WO2013152999A1 - Process for the preparation of caprolactam - Google Patents

Description

 Process for the preparation of caprolactam

The present invention relates to a process for the preparation of ε-caprolactam from adipic acid, which in turn can be produced from regenerative materials. ε-caprolactam is an important intermediate for the preparation of polyamides, especially nylon-6.

It is known that ε-caprolactam, starting from adiponitrile, can be prepared via 6-aminocapronitrile. Usually, the adiponitrile is obtained starting from butadiene or acrylonitrile. The recovery of adiponitrile can also be accomplished from adipic acid by dehydrating amination (see, e.g., U.S. 3,671,566). The adiponitrile results in hemihydrogenation of 6-aminocapronitrile (see, for example, US Pat. No. 5,986,127, US Pat. No. 6,521,779), which is finally converted by cyclizing hydrolysis to the desired ε-caprolactam (cf., for example, US Pat. No. 6,521,779). A fundamental advantage of choosing adipic acid as the starting point for the production of ε-caprolactam consists in the possibility of ε-caprolactam

to produce renewable raw materials, since the educt of adipic acid from glucose-containing, so both renewable and inexpensive materials is accessible (see, WO-A-2010/144862, WO-A-201 1/109051).

A disadvantage of the known synthesis route for the production of ε-caprolactam via adiponitiril is the problem of the regioselective hydrogenation of one of the two

Nitrile groups of the symmetrical adiponitrile. This results in particular in yield losses, since in a not inconsiderable amount hexamethylenediamine is also formed (see, for example, US Pat. Nos. 6,087,296, 6,147,208, 6,462,220). It is an object of the present invention to provide an improved process for the preparation of ε-caprolactam and derivatives thereof starting from adipic acid starting materials. This object is achieved by the embodiments of the present invention characterized in the claims and the present description.

In particular, the invention provides a process for the preparation of ε-caprolactam comprising the steps

(a) reacting adipic acid to adipic anhydride,

 (b) reducing the adipic anhydride to caprolactone and

 (c) aminating the caprolactone to caprolactam

includes. The process according to the present invention is distinguished from the known processes of the adiponitrile synthesis route in particular by the fact that the production of the adipic anhydride avoids the regioselective hydrogenation of the adiponitrile and thus a considerable increase in yield can be achieved.

According to an advantageous embodiment of the method according to the invention, the adipic acid is obtained from glucose or a glucose-containing material such as starch. In this case, the glucose or glucose-containing material (1) is preferably oxidized to produce glucic acid and (2) the glucic acid hydrodeoxygenated to adipic acid.

The above step (1) may, for example, by known in the art

Oxidation process can be performed. For example, US Pat. No. 2,472,168 describes the chemocatalytic oxidation of glucose in the presence of a platinum catalyst, oxygen and a base. Another oxidation method of this type of glucose to glucic acid is e.g. in Journal of Catalysis (1981) Vol. 67, pages 1 to 13. Other oxidation processes are, for example, in US

6,498,269 and WO-A-2008/021054. A particularly preferred adipic acid preparation of this type from glucose or a glucose-containing material is described, for example, in the publications WO-A-2010/144862 and WO-A-201 1/109051, to which reference is made

is fully referenced. Thus, according to the invention, particularly preferred is the above step (1) by reacting the glucose or the glucose-containing material in the presence of oxygen and a

Oxidation catalyst, but in the absence of bases, as described in WO-A-2010/144862 and WO-A-201 1/109051, performed. For further details on the reaction of glucose or containing them

Materials for glucic acid are disclosed in WO-A-2010/144862 (see in particular [0018] to [0036] and [0084] to [0088] (Example 1) of this document) or WO-A-201 1/109051 (see Figures [0060] to [0064] (Example 1) of this document). According to a particularly preferred embodiment, step (1) uses a Pt / Au / TiO 2 catalyst in a continuous fixed-bed reactor in which the

Reaction with oxygen at 350 psi (24.132 bar) for 122 h at 105 ° C (see Example 3 of WO-A-201 1/109051, in particular [0068], [0069] and [0071]).

