FR2490220A1 - PROCESS FOR THE PREPARATION OF 4-AMINOMETHYLMETHYLBENZOIC ACID FROM 4-HYDROXYIMINOBENZOIC ACID - Google Patents

Abstract

IT CONSISTS OF CATALYTICALLY HYDROGENING 4-HYDROXYIMINOMETHYLBENZOIC ACID DISPERSE IN AN ACID OR NEUTRAL AQUEOUS MEDIUM, IN THE PRESENCE OF A CATALYST CONTAINING A PALLADIUM COMPOUND AND / OR A RHODIUM COMPOUND.

Description

The present invention relates to a method

  for the preparation of 4-aminomethylbenzoic acid

  from 4-hydroxyiminomethylbenzoic acid. It relates more particularly to a process for reducing 4hydroxyiminomethylbenzolque acid

  4-aminomethylbenzoic acid using a suitable catalyst

  holding at least one palladium compound or a rhodium compound in an aqueous medium whose pH is not

greater than 7.

  With regard to the process for the preparation of 4-aminomethylbenzoic acid (hereinafter referred to as AM), the following processes have so far been known: (1) the amination of 4-chloromethylbenzoic acid with ammonia, ( 2) reduction of 4-carboxybenzaldehyde in the presence of Raney nickel in methanol containing ammonia (see Japanese Patent No. 34-421), (3) reduction of methyl 4-cyanobenzoate in the presence of Raney nickel alkaline solution

  aqueous (see Japanese patent application No. 48-

  57951) and (4) reduction of 4-cyanobenzoic acid in the presence of a ruthenium catalyst in aqueous alkaline solution (see published Japanese patent application

n 51-32536).

  However, although process (1) is carried out at atmospheric pressure, a large amount of by-products such as a secondary amine and a tertiary amine is formed, and therefore the yield of AM is not favorable; to improve the yield of the process (2), it is necessary to carry out the reaction under high pressure; and the starting material of (3) and (4), 4cyanobenzolque acid, is not easy

  to prepare on an industrial scale.

  Consequently, it can be said that none of the

  processes for the preparation of 4-amiinomethylben- acid

zoique known is not satisfactory.

  One of the aims of the invention is to provide a process for the preparation of 4-a inoTrAthylbenzoic acid

  consisting in catalytically hydrogenating 4- acid

  hydroxyiminomethylbenzol dispersed in a medium

  acidic or neutral aqueous in the presence of a catalyst

  holding at least one palladium compound or a compound

  rhodium. Other goals will appear below.

  The present invention will be explained in more detail, as follows:

  The starting substance of the invention is

  i.e. 4-hydroxyiminomethylbenzoic acid is a

  oxime which can be obtained by reaction of 4-carboxy-

  benzaldehyde and hydroxylamine hydrochloride. 4-carboxybenzaldehyde is obtained by oxidation of mono- or dichloromethylbenzoic acids. However, 4-carborybenzaldehyde obtained as a by-product is used industrially in the production of terephthalic acid, which is a raw material for manufacture.

certain synthetic fibers.

  The catalyst used in the process

  the invention contains at least one member of the group

  taking the palladium compounds and the compounds of

  rhodium, and it is preferably a metallic catalyst

  containing palladium and / or rhodium or a catalytic converter

  mixed lyser comprising one or two members of the palladium and rhodium group and one or more other metals of the platinum group, in particular platinum

  and ruthenium. However, the mixed catalysts

  containing palladium, rhodium and platinum are excluded when the reduction is carried out in an acidic aqueous medium. A unitary catalyst is particularly preferred

  comprising palladium or rhodium.

  The active metallic element contained in the catalyst of the process of the invention is in the form of metal, of a metal compound, such as an oxide, or of a metal alloy. These metals and metal compounds are deposited on a support such as activated carbon or diatomaceous earth, the activated carbon being

  prefer. The preferred catalyst is a combined catalyst.

  taking metallic palladium deposited on carbon

  activated. Ordinarily, the amount of metal element-

  lique deposited on the support is about 2 to 10% by weight relative to the total weight of the catalyst. The amount of catalyst used is such that the sum of the weights of the palladium and of the rhodium is approximately 0.25 to 10% by weight, preferably approximately 0.5 to 5%

  by weight relative to 4-hydroxyiminomethyl-

  benzoic. The reaction medium used in the process of the invention has a pH of less than 7, that is to say that it

it is an acidic or neutral medium.

  In the reduction of an oxime, an organic solvent is generally used as reaction medium; aqueous media are not used due to extremely low solubility and hydrolysis

  likely oxime in an aqueous medium.

  In the process of the invention, however, it is characteristic that the hydrogenation of the oxime dispersed in an aqueous medium can be carried out at a relatively low temperature and under a relatively low pressure: the starting substance, the oxime, in the emulsion state in an acid medium containing a mineral acid, and the AM thus formed by reduction of the oxime is transformed into a salt of the mineral acid. It is assumed that the reason why the mineral acid salt of AM is readily obtained in high yield is that the aminomethyl group

  is protected by mineral acid, which prevents reactions

  secondary tions such as deamination and training

secondary amine cation.

