EP3080064A1

EP3080064A1 - Method for producing hexamethylenediamine

Info

Publication number: EP3080064A1
Application number: EP14809898.1A
Authority: EP
Inventors: Christoph Müller; Martin Bock; Marion DA SILVA; Rolf-Hartmuth Fischer; Benoit BLANK; Alois Kindler; Johann-Peter Melder; Bernhard Otto; Mathias SCHELWIES; Andreas Henninger
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2013-12-13
Filing date: 2014-12-12
Publication date: 2016-10-19
Also published as: JP2017502949A; US20160326092A1; WO2015086819A1

Abstract

The invention relates to a method for producing hexamethylenediamine, wherein a) a muconic acid starting material is provided, which is selected from among muconic acid, esters of muconic acid, lactones of muconic acid, and mixtures thereof, b) the muconic acid starting material is subjected to a reaction with hydrogen in the presence of at least one hydrogenation catalyst in order to form 1,6-hexanediol, and c) the 1,6-hexanediol obtained in step b) is subjected to amination in the presence of an amination catalyst in order to obtain hexamethylenediamine. The invention further relates to hexamethylenediamine which can be produced by means of said method.

Description

Process for the preparation of hexamethylenediamine

BACKGROUND OF THE INVENTION The present invention relates to a process for producing hexamethylenediamine by subjecting muconic acid and / or one of its esters and / or one of its lactones to hydrogenation of the double bonds and reduction of the carboxylic acid and / or carboxylic acid ester groups to 1,6-hexanediol and the resulting 1,6-hexanediol is then subjected to amination to hexamethylenediamine. The present invention furthermore relates to hexamethylenediamine which can be prepared by means of this process.

Background Art Hexamethylenediamine (1,6-diaminohexane) is an important raw material for the production of polyamides, especially polyamide 66 from AH salt (hexamethylenediamine adipate). By the reaction of hexamethylenediamine with phosgene is

Hexamethylene diisocyanate obtained, which is used as a component for the production of polyurethanes.

All industrially used processes for the production of hexamethylenediamine (HMD) proceed via adiponitrile (ADN) as an intermediate, which is characterized by catalytic

Hydrogenation is converted to hexamethylenediamine. The greatest economic importance in this case have the ADN synthesis starting from butadiene and hydrogen cyanide and the Elektrodimerisierung of acrylonitrile, prepared by ammoxidation of propene.

It is known to produce hexamethylenediamine by aminating hydrogenation of 1,6-hexanediol. After such a process, until 1981, hexamethylenediamine was manufactured by Celanese in a plant with a capacity of about 30,000 tons per year

Year produced. The amination was carried out at 200 ° C and 23 MPa with ammonia in

Presence of Raney Nickel. This HMD yields of about 90% were achieved.

By-products were hexamethyleneimine (azepane) and 1,6-aminohexanol.

A disadvantage of the economy of the Celanese process was that the 1,6-hexanediol complex by reaction of cyclohexanone with peracetic acid to

Caprolactone and subsequent catalytic hydrogenation of caprolactone was prepared. The US 3,215,742 also describes a process for the preparation of alkylenediamines, such as. For example, hexamethylenediamine, by reaction of the corresponding diols with ammonia. It is taught that hexamethyleneimine formed as an undesirable by-product can be recycled to the amination hydrogenation stage and further converted to hexamethylene diamine. The hexamethyleneimine can simultaneously serve as a solvent for the amination reaction.

US 3,520,933 uses cobalt, nickel and / or copper-containing catalysts for the aminating hydrogenation.

According to H.-J. Arpe, Industrielle Organische Chemie, 6th edition (2007), Wiley-VCH-Verlag, pages 267 and 270, 1, 6-hexanediol can be prepared by hydrogenation of adipic acid or adipic diesters in the presence of Cu, Co or Mn catalysts. The synthesis is carried out at a temperature of 170 to 240 ° C and a pressure of 5 to 30 MPa. 1, 6-hexanediol can also be obtained by catalytic hydrogenation of caprolactone.

From EP 883 590 B1 it is known to use a carboxylic acid mixture (DCL) instead of pure adipic acid or adipic acid esters prepared from pure adipic acid. This is obtained as a by-product in the oxidation of cyclohexane with oxygen or oxygen containing gases and by water extraction of the reaction mixture. The extract contains adipic acid and 6-hydroxycaproic acid as the main products and besides a variety of mono- and dicarboxylic acids. The carboxylic acids are esterified with a lower alcohol. Adipic diesters are separated by distillation from the esterification mixture and hydrogenated catalytically to 1, 6-hexanediol.

It is advantageous that the waste product DCL is very inexpensive compared to pure adipic acid. On the other hand, a considerable distillative effort has to be made to produce pure 1,6-hexanediol. Particular difficulty prepares the distillative separation of the occurring as by-products 1, 4-cyclohexanediols.

Adipic acid is conventionally obtained by oxidation of cyclohexanol or

Cyclohexanone, synthesized from benzene. But she can also be in

environmentally friendly as derived from biogenic sources.

US 4,968,612 describes a fermentation process for the preparation of muconic acid and the hydrogenation of the resulting muconic acid to adipic acid. Specifically, the Muconsaure as a 40 wt .-% slurry in acetic acid and in the presence of a palladium catalyst on carbon reacted. The water content of the acetic acid used is not specified. A disadvantage of this reaction is the use of corrosive acetic acid, the use of high quality

corrosion resistant reactors required.

K.M. Draths and J.W. Frost, J. Am. Chem. Soc. 1994, 16, 399-400 and W. Niu et al., Biotechnol. Prog. 2002, 18, 201 -21 1 describe the production of cis, cis-muconic acid from glucose by biocatalyzed synthesis with subsequent hydrogenation of the cis, cis-muconic acid with the aid of a platinum catalyst to adipic acid. In both cases, the pH of the fermentation mixture is adjusted to above 6.3 or to a value of 7.0 before the hydrogenation. This results in a solution of muconic acid salts. Since in both cases, the fermentation broth is first centrifuged and only the supernatant is used for the hydrogenation, said after the

Approach of Niu et al. additionally mixed with activated charcoal twice before the hydrogenation and filtered, it can be assumed that the hydrogenation mixture contains no solid muconic acid.

Another process for the production of muconic acid from renewable sources is described, for example, in WO 2010/148080 A2. According to Example 4 in the

Paragraphs [0065] and [0066] of this document are heated 15 g of cis, cis-muconic acid and 150 ml of water for 15 minutes under reflux of the water. After cooling to room temperature, filtration and drying, 10.4 g (69%) of cis-trans-muconic acid are obtained. The mother liquor (4.2 g = 28 wt .-%, based on cis, cis-muconic acid), no longer consists of muconic acid. It contains lactones and other unknown reaction products.

J.M. Thomas et al., Chem. Commun. 2003, 1 126-1 127, describe the hydrogenation of muconic acid to adipic acid with the aid of bimetallic nanocatalysts, which are incorporated by special anchor groups in the pores of a mesoporous silica, in pure ethanol.

J.A. Elvidge et al., J. Chem. Soc. 1950, 2235-2241, describe the preparation of cis, trans-muconic acid and their hydrogenation to adipic acid in ethanol in the presence of a platinum catalyst. Information on the amount of the solvent used and the catalyst are not made.

X. She et al., ChemSus Chem 201 1, 4, 1071-1073, describe the hydrogenation of trans, trans-muconic acid to adipic acid with rhenium catalysts on one Titanium dioxide carrier in solvents selected from methanol, ethanol, 1-butanol, acetone, toluene and water. The hydrogenations are carried out exclusively at an elevated temperature of 120 ° C. With the catalyst used, only a low selectivity with respect to the adipic acid is achieved in water, the main product being the dihydromuconic acid.

WO 2010/141499 describes the oxidation of lignin to vanillic acid, its decarboxylation to 2-methoxyphenol and further conversion to catechol and finally oxidation to muconic acid and the hydrogenation of muconic acid obtained in this way with various transition metal catalysts

Adipic acid. The solvent used for the hydrogenation is not specified.

