Method for producing pyrrolidone-substituted polyols
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- RWTH AACHEN UNIV
- Filing Date
- 2024-07-25
- Publication Date
- 2026-06-10
AI Technical Summary
There is a need for alternative manufacturing methods for substituted aminodioles, particularly substituted 2-amino-L, 3-propandioles, that are sustainable and reduce dependence on fossil resources, as existing methods are inefficient and environmentally impactful.
A procedure for producing pyrrolidone-substituted polyols by reacting substituted or unsubstituted oxolan-2-ones with amino alcohols, such as Serinol, to form pyrrolidone-substituted polyols with high yields, using biomass-based educts and optimizing reaction conditions like temperature and solvent usage.
This method allows for the production of pyrrolidone-substituted polyols with yields over 95% using sustainable biomass-based materials, reducing environmental impact and improving economic efficiency.
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Abstract
Description
[0001] Process for the preparation of pyrrolidone-substituted polyols
[0002] The invention relates to a process for the preparation of pyrrolidone-substituted polyols, in particular pyrrolidone-substituted diols.
[0003] With the rapid growth of the world population, the gradual depletion of non-renewable fossil resources, and the growing problem of environmental pollution, it is essential to reduce the chemical industry's dependence on fossil resources. One approach is the use of biogenic platform chemicals to initiate a transition to a sustainable chemical industry.
[0004] 2-Amino-l,3-propanediol (serinol) and substituted 2-amino-l,3-propanediols are widely used in the chemical industry. For example, the production of polymerizable diols starting from serinol is known. For example, document CN 109467547 A describes the production of 5-dimethylamino-l,3-dioxan-2-one starting from serinol and reacting it with triphosgene. The 5-dimethylamino-l,3-dioxane-2-ketone can be further copolymerized with a cyclic carbonate monomer and a lactone monomer to produce a functional aliphatic polycarbonate and poly(ester-carbonic acid ester) copolymer. Document EP 2809760 B1 describes a process for the degradation of off-odors using 2-amino-l,3-propanediol or substituted 2-amino-l,3-propanediols.EP 3063204 A1 describes a polymer which is a reaction product of an organic di- or polyepoxide with a primary amine, an amino alcohol, an amino acid, a hydroxy acid, a diol, or an alcohol having a condensed or uncondensed aromatic imide group. WO 2020 / 154471 A1 describes lactam-functionalized polymers obtainable from the reaction of a dihydroxylactam with a functional unit having a hydroxyl-reactive functional group.
[0005] There is therefore a need for alternative production methods for substituted aminodiols, especially substituted 2-amino-l,3-propanediols.
[0006] The object of the present invention was to provide a process for the preparation of substituted aminopolyols which overcomes at least one of the aforementioned disadvantages of the prior art.
[0007] This object is achieved by a process for the preparation of pyrrolidone-substituted polyols, wherein a substituted or unsubstituted oxolan-2-one according to the following general formula (I) is reacted with an amino alcohol of the general formula NH2-C(R 7 )((CH2)m-OH)-(CH2)n-OH (II) or NH2-(CH2)o-CH(OH)-(CH2)p-OH (III) to a pyrrolidone-substituted polyol of the following general formula (IV) or (V): wherein:
[0008] R 1 , R 2 independently selected from the group comprising H, C1-C5-
[0009] Alkyl, C2-Cs-alkenyl, Cl, Br, I, F and / or OH, or
[0010] R 1 and R 2 form a doubly bonded oxygen atom (carbonyl oxygen); R 3 , R 6 is independently selected from the group comprising H, C1-C5 alkyl, C2-C5 alkenyl, Cl, Br, I, F and / or OH; and
[0011] R 4 , R5 is independently selected from the group comprising H, C1-C5 alkyl, C2-C5 alkenyl, Cl, Br, I, F and / or OH, or R 4 and R 5 form a double bond;
[0012] R 7 is selected from the group comprising H, -(CH2) q -OH and Ci-Cs-alkyl; and m, n, o, p, q are independently an integer selected from 0, 1, 2, 3, 4, 5, 6, 7.
[0013] Surprisingly, it was found that the process according to the invention allows the production of pyrrolidone-substituted polyols in a single-step reaction. Pyrrolidone-substituted polyols can be produced with a crude product yield of over 95%. The process allows the production of pyrrolidone-substituted polyols from biomass-based starting materials, thus enabling a sustainable reaction process and economical raw material utilization.
[0014] Unless otherwise stated, the term "Ci-Cs-alkyl" encompasses straight-chain or branched alkyl groups having 1 to 5 carbon atoms. Ci-Cs-alkyl groups are preferably selected from the group comprising methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, and / or neopentyl.
