DE1618002A1 - Improved Process for Making Aminonitriles - Google Patents

Description

The Standard Oil Company, Midland Building, Cleveland, Ohio

(UNITED STATES.)

Improved Process for Making Aminonitriles

The present invention "relates to a new method for f continuous production of aminonitriles. In particular, it relates to the continuous production of Aminonitriles from an ammonium or amine salt of a strong protic acid with formaldehyde and hydrogen cyanide. '

A very old process for the preparation of aminonitriles is described in US Pat. No. 2,205,995. This in The method described in this publication is ■ |

but very tedious and the reaction component hydrogen cyanide is generated in situ. According to this prior art method, this is obviously not continuous Could be run sodium cyanide, ammonia or an amine, sulfuric acid and formaldehyde in the usual amounts for individual batches are mixed together and the reaction mixture is left to stand for about 40 hours. That The method according to the invention is much faster ongoing and more effective process than that in the

009834/1838

iÄD ORiGiNAL

U.S. Patent No. 2,205,995. The process of the invention is continuous and hydrogen cyanide acid is used instead of the cyanide used according to the previously known method.

It is known from US Pat. No. 2,855,428 to prepare aminonitriles by introducing ammonia or an amine into a liquid reaction mixture containing formaldehyde and hydrogen cyanide at a low pH in such an amount that the ammonia reacts immediately to form the aminonitrile , and the aminonitrile is trimmed off. In this prior art process, only a catalytic amount of acid is used; additional acid does not need to be added and only formaldehyde and hydrogen cyanide have to be replaced in the reaction mixture. Amine must be added in such an amount that the pH of the reaction mixture does not exceed 1. In this method of the prior art, the addition effect of the amine or ammonia to the reaction mixtures of heat, which also limits the rate of addition.

The process according to the invention is based on the continuous process for the preparation of aminonitriles and represents an improvement of the same that in the older one

009834/1838

German patent application St 26 151 IVb / 12qu dated November 24, 1966 is described and the reaction of hydrogen cyanide, formaldehyde and an ammonium or amine salt of a strong Acid such as sulfuric acid.

The process according to the invention is particularly focused on the production of Eitrilotriacetonitrile applicable.

A difference between the method of US Pat. No. 2,855,4-28 and the aforementioned earlier patent application St 26 151 1ΊΠ> / Ι2ςρι is that in the previously known Process the rate of addition of ammonia or amine must be carefully controlled so that the pH does not rise and the reaction temperature is not too high, while in the process of German patent application St 26 151 IVb / i2q_u the distinct advantage is that such careful control measures are not necessary. In addition, the pH decreases in the process of the German patent application St 26 151 IVb / i2q.u as the reaction continues from what is desirable, while in the process of US Pat. No. 2,855,428 an increase in pH is continuously favored by the addition of the basic amine or ammonia and an increase in pH Cancellation of the desired reaction and the formation of undesired by-products can cause. Another difference between the two processes can be seen in the stage in which the reaction product is isolated. After this The method of US Pat. No. 2,855,428 is said to result in the reaction

003834 / 183-8

and the removal of the aminonitrile is carried out at the same time will; In contrast, "in the present process, the aminonitrile" is at a temperature well below 40.degree Temperature following a reaction time "removed at the desired reaction temperature, and it does not find any further conversion takes place at this low temperature, even with the addition of the worked-up reaction components to the reflux stream. Accordingly, this procedure represents Compared to previously known processes, a faster and easier to carry out process for production of aminonitriles.

The present process involves the preparation of aminonitriles such as ethylenediamine tetraacetonitrile, diethylenetriaminepentaacetonitrile, Methylamine diacetonitrile and especially nitrilotriacetonitrile by rapid continuous Reaction under pressure using a suitable ammonium or amine salt of a strong protic Acid together with formaldehyde and hydrogen cyanide at a temperature in the range of about 40 - 120 ° G.

The basic, nitrogen-containing starting materials that can be used in the present process, include ammonia and primary and secondary mono- and polyamines of 1-20 carbon atoms. Alkylamines, arylamines, Aralkylamines and alkylenediamines with all degrees of substitution can be used, with the implementation incoming part of the amine to the 1-, 2- or 3-position

00983 W1838

the nitrogen atom occupied by hydrogen.