WO 2012/141993 A1 describes the preparation of hexamethylenediamine (HMDA) from muconic diesters, wherein the muconic diesters are amidated in a first step and then directly reduced to HMDA (Route 1) or dehydrogenated after the amidation to nitriles and then hydrogenated to HMDA (Route 2 ) or hydrogenated to adipamide after amidation, dehydrated to adiponitrile and then hydrogenated to HMDA (Route 3). WO 2012/170060 describes a process for the preparation of nitrogen-containing compounds, in particular hexamethylenediamine. The starting point are diammonium adipate-containing fermentation broths. For their preparation, in a suitable embodiment, D-glucose can be converted to cis, cis-muconic acid salts by fermentation. The pH is kept below 7 by the addition of ammonia. Subsequently, the cis, cis-muconate at room temperature in

Presence of 10% platinum on charcoal hydrogenated at a hydrogen pressure of 50 psi (3,4474 bar). The low temperature is necessary because at higher

Temperatures would add ammonia in the sense of a Michael addition to the muconic acid or its salts. The resulting hydrogenated fermentation broth contains

Diammonium adipate (DAA) and optionally monoammonium adipate (MAA) and / or adipic acid (AA). A disadvantage of the method described in WO 2012/170060 is that the DAA and MAA before further implementation in AA

converted, i. the ammonia must be separated. This is done by distillation in two steps, wherein in the first step aqueous DDA solution is distilled so that overhead ammonia and water are separated. The bottom product of

Distillation is cooled and the resulting solid, which consists of MAA, separated. In the second step, an aqueous MAA solution is heated with addition of water and ammonia-containing water vapor is separated off. The solid obtained after cooling consists of adipic acid. The adipic acid thus obtained becomes 1, 6 Hydrogenated hexane and the 1,6-hexanediol aminated with ammonia to hexamethylenediamine.

The present invention has for its object to provide an economical process for the preparation of hexamethylenediamine. If the process on adipic acid proceeds as an intermediate stage on elaborate separation and

Cleaning steps for their preparation, as required in the method described in WO 2012/170060, can be dispensed with. In particular, this process should not start from petrochemical C6 building blocks but from C6 building blocks that can be produced from renewable raw materials. The hexamethylenediamine is to be made available in high yield and purity.

It has now surprisingly been found that this object is achieved by a muconic acid starting material which is selected from muconic acid, esters of muconic acid, lactones of muconic acid and mixtures thereof, a one- or two-stage reaction with hydrogen with hydrogenation of the double bonds and reduction of the carboxylic acid -, carboxylic acid esters and / or lactone groups to 1, 6-hexanediol and the resulting 1, 6-hexanediol then a

Subjecting amination to hexamethylenediamine. In particular, the muconic acid used is derived from renewable (biogenic) sources.

SUMMARY OF THE INVENTION

A first object of the invention is a process for the preparation of

Hexamethylenediamine, comprising: a) providing a muconic acid starting material selected from

Muconic acid, esters of muconic acid, lactones of muconic acid, the hydrogenated monolactone of muconic acid and mixtures thereof, b) the muconic acid starting material of a reaction with hydrogen in

Subjecting at least one hydrogenation catalyst to 1,6-hexanediol, and c) subjecting the 1,6-hexanediol obtained in step b) to an amination in the presence of an amination catalyst to give hexamethylenediamine.

Another object of the invention is hexamethylene diamine, having a C ¹⁴ / C ¹² -lsoto- penverhältnis in the range of 0.5 x 10 ^"12 to 5 × ^{10." 12} Another object of the invention is hexamethylenediamine, which can be prepared starting from biocatalytically from at least one renewable raw material synthesized Muconsaure.

Specifically, the muconic acid starting material provided in step a) contains no salts of the muconic acid.

In a specific embodiment, the hydrogenation in step b) takes place in the liquid phase in the presence of water as the sole solvent.

Muconic acid (2,4-hexadiene dicarboxylic acid) exists in three stereoisomeric forms, the ice, cis, cis, trans, and trans, trans forms, which may be present as a mixture. All three forms are crystalline compounds with high melting points (decomposition), see e.g. B. Römpp Chemie Lexikon, 9th edition, Volume 4, page 2867). It has been found that hydrogenation of Muconsäureschmelzen technically is hardly possible, since the most preferred hydrogenation temperatures are well below the melting points. Therefore, an inert solvent with the highest possible solubility for muconic acid would be desirable for the hydrogenation. At first glance, water as solvent is unsuitable for the person skilled in the art, since muconic acid, in contrast to adipic acid, is poorly soluble in the temperature range from 20 to 100 ° C. As described above, WO 2010/148080 teaches that upon heating cis, cis-muconic acid in water under reflux and subsequent crystallization, cis-trans-muconic acid is obtained in only 69% yield. The remaining mother liquor no longer consists of muconic acid but contains lactones and other unknown reaction products. From these results, those skilled in the art would have expected significantly lower adipic acid yields in the hydrogenation of water-suspended muconic acid, according to the preferred embodiment of the present invention.

EMBODIMENTS OF THE INVENTION

More specifically, the invention includes the following preferred embodiments: FIG. Process for the preparation of hexamethylenediamine comprising: a) providing a muconic acid starting material selected from muconic acid, esters of muconic acid, lactones of muconic acid and mixtures thereof, subjecting the muconic acid starting material to 1, 6-hexanediol to a reaction with hydrogen in the presence of at least one hydrogenation catalyst, and subjecting the 1,6-hexanediol obtained in step b) to an amination in the presence of an amination catalyst to give hexamethylenediamine.

Method according to embodiment 1, wherein in step a) a

Muconsäurausgangsmaterial is provided, wherein the muconic acid is derived from a renewable source, the preparation thereof is preferably carried out by biocatalytic synthesis of at least one renewable raw material.

The method of embodiment 1 or 2, wherein the muconic acid used in step a) ¹² C-lsotopenverhältnis having a ^C-to-14 in the range of 0.5x10 ^"12 to 5 × 10 ^12th

Method according to one of embodiments 1 to 3, wherein the hydrogenation in step b) a muconic acid starting material is used, which is selected from muconic acid, Muconsäuremonoestern, muconic diesters, poly (muconic acid esters) and mixtures thereof.

Method according to one of embodiments 1 to 3, wherein for the hydrogenation in step b) a muconic acid starting material is used which is selected from lactones (III), (IV) and (V) and mixtures thereof:

(III) (IV)

(V)

Method according to one of embodiments 1 to 5, wherein the hydrogenation in step b) takes place in the liquid phase in the presence of a solvent which is selected from water, aliphatic C 1 to C 8 alcohols, aliphatic C 2 to C 6 diols, ethers and mixtures it. Method according to one of embodiments 1 to 5, wherein the hydrogenation in step b) takes place in the liquid phase in the presence of water as sole solvent.

Method according to one of embodiments 1 to 5, wherein for the hydrogenation in step b) a Muconsäurediester is used, which is selected from compounds of general formula (II)

R ¹ OOC-CH = CH-CH = CH-COOR ² (II) in which the radicals R ¹ and R ² independently of one another represent straight-chain or branched C ¹ -C 8 -alkyl, the hydrogenation in step b) taking place in the gas phase.

Method according to one of the preceding embodiments, wherein as

Hydrogenation catalyst in step b) a homogeneous or heterogeneous

Transition metal catalyst is used, preferably a heterogeneous transition metal catalyst.

Method according to one of embodiments 1 to 9, wherein in step b) a muconic acid starting material is used, which is selected from

Muconic acid, muconic acid monoesters, lactones of muconic acid and

Mixtures thereof and the hydrogenation catalyst contains at least 50 wt .-% cobalt, ruthenium or rhenium based on the total weight of the reduced catalyst.

Muconsäurediestern, poly (muconic acid esters) and mixtures thereof and the hydrogenation catalyst at least 50 wt .-% of copper based on the

Total weight of the reduced catalyst contains.

Method according to one of the preceding embodiments, wherein the

Hydrogenation in step b) takes place at a temperature which is in the range of 50 to 300 ° C. 13. The method according to any one of the preceding embodiments, wherein the

Hydrogenation in step b) takes place at a hydrogen partial pressure which is in a range of 100 to 300 bar. 14. The method according to any one of embodiments 1 to 13, wherein the hydrogenation in step b) takes place without intermediate isolation of adipic acid or an ester of adipic acid.

15. The method according to any one of embodiments 1 to 13, wherein step b) the

The following sub-steps include:

Hydrogenating muconic acid or one of its esters in aqueous solution adipic acid in the presence of a first hydrogenation catalyst, and hydrogenating the adipic acid in aqueous solution to 1, 6-hexanediol in the presence of a second hydrogenation catalyst.