  Furthermore, when the reaction medium is a neutral aqueous medium, the reduction of the oxine takes place while this compound is in the quasi-emulsified state and when the reaction is complete, the AM is obtained in the form of crystallites. In neutral medium, it is characteristic that the reaction is carried out in

heterogeneous system.

  When the reaction is carried out in medium

  basic aqueous, although the reaction takes place in a sys-

  homogeneous, we found that the formation of secondary amine as a by-product was inevitable, giving

poor performance in AM.

  As the aqueous acid medium, an aqueous solution of a mineral acid such as hydrochloric acid, sulfuric acid and nitric acid, which form water-soluble salts with AM, is used.

  concentration which is usually 3 to 5%. The quan-

  amount of mineral acid used in the reaction is at

  less than the equivalent amount of acid 4-

  hydroxyiminomethylbenzoic, it is preferably

  about 1 to 3 times the equivalent amount. The amount.

  of the reaction medium is 10 to 50 times the weight of 4hydroxyiminomethylbenzoic acid, preferably

  20 times, both in an acid medium and in a neutral medium.

  The reaction of the invention is usually carried out at a temperature of about 10 to about 80 ° C, and when a palladium catalyst is used, it is carried out fairly regularly at a temperature of about 10 to about 50 ° C. However, when using a rhodium catalyst, a slightly higher temperature

high is necessary.

  The reaction of the invention can be carried out

  killed under hydrogen pressure greater than 1 bar, and is usually easily carried out under pressure

of hydrogen from 1 to 10 bars.

  The duration of the reaction of the invention depends on the conditions of the reaction such as the nature of the catalyst and the quantity thereof, the temperature, the hydrogen pressure, etc., but the absorption of

  hydrogen is usually complete in 2 to 7 hours.

  When the reaction is complete, in the case

  o using an acidic aqueous medium, eliminating the cat-

  lyser by filtering the reaction mixture and the AM crystals are deposited, neutralizing the filtrate, after which the crystals are collected by filtration, and

  the filtrate is concentrated to obtain new crystals

  AM rate. On the other hand, when a neutral aqueous medium is used, concentrated ammonia is added

  or concentrated hydrochloric acid to the reaction mixture

  tional to dissolve the product, and after removing the catalyst by filtration, the filtrate is neutralized

to get the AMX crystals.

  The following non-limiting examples are

  given as title. of illustration of the invention.

Example 1.

  In a 500 ml pressure-resistant glass autoclave, 16.5 g (0.1 mole) of 4-hydroxyiminomethylbenzoic acid are dispersed in 200 ml of 3.5% aqueous hydrochloric acid solution, and added dispersion 1.6 g of 5% palladium on activated carbon (hereinafter abbreviated as 5% Pd-C). We

  performs the catalytic hydrogenation of 4-hydroxy acid

  iminomethylbenzoic under an initial hydro-

  gene of 5 bars at a temperature ranging from room temperature to 450C. The absorption of hydrogen ends after 3 hours. After removing the catalyst by filtration from the reaction mixture, the filtrate is concentrated and the crystals which are collected by filtration

  are deposited, washed with acetone and dried.

  16.0 g of powdery white crystals are obtained.

  at 284 - 288 C. The crystalline product thus obtained is identified as being the hydrochloride of the acid

  4-aminomethylbenzoic by comparing its absorption spectrum

  tion IR with that of an authentic sample of this compound The yield is 85.0% o A saturated aqueous solution of this hydrochloride of 4-aminomethylbenzoic acid (hereinafter abbreviated as AM4ICl) is neutralized with a solution aqueous sodium hydroxide at 20% s and after collecting the crystals which deposit by filtration,

  concentrates the filtrate to obtain an additional quantity

  shut up with crystals. After drying, the total weight of

  crystals thus obtained is 12.5 g.

Example 2.

  The catalytic hydrogenation of 4hydroxyiminomethylbenzoic acid is carried out in the same manner as in Example 1, except that distilled water is used as reaction mixture and that

  operates at a temperature ranging from am-

  biante à 40 C. The absorption of hydrogen is finished after 3 hours. After adding 20 g of concentrated hydrochloric acid to the reaction medium to dissolve the product, the mixture is filtered to remove the catalyst and the filtrate is concentrated under reduced pressure. The crystals which

  are deposited, washed with acetone and dried.

  14.5 g of powdery white crystals are obtained which are identified with 4-aminomethylbenzoic acid by comparing their IR spectrum with that of a sample.

  authentic 4-aminomethyl acid hydrochloride

  benzolque. The yield is 77.3% O By treating the product thus obtained with an alkali in the same manner as in Example 1, 8.2 g of crystals are obtained in the first operation, and 2.6 g of crystals in the second. These crystals are identified with AM by comparing their IR absorption spectrum with that

  authentic sample of 4-aminomethylbenzol acid

than.

