirring to 80 ⁰ C in 200 ml of water. _{A solution of 2 g of Na 2} S · 3 H ₂ O in 30 ml of water is slowly added dropwise under a protective gas atmosphere (nitrogen). Upon complete addition, stirring is continued for 30 minutes at 8O ⁰ C. The catalyst is then filtered off with suction and washed thoroughly free of sulfide with distilled water.

B) Process examples Example

In a 0.7-1 hydrogenation autoclave (stirred autoclave) 81 g of 2,5-dichlorophenol (0.5 mol), 22 g of NaOH (0.55 mol) and 240 ml of water are introduced. 10 g of the after Example 1 prepared catalyst are added.

The autoclave is closed; the air is purged with nitrogen and then the nitrogen with hydrogen. The mixture is then ^{heated to 260 °} C. and hydrogenated for 15 minutes at a hydrogen pressure of about 40-60 atm. When the hydrogenation is complete, 30 ml of concentrated sodium hydroxide solution (~ 0.5 mol) are added to the reaction mixture. The reaction mixture is stirred briefly and vigorously and the catalyst from the liquid reaction mixture

ίο sucked off. The catalyst is (60-70 ⁰ C) is washed with warm 300-400ml water and can then be reused. The reaction solution obtained as a filtrate is cooled and acidified at room temperature with 70 ml of concentrated hydrochloric acid (~ 0.8 mol of HCl). The aqueous mixture is extracted with about 150 ml of methylene chloride in several portions. The organic phases obtained are combined and dried _{over Na 2} SO ₄
The solvent (methylene chloride) is then distilled off and the remaining liquid residue is distilled at about 100 ° C./10 Torr. 61.5 g of 3-chlorophenol (= 96.4% of theory) are obtained. The gas chromatographic analysis showed:

99.36% 3-chlorophenol
0.08% 2,5-dichlorophenol
0.55% phenol

Examples 26-46

The results of Examples 26-46 are listed in Table III below, which are analogous to Example 25, however, changing the hydrogenation time and temperature.

Table III

example
No.

Time min

temperature yield analysis % 2,5-DCP % P C. % of theory % 3-CP 17.0 0.20 230 79 82.7 5.1 0.33 240 85 94.5 - 0.09 0.68 250 90 99.2 0.17 0.65 260 90 99.2 20.1 0.12 220 73 79.6 1.2 0.48 230 90 98.1 0.39 0.74 240 92 98.4 0.31 1.31 250 91 97.9 - 1.24 260 87 98.8 16.7 0.40 200 73 82.3 2.5 0.23 210 91 96.1 0.59 0.53 220 92 98.8 0.07 3.4 230 88 96.5 0.98 1.4 240 88 96.2 0.02 1.6 250 86 97.0 0.30 2.5 260 87 97.2 0.10 1.15 220 91 98.7 0.15 2.9 230 85 96.9 - 3.7 240 89 96.3 - 5.6 250 85 94.4 _ 9.8 260 76 90.2

% 2 CP

26th
27
28
29
30th
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46

30th

30th

30th

30th

60

60

60

60

60

120

120

120

120

120

120

120

240

240

240

240

240 0.10
0.08

0.07
0.03

0.43

0.49
0.03
0.02

0.41

In Table IV above and in the following tables are the analysis results the following abbreviations are used:

3-CP = 3-chloro-phenol 2,5-DCP = 2,5-dichloro-phenol P = phenol

2-CP = 2-chloro-phenol

Examples 47-49

According to the procedure in Example 25, 81 g of 2,5-dichlorophenol, 22 g of NaOH and a mixture are obtained of 120 ml of water and 120 ml of methanol at a hydrogen pressure of 80-90 atü 120 minutes at the in the temperature given in Table IV below. After the hydrogenation and separation

Table IV

Using the catalyst, the methanol is distilled off from the reaction solution. The further work-up the aqueous solution is carried out as described in Example 25 is. In the table below are the results obtained summarized.

example

Time
min

temperature
C.

Yield% of theory

Analysis% 3-CP% 2.5-CP

% P

% 2 CP

47 120 210 83 85.2 13.4 0.34 0.07 48 120 220 87.5 96.8 2.8 0.45 0.04 49 120 230 94 98.9 0.4 0.60 0.02

Examples 50-52

According to Example 25, 81 g of 2,5-dichlorophenol and 240 ml of water are placed in the 0.7-1 hydrogenation autoclave Filled in, but different amounts of sodium hydroxide indicated in Table VI below are used added It is hydrogenated at 230 ° C. and a hydrogen pressure of 80 to 90 atmospheres for 120 minutes When the hydrogenation is complete, 30 ml of concentrated sodium hydroxide solution are added to the reaction mixture and the Reaction mixture stirred briefly and vigorously. Then the catalyst is suction-filtered from the liquid reaction mixture with 300 to 400 ml warm Water (approx. 60 to 70 "C); it can then be used again.