16. The process of embodiment 15, wherein the first hydrogenation catalyst is Raney cobalt and / or Raney nickel.

The process of embodiment 15 or 16, wherein the second catalyst contains at least 50% by weight of elements selected from the group consisting of rhenium, iron, ruthenium, cobalt, rhodium, iridium, nickel, and the total weight of the reduced catalyst Copper.

Process according to any of embodiments 15 to 17, wherein the hydrogenation in step b1) takes place at a temperature which is in the range of 50 to 160 ° C and the hydrogenation in step b2) takes place at a temperature in the range of 160 to 240 ° C is.

A method according to any one of embodiments 15 to 18, wherein

adipic acid-containing water, which is obtained after isolation of the second catalyst after completion of step b2), is used as solvent in step b1). 20. The method according to any one of the preceding embodiments, wherein the hydrogenation in step b) is carried out in n successive hydrogenation reactors, wherein n is an integer of at least two. 21. Method according to embodiment 20, wherein the 1. to (n-1). Reactor has a guided in an external circuit current from the reaction zone.

Method according to one of the embodiments 20 or 21, wherein the

Hydrogenation in the n. Reactor performed adiabatically.

Process according to one of the preceding embodiments, wherein the effluent from the hydrogenation in step b) is subjected to a distillative separation to obtain a fraction enriched in 1,6-hexanediol and the fraction enriched in 1,6-hexanediol is used for the amination in step c) ,

24. Method according to one of the preceding embodiments, wherein the in

Step b) obtained 1,6-hexanediol in step c) is reacted with ammonia in the presence of the amination catalyst to hexamethylenediamine.

25. The method according to any one of the preceding embodiments, wherein the

Amination in step c) is carried out with or without supply of hydrogen.

26. Method according to one of the preceding embodiments, wherein the

Reaction discharge of the amination in step c) is subjected to a separation to obtain a hexamethyleneimine enriched and a hexamethylenediamine depleted fraction.

27. The method of embodiment 26, wherein the hexamethyleneimine

enriched fraction is recycled to the amination in step c).

28. The method according to any one of embodiments 26 or 27, wherein in the

Amination in step c) consists of recycled fraction of hexamethyleneimine and 1,6-hexanediol.

29. A process according to embodiment 28, wherein the recycled to the amination in step c) fraction to 20 to 35 wt .-% of hexamethyleneimine and 80 to 65 wt .-% of 1, 6-hexanediol. 30. The method according to any one of the preceding embodiments, wherein in step c) hexamethyleneimine is used as the sole solvent.

31. Hexamethylenediamine, characterized in that it comprises a C ¹⁴ / C ¹² -lsotopenver- ratio in the range of 0.5 x 10 ^"12 to 5 × ^{10." 12} 32. hexamethylenediamine, characterized in that it can be prepared starting from biocatalytically from at least one renewable raw material synthesized Muconsaure.

DETAILED DESCRIPTION OF THE INVENTION

In the context of the present invention, esters of the muconic acid are the esters with a separate (external) alcohol component. As lactones the

Muconic acids are those obtainable by intramolecular Michael addition

Compounds (III) and (IV) and the product (V) of the hydrogenation of the compound (III) understood:

The lactone (III) is a monolactone which still contains a hydrogenatable carbon-carbon double bond. The lactone (IV), however, is a bis-lactone containing no hydrogenatable carbon-carbon double bond. The lactone (V) can also be formed by intramolecular Michael addition of dihydromuconic acid. Regardless of its preparation, the lactone (V) in the context of the invention is also referred to as "hydrogenated monolactone of muconic acid".

The muconic acid provided in step a) of the process according to the invention comes from renewable sources. For the purposes of the invention, this includes natural (biogenic) sources and non-fossil sources, such as crude oil, natural gas or coal. Preferably, the in step a) of the method according to the invention

provided muconic acid from carbohydrates, eg. As starch, cellulose and sugars, or lignin. Renewable compounds, for example Muconic acid has a different ¹⁴ C to ¹² C isotope ratio than compounds derived from fossil sources such as petroleum. The used in step a)

Muconsaure accordingly has preferably a C ^{^14-to-12} C lsotopenverhältnis in the range of 0.5 * 10 ¹² to 5 × 10 ^12.

The production of muconic acid from renewable sources can be carried out by all methods known to those skilled in the art, preferably biocatalytically. The

biocatalytic production of muconic acid from at least one renewable raw material is described, for example, in the following documents: US Pat. No. 4,968,612, WO 2010/148063 A2, WO 2010/148080 A2 and K. M. Draths and J. W. Frost, J. Am. Chem. Soc. 1994, 16, 339-400 and W. Niu et al., Biotechnol. Prog. 2002, 18, 201 - 21 1.

As stated previously, muconic acid (2,4-hexadiene dicarboxylic acid) exists in three isomeric forms, the ice, cis, cis, trans and trans, trans forms, which may be present as a mixture. For the purposes of the invention, the term "muconic acid" encompasses the different conformers of muconic acid in any desired composition. [Sind alle] Suitable starting materials for the reaction with hydrogen in step b) of the process according to the invention are in principle all conformers of the muconic acid and / or its esters and any mixtures thereof.

In a preferred embodiment, in step b) of the process according to the invention, a starting material is used which is enriched in cis, trans-muconic acid and / or its esters or which consists of cis, trans-muconic acid and / or their esters. Thus, cis, trans-muconic acid and their esters have a higher solubility in water and in organic media than cis, cis-muconic acid and trans, trans -muconic acid.

If a feedstock containing at least one component selected from cis, cis-muconic acid, trans, trans-muconic acid and / or esters thereof is used in step b) of the process according to the invention, this is added to an isomerization before or during the hydrogenation cis, trans-muconic acid or its esters

subjected. The isomerization of cis, cis-muconic acid to cis, trans-muconic acid is shown in the following scheme:

HO

OOH Suitable catalysts are, in particular, inorganic or organic acids, hydrogenation catalysts, iodine or UV radiation. Suitable hydrogenation catalysts are those described below. The isomerization can be carried out, for example, by the process described in WO 201 1/08531 1 A1.

Preferably, the starting material for the reaction with hydrogen in step b) to at least 80 wt .-%, more preferably at least 90 wt .-% of cis, trans-Muconsäure and / or their esters, based on the total weight of all

Muconsäure- and Muconsäureester conformers contained.

For the hydrogenation in step b) it is preferable to use a muconic acid starting material which is selected from muconic acid, muconic acid monoesters,

Muconic diesters, poly (muconic acid esters), lactones of muconic acid and mixtures thereof. In the context of the present invention, the term muconic acid polyester also denotes oligomeric muconic acid esters which have at least one derived from the muconic acid or the diol used for ester formation

Repeating unit and at least two complementary over

Having carboxylic acid ester groups bonded repeat units.

Preferably, the muconic acid monoester used is at least one compound of the general formula (I)

R ¹ OOC-CH = CH-CH = CH-COOH (I) used, wherein the radicals R ¹ independently represent straight-chain or branched Ci-Cs-alkyl.

As muconic acid diester, preference is given to at least one compound of the general formula (II)

R ¹ OOC-CH = CH-CH = CH-COOR ² (II) used, wherein the radicals R ¹ and R ² independently of one another represent straight-chain or branched Ci-Cs-alkyl.

Preferred as poly (muconic acid ester) is at least one compound of the general formula (VI) OO

I I I

R ³ - O -4 C- CH:: CH CH:: CH C- O- CH ₂ - -04-R ^'

In which x is an integer from 2 to 6, n is an integer from 1 to 100, R ^{3 is} H, straight-chain or branched C 1 -C 8 -alkyl or a group HO- (CH 2) _x - stands,

R ^{4 is} H or a group -C (= O) -CH = CH-CH = CH-COOR ⁵ , in which R ^{5 is} H or straight-chain or branched C 1 -C 8 -alkyl, with the proviso that for n = 1 either R ^{3 is} H and R ^{4 is} -C (= O) -CH = CH-CH = CHCOOROR ⁵ or R ^{3 is} a group HO- (CH ₂ ) x- and R ^{4 is} H.

In the context of the invention, the degree of polymerization of the poly (muconic acid ester) denotes the sum of the repeat units which formally derive from muconic acid and the repeat units which formally derive from diols HO- (CH 2) x -OH.

