FR2463126A1 - Conversion of succinonitrile to 2-pyrrolidone - by hydrolysis followed by hydrogenation over a heterogeneous catalyst - Google Patents

Abstract

2-Pyrrolidone is produced by (a) hydrolysing succinonitrile with water at 150-300 (180-250) degrees C and 100-10,000 psig., and (b) hydrogenating the hydrolysis prod. at 200-300 degrees C and 100-10,000 psig. over a heterogeneous catalyst. Pref. step (b) is carried out in the presence of >=0.1 mol. NH3 and 1-400 mols. water per mol. hydrolysed succinonitrile. 2-Pyrrolidone is produced in high yield and may be used to mfr. polypyrrolidone (nylon-4). Pref. catalyst is Ru on a zirconia support.

Description

The present invention relates to a process for the production of 2-
pyrrolidone from succinonitrile. 2-pyrrolidone can be used for the
production of polypyrrolidone ("Nylon-4").

 Various processes have been described for the production of 2 :.

pyrrolidone. For example, U.S. Patent No. 3,644,492:
describes a process for the production of 2-pyrrolidone by contacting.

succinonitrile with hydrogen under pressure in the presence of ca, talyseur-
of hydrogenation and an organic solvent containing nitrogen, at a temperate ---
stripping from 80 to 2000C for a period of less than 3.7 minutes, the operation
being followed by a hydrolysis step carried out by adding water or a solution
aqueous ammonia to the reaction mixture from the previous step,
then heating the reaction mixture to a temperature of 200 to 300 C.

Belgian patent n 839 091 also describes a production process
tion of 2-pyrrolidone from succinonitrile, the reaction steps of which include hydrogenation followed by hydrolysis. In accordance with close
As described in this Belgian patent, succinonitrile is subjected to hydrogenation:
in liquid phase in the presence of ammonia under partial pressure of hydrogen
between 1 and 50 bars, and the reaction product thus obtained is treated in
liquid phase with water, at high temperature. The yields indicated in-
C the examples of the Belgian patent range from 78 to 86 moles 96.

Several patents have described a single step process for the
transformation of succinonitrile into 2-pyrrolidone, as is the case, by
example, U.S. Patents 3,095,423, 3,781,298,
No. 3,966,763 and No. 4 Q36 836. The aforementioned United States patent No. 3,095,423 indicates yields of about 25% for a process in which
succinonitrile is heated in the presence of water to a temperature of 20 to 200 C et
in the presence of a hydrogenation catalyst and - hydrogen under mano pressure -
metric of at least 35 bar. This patent also indicates that the presence
of ammonia in the reaction zone is advantageous because it removes the
formation of secondary amines. The catalysts indicated in the patent of
United States of America No. 3,095,423 supra includes ruthenium oxide,
platinum oxide, catalysts based on noble metals such as platinum and
palladium fixed on carbon or alumina, Raney nickel and cobalt
from Raney.

The U.S. Patent No. 3,781,298 supra describes the
reaction of succinonitrile with hydrogen - in the absence. of an addition of ammonium ---
niac and; -in-- presence of: -catalyeur consisting of - cobalt - of Raney at a
temperature from 250 to 300 C and at a -pressure hydrogen pressure of about 140 to 245 bar, to obtain 2-pyrrolidone. A yield of approximately 62 moles 96 is indicated in this same patent.

U.S. Patent 3,966,763, supra, describes a single-stage hydrogenation process in the presence of water for the transformation of succinonitrile to 2-pyrrolidone, a process in which an activator such as 2 -pyrrolidone is used and yields of 38 to 56 96 are obtained.

 Another one-step process for converting succinonitrile to 2-pyrrolidone is described in the aforementioned U.S. Patent 4,036,836, which indicates yields of 46 to 59.5 mol 96 when the boride nickel is used as a catalyst.

 Succinic acid and maleic anhydride have also been shown as examples of fillers used in the production of gamma-butyrolactone, which can be reacted with ammonia to produce 2-pyrrolidone. U.S. Patent 3,890,361 describes the transformation of succinic acid, succinic anhydride, maleic acid or maleic anhydride to gamma-butyrolactone by contact of the filler with hydrogen in the presence of a hydrogenation catalyst consisting of a uniform mixture of nickel, molybdenum and a third component chosen from barium and thallium. The hydrogenation is carried out at 180-3000C under pressure of 30 at 200 bars. As described in US Pat. No. 3,975,400, gamma-butyrolactone can be transformed into the corresponding lactam, i.e. 2-pyrrolidone, by treatment with ammonia, in the presence or absence of water, at 180-3400C and under pressures from 25 to 280 F; 3rs.

