DE4202512A1 - 4,4'-Di:amino:benzhydrol(s) prepn. - by hydrogenation of 4,4'-di:amino:benzophenone(s) in presence of hydrogenation catalyst and acid and/or salt - Google Patents

Abstract

Prepn. of 4,41-diaminobenzhydrols of formula (I) is effected by reaching 4,41-diaminobenzophenones of formula (II) with H2 at -20 to 100 deg.C/0.5-100 bar in presence of a hydrogenation catalyst and 0-20 mol. equivs. (based on (II)) of an acid and/or salt (e.g. H2SO4, HCl, H3PO4 or NaH sulphate) A = 1,4-phenylene opt. substd. by 1-12C alkyl and/or 1-12C alkoxy' R1 and R2 = H, 1-20C alkyl, 3-8C cycloalkyl, 7-12C aralkyl, aryl (opt. substd. by 1-12C alkyl and/or 1-12C alkoxy), 2-8C omego-hydroxyalkyl, (CH2.CH(R3).O)n CH2.CH(R3)OR4 or 2-7C alkylene (opt. substd. by 1-12C alkyl and opt. interrupted by -O-, -S- or -N(R4)-); R3 = H or Me; R4 = H or 1-20C alkyl; and n = 0-40. Pref. the catalyst is a Pd-contg. catalyst and is used together with 0.001-20 (esp. 0.5-10) mol. equivs. (based on (II)) of an acid. USE/ADVANTAGE - (I) are intermediates for di- and tri-aminotriphenylmethane dyes as well as for inks such as crystal violet lactares, levio-auramines or sulphinates. They are obtd. without the flammability, waste disposal and toxicity problems.

Description

The present invention relates to a new process for the production of 4,4'-Diaminobenzhydrolen by catalytic hydrogenation.

From EP-A-5 475 is a process for the preparation of 4,4'-diaminobenzhydroles from 4,4'-diaminobenzophenones with the help of alkali borohydrides in Presence of alkali hydroxides known. A disadvantage of this method are above all the flammability of the alkali borohydrides and the inevitable occurrence of borate-containing, nitrocidal waste water.

From GB-A-13 98 075 it is known that the mentioned reduction by means of zinc dust and to carry out alkali metal hydroxide in a lower alcohol. The disadvantage of this is working with a u. U. pyrophoric metal powder and in particular the compulsive amount of toxic, zinc-containing wastewater and Zinc hydroxide sludge.

The present invention was therefore based on the object previously remedied disadvantages.

Accordingly, a new and improved process for the production of 4,4'-diaminobenzhydroles of the general formula I

in the

A is a 1,4-phenylene radical which is optionally substituted by C₁- to C₁₂-alkyl and / or C₁- to C₁₂-alkoxy,
R¹ and R² independently of one another are hydrogen, C₁- to C₂₀-alkyl, C₃- to C₈-cycloalkyl, C₇- to C₂₀-aralkyl, optionally aryl substituted by C₁- to C₁₂-alkyl and / or C₁- to C₁₂-alkoxy, C₂- to C₈-ω-hydroxyalkyl,

or a C₂ to C₇ alkylene chain which is optionally substituted by C₁ to C₁₂ alkyl and which is optionally interrupted by oxygen, sulfur and / or N-R⁴,
R³ is hydrogen or methyl,
R⁴ is hydrogen or C₁ to C₂₀ alkyl and
n integers from 0 to 40

mean, which is characterized in that the 4,4'-diamino benzophenones of the general formula II

in which the radicals R¹, R², R³, R⁴ and the index n and the intermediate A have the meanings given above, with hydrogen in the presence of a Hydrogenation catalyst and 0 to 20 molar equivalents of an acid and / or of a salt, based on II, at temperatures from (-20) to 100 ° C and Pressures from 0.5 to 100 bar implemented.