The reaction solution obtained as a filtrate is cooled and at room temperature with 70 ml acidified with concentrated hydrochloric acid. The aqueous mixture is with about 150 ml of methylene chloride in shaken out several portions. The organic phases that arise are cleaned and dried over Na2SC> 4 Then the solvent is distilled off and the remaining residue at about 100 ° C / 10 Torr distilled Table V below shows: Example No., amount used Sodium hydroxide, the yield obtained and its composition according to gas chromatographic analysis.

Table V example

NaOH

yield

% 3-CP% 2,5-DCP

% P

% 2 CP

50 • 30.0 91.5 94.8 1.6 3.5 0.05 51 22.0 93 96.5 0.07 3.4 0 52 18.0 92 93.7 5.2 0.95 0.20

Examples 53-75

81 g of 2 ^ -Dichlorphenol 1 -24 prepared catalyst were respectively 22 g NaOH hydrogenated in a mixture of 120 ml of water and 120 ml of glycol at 230 ⁰ C in these examples were as catalyst 10 g each of the examples used according to the currently selected hydrogenation is specified in the table below. The glycolic aqueous solution is worked up as described in Example 25. The results of the examples are summarized in the table below

Table VI

16

example

catalyst according to Example no.

Time min

yield

g% of theory % 3-CP

% 2.5-CP

% P

% 2 CP

53 1 120 89.5 54 2 120 88 55 3 120 65 56 4th 120 65 57 5 120 80 58 6th 70 88 59 7th 120 88 60 8th 120 83 61 9 90 90 62 11th 120 78 63 12th 90 93 64 13th 120 85 65 14th 120 87 66 15th 120 80 67 16 120 91 68 17th 80 93 69 18th 60 89 70 19th 120 80 71 20th 120 93.5 72 21 120 90 73 22nd 120 84 74 23 120 91.5 75 24 120 86.5 Example 76

Analogously to Example 25, 98.7 g (0.5 mol) of 2,4,5-trichlorophenol, 22 g (0.55 mol) of NaOH and 40 g (0.4 mol ) Na ₂ CO ₃ , 240 ml of water and the contact prepared according to Example 1 are given. It is hydrogenated for 2 hours at 230 ^° C. and 60 atmospheres of hydrogen. When the hydrogenation has ended, the aqueous solution is worked up as described in Example 25.

57 g of distillate with the following composition are obtained:

2-chloro-phenol 0.01% phenol 1.23% 2,5-dichlorophenol 0.02% 3-chloro-phenol 98.24%

The yield of 3-chloro-phenol obtained in this way corresponds to 87% of theory.

Example 77

Analogously to Example 25, 52 g (0.3 mol) of 2,5-dibromophenol, 25 g (0.3 mol) of NaHCO ₃ and 300 ml of water and 10 g of the substance according to Example 10 are added to a 0.7-1 hydrogenation autoclave given catalyst prepared. It is hydrogenated for 11/2 hours at 190 ^° C. and 150 atm. Hydrogen pressure.

After the hydrogenation has ended, 30 ml of concentrated sodium hydroxide solution are added to the reaction mixture, stirred briefly and vigorously and then sucked off the catalyst. The filtrate is cooled and 99.1 93.3 74.3 74.5 84.4 98.1 99.1 90.0 98.5 87.0 96.4 99.3 94.8 98.0 98.4 98.4 98.5 90.7 98.4 99.6 92.5 99.7 98.3

acidified with 70 ml of concentrated hydrochloric acid. This aqueous mixture is extracted by shaking with a total of about 150 ml of methylene chloride in several portions. The organic phases are each separated off, combined and dried over Na2SO4. The methylene chloride is distilled off from the dry organic phase and the remaining liquid residue is distilled in vacuo at about 110 ^° C. and 10 torr. 34.0 g of distillate with the following composition are obtained:

2-bromo-phenol 0.39%

Phenol 4.31 o / o

2,5-dibromophenol 0.04%

3-bromo-phenol 95.25%

The yield of 3-bromo-phenol corresponds to 91% of the

Theory.

