WO2020034057A1

WO2020034057A1 - PROCESS FOR REDUCTIVE AMINATION OF α, β-UNSATURATED KETONE

Info

Publication number: WO2020034057A1
Application number: PCT/CN2018/100180
Authority: WO
Inventors: Shi JIANG; Marc Pera Titus; François JERÔME; Karine VIGIER; Changru MA
Original assignee: Rhodia Operations; Le Centre National De La Recherche Scientifique; Universite De Poitiers
Priority date: 2018-08-13
Filing date: 2018-08-13
Publication date: 2020-02-20

Abstract

A process for reductive amination of α,β-unsaturated ketone is disclosed. A process for preparation of furan-derived amine starting from furfural or derivative thereof is also disclosed. The process is conducted in the presence of supported Ru as catalyst, the support of the supported Ru is selected from ceramics and carbon and preferably from Al ₂O ₃ and C.

Description

[Title established by the ISA under Rule 37.2] PROCESS FOR REDUCTIVE AMINATION OF α, β-UNSATURATED KETONE

TECHNICAL FIELD OF THE INVENTION

The invention relates to a process for the reductive amination of an α, β-unsaturated ketone. The invention furthermore relates to a process for the preparation of a furan-derived amine starting from furfural or a derivative thereof.

BACKGROUND

The depletion of fossil oil reserves has motivated intensive research on the development of chemical products from biomass. Biomass, mostly composed of carbohydrates, is a huge reservoir of renewable carbon with an annual production estimated at 180 billion metric tons. Hence, current research programs target the conversion of carbohydrates into value added chemicals.

Among biomass-derived reagents, furanic compounds produced from carbohydrates (hexoses or pentoses) contained in lignocellulosic biomass are of prime interest, giving access to a rich variety of chemicals and fuels. In particular, furfural is a versatile platform chemical for the production of fuel additives, solvents, polymers, surfactants, perfumes, and agrochemical ingredients. Despite the extensive literature dedicated to furanic compounds, the low selectivity of the chemical reactions due to partial cleavage and/or formation of larger oligomers, such as humines, still hamper the industrial-scale production of high-added valuable chemicals from furanic molecules.

Although the transformation of biomass into valuable nitrogen-containing compounds is highly desired, only few examples have been reported so far on furanic compounds. In particular, primary amines are widely used for the synthesis of polymers, dies, surfactants, pharmaceuticals and agrochemicals. Reductive amination of carbonyl compounds with ammonia (NH ₃) and hydrogen (H ₂) as a nitrogen source and reductant, respectively, has received much attention for the synthesis of primary amines as an alternative to synthetic processes with low atomic efficacy relying on toxic reagents and/or stoichiometric reductants.

Various heterogeneous catalysts have been developed for reductive amination reactions. Nonetheless, the synthesis of primary amines has been limited to the reductive amination of simple aryl and alkyl aldehydes, such as benzaldehyde, due to the formation of secondary and tertiary amines and/or undesired hydrogenation of carbonyl groups. In particular, the selective reductive amination of carbonyl compounds containing reduction-sensitive functional groups, such as heterocycles and halogens, is often difficult.

US 3,565,954 suggests a process for preparing primary amines by reaction of carbonyl compounds with ammonia followed by hydrogenation of the imine produced. As carbonyl compound, furfural is employed and the reaction is conducted in the presence of a catalyst, such as Raney nickel deposited on a kieselgur carrier. The highest yield obtained in one of the examples of this document is 92 %.

The direct reductive amination of aldehydes and ketones using potassium formate as reductant and catalytic palladium acetate is described by B. Basu, et al., Synlett 2003, No. 4, 555-557. This document contains only one example for the reductive amination of an α, β-unsaturated carbonyl compound, which is, however, an aldehyde, namely cinnamaldehyde. The yield in this example is only 69 %and the aromatic phenyl ring is not hydrogenated.

Heterogeneous Ru-based catalysts for one-pot synthesis of primary amines from aldehydes and ammonia are described by B. Dong, et al., in Catalysts 2015, 5, 2258-2270. The reductive amination of furfural to furfuryl amine using Ru/Al ₂O ₃ as catalyst is exemplified. However, in this reaction in a yield of only 75 %is obtained.