Once the reaction has taken place to a substantial extent, the reaction mixture is cooled in order to separate the aminonitrile from the aqueous phase by a suitable method, and the aqueous phase is replenished with reaction components in amounts which essentially correspond to the amounts used in the reaction correspond. the rejuvenated aqueous phase is then the reaction chamber for further reaction and forth% position recycled further quantities aminonitrile. the aminonitrile produced by the present process are useful as chemical intermediates, especially for the manufacture of materials by hydrolysis, for the separation of amino acids are suitable.

With each of the present processes, high purity aminonitriles can be obtained in essentially theoretical yields. The process is in an acid medium ä CARRIED OUT, preferably can at a pH below about 3, and most preferably, etc. at a pH below about 2. ammonium or amine salts of strong protic acids such as sulfuric acid, hydrochloric acid, trichloroacetic acid, phosphoric acid. be used. It has been found that ammonium sulfate, ammonium bisulfate and mixtures thereof are particularly advantageous in the process according to the invention. When using an amine salt, salts of strong protic acids with primary or

0 0 9 8 3 4/1838

secondary alkyl amines, aryl amines, aralkyl amines, alkylenediamines and similarly substituted alkylenediamines are used will. The reaction-entering part of the amines or ammonia are the hydrogen atoms, which are directly connected to the basic nitrogen atom are connected. In the present process, preferably all of the amine or ammonia nitrogen atoms are substituted by acetonitrile groups.

Formaldehyde, aqueous solutions of formaldehyde or polymeric formaldehyde products such as paraformaldehyde can be used as a reaction component used in the method according to the invention will. When using paraformaldehyde in the recycle stage to maintain the chemical There are several advantages to equilibrium in the reaction mixture because water is a reaction product and a dilution of the aqueous phase, if allowed to enlarge it too much in the recirculations.

The molar ratio between the amino and ammonia hydrogen sulfate, Formaldehyde and hydrogen cyanide are not particularly critical as long as sufficient amounts of the reaction components are used are present. The influence of the reaction temperature however, seems to be much more stressed. The stoichiometry for the preferred response between Amminoak, formaldehyde and hydrogen cyanide with the formation of nitrilotriacetonitrile is produced by the following chemical Formula reproduced:

009834/1838

618002

+ 3 E ₂ G = ZQ + J HGIi> 3 M (GH ₂ CU) ₅ + H ₂ SO ₄ + 3

In the case of dureli this (borrowing characterized reaction is the end product nitrilotriacetonitrile, which how ■ mentioned above, by means of a base such as sodium hydroxide can be easily hydrolyzed to form nitrilotriacetic acid or salts thereof, which act as gelling agents It is well known that in the above reaction the quantitative ratios which can be carried out in practice are above from 1 1/2 moles of formaldehyde to 1 1/2 moles of hydrogen oyanide to 1 mole of Amtnonium hydrogen sulfate. The maximum ratio between these response components in relation on ammonium hydrogen sulfate is determined by practical problems such as product separation.

The reaction temperature "in the present process can be in the range of just above 40-120 ° C." At higher reaction temperatures, higher conversion rates are achieved and shorter reaction times are necessary to achieve the desired yields. The pressures in the system adjust themselves The reaction time depends on the desired degree of conversion and the temperature used in each case However, the conversion can take place with acceptable conversion rates in times as short as 5 minutes

The reaction mixture is maintained at one temperature 40 ° G and preferably cooled below 30 ° C to the Separation of the crystalline aminonitrile by filtration, centrifugation or other suitable separation methods to effect. The addition of additional ammonia to the filtrate is also made at these low temperatures carried out.

The reaction vessel can be made of any inert material that is resistant to corrosion by the acidic medium resists.