example

55 g (0.15 mol) of 2,3,6-tribromo-4-chlorophenol, 42 g (0.5 mol) of NaHCO ₃ and 3IX) ml of water are mixed with 10 g of the catalyst prepared according to Example 10 in a 0 , 7-liter hydrogenation autoclave and hydrogenated analogously to the example at 200 ⁰ C and 150 atm hydrogen pressure for about ¹ 1/2 hours. Working up is carried out as described in Example 25. 17 g of distillate are obtained with the following composition:

0.50 0.38 0.22 0.08 5.14 0.07 5.8 15.0 - 6.2 13.2 6.0 15.2 0.23 0.10 0.80 0.83 0.07 0.10 0.73 - 2.0 5.7 0.60 1.33 - - 2.8 9.9 0.21 2.5 1.0 0.13 0.54 0.19 - 4.4 0.40 0.10 0.10 1.9 0.03 1.03 1.6 - 0.60 0.70 - 0.56 0.25 - 0.46 7.1 0.41 0.03 0.5 - 0.02 0.35 - 3.6 3.5 0.40 0.08 0.2 - track 1.7 -

phenol 4-chloro-phenol 3-bromo-phenol

23.2%

9.1%

67.95%

130 219/138

Example 79

Analogously to Example 25, 59 g (033 mol) of 3,4-dichloro-6-methyl-phenol, 15 g (0375 mol) of NaOH and 300 ml of water with the catalyst prepared according to Example 1 are introduced into a 0.7-1 hydrogenation autoclave and 30 minutes at 25O ⁰ C and 100 atm hydrogen pressure hydrogenated Working up is effected as described in example 25th

43 g of distillate are obtained with the following composition:

2-cresol 1.41% by weight

3-chloro-6-methyl-phenol 98.59% by weight

The yield of 3-chloro-6-methyl-phenol corresponds to 90% of theory. M.p .: 73-74 ° C (ligroin).

Example 80

Analogously to Example 25, 35.5 g (0.16 mol) of 2,5-dichloro-4-tert-butyl-phenol with 7.1 g (0.18 mol) of NaOH in 300 ml of water are applied to the catalyst prepared according to Example 1 hydrogenated for 30 minutes at 24O ⁰ C and 100 atm hydrogen pressure The working up is effected as described in example 25th

25.5 g of distillate are obtained with the following composition:

4-tert-butyl-phenol 12%

3-chloro-4-tert-butyl-phenol 833%

2,5-dichloro-4-tert-butyl-

phenol 4.7%

The yield of 3-chloro-4-tert-butyl-phenol is 72% of theory. Mp: 65-66 ° C (petroleum ether).

Example 81

Analogously to Example 25, 133 g (0.5 mol) of pentachlorophenol are hydrogenated in a solution of 105 g (1 mol) of Na ₂ CO ₃ in 220 ml of water with the catalyst prepared according to Example 1 for 25 minutes at 260 ° C. and 150 atm. Hydrogen pressure Work-up is carried out as described in Example 25.

67 g of distillate with the following composition are obtained:

2-chloro-phenol 0.27% phenol 0.31% 2,4-dichlorophenol 0.46% 3-chloro-phenol 10.94% 3,5-dichloro-phenol 88.02%

The yield of 3,5-dichlorophenol isolated by distillation is 75% of theory.

Example 82

32 g (0.13 mole) of tetrachloro-resorcinol ₃ and 300 ml of water with the product prepared according to Example 10 catalyst IV2 hours at 180 ⁰ C and 150 atm hydrogen hydrogenated in a solution of 42 g (0.5 mole) NaHCO Pressure After filtering off the catalyst, the reaction solution is evaporated to dryness. The solid residue is sublimed and gives 7 g (27% of theory) of pure 5-chloro-resorcinol. Mp: 115-116 ° C.

Example 83

40 g (0.087 mole) of 4,4'-dihydroxy-diphenyl-octachloro in a solution of 29 g (0.35 mol) of NaHCO ₃ and 300 ml of water with the catalyst prepared in Example 1 for 10 minutes at 270 ⁰ C and 150 Hydrogenated at hydrogen pressure. Working up is carried out as described in Example 25.

The remaining residue is recrystallized from diisopropyl ether. There are 21.5 g of pure 4,4'-dihydroxy-2,2'-6,6'-tetrachlorodiphenyl (75% of theory) Obtained mp: 186-187 ° C

Example 84

In a 0.7-1 H. hydrogenation autoclave (stirred autoclave) 60 g of 2,4-bis (dimethylamino) -3,6-dichloro-phenol, 10 g of catalyst from Example 10 and 300 ml of toluene

The autoclave is closed, the air is flushed out with nitrogen and then the nitrogen is flushed out with hydrogen. The mixture is then ^{heated to 200 °} C. and hydrogenated at a hydrogen pressure of 200 atmospheres for 60 minutes The catalyst is suctioned off, the toluene solution is washed with about 300 ml of 2N HCl and then _{dried with Na 2} SO _4. The solvent is distilled off and the residue that remains is distilled -Dimethyl-3- chlorophenol exists, corresponding to a yield of 89% of theory. Melting point 67 to 68 ⁰ C (petroleum ether).