The method according to the invention can be carried out as follows:

The 4,4'-diaminobenzophenone II is optionally placed in the presence of a Acid and / or an acidic salt and the hydrogenation catalyst in one Solvent before and hydrogenated at temperatures from (-20) to 100 ° C, preferably (-10) to 80 ° C, particularly preferably at 10 to 50 ° C without pressure or under positive pressure in the range from 1 to 100 bar, preferably 1 to 40 bar. The hydrogenation can be carried out in suspension or fixed bed mode, done discontinuously or continuously. Used catalyst can be traced back into the process.

Hydrogenation catalysts are particularly suitable for processes according to the invention, which contain palladium as the active component. Mixed contacts are also suitable, which additionally contain other precious metals, preferably platinum.  All contacts can be used as full contacts, as a rule however, carrier contacts are used. Such carriers are preferably used which are acid resistant, e.g. B. coal (activated carbon, electrode graphite), sparingly soluble sulfates (e.g. barium sulfate), sintered aluminum oxide or Silicon dioxide. The proportion of precious metal in the weight of the carrier contact can between 0.01 and 20% by weight, preferably between 0.1 and 10% by weight. Between 0.01 and 20% by weight of contact, based on, are used for the hydrogenation on the ketone II, preferably between 0.05 and 5% by weight.

Suitable acids are organic and inorganic acids, preferably Mineral acids such as phosphoric acid, hydrochloric acid and sulfuric acid. As sour Salts are suitable for. B. ammonium, sodium or potassium hydrogen sulfate or dihydrogen phosphate. In general, 0 to 20 molar equivalents are used Acid and / or acid salts, based on the 4,4′-diaminobenzophenones II, preferably 0.001 to 20 molar equivalents, particularly preferably 0.5 to 10 molar equivalents. A procedure in which uses a mineral acid in a stoichiometric excess, d. H. from 2 to 10, in particular 2 to 5 molar equivalents. In addition, one can Moderator for the hydrogenation, e.g. B. nicotinamide, add.

Water, alcohols, for. B. methanol, ethanol, n- and i-propanol, butanols and pentanols, carboxylic acids, e.g. B. formic acid, Acetic acid or propionic acid, amides, e.g. B. formamide, dimethylformamide or pyrrolidone or mixtures thereof; water is particularly preferred. The concentration of ketones II is generally between 1 and 50% by weight, preferably between 10 and 30% by weight.

To isolate the product, the catalyst is separated by filtration or centrifugation and the filtrate is made by adding a base, e.g. B. sodium hydroxide solution, potassium hydroxide solution, sodium or potassium carbonate solution, ammonia solution or sodium methoxide solution neutral to alkaline, preferably to pH 7 to 10. The 4,4'-diaminobenzhydroles I precipitate out aqueous solution in general directly. Organic solvents expediently by distillation, optionally under reduced pressure Pressure largely separated and returned. The raw hydrogenation product will freed of adhering salts by washing with water. Organic contaminants can be recrystallized or digested with a suitable solvent, e.g. B. a hydrocarbon such as cyclohexane, C₆-C₁₀ hydrocarbon, toluene, an ether, e.g. B. methyl tert-butyl ether, an alcohol such as a C₁-C₅ alkanol, a ketone such as. B. acetone, Diethyl ketone, methyl isobutyl ketone, cyclohexanone, an ester such as ethyl acetate and isobutyl acetate or an acid, e.g. B. acetic acid removed will. Water-immiscible solvents used for cleaning  can the aqueous hydrogenation solution before or after the addition of Base to extract the crude hydrol I added.

