DE1282647B - Process for the preparation of hexahydrobenzoic acid - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN AfW PATENT OFFICE Int. Cl .:

C07c

EDITORIAL

BOIj C07d German class: 12O-25 12 g-11/08 12p-5 Number: 1,282,647 File number: P 12 82 647.0-42 (E 28414) Registration date: December 23, 1964 Display day: November 14, 1968

The invention relates to a process for the preparation of hexahydrobenzoic acid.

Hexahydrobenzoic acid is a compound of considerable economic importance because one of the best routes to the synthesis of caprolactam - a monomer used to make polyamides - is via hexahydrobenzoic acid. The caprolactam is prepared by treating the hexahydrobenzoic acid with a nitrosating agent, for example the anhydride of nitrous acid (Nj ₁ O ₃ ) in the presence of concentrated sulfuric acid or oleum. Such a preparation is described in US Pat. No. 3,110,096.

The hydrogenation of benzoic acid to hexahydrobenzoic acid by catalytic route has been used a palladium catalyst carried out (see. French Patent 1,328,779). The palladium catalyst is quickly poisoned by the reaction medium and makes repeated use when used Benzoic acid batches require intermediate regenerations; such regenerations close the Separation of the catalyst from the reaction medium and removal of the acidic organic Material from the catalyst, e.g. B. by washing with an organic solvent and / or a aqueous solution of a base.

French patent 1,328,779 describes the hydrogenation of benzoic acid at elevated temperatures and pressing in the presence of noble metal catalysts. This patent does not contain the slightest indication of the addition of water for the purpose of increasing the rate of hydrogenation, rather the mention of methanol than Example of a solvent and the description of the disadvantages of using a solvent and the advantage of working without solvents, the essential idea of the present invention, Working with the addition of water is definitely gone. When using the process of this patent specification cyclohexanecarboxylic acid can also be produced in high yield and purity, this does not affect the surprising progress of the present invention, which is not compared to the prior art Technology improved yields, but rather in a significantly increased reaction rate you can see.

The same applies to German Auslegeschrift 1150 977, which describes the use of a noble metal catalyst for the hydrogenation of benzoic acid in the vapor phase. Again, there is not the slightest hint of the use of water to accelerate the reaction, and the methods of making
Hexahydrobenzoic acid

Applicant:

Engelhard Industries, Inc.,
Newark, NJ (V. St. A.)

Representative:

ίο Dr.-Ing. W. Abitz and Dr. D. Morf,
Patent attorneys,
8000 Munich 27, Pienzenauer Str. 28

Named as inventor:

Paul N. Rylander, Newark, N. J .;

Nicholas F. Rakoncza, Carteret, N. J. (V. St. A.)

Claimed priority:
V. St. ν. America December 26, 1963
(334 084)

Examples of this publication - none of which uses ruthenium as a catalyst, by the way - are particularly suitable for showing the surprising progress of the process of the present invention: In the examples of this publication, in which the use of noble metal catalysts is described, only 20, reacted for 40, 60 and 100 g benzoic acid per liter of catalyst, while in contrast, according to the present invention, the complete hydrogenation within about 40 minutes by a 5 ° / ₀ catalyst is achieved. The economic importance of such a catalyst saving is obvious in view of the price of noble metal catalysts.

The German Auslegeschrift 1072 620 describes the hydrogenation of terephthalic acid over palladium or ruthenium catalysts using Solvents for terephthalic acid, the preferred solvent used being water.

It should be noted that catalytic processes are a completely empirical matter and in no way predicted the effectiveness of even metals as closely related as those of the platinum group can be. It is known that even closely related compounds work on catalysts respond completely differently, and indeed the behavior of the catalysts of the platinum group

809 637/1283

3 4

is used compared to terephthalic acid and benzoic acid, the frequent regenerations are avoided

different: this is shown very well by the mentioned of the catalyst, as it is e.g. B. when using

Auslegeschrift 1 072 620, which states that palladium catalysts are necessary.