Example 85

Analogously to Example 25, 60 g of 2,4-bis- (dimethylamino-methyl) -3,6-dichloro-phenol, 10 g of catalyst are removed Example 1 and 300 ml of water with a hydrogen pressure of 200 atmospheres for 60 minutes at 150 ° C. The hydrogenated Work-up is carried out as described in Example 25. 24.7 g of crude product are obtained, 8139% of which is from 2,4-Dimethyl-3-chlorophenol exists, corresponding to a yield of 59.5% of theory.

Example 86

Analogously to Example 84, 38 g of 2- (dimethylaminomethyl) -3,4,6-trichloro-phenol, 12 g of pyridine, 10 g of catalyst from Example 1 and 300 ml of toluene are hydrogenated with a hydrogen pressure of 200 atmospheres at 250 ^° C. for 60 minutes The work-up is carried out as in Example 84

AO described. This gives 16 g of crude product which consists of 98.08% 3-chloro-o-cresol, corresponding to a yield of 76% of theory. Melting point: 84 ° C (ligroin).

Example 87

Analogously to Example 84, 22.5 g of 5,6,8-TnChIoM be benzodioxan _S-1, 15 g of pyridine, 6.2 g of catalyst from Example 10 and 200 ml of toluene with a hydrogen pressure of 200 atm for 60 minutes at 28O ⁰ C was hydrogenated Working up is carried out as described in Example 84. This gives 10 g of crude product which consists of 8537% 3-chloro-o-cresol, corresponding to a yield of 63.5% of theory. Melting point 84 ° C (ligroin).

Example 88

Analogously to Example 25, 20 g of tetrachloro-guaiacol, 13 g of NaHCO ₃ , 5 g of catalyst from Example 10 and 240 ml of water are hydrogenated with a hydrogen pressure of 200 atmospheres for 30 minutes at 200.degree. This gives 13.5 g of crude product, which consists of 74% of 3,5-dichloro-guaiacol, corresponding to a yield of 68% of theory. Melting point: 59 to 6O ⁰ C (petroleum ether).

Example 89

Analogously to Example 25, 34 g of 4,5-dichloro-2-phenoxyphenoi, 9 g of NaHCO ₃ , 10 g of catalyst from Example 10 and 300 ml of water are mixed with a water

material pressure of 200 atmospheres hydrogenated at 230 ° C. for 90 minutes. Work-up is carried out as in Example 25 described. 26 g of crude product are obtained in this way 84.5% consists of S-chloro ^ -phenoxy-phenol, accordingly a yield of 74% of theory. Kpi: 130 to 133 ° C.

Example 90

Analogously to Example 25, 42 g of 2,5-dichloro-4-methylmercapto-phenol, 18 g of NaHCO ₃ , 10 g of catalyst from Example 10 and 240 ml of water are hydrogenated at 200 ^° C. for 75 minutes at a hydrogen pressure of 200 atmospheres. Working up is carried out as described in Example 25. 33.2 g of crude product are obtained

The crude product consists of 78.7%, corresponding to a yield of 67.5% of theory, of 3-chloro-4-

methylmercapto-phenol, which, after recrystallization from cyclohexane, has a melting point of 59 to 60 ° C.

Example 91

Analogously to Example 84, 41 g of 2,2'-dihydroxy-3A63 '^', 6'-hexachlorodiphenylmethane are obtained (Hexachlorophene), 33 g of pyridine, 5 g of catalyst from Example 1 and 300 ml of toluene hydrogenated at a hydrogen pressure of 200 atmospheres for 60 minutes at 230 ° C. Work-up is carried out as described in Example 84. 18 g of crude product are obtained

The crude product consists of 813%, corresponding to a yield of 55% of theory, of 2,2'-dihydroxy-6,6'-dichloro-diphenyl-methane, which has a melting point of 176 to 180 ° C after recrystallization from toluene

Claims (1)

Claim: Process for the preparation of 3-halophenols or 3,5-dihalophenols by partial dehalogenation of corresponding more highly halogenated compounds by catalytic hydrogenation, thereby characterized in that one halogen compounds of the general formula