Furthermore, the aldol condensation of furanic compounds has been studied aiming at the production of liquid alkanes. For example, J. Yang, et al., ChemSusChem, 2013, 6, 1149-1152 describes the production of C ₁₀ and C ₁₁ branched alkanes by the aldol condensation of furfural with methyl isobutyl ketone followed by a one-step hydrodeoxygenation under solvent free conditions.

Also M. Li et al., Green Chem. 2014, 16, 4371-4377 report the tandem aldol condensation-hydrogenation reaction of furfural with acetone over a Pd/CN@MgO biofunctional catalyst in a single reactor.

However, in aldol condensation reactions, the desired nitrogen-containing compounds are not obtained. Further reactions are rather required.

It is therefore desirable to provide a process for the reductive amination of an α, β-unsaturated ketone, such as a furan derivative, which is highly selective towards the desired amine and which provides the desired amine in high yield without simultaneous reduction of the furan ring. It is furthermore desirable to provide a process for the preparation of furan-derived amines based on biomass-derived furfural which can be conducted in a single reactor (one-reactor tandem concept) , i.e. a process wherein the aldol condensation and the hydrogenation amination are conducted as one-pot process. Such process would afford the generation of furan-derived amines with molecular complexity and diversity without the need of separating the intermediates.

SUMMARY OF THE INVENTION

The present inventors have found that the reductive amination of an α, β-unsaturated ketone can be conducted in high yield and at high selectivity in the presence of a supported Ru catalyst.

The present invention therefore relates to a process for the reductive amination of an α, β-unsaturated ketone, wherein the process is conducted in the presence of supported Ru as catalyst.

The inventors furthermore found that furan-derived amines can be prepared in good yield starting from furfural or a derivative thereof, in particular from furfural or a derivative thereof being derived from biomass, by first conducting an aldol condensation between the furfural or derivative thereof and a ketone and then conducting a reductive amination of the product obtained in the first step in the presence of a supported Ru catalyst.

DETAILED DESCRIPTION

One embodiment of the present invention relates to a process for the reductive amination of an α, β-unsaturated ketone, wherein the process is conducted in the presence of supported Ru as catalyst.

It was found that supported Ru as catalyst in the reductive amination of an α,β-unsaturated ketone, in particular a furan derivative, results in high yield of the desired amine, in particular the furan-derived amine with only little undesired byproducts, compared to other known catalysts used in reductive amination. This effect will be further demonstrated by the examples and comparative examples below.

The reductive amination of an α, β-unsaturated ketone in the presence of for example ammonia as amine is exemplified by the following general reaction scheme 1:

Scheme 1

wherein R'a nd R”are any suitable residues.

In the preferred embodiment of the invention wherein the α, β-unsaturated ketone is a furan derivative, the general reaction scheme 2 is as follows:

Scheme 2

wherein R” is any suitable residue.

In the process of the invention any supported Ru may be used as catalyst.

In the context of the present invention "supported Ru" is understood as metallic Ru which is supported on a solid support. Any solid material is suitable as solid support, such as those solid supports known to a person skilled in the art as being suitable for supporting a catalyst, such as ceramics and carbon (C) . Suitable ceramics are, for example, Al ₂O ₃, SiO ₂, CeO ₂, ZrO ₂, zeolites etc. Preferred supports are Al ₂O ₃, zeolites (in particular H-BEA) and C, preferably Al ₂O ₃ and C, most preferably C.

In the reductive amination of the present invention any suitable reductant known to a person skilled in the art may be used. A preferred reductant is hydrogen (H ₂) .

In the reductive amination of the present invention any α, β-unsaturated ketone may be used. In the context of the invention, furan derivatives are, however, preferred because they can be obtained from biomass. Furthermore, it was found that if the α, β-unsaturated ketone is a furan derivative, only the double bond in the α, β-unsaturated ketone but not the double bonds in the furan ring are hydrogenated.

In one embodiment the α, β-unsaturated ketone is an α, β-ethylenically unsaturated ketone as exemplified in above Scheme 1, preferably an α, β-ethylenically unsaturated ketone furan derivative as exemplified in above Scheme 2.