Hydrogenation of terephthalic acid only palladium and The temperature of the hydrogenation according to the invention

Ruthenium can be used, other catalysts of 5 can be between about 50 and about 220 ⁰ C,

Platinum group, such as rhodium, on the other hand because of the temperature between about 120 and about 150 ° C. Of the

wrestling yield are practically useless; Pressure would be from about 35 to 700 atmospheres, preferably

now a specialist who for terephthalic acid ranges from about 105 to 210 atmospheres,

given teaching on the hydrogenation of benzoic acid The process can be carried out continuously or essentially, then, to his surprise, it will be carried out continuously. Included

put that for the hydrogenation of benzoic acid Rho- is benzoic acid with a ruthenium catalyst in

dium is an excellent catalyst. Presence of water at the reaction temperature

Finally, the specification of the publication and the reaction pressure must also be given together with hydrogen

the terephthalic acid together with an "inert" in one of two or more parallel-connected Solvent «(water) to use, in the sense of 15 reaction vessels converted. After completing the

be understood, by this measure the hydrogenation in the reactor with the formation of hexa-

Terephthalic acid, as is well known, only softens at about hydrobenzoic acid and during the removal of the

300 ° C sublimed, into a reactive state hexahydrobenzoic acid from the reactor and the

to bring - a measure which when refilling the reactor with benzoic acid, Ruthe-122 ° C-melting benzoic acid unnecessarily appear 20 nium catalyst and water in the aforementioned

got to. The possibility of an acceleration of the ratio, benzoic acid in another of the re-

The course of the reaction by adding water, however, action vessels, as described above, are hydrogenated,

not in the least in this explanatory document either, in that they are rudimentarily combined with

indicated. Hydrogen, the ruthenium catalyst in counter-The advance of the present invention is 25% water in the aforementioned ratio at one

brings into contact not in an increase in the yield, but in the reaction temperature and pressure,

surprising increase in the hydrogenation rate, hexahydrobenzoic acid being obtained. After loading

age. ending of. Hydrogenation in this reactor and

According to the present invention, hexa becomes during the stripping of the hexahydrobenzoic acid hydrobenzoic acid by an improved method 30 and the refilling of this reactor with benzoic acid

manufactured. Hexahydrobenzoic acid is obtained when the hydrogenation of benzoic acid can be carried out first

comparable yields in a much shorter time-mentioned reactor or in another reactor

vacate and run without the need to re-run the catalyst. After the hydrogenation is complete

to regenerate repeatedly. The invention adds one benzoic acid, water and ruthenium processes for the production of hexahydrobenzoic acid 35 catalyst preferably the non-working

by hydrogenating the reactor with hexahydrobenzoic acid, d. H. that in which no hydrogenation

mixed benzoic acid at 50 to 220 ° C and one is conducted at the time during which

Pressure between 35 and 700 atü is hydrogenated in the presence of another reactor.

Ruthenium catalyst is characterized, The ruthenium catalyst can be on a that the hydrogenation be in the presence of at least 40 carriers or be unsupported, is preferred

5 percent by weight of water, based on the water used, it is used with a carrier. The concentration

Amount of benzoic acid. of the ruthenium on the carrier can be between about

Preferably about 25 to 100% of the amount 0.2 and 20%, preferably between about 2 and 5%

weight of benzoic acid applied. Through the combination (based on the weight of the wearer) lie. Beination of ruthenium and water can be reached in 45 games for carrier materials are barium sulfate, calcium

unexpectedly and surprisingly a considerable amount of ciumsulfate, asbestos, carbon, silicon dioxide and

borrowed higher rate of hydrogenation of benzoin diatomaceous earth, with carbon being preferred. Of the

acid as a carrier when using the ruthenium catalyst is preferably finely divided and of such

in the absence of water. It is true that one can get the particle size that they are in a liquid easily

Water can be dispersed along with the ruthenium catalyst 50, but is large enough to

to be easily filtered out of the liquid in considerably larger amounts than 100 percent by weight. A