When using the preferred conditions for the preparation of, for example, nitrilotriacetonitrile, the reaction components are combined and fed into the reaction vessel with the stirrer in operation. The reaction vessel is kept at a temperature of 60-70 ° C. and the reaction is allowed to proceed for half an hour to two hours. The pH of the reaction mixture is initially about 1.5 and decreases as the reaction proceeds. After cooling the reaction mixture to about 0 to 30 ° C., a slurry of finely divided, insoluble crystalline nitrilotriacetonitrile is obtained. The slurry is centrifuged or filtered, or the solid is separated from the aqueous phase by other suitable methods. According to the method of the earlier patent application St 26 151 IVb / i2qu, the greater part of the cold filtrate or the mother liquor is converted into a 00 9834/18 38

Misehtank fed in, where ammonia is added to replace the amount consumed in the reaction. Before adding Part of the filtrate can be added to the top-up quantities of ammonia a flame tower to remove excess water be derived and the hydrogen cyanide ■ can from this The filtrate was separated overhead and mixed with the aqueous reaction mixture be combined before implementation begins. The residue from the flame tower becomes the ammonia mix tank pumped where the temperature is kept at 0 - 30 ° C · Additional hydrogen cyanide including the ^

Quantities from the flame tower become the electricity from the ammonia mixer added and this liquid stream is fed to a second mixing tank, in the paraformaldehyde before the addition of the hydrogen cyanide in the recycle stage can be added. The temperature of this part of the recycled reaction mixture is then increased to 40-50 ° C increased and, if necessary, additional sulfuric acid is added. The reaction mixture is then poured into the Fed into the reactor. In that part of the recirculated liquid stream in which the temperature is below- ™ half is kept about 40 ° C, no reaction takes place with the formation of aminonitrile.

It has now been found that some of the formaldehyde and of the hydrogen cyanide in the above reaction mixture is converted into the by-product glycolonitrile of the formula HOCHoON that will result in concentrations in the recycle stream Can accumulate in the range of $ 1 - $ 38 9 and more · This

009834/1838

By-product goes with hydrogen cyanide and ammonium salts ^; no more reaction, which results from the fact that it no longer reacts with hydrogen cyanide and ammonium hydrogen sulfate by reacting for one hour at 80 ° C .; in addition, hydrogen cyanide and formaldehyde are removed from the reaction mixture by their formation, whereby the formation of nitrilotriacetonitrile is reduced.

According to the present invention, nearly quantitative Yields of nitrilotriacetonitrile in the recycle process of the earlier German patent application St 26 151 IVb / i2q.u can be achieved by using part of the after Separation of the nitrile remaining filtrate or mother liquor is drawn off, this drawn off from the filtrate Part is mixed with ammonia up to a pH of more than 7 at relatively low temperatures and the so treated Part of the main recycle stream is fed back, which is returned to the reactor. the The exact nature of the reaction taking place after the addition of ammonia to the filtrate is not known; However, it can be assumed that the glycolonitrile dissociates with the formation of formaldehyde and hydrogen cyanide, both of which are the starting products in the formation of the Mtrilotriacetonitrile can be used in the reactor.

In a preferred embodiment of the invention The process is carried out after the solid nitrilotriacetonitrile has been separated off and the hydrogen cyanide has been stripped off

0 09834/1838

the remaining liquid phase, the total liquid phase or a portion thereof, such as zl, 1/10 or 1/2 volume der.flüssigen phase .In fed a water stripper by the excess water is separated. In this aqueous phase, water collects, since water is formed in the reactor and water originates from aqueous formaldehyde, provided this is used as the starting product. The aqueous phase or part thereof is concentrated to about 20-60 # of its original volume in the water stripper. The remaining part of the non-concentrated aqueous phase is returned to the main reactor% stream. The concentrated filtrate is cooled to a temperature below 30 ° G and aqueous or anhydrous ammonia is added. The use of low temperatures during the addition of the ammonia is essential to avoid coloration as much as possible. With the addition of the ammonia, an exothermic reaction probably takes place between the ammonia and the sulfuric acid present; therefore, it is desired, the ammonia to the concentrated aqueous g phase at temperatures somewhat below 30 ° C and "preferably in the range of approximately 0 - add 15 ° C" At this point of the process, ammonia is added in an amount sufficient to adjust the pH of the reaction mixture to above 7 and to provide the ammonia necessary for the entire recycle stream to form the nitrilotriacetonitrile in the reactor. The reaction with ammonia generally does not take more than 15 minutes

0 09834/1838

mixed aqueous mixture is then treated with the untreated Recycle stream combined within the shortest possible time. Again, it is preferred that mixing takes place at a temperature below 30 ° C. The pH of the reaction mixture to be returned is then adjusted to less than 2 by adding sulfuric acid and the content of hydrogen cyanide and formaldehyde is then adjusted by adding such amounts of these reactants as are necessary for nitrilotriacetonitrile formation are necessary.