The furan derivative used as α, β-unsaturated ketone in the preferred embodiment of the process of the present invention can have the chemical formula (I) :

wherein R ¹ is a hydrocarbon residue which may be interrupted by one or more heteroatoms and which may be substituted with one or more functional groups, and

R ², R ³ and R ⁴ independently of each other are a hydrocarbon residue which may be interrupted by one or more heteroatoms and which may be substituted with one or more functional groups.

R ¹ and the substituents on the furan ring (R ², R ³ and R ⁴) are not particularly limited because the reductive amination takes place at the carbonyl moiety and the double bonds. Therefore, the substituents on the furan ring and R ¹ can be selected by the skilled person according to the desired end product. For example, R ¹ can be a hydrocarbon residue comprising 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms.

The hydrocarbon residue may be interrupted by one or more heteroatoms which can for example be selected from N, O, S and P. In this context, "interrupted" means that the heteroatom is situated between at least two carbon atoms.

The hydrocarbon residue may be substituted with one or more functional groups which may for example be selected from halogen, hydroxyl, carbonyl, carboxyl, ester, amine, amide, imide, cyanate, isocyanate, nitro, sulfonyl, thiocyanate, isothiocyanate, and phosphate. Any functional group may be situated at any position of the hydrocarbon residue, and, in case of for example carbonyl or ester, may interrupt the hydrocarbon residue.

Suitable hydrocarbon residues are for example alkyl which may be linear or branched, alkenyl which may be linear or branched, alkinyl which may be linear or branched, cycloalkyl and aryl, in particular phenyl. Combinations of these groups are possible as well, such as for example combinations of linear and cyclic groups, such as alkylaryl, alkyl-cycloalkyl, arylalkyl and cycloakyl-aryl groups.

If the hydrocarbon residue comprises one or more carbon-carbon double or triple bond, it is possible that also such double or triple bond will be hydrogenated in the reductive amination reaction in the process of the invention.

Preferred groups for R ¹ are methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl and decyl.

The substituents on the furan ring, R ², R ³ and R ⁴, may be H or hydrocarbon residues which preferably are defined as the hydrocarbon residue for R ¹. In a certain embodiment, R ¹ is a C ₁ to C ₂₀, preferably C ₁ to C ₁₂ alkyl group which may be linear or branched, R ² is H or -CH=CH-CO-R ⁵, wherein R ⁵ is a C ₁ to C ₂₀, preferably C ₁ to C ₁₂ alkyl group which may be linear or branched, and R ³ and R ⁴ are both H. In this embodiment, R ⁵ and R ¹ may be the same or different, preferably R ⁵ and R ¹ are the same.

The reductive amination reaction in the process of the present invention may be conducted with ammonia, R ⁶-NH ₂ or R ⁶-NH-R ⁷, wherein R ⁶ and R ⁷ independently are a hydrocarbon residue which may be interrupted by one or more heteroatoms and which may be substituted with one or more functional groups. This hydrocarbon residue may have the same preferred embodiments as described for R ¹ above. Additionally, in case of R ⁶-NH-R ⁷, the substituents R ⁶ and R ⁷ together with the nitrogen atom to which they are attached may form a ring. Furthermore, among the functional groups with which the hydrocarbon residues for R ⁶ and R ⁷ may be substituted, amines are preferred.

In one embodiment, R ⁶ and, if present, R ⁷, independently are a C ₁ to C ₁₂ alkyl group which may be linear or branched and which may be substituted with one or more, preferably one amine (s) .

Preferred amines used in the reductive amination of the α, β-unsaturated ketone in the process of the present invention are ammonia, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, methyldiamine, ethyldiamine, propyldiamine, butyldiamine, pentyldiamine and hexyldiamine.

As catalyst any known supported Ru catalyst may be used. Suitable catalysts of this kind is, such as Ru/C are, for example, available from Johnson Matthey. Ru/Al ₂O ₃ is for example available from Alfa Aesar.

The amount of supported Ru catalyst used in the process of the invention is not particularly limited but it was found that a certain minimum amount is desirable for obtaining good yield and selectivity. Therefore, in a preferred embodiment, the supported Ru is used in an amount of at least 1 wt%, preferably at least 2 wt%, more preferably at least 3 wt%, even more preferably at least 4 wt% and most preferably at least 5 wt%, each based on the weight of the α, β-unsaturated ketone.