Water, based on the benzoic acid used, and typical carbon carriers for the invention

use as much as 200% water and even more, the application has the following particle size distribution

but there is little advantage in hydrogenation with lung:

more than 100% water based on the 55 microns used

Benzoic acid. In fact, water 1 to 10. 35 ° /

amounts that are significantly greater than 100%, a> 10 to 20 '···· ■■ ^ o

or several reaction vessels of considerably larger - ^ o to 30 '! " 15 ° / °

Expansion will be required, which will cost • _> 3q to 40 8 ° / °

multiply to a significant extent. 60 - ^ q "^ _^0/0

After the hydrogenation is complete, the ruthenium °

catalyst from the reaction product, for example the amount of ruthenium catalyst used separated by filtration. It can then vary widely and is based on the wage Regeneration returned to the reaction vessel in the range of about 0.2 to 15 weight and with a new approach benzoic acid, 65 percent (based on benzoic acid). Water and hydrogen under the same reaction- The benzoic acid is hydrogenated while that with conditions, as stated above, brought into contact hexahydrobenzoic acid, in addition to water will. When one is mixing the ruthenium catalyst. The hexahydrobenzoic acid is generally

generally be present in the organic portion of the reaction mixture in amounts within the range of about 20 to 80 weight percent with benzoic acid in amounts of about 80 to 20 weight percent, preferably about 70 to 30 weight percent hexahydrobenzoic acid and about 30 to 70 weight percent benzoic acid. The hydrogenation could be carried out without any hexahydrobenzoic acid initially being present, but it is more difficult to control the temperature and the benzoic acid is not so easy to handle ^{because of its high melting point (120 ° C.).}

F i g. 1 is a graph showing the rates of hydrogenation of benzoic acid at the catalysis by ruthenium in the presence of water according to the invention and with the hitherto applied palladium, also in the presence of water, compares.

The following examples illustrate the invention.

example 1

The purpose of this example is to compare the activity of ruthenium and palladium catalysts for the hydrogenation of benzoic acid to hexahydrobenzoic acid to show. The experiments are carried out with and without the addition of water. The procedure is the following:

In a reaction vessel type "Magne Dash", which is immersed in a constant temperature bath, is added 1.5 g of catalyst and 100 g of a solution consisting of 30 ° / _0% benzoic acid and 70 hexahydrobenzoic acid. One heats the

ίο reactor to 130 ⁰ C and feeds hydrogen to the reaction mixture at a pressure of about 158 atü. The pressure is kept at about 158 atmospheres throughout the experiment. The stirrer is switched on. A manometer on the hydrogen tank

ts which hydrogen feeds into the reactor shows the Pressure drop, which corresponds to the hydrogen reacted with the benzoic acid. In particular: The pressure drop is read off and recorded at intervals. Similar experiments are also carried out

so through, with the exception that 15 ml of water are added to the reaction mixture. The pressure drop, which corresponds to the hydrogen reacted with the benzoic acid at different times, Table I below shows.

Table I.

Ver
search
No. catalyst Catalv
sator
lot Benzoin
acid-
lot Hexahydro
benzoic acid
lot lot
H ₂ O Obisl H ₂ -
Time
Obis5 Pressure ab
cuts
0 to 10 all in at
(Minutes
0 to 15 )
0 to 30 Remarks 1 5 ° / oPd / C 1.5 g 30 g 70 g 0 0.7 2.8 4.9 7.0 10.5 2 5% Pd / C 1.5 g 30 g 70 g 15 ml 3.5 5.6 7.0 9.1 14.8 Response in 75 Wed
do not wear off
closed 3 5% Ru / C 1.5 g 30 g 70 g 0 0.7 Z ₅ O 4.9 7.7 14.1 4th 5% Ru / C 1.5 g 30 g 70 g 15 ml 4.2 17.6 29.5 37.3 - Response in 20 Wed
utes finished 5 5 ° / ₀ Ru / C 1.5 g 30 g 70 g 0 0.7 2.8 5.6 7.7 14.8 6th 5 ° / ₀ Ru / C 1.5 g 30 g 70 g 15 ml 4.2 25.3 40.8 - - Response in 11 Wed
utes finished 7th 5% Ru / C 1.5 g 30 g 70 g 15 ml 7.0 25.3 41.5 - - Response in 11 Wed
utes finished

The data in Table I show the superiority of the combination of ruthenium and water experiments 4, 6 and 7 from the standpoint of catalytic activity for the hydrogenation of benzoic acid compared to the combination of palladium and water according to experiment 2.