The substituents R¹, R², R³ and R⁴, the index n and the intermediate A in compounds I and II have the following meanings:

A 1,4-phenylene,
1,4-phenylene, such as 3-methylphenylene and 3,5-dimethylphenylene, substituted one to four times by C₁- to C₁₂-alkyl,
1,4-phenylene, such as 3-methoxyphenylene, substituted one to four times by C₁ to C₁₂ alkoxy,
R¹ and R² independently
Hydrogen,
unbranched or branched C₁ to C₂₀ alkyl, preferably unbranched or branched C₁ to C₈ alkyl, such as n-pentyl, isopentyl, sec-pentyl, tert-pentyl, neo-pentyl, 1,2-dimethylpropyl, n-hexyl, iso-hexyl, sec.-hexyl, n-heptyl, iso-heptyl, n-octyl and iso-octyl, particularly preferably C₁- to C₄-alkyl such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec.-butyl, tert.-butyl,
C₃- to C₈-cycloalkyl, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl,
C₇ to C₂₀ aralkyl, preferably C₇ to C₁₀ aralkyl such as benzyl, 1-phenethyl and 2-phenethyl,
C₂- to C8-ω-hydroxyalkyl such as 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 2-hydroxybutyl, 3-hydroxybutyl and 4-hydroxybutyl,
Aryl, such as phenyl, 1-naphthyl and 2-naphthyl, preferably phenyl,
aryl monosubstituted to trisubstituted by C₁ to C₁₂ alkyl, preferably phenyl monosubstituted to trisubstituted by C₁ to C₄ alkyl, such as 2-methylphenyl, 4-methylphenyl, 2-ethylphenyl, 4-ethylphenyl, 3-methylphenyl, 2,4-dimethylphenyl, 3,4-dimethylphenyl and 3,4,5-trimethylphenyl,
aryl which is mono- to trisubstituted by C₁- to C₁₂-alkoxy, preferably mono- to trisubstituted by C₁- to C durch-alkoxy, such as 2-methoxyphenyl, 2-ethoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 3,4-dimethoxyphenyl and 3,4,5-trimethoxyphenyl,
phenyl which is substituted two to five times by C₁- to C₁₂-alkyl and C₁- to C₁₂-alkoxy, such as 2-methyl-4-methoxyphenyl,

a C₂ to C₇ alkylene chain which is optionally interrupted by oxygen, sulfur and / or N-R⁴, such as (CH₂) ₂, (CH₂) ₃, (CH₂) ₄, (CH₂) ₅, (CH₂) ₆, ( CH₂) ₇, CH₂-O-CH₂, CH₂-S-CH₂, CH₂-N (CH₃) -CH₂, (CH₂) ₂-O- (CH₂) ₂, (CH₂) ₂-S- (CH₂) ₂ and ( CH₂) ₂-N (CH₂) - (CH₂) ₂
by C₁ to C₁₂ alkyl mono- to pentasubstituted C₂ to C₇ alkylene chain, which is optionally interrupted by oxygen, sulfur and / or N-R⁴, such as

Hydrogen,
Methyl,
hydrogen
unbranched or branched C₁ to C₂₀ alkyl, preferably unbranched or branched C₁ to C₈ alkyl, such as n-pentyl, isopentyl, sec-pentyl, tert-pentyl, neo-pentyl, 1,2-dimethylpropyl, n-hexyl, iso-hexyl, sec.-hexyl, n-heptyl, iso-heptyl, n-octyl and iso-octyl, particularly preferably C₁- to C₄-alkyl such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec.-butyl, tert.-butyl,
n is an integer from 0 to 40, preferably from 0 to 20, particularly preferably from 0 to 10.

Suitable benzophenones II are e.g. B.

4,4′-diamino-benzophenone,
4,4'-bis-dimethylamino-benzophenone,
4,4'-bis-diethylamino-benzophenone,
4,4'-bis (2-hydroxyethyl-methylamino) benzophenone,
4,4'-bis (2-hydroxyethyl-ethylamino) benzophenone,
4,4'-bis (phenylmethylamino) benzophenone,
4,4'-bis (phenylethylamino) benzophenone,
4,4′-bis-pyrrolidino-benzophenone,
4,4′-bis-piperidino-benzophenone,
4,4′-bis-morpholino-benzophenone,

The 4,4'-diaminobenzhydroles which can be prepared by the process according to the invention I are intermediates for the production of di- and triamino triphenylmethane dyes and printing copy dyes such as crystal violet lactone, Leukauramines and sulfinates of the diaminobenzhydrols (e.g. EP-A-5 475).