The reductive amination in the process of the invention can be conducted under usual process parameters well known to a person skilled in the art. In view of yield and selectivity of the process it is, however, preferred to conduct the reductive amination at a temperature of at least 80℃, preferably in the range of 80℃ to 120℃, more preferably in the range of 90℃ to 110℃, such as about 100℃.

The reductive amination in the process of the present invention can be conducted using H ₂. The pressure of H ₂ during the reaction is not particularly limited and can be selected according to the requirements. It was, however, found that in view of selectivity and yield it is desirable that the H ₂ is used at a pressure of at least 5 bar, preferably in the range of 5 bar to 30 bar, more preferably in the range of 10 bar to 20 bar, such as in the range of 12 bar to 18 bar.

The reaction time is also not particularly limited and can be selected by the skilled person according to the desired yield and purity of the desired furan-derived amine product. For example, the reaction can be conducted for at least 8 hours, preferably at least 10 hours, more preferably at least 12 hours, such as about 14 hours.

A further advantage of the use of supported Ru as catalyst in the reductive amination in the process of the present invention is that the catalyst can be reused in several consecutive reactions and/or recycled after the first use or after the first or one of the further reuses. Recycling can be conducted for example by washing with ethanol, drying under vacuum at 80℃ and reducing at 180℃. Such recycled catalyst shows almost the same activity as fresh catalyst. Therefore, in the process of the invention, fresh catalyst, recycled catalyst or a mixture thereof can be employed.

In a second embodiment, the present invention relates to a process for the production of a furan-derived amine comprising the steps of

1. conducting an aldol condensation between furfural or a derivative thereof and a ketone, and

2. conducting a reductive amination of the product received in step 1,

wherein the reductive amination is conducted as described with respect to the first embodiment of the invention including the preferred embodiments thereof.

This embodiment of the invention is exemplified by the following general reaction scheme:

1.

2.

wherein R” is any suitable residue.

The aldol condensation is conducted with furfural or a derivative thereof. Suitable derivatives are, for example, 5-hydroxymethyl furfural, 5-aminomethyl furfural and diformylfuran. Among the furfural derivatives diformylfuran is preferred.

The ketone used in the aldol condensation is not particularly limited and can be selected by a person skilled in the art according to the desired furan-derived amine. For example, the ketone can have the chemical formula (II) :

wherein R ⁸ is a hydrocarbon residue which maybe interrupted by one or more heteroatoms and which may be substituted with one or more functional groups. Preferably, R ⁸ is selected such that in the aldol condensation a furan derivative of the above chemical formula (I) is obtained (i.e. R ⁸ is defined as R ¹ above) . Thus, also the above preferred embodiments for R ¹ are applicable for R ⁸.

The aldol condensation can be conducted using usual process parameters well known to a person skilled in the art. For example, the aldol condensation can be conducted in the presence of a base catalyst, such as

A26 in hydroxide form, available from Sigma-Aldrich. The reaction can, for example be conducted at an elevated temperature of about 120℃ for about 2 hours without the presence of any additional solvent.

It was furthermore found that in the process of the second embodiment of the present invention steps 1 and 2 can be conducted as one-pot process. Thus, the aldol condensation and the reductive amination can be conducted in one reactor without separating the α, β-unsaturated ketone obtained in the aldol condensation step. It is rather possible to charge the reactor with the furfural or a derivative thereof, the ketone, the amine, the catalysts and H ₂ and then conduct both reaction steps, i.e. the aldol condensation and the reductive amination without separating any intermediate products. It was found that nevertheless the desired furan-derived amine can be obtained at high overall yield of about 70 %.

In a further embodiment of the present invention the furfural or derivative thereof used in the aldol condensation in step 1 of the above process is derived from biomass. In this case, the process comprises the further step of deriving the furfural or the derivative thereof from biomass. This additional step is conducted prior to step 1 above.

The conversion of biomass to furfural can be conducted as described for example in WO 2014/008364, the content of which is incorporated herein by reference.

In the attached figures,

Figure 1 shows the influence of a catalyst on the yields of the desired product (a) and the undesired byproduct (b and d) ,

Figure 2 shows the influence of H ₂ pressure on the yields of the desired product (a) and the undesired byproduct (b) ,

Figure 3 shows the influence of NH ₃ pressure on the yields of the desired product (a) and the undesired byproduct (b) ,

Figure 4 shows the yields of the desired product (a) and the undesired byproduct (b) depending on the use of fresh, reused and refreshed catalyst.

