DE1014096B - Process for the production of phthalic acids from their ammonium salt-amide mixtures by hydrolysis - Google Patents

Description

GERMAN

The invention relates to a process for the production of phthalic acids from their ammonium salt and amide mixtures.

Alkyl aromatic hydrocarbons, such as the three xylene isomers, 1,3-dimethyl-5-tert.-butylbenzene, toluene and the like, by heating with ammonium sulfate, a sulfide such as hydrogen sulfide or ammonium sulfide, and water at a temperature from about 290 ° to the critical temperature of the water below Overpressure, which is able to keep part of the water in the liquid phase, to the corresponding carboxylic acids are oxidized. In an experiment typical of this process, 1 mole of xylene, 1.83 moles of ammonium sulfate, 0.18 moles of ammonium sulfide and 30 moles of water under a pressure of 196 atmospheres for about 2 hours 327 ° heated. 97% of the xylo.l was converted and the yield of phthalic acid derivatives was 91% of that Theory. The reaction mixture produced in this oxidation process consists of ammonium phthalates and Phthalic acid amides. There are three types of compounds of the following general formulas:

Ar (COONHJ ₂ , Ar (CONH ₂ ) ₂
and NH ₂ OCArCOONH ₄

The reaction mixture thus contains diammonium phthalate, phthalic acid diamide and the ammonium salt of phthalic acid monoamide.

In this mixture, about 60 to 80% of the total acid groups are in the form of the ammonium salt and the remainder in the form of _{the amide, i.e. 60 to 80% of the side chains of the reaction products consist of the ammonium carboxylate radical --COONH 1} , the remaining part of the amide radical - CONH ₂ . Throughout the description and in the claims, the term "." Means mixtures of ammonium salts and amides of phthalic acid,! Mixtures of the above three compounds.

In the above-mentioned oxidation process there is an extensive conversion of xylene and a high conversion rate Yield of phthalic acid achieved, the extraction of phthalic acid with a for most technical However, the degree of purity required for the purposes of the crude oxidation product is difficult. One Phthalic acid suitable for any commercial use must have a nitrogen content, calculated as ammonia, of below about 0.1 weight percent, and in many cases e.g. B. in the production of alkyd resins is a nitrogen content of less than 0.03 percent by weight is required. This low nitrogen content is not easy to reach. It can be obtained by saponifying the ammonium salt-amide mixture can be achieved with caustic soda, resulting in a solution of sodium phthalates, from which the phthalic acids are precipitated by adding acid will. This procedure involves a considerable process

for the production of phthalic acids

from their ammonium salt ami d-

Mixing by hydrolysis

Applicant:

California Research Corporation,
San Francisco, Calif. (V. St. A.)

Representative: Dr. W. Beil, lawyer,
Frankfurt / M.-Höchst, Antoniterstr. 36

Claimed priority:
V. St. v. America July 12, 1954

Harry J. Aroyan, El Cerrito, Calif.,

and John B. Wilkes, Albany, Calif. (V. St. Α.),

have been named as inventors

Consumption of caustic soda and sulfuric acid, which significantly increases the cost of phthalic acids.

It has been found that the hydrolysis can also be carried out in a strongly acidic medium, ie with a content of 2 moles of sulfuric acid per mole of phthalic acid, at a high temperature. However, even with most of the corrosion-resistant materials now available, this process is accompanied by extremely severe corrosion and requires frequent replacement of the expensive equipment with a simultaneous reduction in the capacity of the process.
It has now been found that mixtures can be hydrolyzed from ammonium salts and amides of phthalic acids phthalic acids to low nitrogen content, when one brings an aqueous solution of the mixture with a mineral acid to a _pH value of about 2.5 to 3.5 (this p _H range is indicated by the addition

of approximately 1 equivalent of sulfuric acid per equivalent of ammonium carboxylate contained in the mixture) and the mixture acidified in this way for about 10 to 60 minutes to over 150 ° (if desired to 200 to 260 °, preferably to 220 to 260 °) heated under a pressure which is above atmospheric pressure and sufficient to to keep a substantial part of the water in the liquid phase. The resulting mixture is brought to a temperature cooled below about 120 ° and then filtered to obtain a filter cake that consists essentially of