The step of hydrodeoxygenation of glucic acid to adipic acid is preferably carried out according to WO-A-2010/144862 or WO-A-201/109051

Reacting the glucic acid in the presence of a hydrodeoxygenation catalyst, a halide source and hydrogen. With regard to suitable catalysts and halide sources and suitable further reaction conditions, reference is made to the relevant statements in WO-A-2010/144862 (cf., in particular, [0037] to [0068] and [0089] to [0092] (Example 2) of this document ) and in WO-A-109051 (see in particular [0065] to [0067] (Example 2) of this document). Most preferably, the hydrodeoxygenation of glucic acid to adipic acid is conducted in a continuous fixed bed reactor with a Pt / SiO 2 / Rh catalyst, the glucaric acid dissolved in 0.2 M HBr / acetic acid and hydrogenated at 1000 psi (68.947 bar) in a The first reactor section is reacted at 110 ° C. and in a second reactor section at 140 ° C. (cf., [0070], [0072] and [0073] (Example 3) of WO-A-201 1/109051).

The step (a) of the process according to the invention is preferably carried out by

Reaction of adipic acid in the presence of acetic anhydride. Preferably For this adipic acid in acetic anhydride for a suitable period of time, for example. 2 to 8, more preferably 3 to 5, more preferably about 4 hours, advantageously heated under reflux and the resulting acetic acid and remaining acetic anhydride removed and the product recovered from the residue by distillation.

In step (b) of the process according to the invention, the anhydride is reduced to the lactone. This step is preferably carried out in the presence of hydrogen and a reduction catalyst and in the presence of an alkali metal salt and / or an alkali metal hydroxide. Particularly suitable catalysts comprise at least one metal of group VII of the periodic table (preferably iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium and / or platinum) or a combination of such a metal with at least one element selected from groups IVa, VIb and VIIb of the Periodic Table (preferably lead, molybdenum and / or rhenium). Correspondingly preferred reactions of this type are described in EP-A-0543340, and reference is expressly made to the relevant disclosure of this document.

Alternative reactions of adipic anhydride to caprolactone can be found, for example, in the publications GB-A-2194232, JP-A-8217707, JP-A-2002088076, JP-A-

50089347 and WO-A-2005/051875, to the relevant disclosure contents of which reference is made in its entirety.

The amination of caprolactone to the desired caprolactam takes place

usually by reaction with ammonia and hydrogen, typically in the presence of water or steam, and advantageously in the presence of a catalyst. In a preferred embodiment, the amination according to. Step (c) with ammonia in the presence of hydrogen and steam and an amination catalyst, which preferably comprises one or more metal oxides, particularly preferably copper oxide, chromium oxide and / or titanium dioxide. An amination of this type is described, for example, in JP-A-9003041, to the

Disclosure is fully incorporated by reference. Other amination reactions of caprolactone for caprolactam, which are likewise suitable according to the invention, are, for example, the publications JP-A-2003341427, DE-A-21 1 1216, FR-A. A-2506874, JP-B-48015316, JP-A-48029739, JP-A-48034190, JP-B-48039950 and JP-A-49132095.

The present invention is further illustrated by the following examples and the accompanying drawings.

FIG. 1 shows a preferred synthetic route according to the present invention for the production of ε-caprolactam via adipic acid, starting from glucose. EXAMPLES

Example 1 Adipic acid to adipic acid anhydride

Adipic acid and acetic anhydride are refluxed for 4 hours. Thereafter, acetic anhydride and resulting acetic acid are removed in vacuo. The remaining residue is distilled under high vacuum, the product fraction passes at 1 10-120 ° C and 4-10 mbar as a violet-purple liquid, which solidifies after a few days. The yield is typically 84%. Example 2: Adipic anhydride to ε-caprolactone

The reaction of adipic anhydride is carried out to caprolactone according to Example 1 of EP-A-0543310, but adipic anhydride instead

Maleic anhydride is used as starting material. The yield of this reaction is usually over 90%, up to 99%, based on the anhydride.