The effect of the reaction of the glycolonitrile with ammonia on the conversion to nitrilotriacetonitrile is shown in the figurative example in which both the ammonia treated and untreated filtrates were returned.

example

Experiment A, in which the filtrate not treated with ammonia was recycled as follows, was carried out in one Glass tube reactor carried out. This reactor consisted of a glass-lined pipe 10.2 cm in diameter, which was closed at both ends by flanges. That Pipe was heated by passing hot water or steam through a tightly wound copper coil became. The tube was placed on a shaker, that caused weak fluid movement. Cold ones were used to load the tubular reactor

0098-34 / 1 838

Reaction components entered, the tube is then closed and the reaction mixture then heated to the desired reaction temperature with continued stirring. Heating up took 25-30 minutes. The reactor was then kept at reaction temperature for one hour and then cooled as quickly as possible before opening.

Experiment B, described below, which explains the influence of the recycling of the ammonia-treated filtrate, was carried out in a modified Parr hydrogenation apparatus. Heating and cooling were thereby achieves that water through an approximately 0.5 cm thick copper tube wound around a thick-walled 500 ecm reaction flask was directed. The contents of the reaction vessel were stirred by shaking. The temperature of the reaction * - mixture was measured by means of a thermocouple, which is located in a sealed glass tube in a rubber stopper found. In all cases the product was quenched to 0 ° 0 and using filter cloth or Filter paper filtered in a Buchner funnel. The nitrilotriacetonitrile crystals were about 2 volumes Water washed. Additional wash water was for products necessary, the excess amounts of strongly colored filtrate contained. Aqueous formaldehyde which did not contain any inhibitor was used in all experiments. That in that Aqueous formaldehyde used in the initial reaction mixture contained 57% foraiaXaeliyd and 50% solutions,

Ö0S834 / 1838

-H-

were used for admixture in the recycle stream. The hydrogen cyanide used had a purity of $ 99 The ammonium bisulphate and ammonia had the usual degree of purity for organic syntheses.

Experiment A;

This experiment illustrates the recycling of filtrates not treated with ammonia. It is only used for comparison purposes and is outside the scope of the present invention. 0.57 moles of concentrated ammonia was used added to an aqueous solution containing 0.74 mol of ammonium hydrogen sulfate in 358 g of water. The solution was cooled to 0 ° G and there were 3 moles of a 48 $ aqueous solution of formaldehyde, 6 mol of hydrogen cyanide and 65 ecm of water were added. The mixture was then in the Tube reactor heated to 80 ° C. for 1 hour. A conversion to nitrilotriacetonitrile of $ 97.8 was achieved. The nitrilotriacetonitrile was filtered off and all of the filtrate from this reaction was mixed with the starting Substances made up in the same molar ratio as stated above. The mixture was then placed in the tubular reactor reacted at 80 ° C for one hour and there was a conversion to nitrilotriacetonitrile in the amount of 35.3 # observed.

Try bi

This experiment illustrates recycle of treated with ammonia Büokflußstromi it is upstream from the scope of the