In a first preferred embodiment, the hydrogenation in step b) is carried out using a muconic acid starting material selected from muconic acid, muconic acid monoesters, muconic diesters, poly (muconic acid esters) and

Mixtures thereof.

In a second preferred embodiment, the hydrogenation in step b) is carried out using a muconic acid starting material selected from lactones (III), (IV) and (V) and mixtures thereof:

(III) (iv)

Specifically, for the hydrogenation in step b), a muconic acid starting material is used which is selected from muconic acid, muconic acid monoesters, muconic diesters, poly (muconic acid esters) and mixtures thereof, and the hydrogenation is carried out in the liquid phase.

In a first embodiment of the process according to the invention, the hydrogenation in step b) takes place in the liquid phase in the presence of a solvent which is selected from water, aliphatic C 1 to C 8 alcohols, aliphatic C 2 to C 6 diols, ethers and mixtures thereof. Preferably, the solvent is selected from water, methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol and tert-butanol, ethylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, tetrahydrofuran, 2-methyltetrahydrofuran, diethyl ether, methyl tert-butyl ether and mixtures thereof. Aliphatic C to C5 alcohols, water and mixtures of these solvents are preferred. Particularly preferred are methanol, n-butanol, isobutanol, water and mixtures of these solvents.

Furthermore, it is preferred to use the target product 1, 6-hexanediol as a solvent. In this case, 1, 6-hexanediol can be used alone or in admixture with alcohols and / or water.

It is preferred that for the hydrogenation in the liquid phase, a solution is used, the 10 to 60 wt .-% muconic acid or one of its esters, more preferably 20 to 50 wt .-%, most preferably 30 to 50 wt. %, contains.

In a second preferred embodiment, at least one muconic acid diester of the general formula (II) is used for the hydrogenation in step b).

R ¹ OOC-CH = CH-CH = CH-COOR ² (II) used, wherein the radicals R ¹ and R ^{2 are} independently straight-chain or branched Ci-Cs-alkyl and the hydrogenation is carried out in the gas phase.

Suitable hydrogenation catalysts for the reaction in step b) are in principle the transition metal catalysts known to those skilled in the art for hydrogenating carbon-carbon double bonds. In general, the catalyst includes at least one transition metal of groups 7, 8, 9, 10 and 11 of the periodic table according to IUPAC. Preferably, the catalyst comprises at least one transition metal selected from the group consisting of Mn, Re, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu and Au. Particularly preferably, the catalyst has at least one transition metal from the group Co, Ni, Cu, Re, Fe, Ru, Rh, Ir. The hydrogenation catalysts consist of said transition metals as such or comprise said transition metals supported, as precipitation catalysts, as Raney catalysts or as mixtures thereof. As inert carrier material for the invention used in step b)

Hydrogenation catalysts may comprise virtually all prior art support materials which are advantageously used in the preparation of supported catalysts, for example carbon, S1O2 (quartz), porcelain, magnesium oxide,

Tin dioxide, silicon carbide, T1O2 (rutile, anatase), Al2O3 (alumina), aluminum silicate, steatite (magnesium silicate), zirconium silicate, cersilicate or mixtures thereof

Support materials used. Preferred support materials are carbon, alumina and silica. A particularly preferred carrier material is carbon. As the silica support material can silica materials of different origin and production, for. B. pyrogenic silicas or wet-chemically prepared silicas, such as silica gels, aerogels or

Precipitated silicas, used for catalyst preparation (for the preparation of various SiO 2 starting materials see: W. Büchner, R. Schliebs, G.

Winter, K.H. Buchel: Industrial Inorganic Chemistry, 2nd ed., P. 532-533, VCH Verlagsgesellschaft, Weinheim 1986).

The hydrogenation catalysts can be used as shaped bodies, for. B. in the form of spheres, rings, cylinders, cubes, cuboids or other geometric bodies. Unsupported catalysts can be formed by conventional methods, e.g. By extruding, tableting, etc. The shape of supported catalysts is determined by the shape of the support. Alternatively, the support may be subjected to a molding process before or after application of the catalytically active component (s). The transition metal catalysts K can, for. B. in the form of pressed cylinders, tablets, pastilles, carriage wheels, rings, stars or extrudates, such as solid strands, polylobären strands, hollow strands and

Honeycomb bodies or other geometric bodies, are used.

The catalyst particles generally have an average of the (largest)

Diameter of 0.5 to 20 mm, preferably 1 to 10 mm, on. These include z. B. transition metal catalysts K in the form of tablets, for. B. with a diameter from 1 to 7 mm, preferably 2 to 6 mm, and a height of 3 to 5 mm, rings with z. B. 4 to 7 mm, preferably 5 to 7 mm, outer diameter, 2 to 5 mm in height and 2 to 3 mm hole diameter, or strands of different lengths

Diameter of z. B. 1, 0 to 5 mm. Such forms can be obtained in a manner known per se by tableting, extrusion or extrusion. For this purpose, the catalyst composition customary auxiliaries, for. As lubricants such as graphite,

Polyethylene oxide, cellulose or fatty acids (such as stearic acid) and / or molding aids and reinforcing agents such as glass, asbestos or silicon carbide fibers.

The catalyst can be present under the hydrogenation conditions both as a homogeneous and as a heterogeneous catalyst. Preferably, the catalyst is present under the hydrogenation conditions as a heterogeneous catalyst. If a heterogeneous catalyst is used, this can be applied, for example, to a reticulated carrier. Alternatively or additionally, the heterogeneous catalyst can be applied to the inner wall of a tubular support, wherein the tubular support is flowed through by the reaction mixture. Alternatively or additionally, the catalyst can be used as a particulate solid. In a preferred embodiment, the hydrogenation in step b) takes place in the liquid phase and the catalyst is in the form of a suspension. If a liquid reaction product is removed from the reaction zone, the suspended catalyst can be kept in the reaction zone by retention methods known to those skilled in the art. These retention methods preferably comprise a cross-flow filtration, a

Gravity filtration and / or filtration by means of at least one filter candle.

Hydrogenation of muconic acid, muconic acid monoesters and lactones

In a first process variant, a muconic acid starting material is used for the hydrogenation in step b), which is selected from muconic acid,

Muconic acid monoesters, lactones of muconic acid and mixtures thereof.

According to this process variant, the hydrogenation in step b) is preferably carried out using a hydrogenation catalyst which contains at least 50% by weight of cobalt, ruthenium or rhenium, based on the total weight of the reduced catalyst.

If catalysts which contain at least 50% by weight of cobalt are used for the hydrogenation, they may furthermore contain, in particular, phosphoric acid and / or further transition metals, preferably copper, manganese and / or molybdenum. The preparation of a suitable catalyst precursor is known from DE 2321 101. This contains in the unreduced, calcined state 40 to 60 wt .-% cobalt (calculated as Co), 13 to 17 wt .-% copper (calculated as Cu), 3 to 8 wt% manganese (calculated as Mn), 0.1 to 5 wt .-% of phosphates (calculated as H3PO4) and 0.5 to 5 wt .-% molybdenum (calculated as M0O3). EP 636 409 B1 describes the preparation of further suitable cobalt catalyst precursors containing from 55 to 98% by weight of cobalt, from 0.2 to 15% by weight of phosphorus, to from 0.2 to 15% by weight. % of manganese and 0.2 to 15 wt .-% of alkali metals (calculated as oxide) exist. Such catalyst precursors can be reduced to the active, metallic cobalt-containing catalysts by treatment with hydrogen or mixtures of hydrogen and inert gases such as nitrogen. These catalysts are full contacts, which are predominantly made of metal and contain no catalyst support. Hydrogenation of muconic diesters and muconic acid polyesters

In a first process variant, a muconic acid starting material is used for the hydrogenation in step b), which is selected from muconic diesters, poly (muconic acid esters) and mixtures thereof.

According to this process variant, the hydrogenation in step b) preferably uses a hydrogenation catalyst which contains at least 50% by weight of copper, based on the total weight of the reduced catalyst. Suitable catalysts are in principle all suitable for the hydrogenation of carbonyl homogeneous and heterogeneous catalysts such as metals, metal oxides, metal compounds or mixtures thereof into consideration. Examples of homogeneous catalysts are, for example, in Houben-Weyl, Methods of Organic Chemistry, Volume IV / 1 c, Georg Thieme Verlag Stuttgart, 1980, pp 45-67 and examples of heterogeneous catalysts are, for example in Houben-Weyl, methods of organic chemistry , Volume IV / 1 c, pp 16 to 26 described.