Example 3.

  In the same way as in Example 1, except 1O which is used as catalyst 5% of rhodium on activated carbon support (hereinafter abbreviated as 5% Rh - C), the hydrogenation is carried out catalytic

  4-hydroxyiminomethylbenzoic acid at a temperature

  ture ranging from room temperature to 600C. The absorb-

  tion of hydrogen ends after 5 hours. In process

  as the reaction mixture as in Example 2, 14.0 g of a white powdery product are obtained, melting at 282-2850C, which is identified with AM-HCl by comparing its IR absorption spectrum to that of a sample

  authentic of AM.HC1, the yield is 74.6%.

  By neutralizing the product obtained with an alkali, 10.2 g of a white powdery substance are obtained,

  that we identify with AM by IR spectrography.

Examples 4 to 6.

  A series of hydrogen experiments are carried out.

  catalytic nation in the same manner as in Example 1, but using each of the mixed catalysts indicated

  in the table at a temperature ranging from temperature

  room temperature at 500C. In these experiments, the hydrogenation reactions of the oxime part and of the benzene nucleus can be followed by observing the quantity of hydrogen consumed, corresponding to the drop in pressure.

of hydrogen in the autoclave.

  When the reaction is complete, the catalyst is removed by filtering the reaction mixture, and after confirming that the filtrate contains only AM.HC1 by the presence of UV absorption at 228 nm, the filtrate is concentrated. The crystals which settle are collected by filtration and dried. The product

  is identified as AM-HC1 by IR analysis.

  Table * Note: 5% Pt-C denotes a catalyst containing 5%

  by weight of platinum on activated carbon.

  % Ru-C denotes a catalyst containing 5%

  by weight of ruthenium on activated carbon.

Example 7.

  In the same way as in Example 1, except

  that distilled water is used as the reaction medium

  and that the catalyst is a mixed catalyst consisting of 1.6 g of 5% Pd-C, 1.6 g of 5% Pt-C and

  1.6 g of 5% Rh-C, catalytic hydrogenation is carried out

  tick of 4-hydroxyiminomethylbenzoic acid at a temperature between room temperature and C. The absorption of hydrogen ends at the end

about 4 hours.

  As crystals appear in the middle

  20 ml of hydrochloric acid are added to the mixture.

  concentrated dric to dissolve them, and the catalyst is removed by filtration of the solution. Concentration of the absorption duration is concentrated Product N0 @ E Catalystation of H2 (g) (h) weight (g) identification% PdC1.6 1 4 * 2.5 13.7 AM kHC1% Pt-C 1.6% Pt -C 1.6 Rh-C 1.6 5.0 13.1 -id% Rh-C 1, .6% Pd-C 1.6

6 5Ru-C 1 2.5 13.5 id-

  % Ru-C 1.6 the filtrate and acetone is added to the concentrate. he

  deposits crystals which are collected by filtration

  tion and dries. 14.5 g of powdery white crystals are obtained, melting at 284-2860C, identified with AM-HC1 by IR analysis. The yield is 77%.

Claims (11)

  jo Process for the preparation of 4-amino acid   methylbenzoic, characterized in that one hydrogenates   catalytically acid 4-hydroxviminomethylbenzol-   dispersed in an aqueous, acidic or neutral medium, in the presence of a catalyst containing a palladium compound dium and / or a rhodium compound.   2. Method according to claim 1 charac-   terized in that the catalyst is a mixture comprising a palladium compound or a rhodium compound and a compound of an element of the platinum group chosen from ruthenium, osmium, iridium and platinum, provided that when the aqueous medium contains a mineral acid, a mixture of a palladium compound, a rhodium compound and a platinum compound.   3. Method according to claim 2, characterized in that the compound of an element of the platinum group is a platinum compound or a ruthenium compound.   4. Process - according to claim 1, charac-   terized in that the catalyst comprises a compound of   palladium or a rhodium compound and a support.   5. Method according to claim 1, characterized in that the catalyst comprises a compound   palladium deposited on a support.   6. Method according to claim 5,   characterized in that the support is activated carbon.   7. Method according to claim 1, characterized in that the catalyst comprises a compound rhodium deposited on a support.   8. Method according to claim 7, charac-   terized in that the support is activated carbon.   9. Method according to claim 1,   characterized in that 4-hydroxyiminomethyl-   benzoic is catalytically hydrogenated at a temperature from 10 to 80 C.   10. Method according to claim 1,   characterized in that 4-hydroxyiminomethyl-   benzoic is catalytically hydrogenated under pressure   initial hydrogen from 1 to 10 bars.   11. Method according to claim 1,   characterized in that 4-hydroxyiminomethyl-   benzolque is catalytically hydrogenated for 2 to 7 hours.