. 00S834 / 1838

lying invention includes. A solution of 0.417 mol of ammonium hydrogen sulfate, 0.209 mol of concentrated aqueous ammonia and 144.8 ecm of water was cooled in a bath measuring 0 ° C. and consisting of methanol and ice as a coolant. To this end, 2.5 mol of hydrogen cyanide and then slowly 1.25 mol of formaldehyde in the form of a 56.8% aqueous solution were added. The pH of the reaction mixture was controlled. The reaction mixture was heated to 80 ° C. and held at this temperature for one hour. The reaction mixture was then quenched at -10 ° G and M, the solid was separated by filtration nitrilotriacetonitrile the cold supervisor chiämmung. 0.523 moles of nitrilotriacetonitrile was recovered, which is calculated to be a yield of $ 77.4 based on treated glycolonitrile and freshly added formaldehyde. The filtrate had a total volume of 193 ecm and was divided into two portions. One portion of the filtrate was concentrated and treated with ammonia and additional hydrogen cyanide and formaldehyde were added to make up these reaction components. 100 cc of the filtrate was concentrated to a volume of 21 com in a Buchler vacuum rotary evaporator and the concentrated filtrate was found to contain 0.077 mol of glycoltiitrile. This concentrated filtrate was cooled to -10.degree. C. and 0.352 mol of concentrated ammonia was slowly added so that the temperature of the resulting mixture did not exceed 20.degree.-25.degree. The pH of the resulting mixture was 9.89. 1.101 mol of a 36.8 # solution of formaldehyde and 0> Q6 mol of concentrated sulfuric acid 00.3834 / 1838 were then added

admitted. The pH of the adjusted solution was 1.49 More sulfuric acid was added to bring the pH to 0.72. The solution was with the leftover 93 ecm of the original filtrate combined, the G-emic was cooled to 0 ° C. and 1.91 mol of hydrogen cyanide were added.

In the first cycle that now follows, the G-mixture described above was heated to 80 ° G for 1 hour. That Nitrilotriacetonitrile formed was as described above separated and a yield of $ 73.5 was achieved. The total amount of the filtrate was 205 ecm. 110 ecm of the filtrate were concentrated to 44.3 g. This concentrated filtrate was examined and found to be 0.078 mole of glycolonitrile. The mixture was cooled to -10 ° 0 and 0.347 mol of concentrated ammonia was added. The pH of the resulting solution was 9.31 «For this purpose, 1.084 mol of a 36.8 $ aqueous Formaldehyde solution and 0.084 mol of concentrated sulfuric acid were added. The pH of the resulting solution was 0.95 · The mixture was then mixed with the 95 ecm of the original Filtrate combined with another 6 ecm V / ater. The resulting mixture was cooled to 0 ° C and 1.931 moles of hydrogen cyanide were added. The reaction mixture was added to the reaction vessel as a second circulation fed back.

The reaction mixture of 009834/1838 described directly above

The second round was heated to 80 ° O for 1 hour. That
The reaction mixture was cooled and the nitrilotriacetonitrile formed was separated off as described above and the filtrate was returned to the reaction vessel as a third circulation.

The mixture of the third circulation was again heated to 80 ° C. for 1 hour and nitrilotriacetonitrile was formed in a yield of $ 72.5. The filtrate was treated as described above and again for the fourth time
fed to the reaction vessel.

The conversion of the fourth circulating stream, which originated from the previous stage described above, gave nitrilotriacetonitrile in a yield of 76.8 ia in the case of a corresponding conversion.

Patent claims:

009834/1838

Claims (2)

Patent claims: 1. A process for the preparation of aminonitriles, characterized in that I. a G-emic from a) a primary amine with 1-20 carbon atoms, a secondary amine with 1-20 carbon atoms and / or a polyamine with 1-20 carbon atoms in the form of their salts with a strong protic Acid, b) formaldehyde and c) hydrogen cyanide reacted under autogenous pressure at a temperature above about 40 ° C and up to about 120 ° C will, II. At least part of the reaction mixture from stage I is cooled to a temperature below about 40.degree and the aminonitrile is separated from the mother liquor, III, at least part of the mother liquor obtained from stage II with an additional amount of the reaction component is added at a temperature below 30 ° G in such an amount that a pH of more than 7 is achieved and the portion treated in this way with the remainder of the mother liquor obtained from stage II is reunited, IV. The resulting mixture from stage III with the reaction components in essentially the same molar ratio as used in the formation of the aminonitrile consumed, replenished and 009834/1838 V. the mother liquor refreshed in stage IT is circulated to stage I. 2. The method according to claim 1, characterized in that the reaction component a) is ammonia. / 5. The method according to claim 1 or 2, characterized in that the protic acid is sulfuric acid. 009834/1838 Blank page