Preference is given to using catalysts which contain one or more of the elements from subgroups I and VI. to VIII. of the Periodic Table of the Elements, preferably copper, chromium, molybdenum, manganese, rhenium, ruthenium, cobalt, nickel or palladium, particularly preferably copper, cobalt or rhenium.

Also in the hydrogenation of Muconsäurediester, oligoester and polyester, the already mentioned cobalt, ruthenium or rhenium-containing catalysts be used. However, it is preferred to use at least 50 wt .-% copper (based on the total weight of the reduced catalyst) containing catalysts instead of these catalysts. The catalysts may consist solely of active components or their

Active components can be applied to carriers. Suitable carrier materials are, in particular, O 2 O 3, Al 2 O 3, SiO 2, ZrO 2, ZnO, BaO and MgO or mixtures thereof. Particular preference is given to catalysts, as described in EP 0 552 463 A1. These are catalysts which in the oxidic form the composition

CUaAlbZr _c MndOx, where a> 0, b> 0, c a 0, d> 0, a> b / 2, b> a / 4, a> c and a> d and x are for maintaining the electron neutrality per Formula unit required number of

Called oxygen ions. The preparation of these catalysts, for example, according to the specifications of EP 552 463 A1 by precipitation of sparingly soluble

Compounds are made from solutions containing the corresponding metal ions in the form of their salts. Suitable salts are, for example, halides, sulfates and nitrates. Suitable precipitants are all agents which lead to the formation of such insoluble intermediates, which can be converted by thermal treatment in the oxides. Particularly suitable intermediates are the hydroxides and carbonates or bicarbonates, so that alkali metal carbonates or ammonium carbonate are used as particularly preferred precipitants. There is a thermal treatment of the intermediates at temperatures in the range of 500 ° C to 1000 ° C. The BET surface area of such catalysts is between 10 and 150 m ² / g.

Furthermore, catalysts are suitable which have a BET surface area of 50 to 120 m ² / g, wholly or partially contain crystals with spinel structure and copper in the form of copper oxide.

The WO 2004/085 356 A1 describes for the inventive method suitable copper catalysts, the copper oxide, alumina and at least one of the oxides of lanthanum, tungsten, molybdenum, titanium or zirconium and additionally powdered metallic copper, copper flakes, powdered cement, graphite or containing a mixture thereof. These catalysts are particularly suitable for all mentioned ester hydrogenations. The hydrogenation in step b) can be carried out batchwise or continuously, with continuous hydrogenation being preferred. The hydrogenation in step b) can be carried out in the liquid phase or in the gas phase. The catalyst loading in continuous operation is preferably 0.1 to 2 kg, more preferably 0.5 to 1 kg to be hydrogenated starting material per kg

Hydrogenation catalyst.

The molar ratio of hydrogen to muconic acid starting material is preferably from 50: 1 to 10: 1, more preferably from 30: 1 to 20: 1. The

Muconsäurausgangsmaterial is according to the invention is selected from muconic acid, esters of muconic acid, lactones of muconic acid and mixtures thereof. If, for the hydrogenation in step b), a muconic acid starting material is used which is selected from at least two of the abovementioned compounds, the amount of hydrogen used, depending on the proportion of the compounds to be hydrogenated, is chosen according to the abovementioned design rule. In a special embodiment of the method according to the invention, the

Hydrogenation in n successive (series) hydrogenation reactors, wherein n is an integer of at least 2. Suitable values for n are 2, 3, 4, 5, 6, 7, 8, 9 and 10. Preferably, n is 3 to 6 and in particular 2 or 3. In this embodiment, the hydrogenation is preferably carried out continuously.

The reactors used for the hydrogenation may independently have one or more reaction zones within the reactor. The reactors may be the same or different reactors. These can be z. B. each have the same or different mixing characteristics and / or be subdivided by internals one or more times.

Suitable pressure-resistant reactors for the hydrogenation are known to the person skilled in the art. These include the commonly used reactors for gas-liquid reactions, such as. B. tube reactors, tube bundle reactors, gas circulation reactors, bubble columns,

Loop apparatuses, stirred tanks (which may also be designed as stirred tank cascades), air-lift reactors, etc.

The inventive method using heterogeneous

Hydrogenation catalysts can be carried out in fixed bed or suspension mode become. The fixed bed mode can be z. B. in sump or in trickle run. The hydrogenation catalysts are preferably used as

Formed body used as described above, for. B. in the form of pressed cylinders, tablets, pastilles, carriage wheels, rings, stars or extrudates, such as solid strands, polylobären strands, hollow strands, honeycomb bodies, etc.

In the suspension mode heterogeneous catalysts are also used. The heterogeneous catalysts are usually used in a finely divided state and are finely suspended in the reaction medium before.

Suitable heterogeneous catalysts and processes for their preparation are those described above.

In the hydrogenation on a fixed bed, a reactor is used, in whose

Inside the fixed bed is arranged, through which the reaction medium flows. The fixed bed can be formed from a single or multiple beds. Each bed may have one or more zones, wherein at least one of the zones contains a material active as a hydrogenation catalyst. Each zone can have one or more different catalytically active materials and / or one or more different inert materials. Different zones may each have the same or different compositions. It is also possible to provide a plurality of catalytically active zones, which are separated from each other, for example, by inert beds. The individual zones can also

have different catalytic activity. For this purpose, various catalytically active materials can be used and / or at least one of the zones an inert material can be added. The reaction medium flowing through the fixed bed contains at least one liquid phase. The reaction medium may also contain a gaseous phase in addition. As reactors in the hydrogenation in suspension in particular

Loop apparatuses, such as jet loops or propeller loops, stirred tanks, which can also be configured as stirred tank cascades, bubble columns or air-lift reactors are used. Preferably, the continuous hydrogenation of the inventive

Process in at least two consecutively connected (in series)

Fixed bed reactors. The reactors are preferably operated in direct current. The feeding of the feed streams can be done both from above and from below. If desired, in a hydrogenation apparatus of n reactors, at least two of the reactors (ie, 2 to n of the reactors) may have a different temperature from each other. In a specific embodiment, each downstream reactor is operated at a higher temperature than the previous reactor. In addition, each of the reactors may have two or more different temperature reaction zones. Thus, for example, in a second reaction zone another, preferably a higher, temperature than in the first reaction zone or in each subsequent reaction zone, a higher temperature than in a

be set before the reaction zone, z. B. to achieve the fullest possible conversion in the hydrogenation.

In a specific embodiment, the hydrogenation in step b) is a

Hydrogenation from at least two reactors or at least one reactor with at least two reaction zones used. Then, the hydrogenation is carried out initially in a temperature range of 50 to 160 ° C and then in a

Temperature range from 160 to 240 ° C. In this procedure, initially the carbon-carbon double bonds can be hydrogenated in the upstream part of the hydrogenation apparatus and subsequently essentially the carboxylic acid and / or carboxylic acid ester groups can be reduced in the downstream part of the hydrogenation apparatus.

If desired, in a hydrogenator of n reactors, at least two of the reactors (i.e., 2 to n of the reactors) may have a different pressure from each other. In a specific embodiment, each downstream reactor is operated at a higher pressure than the previous reactor.

The feeding of the hydrogen required for the hydrogenation can be carried out in the first and optionally additionally in at least one further reactor.

Preferably, the feed of hydrogen takes place only in the first reactor. The amount of hydrogen fed to the reactors results from the amount of hydrogen consumed in the hydrogenation reaction and optionally with the exhaust gas

discharged amount of hydrogen.

The setting of the reacted in the respective reactor portion of compound to be hydrogenated can, for. B. on the reactor volume and / or the residence time in the reactor. The conversion in the first reactor, based on formed adipic acid or

Adipic acid ester is preferably at least 70%, more preferably at least 80%. The total conversion in the hydrogenation, based on hydrogenatable starting material, is preferably at least 97%, particularly preferably at least 98%, in particular at least 99%.

The selectivity in the hydrogenation, based on formed 1,6-hexanediol, is preferably at least 97%, particularly preferably at least 98%, in particular at least 99%.