Examples

Suitable for identifying and quantifying the components in the product 1 H NMR spectroscopy; e.g. B. are in the hydrogenation of 4,4'-bis diethylamino-benzophenone (1), to 4,4′-bis-diethylaminobenzhydrol (2) or in hydrogenolysis to 4,4′-bis-diethylamino-diphenylmethane (3) following ¹H-NMR bands of diagnostic value (measurements in D₆-DMSO with Tetramethylsilane from internal standard):

1: δ = 7.5-7.6 ppm (doublet, 4H),
2: δ = 5.4 ppm (doublet, 1H),
3: δ = 3.6 ppm (singlet, 2H).

The following examples illustrate the process according to the invention.

Example 1 Preparation of 4,4'-bis-diethylaminobenzhydrol in aqueous sulfuric acid to Pd / BaSO₄

The solution of 32.5 g of 4,4'-bis-diethylamino-benzophenone and is hydrogenated 25 g conc. Sulfuric acid in 160 ml water after adding 6.0 g hydrogenation contact (5% Pd on BaSO₄) at room temperature (approx. 25 ° C) and normal pressure (1 bar). The H₂ intake is 2720 ml within 5 h. After inerting and filtering off the catalyst, the hydrogenation solution is omitted Stir in 225 g of 10% aqueous sodium hydroxide solution, the precipitate sucks , wash it twice with 100 ml water and dry it at 40 ° C under reduced pressure. 33.3 g of product are obtained by NMR spectrometry determined content of 90 mol% 4,4'-bis-diethylaminobenzhydrol and 10 mole% 4,4'-bis-diethylaminodiphenylmethane; is the starting material no longer detectable.

Example 2 Preparation of 4,4'-bis-diethylaminobenzophenone in aqueous sulfuric acid on Pd / BaSO₄ at 0 to 5 ° C

The procedure is analogous to that described in Example 1, but the hydrogenation is carried out at 0 to 5 ° C and works after taking 2260 ml of hydrogen on. 31.8 g of product with 91 mol% of 4,4'-bis-diethylamino-benzhydrol are obtained, 5 mol% 4,4'-bis-diethylaminobenzophenone and 4 mol% 4,4'-bis- diethylaminodiphenylmethane.

Example 3 Preparation of 4,4'-bis-diethylaminobenzhydrol in aqueous sulfuric acid on Pd / activated carbon

Analogously to Example 1, 32.1 g of 4,4'-bis-diethylamino-benzophenone are hydrogenated in 445 g of 5.45% strength aqueous sulfuric acid over 1 g of hydrogenation contact (10% Pd Activated carbon) at room temperature (20 ° C). After taking in 2620 ml of hydrogen within 21 hours, work up as described in Example 1, however, after adding the base, the product is extracted with 200 ml of methyl tert. butyl ether and evaporate the extract. 31.4 g of product are obtained 92 mol% of 4,4'-bis-diethylamino-benzhydrol and 8 mol% of 4,4'-bis-diethylamino-diphenylmethane; the educt is no longer detectable.  

Example 4 Preparation of 4,4'-bis-diethylaminobenzhydrol in methanolic hydrochloric acid on Pd / activated carbon

A solution of 49.0 g of 4,4'-bis-diethylamino-benzophenone and is hydrogenated 45 g of 37% hydrochloric acid in 300 ml of methanol after adding 9 g of hydrogenation catalyst (10% palladium on activated carbon) at room temperature (approx. 20 ° C). The hydrogen uptake is 3920 ml within approx. 2 h. Man works as described in Example 1 and cleans the raw product by digesting with 70 ml of n-hexane at room temperature for one hour. Man receives 25.0 g of product with 93 mol% of 4,4'-bis-diethylamino-benzhydrol and 7 mole% 4,4'-bis-diethylamino-diphenylmethane; the ketone is no longer detectable.