Example 2

The purpose of the experiments below is to compare the activity of ruthenium and palladium repeated use, for the hydrogenation of benzoic acid to hexahydrobenzoic acid. The following procedure was applied:

Catalyst and water, benzoic acid and hexahydrobenzoic acid are placed in a shaking autoclave fed, which has a shaking frequency of 40 movements per minute. The reaction mixture is heated and the temperature is kept at 135.degree. In all experiments, the system is initially brought to 150 at; as soon as the pressure has fallen to 100 at the system is brought back to 150 at. The total pressure drop corresponds to the hydrogen uptake.

The results of the successive comparative tests, which the activity of the ruthenium and Palladium catalysts for hydrogenation of benzoic acid are shown in the curves of the graphic Representation of the F i g. 1 reproduced. In the graph are the percent hydrogenation,

d. H. the percent benzoic acid, which with hydrogen have reacted are plotted as ordinate values and the time as abscissa values.

Curves A, B and C of FIG. 1 show the rate of hydrogenation of benzoic acid in three successive experiments, namely experiments 8, 9 and 10, respectively, using a palladium catalyst. In each case, 10 g of a 5 ° / _o by weight used palladium-carbon catalyst, which contains about 5 g of water. In each case, 100 g of benzoic acid, which is dissolved in 100 g of hexahydrobenzoic acid, are used. After the end of experiment 8, the catalyst is re-used without regeneration.

used. At the end of Experiment 9, the catalyst becomes regenerated.

Table II below shows that for the complete hydrogenation of benzoic acid to hexahydrobenzoic acid time required in each of trials 8, 9, and 10.

Table II Table IV

Attempt no. Time to finish Regeneration δ
9
10 1 hour 9 minutes
2 hours 6 minutes
2 hours 23 minutes no
Yes

Attempt no. Time to finish Regeneration 11 1 hour 11 minutes 12th 1 hour 22 minutes Yes 13th 1 hour 43 minutes Yes 14th 2 hours 3 minutes Yes 15th 3 hours 22 minutes Yes

Attempt no. Time to finish Regeneration 16 45 minutes 17th 39 minutes no 18th 37 minutes no 19th 40 minutes no 20th 38 minutes no 21 40 minutes no 22nd 43 minutes no 23 48 minutes no 24 45 minutes no 25th 48 minutes no 26th 47 minutes no 27 50 minutes no 28 50 minutes no 29 51 minutes no 30th 50 minutes no 31 50 minutes no 32 53 minutes no 33 53 minutes no 34 55 minutes no 35 53 minutes no

IO

Experiments 12, 13, 14 and 15 of Table III below show those for the complete Hydrogenation of benzoic acid to hexahydrobenzoic acid required time in each experiment Palladium catalyst was used and the catalyst was regenerated between each attempt. There were 10 g of a 5% palladium-carbon catalyst ver ao applied, which contained about 5 g of water.