For removing the heat of reaction arising during the exothermic hydrogenation, one or more of the reactors may be provided with at least one cooling device. In a specific embodiment, at least the first reactor is provided with a cooling device. The heat of reaction can be removed by cooling an external recycle stream or by internal cooling in at least one of the reactors. For internal cooling, the customary devices, in general hollow body modules, such as field tubes, tube coils,

Heat exchanger plates, etc. are used. Alternatively, the reaction can also be carried out in a cooled tube bundle reactor.

Preferably, the hydrogenation is carried out in n successive hydrogenation reactors, wherein n is an integer of at least two, and wherein at least one reactor via a guided in an external circuit current from the

Reaction zone (external recycle stream, liquid circulation,

Loop mode). Preferably, n stands for two or three.

The hydrogenation is preferably carried out in n hydrogenation reactors connected in series, where n is preferably two or three, and the first to (n-1). Reactor has a guided in an external circuit current from the reaction zone.

The hydrogenation is preferably carried out in n hydrogenation reactors connected in series, n preferably being two or three, and the reaction being carried out adiabatically in the nth reactor (the last reactor through which the reaction mixture to be hydrogenated is passed). Preferably, the hydrogenation is carried out in n series-connected hydrogenation reactors, where n is preferably two or three, and wherein the n. Reactor is operated in a straight pass. If a reactor is operated "in straight pass", it should be understood here and below that a reactor without recirculation of the

Reaction product is operated in the sense of loop method. The

Operation in a straight pass does not exclude backmixing internals and / or stirring devices in the reactor.

If the hydrogenated reaction mixture in one of the reactors downstream of the first reactor (ie the second to nth reactor) has only small amounts of hydrogenatable muconic acid, then the heat of reaction occurring during the reaction is insufficient to maintain the desired temperature in the reactor. can also do one

Heating the reactor (or individual reaction zones of the second reactor) may be required. This can analogously to the previously described removal of

Heat of reaction by heating an external recirculation flow or by internal heating done. In a suitable embodiment, the heat of reaction from at least one of the previous reactors can be used to control the temperature of a reactor.

Furthermore, the heat of reaction removed from the reaction mixture can be used to heat the feed streams of the reactors. This can z. B. the feed stream of the compound to be hydrogenated in the first reactor at least partially mixed with an external recycle stream of this reactor and the combined streams are then fed into the first reactor. Furthermore, at m = 2 to n

Reactors of the feed stream from the (m-1) -th reactor in the mth reactor with a recycle stream of the mth reactor mixed and the combined streams are then fed into the mth reactor. Furthermore, the feed stream of the compound to be hydrogenated and / or another feed stream by means of a

Heat exchanger are heated, which is operated with extracted hydrogenation heat.

In a special embodiment of the process, a reactor cascade of n reactors connected in series is used, the reaction being carried out adiabatically in the nth (nth) reactor. This term is used in the context of

understood in the present invention in the technical and not in the physico-chemical sense. Thus, upon passing through the second reactor, the reaction mixture usually undergoes one due to the exothermic hydrogenation reaction

Temperature increase. Under adiabatic reaction is a Approach understood in which the released in the hydrogenation

Amount of heat absorbed by the reaction mixture in the reactor and no cooling is used by cooling devices. Thus, the reaction heat is removed with the reaction mixture from the second reactor, except for a residual portion which is discharged by natural heat conduction and heat radiation from the reactor to the environment. Preferably, the nth reactor is operated in a straight pass.

In a preferred embodiment, a two-stage reactor cascade is used for the hydrogenation, wherein the first hydrogenation reactor has a current conducted in an external circuit from the reaction zone. In a specific embodiment of the process, a reactor cascade of two reactors connected in series is used, the reaction being carried out adiabatically in the second reactor.

In a further preferred embodiment, the hydrogenation is a three-stage

Reactor cascade used, wherein the first and the second hydrogenation reactor have a guided in an external circuit current from the reaction zone. In a specific embodiment of the process, a reactor cascade of three reactors connected in series is used, the reaction being carried out adiabatically in the third reactor.

In one embodiment, additional mixing can take place in at least one of the reactors used. An additional mixing is particularly advantageous if the hydrogenation takes place at high residence times of the reaction mixture. For mixing z. B. the currents introduced into the reactors are used by introducing them via suitable mixing devices, such as nozzles, in the respective reactors. For mixing, it is also possible to use streams in an external circuit from the respective reactor.

To complete the hydrogenation, a discharge is taken from the first to (n-1) th reactor, which still contains hydrogenatable components and is fed into the respective downstream hydrogenation reactor. In a specific embodiment, the discharge is separated into a first and a second partial stream, wherein the first partial stream is recycled as a circular stream to the reactor to which it was taken and the second partial stream is fed to the subsequent reactor. The discharge may contain dissolved or gaseous portions of hydrogen. In a specific embodiment, the discharge from the first to (n-1) th reactor becomes a

Supplied phase separation vessel, separated into a liquid and into a gaseous phase, the liquid phase separated into the first and the second partial stream and the gas phase at least partially fed separately to the subsequent reactor. In an alternative embodiment, the discharge from the first to (n-1) th reactor is fed to a phase separation vessel and separated into a first liquid hydrogen-depleted substream and a second hydrogen-enriched substream. The first partial flow is then recycled as a circulating stream to the reactor, to which it has been removed and the second partial flow fed to the subsequent reactor. In a further alternative embodiment, the feed of the second to nth reactor with hydrogen is not carried out via a hydrogen-containing feed taken from the upstream reactor, but with fresh hydrogen via a separate feed line.

The process variant described above is particularly advantageous for controlling the reaction temperature and the heat transfer between

Reaction medium, limiting apparatus walls and environment. Another way to control the heat balance is in the regulation of

Inlet temperature of the feed of the compound to be hydrogenated. Thus, a lower temperature of the incoming feed usually leads to an improved removal of the heat of hydrogenation. As the catalyst activity decreases, the inlet temperature may be set higher to achieve a higher reaction rate and thus to compensate for the decreasing catalyst activity. Advantageously, the service life of the hydrogenation catalyst used can thus be extended as a rule.

Single-stage or two-stage hydrogenation

In a first preferred embodiment, the hydrogenation is carried out in step b) without intermediate isolation of adipic acid or an ester of adipic acid.

In a second preferred embodiment, step b) of

process according to the invention the following substeps: b1) hydrogenation of muconic acid or one of its esters in aqueous solution

Adipic acid or one of its esters in the presence of a first

Hydrogenation catalyst, and

b2) hydrogenating the adipic acid or one of its esters in aqueous solution to 1,6-hexanediol in the presence of a second hydrogenation catalyst.

It is preferred here that the first catalyst is Raney cobalt and / or Raney nickel and / or Raney copper. Furthermore, it is preferred that the second Catalyst based on the total weight of the reduced catalyst contains at least 50 wt .-% of elements selected from the group consisting of rhenium, iron, ruthenium, cobalt, rhodium, iridium, nickel and copper. To the

Hydrogenation of adipic acid, adipic acid monoesters and adipic diesters, it is particularly preferred that the second catalyst contain at least 50% by weight of elements selected from the group consisting of rhenium, ruthenium and cobalt. For hydrogenating an adipic acid oligoester or polyester, it is particularly preferred that the second catalyst contain at least 50% by weight of copper. The hydrogenation in step b1) is preferably carried out at a temperature in the range of 50 to 160 ° C, more preferably 60 to 150 ° C, most preferably 70 to 140 ° C. In this temperature range are preferably more than 50%, more preferably more than 70%, most preferably more than 90% of the in the

Muconsäure existing carbon-carbon double bonds hydrogenated.

The hydrogenation in step b2) is preferably carried out at a temperature which is in the range from 160 to 240 ° C., particularly preferably from 170 to 230 ° C., very particularly preferably from 170 to 220 ° C. In this case, the not yet hydrogenated carbon-carbon double bonds and the carboxyl groups are hydrogenated.

Step b1) can be carried out, for example, in a first loop reactor and step b2) in a second loop reactor. The reaction of step b2) can be completed in a subsequent tubular reactor. But it is also possible to make do with a loop reactor, if created in this two temperature zones. Again, a tubular reactor connects in a straight passage. The hydrogenations can be carried out in bottom or trickle mode.