709 658/412

Phthalic acids. It is desirable to heat the cooled, preferably to 205 to 260 °, in order to effect the mixture with a strong mineral hydrolysis of the amide groups before filtering. Once the acid again to a _pH value of 3 to 3.5 calculated phthalic acid salt of the amide solution ■ ". Acidify A one-step treatment of this kind has reached approximately 8 to 25 percent by weight, it reduces the nitrogen content of Phthalsäureprodukts It is advantageous to add the sulfuric acid at an elevated temperature, determined as ammonia, of an initial value usually between, for example, about 66 to 121 °, in order to avoid the formation of 6 and 10%, to about 0.6 of a viscous sludge because the phthalic "up 1%. A further reduction in the nitrogen content of acids and amides precipitated by the addition of acids can be achieved by using the phthalic acid filter. While the acid addition advantageously slurried in * 'cake with so much water that a solid is carried out io-mentioned higher temperature, content of from about 2 to 50 percent by weight, preference, the p _H values to control the addition of acid at S, as by 10 to 25 percent by weight, and determined to be about 21 °. It should be noted that the Open in. · ,, the hydrolysis at about 150 ^D, preferably about description and in the claims

220 to 260 °, repeated. For certain usage guided p _H values were determined at about 21 °% purposes that an extremely high purity of 15 and that the actual _pH value at elevated temperature

Require phthalic acid, a third hydrolysis stage can deviate considerably from the value measured at 21 ° ^:

be connected. can. :

According to another embodiment of the invention, Fig. 2 shows the reduction in nitrogen content

according to the method is in the first hydrolysis of a mixture of ammonium salts and amides of stage obtained phthalic acid filter cake with as much aqueous 20 phthalic acids by three-stage hydrolysis. In all three

riger bisulfate solution, such as ammonium bisulfate or alkali hydrolysis stages, the acidified salt amide

bisulfate solution, slurried that a slurry with mixtures under a pressure of 35 atmospheres for 60 minutes;

a solid content of about 2 to 50 weight- heated to 241 ° and with progressive hydrolysis:

percent, preferably from 10 to 25 percent by weight, samples taken for analysis. That was in every step

is produced which has a _pH value of about 1.0 to 1.8. 25 p _H value of the initial mixtures from 3 to 4. While

This slurry is then heated to a temperature higher than the 60-minute hydrolysis of the p _H value rose

150 °, namely to 180 to 275 °, preferably to 205 to 4.7 to 5.2, since the amide groups to ammonium : "'

to 260 °, heated using an overpressure, carboxyl groups were hydrolyzed and that from the

which is sufficient to keep the water in the liquid phase. Amide groups formed ammonia hydrogen ions

It is then cooled and filtered to produce a filter cake 30 for the formation of ammonium radicals! "L

to obtain, which essentially consists of phthalic acids. After completion of the first stage, the reaction was ν

consists. The cooled to 82 ³ in this embodiment of the process mixture, at a _pH value below 4.0 -

desired _pH value, ie the value of 1.2 to 1.8, acidified and filtered. The nitrogen content of the filter τ

is obtained by taking the bisulfate content of the cake from the first stage, calculated as

slurry to about 1 mole of bisulfate per mole of ammonia, 0.74%. This filter cake was again ■

Filter cake of the first hydrolysis stage contained on slurried and this sludge heated to a, /,

Nitrogen (determined as ammonia) adjusts, and to effect further hydrolysis. The filter cake from the

In addition a certain excess of neutral second stage, by adjusting the p _H -value of -s

Adds sulfates, which buffer the mixture. Product from the second stage to 3 to 4 and then

In Fig. 1, the change of the p _H -value is 40 following filtration obtained in addition, had a nitrogen

from sulfuric acid to a solution with an ammonium salt content of 0.05, calculated as ammonia. The third i

Amide mixture of phthalic acids shown graphically. The hydrolysis step was carried out using the

Fig. 2 shows the reduction in the nitrogen content of a filter cake from the second hydrolysis stage

Ammonium salt-amide mixture of phthalic acids that is slurried on and heated for further hydrolysis

by three-stage hydrolysis in which to effect 45 in the reaction mixture. The final phthalic acid product had

no free mineral acid is present, a nitrogen content of 0.013%, calculated as Ammo

graphically represented. Fig. 3 shows schematically the niak. For many uses of isophthalic acid:

Arrangement of the apparatus and the flow diagram for the and terephthalic acid hydrolysis product is a stick-

Implementation of the method according to the invention. substance content below 0.06 percent by weight, calculated as

A typical ammonium phthalate-phthalic acid amide- 50 ammonia, satisfactory, while a product with a

The mixture was titrated with 19 η sulfuric acid. The nitrogen content of less than 0.03%, calculated as Ammo

The titration curve is shown in Fig. 1. The phthalic acid niac, for the production of alkyd resins, in which the

Salt-phthalic acid amide solution had a calculated purity requirement that is strictest to meet

Phthalic acid content of 15.5 g per 100 g of solution, which appears to be.