 The direct transformation of succinic acid or maleic anhydride into 2-pyrrolidone is described in US Patents 3,812,148, 3,812,149 and 3,884,936. - United States of America No. 3,812,148 cited above describes the reaction of succinic acid or its precursor with hydrogen and ammonia in aqueous medium in a molar ratio of ammonia to succinic acid of 1.3 : 1 to 1: 7: 1, at a temperature of 250 to 275 "C, at a gauge pressure of 105 to 140 bars and in the presence of a ruthenium catalyst fixed on the alumina. The aforementioned US Patent No. 3,812,149 is identical except that a rhodium catalyst is used therein. These two patents mention yields of 2-pyrrolidone of 90 or 35%. United States of America No. 3,884,936 cited above also describes a direct preparation of 2-pyrrolidone by reaction of maleic acid or maleic anhydride with hydrogen and ammonia in aqueous medium in a molar ratio of ammonia to 1 1: 1 to 1.2: 1 maleic acid or anhydride using palladium fixed on carbon as catalyst.

The present invention, which provides a two-step process for the production of 2-pyrrolidone, involves a step of hydrolyzing a nitrile as described in detail in the following. The hydrolysis of nitrile groups has been described in the prior art (see, for example, Morrison and Boyd, "Organic
Chemistry ", second edition, 1966, page 588).

The present invention provides a process for the production of 2pyrrolidone, which process comprises: (a) bringing succinonitrile into contact with water at a
temperature from 150 to 300 C and a gauge pressure of 3.5
at 700 bars to thereby hydrolyze the succinonitrile, and (b) bringing the hydrolyzed succinonitrile into contact with
hydrogen in the presence of a heterogeneous hydrogenated catalyst
nation, at a temperature of 200 to 3000C and at a pressure
pressure from 7 to 700 bars, to obtain 2-pyrrolidone.

Among other factors, the present invention is based on the fact that, when starting from a charge formed of succinonitrile, a high yield of 2-pyrrolidone is obtained by hydrolysis followed by hydrogenation in accordance with the present invention. The high yield obtained by process is particularly unexpected, since the sequence of steps involved in the present invention, i.e., hydrolysis followed by hydrogenation, is the reverse of the two-step sequence taught in the prior art for obtaining 2-pyrrolidone from succinonitrile.

 Preferably, the hydrolysis of succinonitrile in accordance with the present invention is carried out at a temperature of approximately 180 ° C., 250 ° C. A temperature of approximately 190 to 2300 ° C. is particularly appreciated. hydrolysis steps are sufficient to maintain the water in the liquid phase present in the hydrolysis reaction zone at the elevated temperature used for hydrolysis, usually the gauge pressure is maintained between 7 and 70 bars.

 The water: succinonitrile molar ratios which are preferred in the feed subjected to the hydrolysis operation is between approximately 200: 1 and 2: 1 and in particular between approximately 30: 1 and 5: 1. The contact time, in the hydrolysis step, can range from 0.1 to 20 hours, and preferably from 0.25 to 4 hours.

The hydrolysis operation can be catalyzed by the addition of acids or bases. However, strong acids or strong bases tend to be deactivated by the carboxylated and ammoniated products of hydrolysis. Likewise, their presence complicates the separation of the product. Therefore, it is preferable not to use these catalysts. The rate of hydrolysis can be slightly improved by adding ammonia or carboxylated compounds to change the equal proportion of these basic groups and weak acids which are formed in the hydrolysis reaction. This can be achieved in two simple ways (1) a little ammonia, which is a net by-product of the two process
stages, can be recycled in the hydrolysis stage, or (2) some hydrolysis product can be recycled in this area
after removing a little ammonia.

 The hydrolysis conditions are preferably maintained so that at least one of the nitrile groups of the succinonitrile is converted into a carboxyl type group, that is to say into an amide or into a carboxyl group or into its salt ammonium. The other nitrile group of succinonitrile can remain free, giving a reaction product which is suitable for the second stage of the process of the invention, namely the hydrogenation / cyclization stage.

 According to the invention, the hydrolysis conditions are preferably established so that at least a portion of the succinonitrile is converted into products of the succinic acid type, for example various amides and various ammonium salts. Conditions suitable for the conversion of a relatively large proportion of succinonitrile to succinic acid compounds involve a higher temperature or longer periods of time than those used for the conversion of only one of the nitrile groups of succinonitrile to a carboxyl type group.