Workup of 1, 6-hexanediol

In a preferred embodiment of the process according to the invention, the discharge from the hydrogenation in step b) is subjected to a distillative separation

Extraction of a fraction enriched in 1, 6-hexanediol and subjected to the 1, 6-hexanediol-enriched fraction for amination in step c).

The reaction product obtained in the hydrogenation of muconic acid in water as solvent is an aqueous 1,6-hexanediol solution. After cooling and venting of the hydrogenation, the water is preferably removed by distillation and 1, 6-hexanediol can in high purity (> 97 %). If the muconic acid hydrogenation is carried out, for example, in methanol as solvent, part of the muconic acid is converted in situ into the monomethyl muconate and muconic acid dimethyl ester. The hydrogenation is a solution of 1,6-hexanediol in a mixture of methanol and water. By distillation, methanol and water are separated from 1, 6-hexanediol. Methanol is preferably separated from water and recycled to the hydrogenation. Water is discharged.

If n-butanol or i-butanol is used as the solvent in the hydrogenation of hydrogen chloride, a liquid two-phase mixture is obtained after cooling and venting of the hydrogenation effluent. The aqueous phase is separated from the organic phase by phase separation. The organic phase is distilled. When

Butanol is separated overhead and preferably recycled to the Muconsäure hydrogenation. 1, 6-hexanediol can, if necessary, be further purified by distillation.

If muconic acid diesters are used for the hydrogenation, largely anhydrous solutions of 1,6-hexanediol are obtained, which can be worked up by distillation to give pure 1,6-hexanediol. The resulting alcohols are preferably recycled to the esterification step.

In hydrogenation of muconic acid oligo- and polyesters, the 1, 6-hexanediol as

Diol component included, falls to a predominantly from 1, 6-hexanediol existing hydrogenation. hexamethylenediamine

In step c) of the process according to the invention, 1,6-hexanediol, obtained by a process comprising the steps a) and b), as previously defined, is subjected to an amination in the presence of an amination catalyst to obtain hexamethylenediamine.

The 1,6-hexanediol is preferably reacted with ammonia in the presence of the amination catalyst to hexamethylenediamine in step c). The amination according to the invention can be carried out without the supply of hydrogen, but preferably with the supply of hydrogen.

As catalysts in one embodiment of the invention are preferably predominantly cobalt, silver, nickel, copper or ruthenium or mixtures thereof Metals used. By "predominantly" it is to be understood that one of these metals contains more than 50% by weight in the catalyst (calculated without carrier) The catalysts can be used as unsupported catalysts, ie without catalyst carrier or as carrier catalysts. The carriers used are preferably SiO 2, Al 2 O 3, T 2 O 2, ZrO 2, activated carbon, silicates and / or zeolites

Catalysts are preferably used as fixed bed catalysts. It is also possible to use cobalt, nickel and / or copper in the form of Raney type suspension catalysts. In one embodiment of the invention, the amination of the 1,6-hexanediol is carried out in a homogeneous phase and the catalyst is a complex catalyst containing at least one element selected from groups 8, 9 and 10 of the Periodic Table (IUPAC) and at least one donor ligand. Such catalysts are

for example, from WO 2012/1 19929 A1 known.

The amination is preferably carried out at temperatures of 100 to 250 ° C, more preferably 120 to 230 ° C, most preferably 100 to 210 ° C.

The total pressure is preferably in the range of 5 to 30 MPa, more preferably 7 to 27 MPa, most preferably 10 to 25 MPa.

The molar ratio of 1,6-hexanediol to ammonia is preferably 1 to 30, more preferably 1 to 25, most preferably 1 to 20. The amination can be carried out without solvent. However, it is preferably carried out in the presence of at least one solvent. Preferred solvents are water, ethers or mixtures of these solvents, ethers being particularly preferably selected from dioxane, tetrahydrofuran, 2-methyltetrahydrofuran, dioxolane, dibutyl ether and methyl tert-butyl ether.

In a preferred embodiment of the process according to the invention, the aqueous 1,6-hexanediol solutions obtained in the hydrogenation of muconic acid are used without work-up in the amination step. It may be advantageous to completely or partially dehydrate part of the aqueous 1,6-hexanediol obtained in step c). In the case of partial dewatering, it is possible, for example, to remove 50%, preferably 70%, particularly preferably 90%, of the water present in the crude 1,6-hexanediol. This can be z. B. by evaporation the water at 50 to 90 ° C at reduced pressure (eg on a rotary evaporator) or by distillation.

In a particularly preferred embodiment, the amination is carried out in the presence of hexamethyleneimine as solvent or hexamethyleneimine / water mixtures.

The amount of solvent is preferably such that 5 to 80, preferably 10 to 70, particularly preferably 15 to 60 wt .-% strength 1, 6-hexanediol solutions.

10 to 150 liters, preferably 10 to 100 liters of hydrogen are fed per mole of 1,6-hexanediol.

In one embodiment of the invention, the amination of 1,6-hexanediol with ammonia takes place in a first substep c1) to give a mixture of 1-amino-6-hydroxyhexane and hexamethylenediamine which contains more than 50% by weight of 1-amino Contains 6-hydroxyhexane. This is separated in a partial step c2) together with hexamethylenediamine from unreacted 1, 6-hexanediol and reacted in a sub-step c3) with further ammonia to hexamethylenediamine.

The amination can be discontinuous or continuous, in the liquid or

Gas phase can be carried out, with a continuous process is preferred. The workup of the still 1-amino-6-hydroxyhexane-containing target product

Hexamethylenediamine is preferably carried out by distillation. Since 1-amino-6-hydroxyhexane and hexamethylenediamine have very similar vapor pressures, becomes pure

Hexamethylenediamine discharged. Mixtures of 1-amino-6-hydroxyhexane and hexamethylenediamine are recycled to the distillation stage.

In a further, particularly preferred embodiment, that in the

Aminierung of 1, 6-hexadiol formed hexamethyleneimine by distillation from the

Aminierungsaustrag separated and returned to the amination stage. If the recycled Hexamethylenimin amount 34 wt .-%, (based on the

Total weight of 1,6-hexanediol and hexamethyleneimine), advantageously no additional hexamethyleneimine is formed. Hexamethyleneimine can be separated by distillation as an azeotrope with water. The resulting hexamethylenediamine may be subjected to further purification. This preferably comprises at least one distillation step. In a specific embodiment, the resulting hexamethylenediamine is passed through

fractional distillation to "fiber grade" (i.e., a hexamethylenediamine content of at least 99.9%). If the hexamethylenediamine isomeric compounds 2-aminomethylcyclopentylamine (AMCPA) and / or 1,2-diaminocyclohexane (DACH) are contained as by-products, these can be prepared according to US Pat. No. 6,251,229 B1 at pressures of from 1 to 300 mbar using low-loss distillation columns split off.

The hexamethylenediamine prepared by the method of this invention from renewable sources typically has a ¹⁴ ^C-to-12 C lsotopenverhältnis in the range of 0.5 x 10 ¹² to 5 × 10 ^"12. The invention is based on the following non-limiting Examples explained in more detail.

Examples Example 1:

Preparation of muconic acid cis, cis-muconic acid was prepared according to the procedure in K.M. Draths, J.W. Frost, J. Am. Chem. Soc., 1 16 (1994), pages 399-400 by means of the Escherichia coli mutant

AB2834 / pKD136 / pKD8.243A / pKD8.292 biocatalytically produced from D-glucose.

Example 2:

Preparation of Adipic Acid A suspension of 24 g of cis, cis-muconic acid and 1 g of Raney Ni in 56 g of water was introduced into a 250 ml stirring autoclave, 3 MPa of hydrogen were pressed in and heated to 80.degree. After reaching the temperature of 80 ° C, the pressure was increased to 10 MPa and replenished so much hydrogen that the pressure remained constant. After 12 h reaction time was cooled to a temperature of 60 ° C, on

Normal pressure relaxed and filtered off the solution from the catalyst. It was then slowly cooled to 20 ° C and thereby crystallized adipic acid as a white solid. In addition to adipic acid, lactone (V) was used in the solution

be detected. The yield of adipic acid was 95% and of lactone (V) 5%. The mother liquor was returned to the hydrogenation. Example 3:

Preparation of 1,6-hexanediol 15 g / h of a mixture of 33% of adipic acid and 67% of water were introduced at a feed temperature of 70 ° C. into a 30 ml tubular reactor containing 20 ml of catalyst (66% CoO, 20%). CuO, 7.3% Mn ₃ 0 ₄ , 3.6% M0O3, 0.1% Na ₂ O, 3% H ₃ P0 ₄ ,

Production according to DE 23 21 101 A; 4 mm strands; Activation with hydrogen up to 300 ° C) were hydrogenated in trickle mode at a temperature of 230 ° C and a pressure of 25 MPa. The reactor effluent was separated in a separator of excess hydrogen (amount of flue gas 2 l / h) and reached on the one hand via a pump as recycle stream back to the head of the reactor, where it is combined with the feed stream (inlet: circulation = 1:10), and on the other hand in a

Discharge vessel. The discharges were analyzed by gas chromatography (% by weight, method with internal standard). The yield of 1, 6-hexanediol was 94%, the conversion of adipic acid was 98.5%. Other products found were 3% 6-hydroxycaproic acid, 1% 6-hydroxycaproic acid 1,6-hexanediol ester and 1% hexanol.