Example 3: ε-caprolactone to ε-caprolactam

As described in JP-A-9003041, the caprolactone with ammonia in

Presence of hydrogen in the vapor phase using a

Catalyst of copper oxide, chromium oxide and titanium dioxide reacted, wherein the yield is typically 80%, based on the lactone. Example 4: Production of adipic acid from glucose

4.1 Glucose to Glucärsäure Glucärsäure is made of glucose gem. Example 3 of WO-A-201 1/109051, in which first a Pt / Au / TiO ₂ catalyst as described in [0068] of WO-A-2010/144862 is formed and then reacted with hydrogen (5%) in nitrogen (95%) at 350 ° C for 3 hours (see WO-A-201 1/109051). As described in WO-A-201 1/109051, the catalyst is introduced into a continuous fixed bed reactor and charged with aqueous glucose solution and oxygen at 350 psi (24.132 bar) and 105 ° C. The reaction takes place for 122 h. 4.2 Glucic acid to adipic acid

The gem. 4.1 glucic acid is, as described in Example 3 of WO-A-201 1/109051 hydrodeoxygenated to adipic acid. A Pt / SiO ₂ / Rh catalyst prepared as described in WO-A-201 1/109051 is used.

The glucaric acid is dissolved in a solution of glucaric acid containing 0.2 M HBr in acetic acid. The solution is reacted with hydrogen at 1000 psi (68.947 bar) in a first reactor section at 110 ° C. in a continuous reactor containing the catalyst as a fixed bed and at 140 ° C. in a second reactor section (see Example 3, 0072], WO-A-201 1/109051). The purification of the

Reaction product is made by recrystallization first from acetic acid and then (3x) from water (see Example 3, [0073], WO-A-201 1/109051).

Claims

claims 1 . Process for the preparation of ε-caprolactam, comprising the steps:  (a) reacting adipic acid to adipic anhydride;  (b) reducing adipic anhydride to caprolactone; and  (c) aminating the caprolactone to caprolactam. 2. The method of claim 1, wherein the adipic acid is prepared from glucose and / or a glucose-containing material. 3. The method of claim 2, wherein production of adipic acid the  Steps:  (1) oxidizing the glucose or the glucose-containing material to produce glucic acid and  (2) Hydrodeoxygenating the glucic acid to adipic acid  includes. 4. The method of claim 3, wherein step (1) is carried out by reacting the glucose or the glucose-containing material in the presence of oxygen and an oxidation catalyst in the absence of bases. 5. The method according to claim 3 or 4, wherein in step (2) the glucic acid in the presence of hydrogen, a halide source and a  Hydrodeoxygenierungskatalysators is converted to adipic acid. 6. The method according to any one of the preceding claims, wherein the  Adipic acid in step (a) in the presence of acetic anhydride  Adipic anhydride is reacted. 7. The method according to any one of the preceding claims, wherein the Adipic anhydride in step (b) in the presence of hydrogen and a reduction catalyst and in the presence of an alkali metal salt and / or an alkali metal hydroxide is reduced to ε-caprolactone. 8. The method of claim 7, wherein the catalyst comprises at least one metal of group VII of the periodic table or a combination of such a metal with at least one element selected from groups IVa, VIb and VI Ib of the periodic table. 9. The method according to any one of the preceding claims, wherein the ε-caprolactone is reacted in step (c) with ammonia in the presence of hydrogen and water vapor using an amination catalyst. 10. The method of claim 9, wherein the catalyst is copper oxide,  Molybdenum oxide, chromium oxide and titanium dioxide.