Phthalic acids in the solution of approximately 95% isophthalic 55 The corrosion rates for stainless _f

acid and 5% terephthalic acid. Under the conditions shown in Fig. 2

The titration curve can be seen from the fact that a stronger first hydrolysis stage is examined. The ;

Drop of the p _H -value occurs, once the initial corrosion rate of ammonium in the first

salt-amide solution added acid amount of 20 to hydrolysis was at a _pH value of about 3

cm ³ increases. This drop in the p _H -value occurs, 60 for stainless steel, "Type 304 - (18 to 20% Cr,

after about 1 equivalent of sulfuric acid per 8 to 11% Ni, max. 2% Mn, max. 0.08% C) 0.66 mm

Equivalent ammonium carboxylate of the ammonium salt and for stainless steel 'Type 316 .. (16 to 18% Cr,, ■;

Amide mixture was added. After adding 10 to 14% Ni, 1.75 to 2.75% Mo, max. 0.1% C)

this amount of sulfuric acid is essentially every 0.74 mm per year. The corrosion rates

The ammonium carboxylate groups contained in the solution amounted to 65 for these two stainless steels

the ammonium residue is replaced by hydrogen, and this lasts for the first few minutes of the hydrolysis treatment,

are now in the form of carboxyl groups. After the addition when the _pH value of the hydrolysis reaction mixture

This amount of acid, ie, after the _pH value was increased to 4.0 by 0.51 mm per year. -

Ammonium salt amide solution to approximately 2.5 to 3.5 isophthalic acid, terephthalic acid and mixtures of these: *:

has been set, the solution can be over 150 ³ , pre- 70 acids with a nitrogen content, calculated as Ammo-: ||

5 8

niak, below 0.03 ⁰ Z ₀ , can easily be converted into two hydrolysis amides of isophthalic acid and terephthalic acid. A tier can be obtained. The first hydrolysis step is a crude reaction product, which is illustrated by the oxidation of as shown in Figure 2, by adjusting the p _H -. Was prepared of 95% m-xylene, is represented by the value of an aqueous solution of a mixture from line 1 in the container 2 headed. Through line 3 ammonium salts and amides of iso- and Terephthai- 5 96 ° / ₀ sulfuric acid is introduced in the conduit 1, acid to 2.5 to 3.5 and heating for 10 to 60 minutes where it joins with the aqueous mixture of Ammcniuindes acidified mixture to 230 to 260 ° under a salt and amides of isophthalic acid mixes. The amount of pressure carried out by about 35 atmospheres. The hydrolysis of the introduced through line 3, sulfuric acid is so mixture is then controlled to a temperature below about that the mixture produced in the container 2 is cooled to 120 ° and sulfuric acid added to the io a _pH value of 2.5 to 3 , 5 has. A Leip by the _H value of the hydrolysis product to 2.5 to 3.5 one device 1 introduced, for example, feed has bezustellen (the _pH value was determined at 21 °). That added on to the total charge, a calculated chilled product is then nitrated and the filter isophthalic acid content of approximately 20%. As a result of the cake with an aqueous bisulfate solution slurried essence of o-xylene and the partial oxidation and heated under excess pressure to 175 to 260 °, around the 15 of a very small amount of m-xylene are in the charge to complete hydrolysis. The second hydrolysis- small amounts of o-phthalic acid, benzoic acid and toluene, in which an aqueous bisulfate solution used acid. Approximately ^{1 to} ₂ kg of sulfuric acid is used each time, is explained on the basis of the following examples. reclmetes kilograms contained in the charge

. Phthalic acids are introduced into the container 2. Whose

Example 1 _{20 contents are} vigorously stirred at about 93 to 121 ° so that

The filter cake from the first shown in Fig. 2 ensures thorough mixing with the sulfuric acid hydrolysis stage, the hydrolysis product being the first. The acidified mixture reasonable from 2.5 to 3.5 with a _pH-value stage before filtration to a _pH value of 3 is had through the conduit 4 from the Besäuert was diluted with water, the 13.2 g container 2 removed and through the heat exchanger 5 contained in sodium sulfate and 4.65 g sulfuric acid per liter, 35 passed the hydrolysis device 6. Muddled in the heat out. The calculated isophthalic acid content of exchanger 5 is the mixture to about 200 to 230 ° sludge was 170 g per liter. This mud had heated up. Live steam is introduced through line 7 into the p _n value of 1.45 at 21 °. The slurry was introduced into hydrolyzer 6 to heat the mixture to 240 ³ under a pressure of about 35 atmospheres. roll and bring its temperature to 230 to 260 °. As the hydrolysis progressed, samples were taken and examined for nitrogen. At the end of line 8 into a second hydrolysis vessel 9. In the course of 30 minutes, the nitrogen content of isophthalic acid, line 8, sulfuric acid or calculated as ammonia, was reduced to 0.036 percent by weight and ammonium bisulfate solutions in such an amount after 60 minutes to 0.022 are guided back by weight, that the _pH value of the liquid in Leigegangen. The _pH value of the hydrolysis product was 35 tung 8 is lowered from about 5 to about 3.5. The dwell after 60 minutes, measured at 21 °, 2.7. time of the reaction mixture in the hydrolysis vessels