The following examples are given by way of non-limiting illustration of the present invention.

EXAMPLES

Materials

5%Ru/C (49.90%moisture, Johnson Matthey) , 5%Ru/Al ₂O ₃ (Alfa Aesar) , 5%Ru/CeO ₂, H-BEA (beta zeolite, Clariant) , Amberlyst-26 in hydroxide form (moisture 66-75%, Sigma-Aldrich) , furfural (99%, Sigma-Aldrich) , methyl isobutyl ketone (MIBK) (≥99%, Sigma-Aldrich) , ethanol (99.5%, J&K) , acetophenone (≥99%, Sigma-Aldrich) , 2-pentanone (≥99%, Sigma-Aldrich) , 2-heptanone (≥98%, Sigma-Aldrich) .

Example 1

1.1 Aldol Condensation

The experiment was performed in a 30-mL tubular glass reactor with a sealable arrangement on top. The reaction was performed using 1 g of furfural, 10 g of MIBK and 0.2 g of Amberlyst-26 catalyst in the glass tube preheated in an oil bath at 120℃ for 2 h with stirring speed of 600 rpm. The product was analyzed and quantified using an Agilent 7890 GC equipped with a HP-5 capillary column with 5 wt%phenyl groups and using n-dodecane as an internal standard. ¹H and ¹³C NMR and GCMS analysis were also carried out.

1.2 Reductive Amination

The experiments were carried out in a 20-mL stainless steel reactor equipped with a pressure gauge and a safety rupture disk. In a given experiment, the reactor was charged with 0.3 g of the aldol condensation product from experiment 1.1 above, 1 g of ethanol and 30 mg of the pre-reduced catalyst. The reactor was sealed and flushed with N ₂ three times. Then, NH ₃ (5 bar) and H ₂ (15 bar) were introduced to the reactor. The reactor was placed on hot plate provided with magnetic stirring at 100℃ for 14 h. After the reaction, the reactor was cooled down to room temperature and the mixture was analyzed using an Agilent 7890 GC equipped with a HP-5 capillary column with 5wt%phenyl groups and using n-dodecane as an internal standard. ¹H and ¹³C NMR, as well as GC-MS analyses, were further conducted.

A series of catalysts based on supported Ru (5 wt%Ru/Al ₂O ₃, , 5 wt%Ru/CeCO ₂, 5 wt%Ru/H-BEA, 5 wt%Ru/C; here wt%relates to Ru loading on the support) were tested to perform the reductive amination of the aldolization. The results are shown in Figure 1. Among the different catalysts, 5wt%Ru/C exhibits the best performance towards the primary amine (a) . Two additional byproducts are also observed: b with the α, β insaturation reduced, and the reduced byproduct d. Noteworthy, the imine intermediate c was not detected.

Example 2

By repeating Example 1.2 the effect of the H ₂ pressure on the reductive amination reaction was further explored on one of the best performing catalysts (5%Ru/C) . The results are shown in Figure 2. The H ₂ pressure exerts a positive effect on the yield to the target product a in detriment to byproduct b. A H ₂ pressure of 15 bar affords full conversion of the aldolization reactant and a yield of 96%to a after 14 h reaction at 100 ℃ using a molar ratio between the reactant 1 and NH ₃ of 1/10.

Example 3

By repeating Example 1.2 the effect of the NH ₃ pressure on the reductive amination reaction over 5%Ru/C was further explored. The results are shown in Figure 3. The NH ₃ pressure only exerts a moderate effect on the formation rate of the amine product a.

Example 4

Analog to example 1.2 recyclability and reuse of 5%Ru/C was further studied. The results are shown in Figure 4. The catalyst show an excellent catalytic performance for 5 consecutive runs with neither loss of activity nor effect on the carbon balance. The yield to the product decreases slightly from 96%to 82%after the 4 ^th run. A further catalytic test on the refreshed catalyst after the 4 ^th run followed by washing with ethanol, drying under vacuum at 80℃ overnight and reducing at 180℃ for 1 h shows an activity almost unchanged.