Example 5 Preparation of 4,4'-bis-diethylaminobenzhydrol in aqueous ammonium Hydrogen sulfate solution on Pd / activated carbon

A solution of 32.4 g of 4,4'-bis-diethylaminobenzophenone and is hydrogenated 34.5 ammonium hydrogen sulfate in 250 ml of water after adding 6 g Hydrogenation catalyst (10% palladium on activated carbon) at room temperature (approx. 20 ° C). The hydrogen uptake is 2740 ml in 4.5 h. The raw product, that is obtained after the workup described in Example 1 is obtained 65 ml of cyclohexane recrystallized. 24.4 g of product are obtained 89.5 mol% of 4,4'-bis-diethylamino-benzhydrol and 10 mol% of 4,4'-bis-diethylamino-diphenylmethane; the ketone is undetectable.

Comparative example Hydrogenolysis in the hydrogenation of 4,4'-bis-diethylamino-benzophenone in Absence of acid

The solution of 16.7 g of 4,4'-bis-diethylaminobenzophenone in 100 ml of methanol is hydrogenated at 21 ° C. after the addition of 3 g of 10% palladium on activated carbon. The reaction mixture takes up only 50 ml of H₂ within 10 min, then stops the H₂ absorption. After increasing the reaction temperature to 40 ° C a further 600 ml of H₂ are added within approx. 4 h. After filtering the catalyst and stripping off the solvent gives 17.0 g of a viscous oil that gradually crystallizes.  

The NMR spectrum of an average sample shows that a mixture of 74 mol% of starting material and 26 mol% of 4,4′-bis-diethylamino-diphenylmethane (hydrogenolysis product) is present; the desired 4,4'-bis-diethylaminobenzhydrol is undetectable. The portion determined by NMR spectrometry and the proportion of hydrogenolysis product calculated from the hydrogen uptake match exactly.

Claims (4)

1. Process for the preparation of 4,4'-diaminobenzhydroles of the general formula I in which A is a 1,4-phenylene radical optionally substituted by C₁ to C₁₂ alkyl and / or C₁ to C₁₂ alkoxy,
R¹ and R² independently of one another are hydrogen, C₁- to C₂₀-alkyl, C₃- to C₈-cycloalkyl, C₇- to C₂₀-aralkyl, optionally aryl substituted by C₁- to C₁₂-alkyl and / or C₁- to C₁₂-alkoxy, C₂- to C₈-ω-hydroxyalkyl, or a C₂ to C₇ alkylene chain which is optionally substituted by C₁ to C₁₂ alkyl and which is optionally interrupted by oxygen, sulfur and / or N-R⁴,
R³ is hydrogen or methyl,
R⁴ is hydrogen or C₁ to C₂₀ alkyl and
n are integers from 0 to 40, which is characterized in that the 4,4′-diamino benzophenones of the general formula II in which the radicals R¹, R², R³, R⁴ and the index n and the intermediate A have the meanings given above, with hydrogen in the presence of a hydrogenation catalyst and 0 to 20 molar equivalents of an acid and / or a salt, based on II, at temperatures of (-20) to 100 ° C and pressures from 0.5 to 100 bar. 2. The method according to claim 1, characterized in that as Hydrogenation catalysts Palladium-containing catalysts are used. 3. The method according to claim 1, characterized in that one in Presence of 0.001 to 20 molar equivalents of an acid, based on the 4,4'-diaminobenzophenone II, works. 4. The method according to claim 1, characterized in that one in Presence of 0.5 to 10 molar equivalents of an acid, based on the 4,4'-diaminobenzophenone II, works.