 For the hydrogenation stage, the temperature can range from approximately 20 to 300 ° C. depending on the product of the hydrolysis stage. In one embodiment of the invention, the hydrolysed mixture is subjected to a hydrogenation in two stages .

In the first step at low temperature (around 20-1500C), all residual nitrile groups are hydrogenated. In the second step (about 200-3006C) carboxyl groups are hydrogenated and cyclization to 2-pyrrolidone takes place. If we use. relatively mild hydrolysis conditions, and if a considerable number of nitrile groups remain, the two-step approach may be desirable. If a more severe hydrolysis is carried out, the low temperature step may be unnecessary. In both cases, the final hydrogenation temperature is advantageously between around 200 and 3000C. It is preferably between approximately 210 and 2800C, in particular between approximately 215 and 255 C.

A temperature of about 235 "C has been found to be particularly suitable for the hydrogenation step of the present invention.

 The manometric pressure for conducting the hydrogenation stage is advantageously between 7 and 700 bars, and preferably between approximately 14 and 175 bars. The pressure is preferably sufficient to maintain the water and the ammonia in the liquid phase.

 The feed of the hydrogenation step of the present invention may be the total mixture from the previous step of hydrolysis of the process, or a portion of the ammonia and / or water may be removed before the reaction product from the hydrolysis step is not loaded into the hydrogenation step. Preferably, the whole or substantially whole mixture resulting from the hydrolysis step is loaded into the hydrogenation step of the present invention.

In the hydrolysis step, ammonia is formed in proportion to the conversion of the nitrile groups of succinonitrile to carboxyl groups. Thus, the theoretical maximum amount of ammonia that can be formed in the hydrolysis step is 2 moles per mole of succinonitrile feed introduced in the hydrolysis step. If the succinonitrile is only hydrolyzed up to the amide stage, which is not usually the case, it is then preferable to add a little ammonia to the charge introduced into the hydrogenation zone, Since there is little or no ammonia in the effluent from the hydrolysis step which is normally charged in the hydrogenation zone. The conditions prevailing in the reaction zone Hydrogenation are preferably maintained so that there is at least 0.10 mole and there usually is not more than 5.0 moles of ammonia per mole of succinic reactant. Preferably, the amount of ammonia is between 0.25 and 2 moles per mole of succinic reaction substance.

 The term "succinic reactant" is used in its general sense to cover hydrolyzed succinonitrile, whether its hydrolysis is partial or total or whether it contains carboxyl groups or amide groups. If the succinic reactant which is in the hydrogenation stage is in the form of an amide, ammonia is released in the hydrogenation / cyclization reaction by which 2-pyrrolidone is produced in zone d Hydrogenation. Thus, the ammonia content in the hydrogenation zone is maintained not only by the ammonia which can be charged in the hydrogenation stage as part of the reaction effluent of the hydrolysis stage or under the form of a stream of ammonia added separately, but also by ammonia which can be generated from the feed introduced into the hydrogenation reaction zone while this feed is converted into 2pyrrolidone.

 Preferably, the hydrogenation reaction is carried out in the liquid phase, water constituting the liquid medium. The molar ratio of water to the succinic reactant is preferably between 1: 1 and 400: 1, and in particular between 2: 1 and 50: 1 in the reaction zone of the hydrogenation stage. Like ammonia, water can optionally be added to the reaction zone separately, and the amount of water in this zone can also be increased by converting the succinic reactant to 2pyrrolidone. from the transformation of succinic acid into 2pyrrolidone, 3 moles of water are generated, and in the case of the conversion of beta-cyanopropionic acid to 2-pyrrolidone, 1 mole of water is formed, while in the conversion of beta-cyanopropionamide to 2-pyrrolidone, one mole of ammonia is formed, but no water is formed.

 The amount of hydrogen which is charged into the hydrogenation reaction zone is preferably sufficient so that there is a ratio of 2: 1 to 200: 1 moles of hydrogen per mole of succinic reactant, this is ie per mole of the charge formed of hydrolysed succinonitrile introduced into the hydrogenation zone. In any case, a sufficient quantity of hydrogen is preferably charged to maintain an appreciable partial pressure of hydrogen in addition to the pressure necessary to maintain the reaction conditions in the liquid phase of the succinic reactant in the presence of liquid state. The high gauge pressure is preferably between 35 and 175 bars, and in particular between 70 and 140 bars.