Example 5

The reduction amination over 5%Ru/C was further extended to other α, β-unsaturated ketones issued from the aldol condensation reaction of furfural with biobased ketones with variable chain length. In all cases a yield higher than 90%to the desired product is obtained.

Reaction conditions: 5%Ru/C (30 mg) , α, β-unsaturated ketone (0.3 g) , EtOH (1 g) , NH ₃ (0.3 g) , H ₂ (15 bar) , 100℃, 6 h.

Example 6

In this example the aldolization and reductive amination reactions were conducted simultaneously in the same reactor (one-reactor tandem concept) . To this aim, two catalysts were introduced to the reactor: (1) Amberlyst-26 (65 mg) for catalyzing the aldol condensation reaction between furfural (162 mg) and MIBK (169 mg) in ethanol (1 g) , and (2) 5%Ru/C (30 mg) for catalyzing the reductive amination. The reaction was kept constant at 100℃ for the two reactions. NH ₃ (0.3 g) and H ₂ (15 bar) were introduced after 4 h to ensure that enough aldolization product was formed. The amine product a was generated with a yield of 70%.

Claims

Process for the reductive amination of an α, β-unsaturated ketone, wherein the process is conducted in the presence of supported Ru as catalyst.
Process according to claim 1, wherein the support of the supported Ru is selected from ceramics and carbon and preferably from Al ₂O ₃ and C, and wherein the support most preferably is C.
Process according to claim 1 or 2, wherein the reductive amination is conducted in the presence of H ₂ as reductant.
Process according to any one of the preceding claims, wherein the α, β-unsaturated ketone is a furan derivative.
Process according to claim 4, wherein the furan derivative has the chemical formula (I) :

wherein

R ¹ is a hydrocarbon residue which may be interrupted by one or more heteroatoms and which may be substituted with one or more functional groups, and

R ², R ³ and R ⁴ independently of each other are H or a hydrocarbon residue which may be interrupted by one or more heteroatoms and which may be substituted with one or more functional groups.
Process according to claim 5, wherein in the chemical formula (I) R ¹ is C ₁ to C ₂₀ alkyl group which may be linear or branched, R ² is H or-CH=CH-CO-R ⁵, wherein R ⁵ is a C ₁ to C ₂₀ alkyl group which may be linear or branched, and R ³ and R ⁴ are H.
Process according to any one of the preceding claims wherein the α, β-unsaturated ketone is reacted with ammonia, R ⁶-NH ₂ or R ⁶-NH-R ⁷, wherein R ⁶ and R ⁷ independently are a hydrocarbon residue which may be interrupted by one or more heteroatoms and which may be substituted with one or more functional groups and wherein R ⁶ and R ⁷ together with the nitrogen atom to which they are attached may form a ring.
Process according to claim 7, wherein R ⁶ and R ⁷ are a C ₁ to C ₁₂ alkyl group which may be linear or branched and which may be substituted with one or more, preferably one amine (s) .
Process according to any one of the preceding claims, wherein the supported Ru catalyst is used in an amount of at least 1 wt%, preferably at least 2 wt%, more preferably at least 3 wt%, even more preferably at least 4 wt%and most preferably at least 5 wt%, each based on the weight of the α, β-unsaturated ketone.
Process according to any one of the preceding claims, wherein the reductive amination is conducted at a temperature of at least 80℃, preferably in the range of 80℃ to 120℃, more preferably in the range of 90℃ to 110℃.
Process according to any one of the preceding claims, wherein the reductive amination is conducted at a H ₂ pressure of at least 5 bar, preferably in the range of 5 bar to 30 bar, more preferably in the range of 10 bar to 20 bar.
Process for the preparation of a furan-derived amine comprising the steps of

1. conducting an aldol condensation between furfural or a derivative thereof and a ketone, and

2. conducting a reductive amination of the product obtained in step 1. according to the process of any one of claims 1 to 11.
Process according to claim 12, wherein the ketone has the chemical formula (II) :

wherein R ⁸ is a hydrocarbon residue which may be interrupted by one or more heteroatoms and which may be substituted with one or more functional groups.
Process according to claim 12 or 13, wherein steps 1 and 2 are conducted as one-pot process.
Process according to any one of claims 12 to 14, further comprising the step of deriving the furfural or the derivative thereof from biomass.