. . is usually 10 minutes to 1 hour, more usually

Example 2 is about 25 to .45 minutes. The cold one, like later

Example 1 was repeated by describing the isophthalic filtrate obtained is ent through line 11 acid aging cake from the first stage with water which is introduced into the lower part of the hydrolysis vessel 9, 26 g of sodium sulfate and 9.5 g of sulfuric acid per liter - keeping temperature and speed of this straw slurried. The isophthalic acid content of the mes can be adjusted so that the hydrolysis mixture in the sludge was again 170 g per liter of water. The lower part of the training Hydrolysiergefäßes 9 had gear mud to about 121 ° at 21 ° a _pH value of 1.27. or below is cooled. After heating to 240 ^{3 for} 30 minutes, the 45 denier operated under 35 to 49 atmospheric pressure was 0.03 percent by weight and the water-nitrogen content of the isophthalic acid, calculated as the proportion of the hydrolysis mixture in the liquid phase after ten has elapsed. The cooled mixture becomes 0.018 percent by weight through line 12 for 60 minutes. The _pH value of the removed from the Hydrolysiergefäß 9 and into the cooler 13 hydrolysis was directed overall to 1.67 after 60 minutes. Through the line 14 will rise into the cooler 13. The initial corrosion rate for stainless 50 sulfuric acid introduced in genügendar amount to the steel, "type 304.-, was under the conditions of _pH value to bring the mixture to 3.5 to about 2.5, of this example, 0.79 mm per year, however, this part of the water contained in the hydrolysis mixture decreases with speed during the hydrolysis - it is evaporated in the cooler 13 and the vapors are reduced by the acidity. This low corro line 15 has probably been removed. The rate of ionization occurring in the cooler 13 can be attributed to the fact that the sludge is passed through the line 16 to the filtering device. The filtrate obtained is at temperature. For example, the dissotiation con - through the line 18 in the filtrate collecting tank 19 is dammed of the bisulfate ion into a hydrogen and a sulfate - conducts. A portion of the filtrate is ion through the conduit 20 at room temperature is 2 x 10 ^"2 while removed from the container 19 and the cooler 21 zugebei 205 ° to about 1 x 10 60 -. Is estimated ⁵ performs Due to Another. Part of the filtrate is removed from the system due to the unusual property of the bisulfate ion device 22. From this part it can be used as a source for hydrogen ions, so that the benzoic and toluic acids are obtained, and the amide groups are hydrolyzed without increasing the acidity Aqueous residual solution, which consists mainly of aqueous hydrolysis reaction mixture up to a degree at 65% ammonium sulfate solution, can otherwise be returned to the oxydem the rate of corrosion inadmissibly high in the cooler 21

Fig. 3 shows the arrangement of the device and this is usually set to a temperature of 21 to 65 °

Flow diagram for the implementation of a two-stage cools, the cold filtrate is removed from the cooler 21 and

hydrolysis of mixtures of ammonium salts and 70 through line 11, as described above, in the