 Advantageous catalysts for use in the hydrogenation step include the Group VIII metals, namely iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum. The "hydrogenation 4 group VIII metals which are appreciated include cob-'t, nickel, ruthenium, rhodium, palladium, iridium and platinum. Group VIII metals such as cobalt, nickel, palladium and ruthenium.

 The group VIII metal is preferably fixed on a support, for example on an inorganic refractory material such as alumina or silica or mixtures of alumina and silica. Zirconium oxide constitutes a particularly appreciated support.

Raney cobalt or Raney nickel type catalysts can be used in the hydrogenation step. Cobalt or nickel from
Raney is prepared according to known methods for the preparation of these hydrogenation catalysts.

A particularly preferred hydrogenation catalyst is ruthenium fixed on a refractory support such as alumina, silica, a mixture of silica and alumina, carbon or zirconium oxide. A particularly preferred form of ruthenium catalyst attached to a support is ruthenium attached to zirconium oxide, as described in detail in U.S. Patent Application No. 887,574, filed March 1 1978.

 Preferred amounts of metal or Group VIII metals on the supports mentioned above range from 0.1 to 25% by weight and preferably from 0.2 to 10% by weight.

 Preferably, the amount of catalyst used in the hydrogenation reaction zone is from 0.01 to 5.0, and preferably from 0.02 to 20 parts by weight of the succinic reaction charge.

The invention is illustrated by the following example:
21.25 moles of succinonitrile, 4.6 moles of succinic anhydride and 352 moles of water are loaded into an 18.9 liter stainless steel autoclave equipped with a stirrer. The reactor is charged at room temperature, then heated to 2100C. Its content is maintained at this temperature and at a gauge pressure of approximately 16.8 bars, with stirring for approximately 3 hours.

 Succinic anhydride is included as an acid catalyst for hydrolysis; however, other laboratory tests have determined that its presence is not essential.

 A 2000 g portion of the reaction product, i.e. the total reactor effluent of 18.9 liters above, is loaded into a 3.8 liter reactor at room temperature. A hydrogenation catalyst (ruthenium at;, 8 96 fixed on zirconium oxide) is introduced in an amount of 150 g into the 3.8 liter reactor, in the form of powder. Hydrogen gas is introduced at room temperature into the reactor up to a pressure of 105 to 133 bars.

 The reactor is then heated to 235 "C while stirring its contents. The temperature is maintained at 2350C for approximately 20 hours.

 The product of this hydrogenation step is analyzed by chroma tography; the yield of 2-pyrrolidone is 89 mol 96 based on the succinonitrile charged in the hydrolysis step.

 In a repeated test relating to the hydrogenation stage, a yield of approximately 90 mol% is obtained, which confirms the high yield of 89% - obtained above. In this repeated test, a one liter reactor is used for the hydrogenation stage and the charge consists of a portion of the total reaction product obtained in the hydrolysis stage carried out in the autoclave of 18.9 liters, as described above. The reaction conditions of this repeated hydrogenation test are generally the same, except for the contact time used for the hydrogenation step, which is only 12 hours.

Claims (7)

 1. - Process for the production of 2-pyrrolidone, characterized in that it consists: (a) in bringing succinonitrile into contact with water at a  temperature from 150 to 300 "C and under a gauge pressure of  7 to 700 bars to thus hydrolyze succinonitrile; and (b) bringing the hydrolyzed succinonitrile into contact with  hydrogen in the presence of a heterogeneous hydrogenated catalyst  nation, at a temperature of 200 to 3000C and under pressure  pressure from 7 to 700 bars, so as to obtain 2  pyrrolidone.  2. - Method according to claim 1, characterized in that step (b) is implemented in the presence of at least 0.10 mole of ammonia per mole of hydrolyzed succinonitrile and from 1 to 400 moles of water per mole of hydrolyzed succinonitrile.  3. - Method according to claim 2, characterized in that the hydrolysis is carried out at 180-2500C.  4. - Method according to claim 2, characterized in that the hydrolysis conditions are established so as to transform at least one portion of succinonitrile into succinic acid in step (a). 5. - Method according to claim 2, characterized in that the catalyst used in step (b) is a group VIII metal.  6. - Process according to claim 2, characterized in that the catalyst is a group VIII metal fixed on a porous mineral support.  7. - Method according to claim 2, characterized in that the catalyst is ruthenium fixed on a support consisting of zirconium oxide.