Preparation of hexamethylenediamine:

The preparation of hexamethylenediamine from 1,6-hexanediol based on muconic acid was carried out analogously to US Pat. No. 3,215,742, Examples 1 and 2.

Example 4:

Amination of 1,6-hexanediol

The water content of the crude 1, 6-hexanediol prepared according to Example 3 of this application was lowered by evaporation at 70 ° C and water jet vacuum to 5 wt .-%.

193 g of crude 1, 6-hexanediol was stirred with the amounts of dioxane, Raney nickel and liquid ammonia described in Example 1 in an autoclave for 5 hours at 200 ° C and 200 bar. Then the autoclave was cooled and relaxed. Gas chromatographic analysis of the reaction showed that 55% of 1,6-hexanediol had been converted into a mixture consisting of 65% hexamethylenediamine and 35% hexamethylimine.

Example 5:

Amination of mixtures of crude 1, 6-hexanediol and hexamethyleneimine 17 g of partially dehydrated crude 1,6-hexanediol and 54 g of hexamethyleneimine were dissolved in 50 g of dioxane. This solution was stirred in an autoclave together with 540 g of liquid ammonia and 72 g of Raney nickel at 180 to 183 ° C for six hours. The autoclave was cooled and relaxed. Gas chromatographic analysis revealed that the 1,6-hexanediol conversion was 35%. The Hexamethylendiamin- yield was 98%, based on reacted 1,6-hexanediol.

Claims

Patent claims

1 . Process for the production of hexamethylenediamine, in which a) a muconic acid starting material is provided which is selected from muconic acid, esters of muconic acid, lactones of muconic acid, the hydrogenated monolactone of muconic acid and mixtures thereof, b) the muconic acid starting material is reacted with hydrogen in the presence at least one hydrogenation catalyst to produce 1,6-hexanediol

c) the 1,6-hexanediol obtained in step b) undergoes an amination in the presence of an amination catalyst to give hexamethylenediamine and

2. The method according to claim 1, wherein in step a) a muconic acid starting material is provided, in which the muconic acid comes from a renewable source, the production of which is preferably carried out by biocatalytic synthesis from at least one renewable raw material.

3. The method according to claim 1 or 2, wherein the muconic acid used in step a) has a ¹⁴ C to ¹² C isotope ratio in the range of 0.5x10 ^"12 to 5 * ^10-12 . 4. Method according to one of the claims 1 to 3, wherein for the hydrogenation in step b) a muconic acid starting material is used which is selected from muconic acid, muconic acid monoesters, muconic diesters, poly(muconic acid esters) and mixtures thereof. 5. Process according to one of claims 1 to 3, wherein For the hydrogenation in step b), a muconic acid starting material is used which is selected from the lactones (III), (IV) and (V) and mixtures thereof:

(III) (IV)

(V) Process according to one of claims 1 to 5, wherein the hydrogenation in step b) takes place in the liquid phase in the presence of a solvent selected from water, aliphatic d- to Cs-alcohols, aliphatic C2- to C6-diols, ethers and mixtures from it.

Process according to one of claims 1 to 5, wherein the hydrogenation in step b) takes place in the liquid phase in the presence of water as the sole solvent.

Process according to one of claims 1 to 5, wherein for the hydrogenation in step b) a muconic acid diester is used which is selected from compounds of the general formula (II)

R ¹ OOC-CH=CH-CH=CH-COOR ² (II) in which the radicals R ¹ and R ² independently represent straight-chain or branched Ci-Cs-alkyl, the hydrogenation in step b) taking place in the gas phase.

Process according to one of claims 1 to 8, wherein in step b) a muconic acid starting material is used which is selected from muconic acid, muconic acid monoesters, lactones of muconic acid and mixtures thereof and a heterogeneous hydrogenation catalyst is used which has at least 50% by weight. % cobalt, ruthenium or rhenium based on the total weight of the reduced catalyst, or in step b) a muconic acid starting material is used which is selected from muconic diesters, poly(muconic acid esters) and mixtures thereof and a heterogeneous hydrogenation catalyst is used which contains at least 50% by weight of copper based on the total weight of the reduced catalyst. 10. The method according to any one of the preceding claims, wherein the hydrogenation in step b) takes place at a temperature which is in the range from 50 to 300 ° C.

1 1 . Method according to one of the preceding claims, wherein the hydrogenation in step b) takes place at a hydrogen partial pressure which is in a range from 100 to 300 bar. 12. The method according to any one of claims 1 to 1 1, wherein the hydrogenation in step b) takes place without intermediate isolation of adipic acid or an ester of adipic acid.

Method according to one of claims 1 to 1 1, wherein step b) comprises the following sub-steps:

Hydrogenating muconic acid or one of its esters in aqueous solution to adipic acid in the presence of a first hydrogenation catalyst, and hydrogenating the adipic acid in aqueous solution to 1,6-hexanediol in the presence of a second hydrogenation catalyst.

The method of claim 13, wherein the first hydrogenation catalyst is Raney cobalt and/or Raney nickel and wherein the second catalyst contains at least 50% by weight of elements selected from the group consisting of rhenium, based on the total weight of the reduced catalyst , iron, ruthenium, cobalt, rhodium, iridium, nickel and copper.

Method according to one of claims 13 or 14, wherein the hydrogenation in step b1) takes place at a temperature which is in the range of 50 to 160 ° C and the hydrogenation in step b2) takes place at a temperature which is in the range of 160 to 240 °C.

Method according to one of claims 13 to 15, wherein adipic acid-containing water, which is obtained during isolation of the second catalyst after completion of step b2), is used as a solvent in step b1).

17. The method according to any one of the preceding claims, wherein the hydrogenation in step b) is carried out in n series-connected hydrogenation reactors, where n is an integer of at least two and where 1. to (n-1). Reactor has a stream from the reaction zone carried in an external circuit and the hydrogenation is carried out adiabatically in the nth reactor.

18. The method according to any one of the preceding claims, wherein the output from the hydrogenation in step b) is subjected to a distillative separation to obtain a fraction enriched in 1,6-hexanediol and the fraction enriched in 1,6-hexanediol is subjected to amination in step c ) is used.

19. The method according to any one of the preceding claims, wherein the 1,6-hexanediol obtained in step b) is reacted in step c) with ammonia in the presence of the amination catalyst to give hexamethylenediamine.

20. The method according to any one of the preceding claims, wherein the amination in step c) is carried out without or with the addition of hydrogen.

21. Method according to one of the preceding claims, wherein the reaction product from the amination in step c) undergoes a separation to obtain a hexamethyleneimine enriched and a hexamethylenediamine depleted

Fraction is subjected and the fraction enriched in hexamethyleneimine is recycled into the amination in step c).

22. The method according to claim 21, wherein the fraction returned to the amination in step c) consists of hexamethyleneimine and 1,6-hexanediol.

23. The method according to claim 22, wherein the fraction recycled into the amination in step c) consists of 20 to 35% by weight of hexamethyleneimine and 80 to 65% by weight of 1,6-hexanediol.

24. The method according to any one of the preceding claims, wherein in step c) hexamethyleneimine is used as the only solvent.

25. Hexamethylenediamine, characterized in that it has a C ¹⁴ /C ¹² isotope ratio in the range of 0.5 x 10 ^"12 to 5 x 10 ^"12 .

26. Hexamethylenediamine, characterized in that it can be produced starting from muconic acid synthesized biocatalytically from at least one renewable raw material.