lower part of the hydrolysis vessel 9 out. The Indian Filtration device 17 accumulating filter cake is brought through lines 23 and 24 into the stirred tank 25, where it is with water, which is about 2.5 percent by weight sodium sulfate and about 0.8 to 1.0 percent by weight Contains sulfuric acid, is slurried. Sodium sulfate and sulfuric acid, d. H. Sodium bisuliate and excess Water containing sodium sulfate is passed through lines 27 and 24 into the stirred tank 25. The sludge produced here is removed from the container through the line 28 and fed into the distributor 29. The hydrolyzing vessels 30, 31 and 32 operate discontinuously, and their connection performances are like that arranged that at the same time a vessel is filled via the distributor line 29 and heated to the hydrolysis temperature, the second vessel is maintained under a pressure of about 35 to 49 atmospheres at 232 to 274 ° in order to achieve the To effect hydrolysis and the third vessel containing the hydrolyzed sludge is emptied. By the distribution line 33, live steam is blown into the individual vessels, which is blown from the vessels through the distribution line 34 and the line 35 escapes again. In the embodiment of the shown in the figure In the process, the vessel 30 is filled with sludge from the manifold 29 and with steam from the manifold 33 heated. The filling and heating of the vessel is continued until it reaches its capacity and the charge is heated to 175-260 °. Vessel 31 is at a temperature of 175 to 260 ° kept under pressure to hydrolyze the amide contained in the sludge. Vessel 32 is made by evaporation of the water removed through lines 34 and 35 from the hydrolyzing temperature to about 120 ° chilled down. The cooled hydrolysis product obtained in the vessel 32 is passed through the line 36 into the sludge container 37 led. The sludge is passed from this through the line 38 into the filtering device 39. Of the Filter cake is removed through line 40 and the filtrate through line 41. Subsequently to the The operation following the operation described, vessel 32 is filled and heated, the contents of the vessel 30 is kept under pressure at the hydrolysis temperature and the contents of the vessel 31 are cooled and withdrawn.

From the mixtures of their ammonium salts and amides in the manner described with reference to Fig. 3 Isophthalic acid and terephthalic acid produced have a nitrogen content of less than 0.03%, determined as ammonia. If these products instead of phthalic anhydride in the usual production of alkyd resin are used, the resin is free of tar and sulfides and shows "Gardner colors" · in the range of 4 to 6. In in the same way, o-phthalic acid, tert-butyl-isophthalic acid and tert-butyl-o-phthalic acid with an extremely low nitrogen content from mixtures of their ammonium salts and amides. Mixtures of ammonium salts and amides of tert-butyl-isophthalic acid and tert-butyl-o-phthalic acid are obtained if 1,3-dimethyl-5-tert-butylbenzene or 1,2-dimethyl-4-tert-butylbenzene be oxidized in the above-mentioned manner. The method according to the invention is suitable are particularly good for the production of pure phthalic acids from mixtures of ammonium salts and amides of phthalic acids, which are characterized by their limited water solubility. But it can also be used to manufacture other aromatic acids, such as benzoic acid and toluic acid, from the mixtures of their ammonium salts and amides can be used. The name »Phthalic Acids» in the claims includes not only the three isomeric phthalic acids but also the tert-butyl-substituted ones Isophthalic acids and o-phthalic acids, the as mixtures of their ammonium salts and amides in the

ίο the above-mentioned oxidation occur.

The second stage of hydrolysis, which uses an aqueous mixture of sodium bisulfate and sodium sulfate, can optionally carried out in a continuous manner parallel to the first hydrolysis stage. The one in the Drawing shown discontinuous hydrolysis has the advantage that during the time in which a The vessel is cooled and emptied, the phthalic acid crystals can grow. By cooling the hot hydrolysis product at a rate not exceeding about The main part of the solid acid has a particle size of 8 ° per minute of more than 0.074 mm mesh size. Crystals of this size can easily be filtered off and are suitable for use in alkyd resin manufacture. With the continuous working method smaller crystals are obtained, which in order to increase the particle size of the solid acid sufficiently and use it for To make the usual preparation of alkyd resins suitable, be subjected to a flocculation treatment have to.

Claims (2)

PATENT CLAIMS: 1. A process for the production of phthalic acids from their ammonium salt-amide mixtures by hydrolysis with strong mineral acids at elevated temperature, characterized in that the hydrolysis at a _pH value of about 2.5 to 3.5 and a temperature between 150 and 315 ° and under a pressure that is able to keep a substantial part of the water in the liquid phase, the mixture is cooled to below about 120 ° and the phthalic acids are separated therefrom in a known manner. 2. The method according to claim 1, characterized in that an aqueous solution of the starting _{mixture is acidified with sulfuric acid up to a p ir} value of about 2.5 to 3.5, the acidified mixture under a pressure that a substantial part of the water in capable of maintaining the liquid phase at a temperature of about 220 is heated to 260 °, then cooled to below about 120 °, the cooled mixture is added sulfuric acid so much that its _pH value is reduced to about 2.5 to 3.5 , then filtered, the phthalic acids obtained as filter material are mixed with water to form a sludge with a solids content of about 2 to 50 percent by weight and the hydroryysis treatment is repeated under the conditions of the first hydrolysis, but optionally using a bisulfate solution instead of sulfuric acid. Considered publications: Gattermann, “The Practice of the Organic Chemist 1952, p. 371, para. 1;
Karr er, "Textbook of Organic Chemistry", 1954, P. 226. 1 sheet of drawings