Table III

Curves D, E, F and G of FIG. 1 show the superior rate of hydrogenation which the combination of the ruthenium catalyst and water of this invention provides over the combination of a palladium catalyst and water of curves A, B and C. The superiority of the Ruthe test results, as shown by the curves A, B nium-water combination compared to the palladium and C in FIG. 1 and Tables II and III indicate water combination from the point of view of the total that the palladium catalyst, although it takes time, which shows a better effect to complete the hydrogenation of the with a regeneration, 35 benzoic acid to hexahydrobenzoic acid is required, progressive and even with a regeneration at, a comparison of the results of Table IV above shows repeated uses significantly more inactivated with those of Tables II and III. In the case of the data of the ruthenium catalyst without regeneration, a slight increase in the total can be seen - the data of the comparative experiments with the downtime required for the complete hydrogenation of the phenium catalyst show the curves D, E, F and G 40 borrowed tests 20 to 35, at least in part, of FIG. 1 and the following Table IV. It is extremely desirable and economically advantageous to write off an industrially caused loss of catalyst. After each of the attempts given in Table IV, if one were able to use a material as a catalyst, the catalyst was filtered into one that does not require regeneration, filtered crucible, and then into the reactor's costly and time consuming regeneration vessel for the next Attempt washed back; process with the associated loss of considerable therefrom resulted from handling a ver-quantities of catalyst avoided in this way
will.

Curves D, E, F and G of FIG. 1 show the

Showing the rate of hydrogenation of benzoic acid in four 5 results.

successive experiments, namely the The results of the following Example 3 show the

seek 16, 17, 18 and 19, respectively, using a 5% ruthenium-carbon catalyst. After each experiment, the catalyst is filtered off and used again for the next experiment without regeneration. 5 g of a 5 ° / _o by weight used ruthenium-carbon catalyst. The starting product for each experiment is 100 g of benzoic acid dissolved in g of hexahydrobenzoic acid. 50 g of water are present in the reaction mixture. Twenty consecutive experiments, namely experiments 16 to 35, are carried out, the results of experiments to 19 being recorded as curves D, E, F and G, respectively, as mentioned above, and the time required for complete hydrogenation of the benzoic acid led to hexa- 65.

hydrobenzoic acid is required, in the after- Table V shows the pressure drop, which with the

Table IV below is given for each of Runs 16 to 35 benzoic acid at different time intervals. corresponds to set hydrogen.

g g

reduction in the amount of catalyst used. Run 16 of Table IV actually has the activity of the catalyst is greatly improved, like the above

Effect of the amount of water in the reaction mixture on the rate of hydrogenation of benzoic acid.

55

Example 3

The procedure used for the hydrogenation experiments of this example is similar to that of the example 1. In each experiment, 30 g of benzoic acid, 70 g of hexahydrobenzoic acid and 0.5 g of a 5% strength Ruthenium-carbon catalyst used. The amount of water varies from 0 to 60 g as shown in Table V. The tests are carried out at 130 ° C and 158 atm.

Table V

10

Η, Ο added Obis5 Hi pressure drop in at 0 to 15 0 to 30 Time until
Λ Un _n UI ₁₁ O Attempt no. 0.7 for periods of time (minutes) 2.8 4.2 f \ DSCHiUlJ 0 4.9 O to 10 11.9 21.8 * 36 15 g 8.4 1.4 24.6 40.1 80 minutes 37 30 g 11.2 9.1 30.2 30 minutes 38 45 g 11.9 16.2 31.6 - 26 minutes 39 60 g 21.1 23 minutes 40 21.8

* At 70 minutes Ap = 10.5 at. The experiment was not continued until it was complete.

The data in Table V show that the rate of hydrogenation the benzoic acid depends on the amount of water present. As soon as the water weight that of the benzoic acid present is the same, there is little advantage to be achieved by adding more water. ao

Claims (2)

Patent claims: 1. A process for the preparation of hexahydrobenzoic acid by hydrogenating mixed with hexahydrobenzoic acid, benzoic acid at 50 to 22O ⁰ C and a pressure of 35-700 atmospheres in the presence of a ruthenium catalyst, d ABy in that the hydrogenation in the presence of at least about 5 weight percent water based, on the amount of benzoic acid used. 2. The method according to claim 1, characterized in that that one has water in an amount of about 25 to 100 percent by weight of the benzoic acid begins. Considered publications:
German Auslegeschriften No. 1072 620.1150 977; French patent specification No. 1,328,779. 1 sheet of drawings 809 637/1283 11.68 ® Bundesdruckerei Berlin