[0015] Unless otherwise stated, the term "C2-C5 alkenyl" encompasses straight-chain or branched alkenyl groups having 2 to 5 carbon atoms. C2-C5 alkenyl groups are preferably selected from the group comprising ethenyl, propenyl, and butenyl.
[0016] Unless otherwise stated, compounds with Arabic numbers differ from Roman numbered compounds in the context of the present invention, ie they are each different compounds. Amino alcohols of the general formulas NH2-C(R 7 )((CH2) m -OH)-(CH2) n - OH (II) or NH2-(CH2)o-CH(OH)-(CH2) P-OH (III), where R 7 is selected from the group comprising H, -(CH2) q -OH and Ci-Cs-alkyl and m, n and q as well as o and p can each independently be 0, 1, 2, 3, 4, 5, 6 or 7.
[0017] An amino alcohol of the general formula NH2-C(R 7 )((CH2) m -OH)-(CH2) n -OH (II), where R 7 is selected from the group comprising H, -(CEE)-OH and Ci-Cs-alkyl, and m, n and q can independently be 0, 1, 2, 3, 4, 5, 6 or 7, has at least two hydroxyl groups, but can also be a triol.
[0018] In preferred embodiments, the amino alcohol is a diol of the formula NH2- C(R 7 )((CH2)m-OH)-(CH2) n -OH (II) with R 7 is hydrogen or methyl and m = n is selected from 0, 1, 2, 3, or m=0 and n=1 or 2, or m=1 and n=2, 3, 4, 5, 6 or 7. Preferred amino alcohols of the formula (1) where m and n are selected from 0, 1, 2, 3, or m=0 and n=1 or 2, or m=1 and n=2, 3, 4, 5, 6 or 7 are selected from the group of compounds (4) to (15) as indicated below:
[0019]
[0020] In particularly preferred embodiments, the amino alcohol is a diol of the formula NH2-C(R 7 )((CH2)m-OH)-(CH2)n-OH (II) where R 7 can be hydrogen or methyl and m and n are preferably 1. These 2-amino-l,3-propanediols are commonly referred to as serinol and methylserinol, respectively.
[0021] In further embodiments, the amino alcohol is of the formula NH2-C(R 7 )((CH2) m -OH)- (CH2) n -OH (II) a triol of the following formula (2) where R 7 -(CH2) q -OH is: Preferred is a triol NH2-C(-(CH2)q-OH)((CH2) m -OH)-(CH2) n-OH of formula (2) with m=n=q selected from 1, 2, 3. Preferred amino alcohols of formula (2) are selected from the group of compounds (16) to (18) as indicated below:
[0022]
[0023] Amino alcohols of the general formula NH2-(CH2) can also be used. o -CH(OH)- (CH2) P -OH (III), where o and p can preferably each independently be 1, 2, 3 or 4. Preferred amino alcohols of the formula (III) are selected from the group of compounds (19) to (24) as indicated below:
[0024] The amino alcohol, in particular serinol or methylserinol, is reacted with a substituted or unsubstituted oxolan-2-one of the general formula (I): wherein:
[0025] R 1 , R 2 independently selected from the group comprising H, C1-C5-
[0026] Alkyl, C2-Cs-alkenyl, Cl, Br, I, F and / or OH, or
[0027] R 1 and R 2 form a doubly bonded oxygen atom (carbonyl oxygen); R 3 , R 6 independently selected from the group comprising H, C1-C5-
[0028] Alkyl, C2-Cs-alkenyl, Cl, Br, I, F and / or OH; and
[0029] R 4 , R 5 independently selected from the group comprising H, C1-C5-
[0030] Alkyl, C2-Cs-alkenyl, Cl, Br, I, F and / or OH, or
[0031] R 4 and R 5 form a double bond.
[0032] Preferably, R 1 and R 2 independently selected from hydrogen and Ci-Cs-alkyl, in particular methyl, or R 1 and R 2 form a doubly bonded oxygen atom (carbonyl oxygen). Preferably, R 3 and R 6independently selected from hydrogen, C1-C5 alkyl, in particular methyl, or C2-C5 alkenyl. In the case of C2-C5 alkenyl groups, it is preferred that the unsaturated bond is not located directly on the ring. In embodiments in which R 3 or R 6 a C2-Cs alkenyl group, R 4 and R 5 preferably hydrogen.
[0033] Preferably, R 4 and R 5 independently selected from hydrogen, C1-C5 alkyl, in particular methyl, or C2-C5 alkenyl, or R 4 and R 5 form a double bond. In embodiments where R 4 and R 5 form a double bond, R 3 and R 6 preferably hydrogen.
[0034] In preferred embodiments, the substituted or unsubstituted oxolan-2-one has the following formula (VI): wherein:
[0035] R 1 , R 2is independently selected from the group comprising H, and Ci-Cs-alkyl, or R 1 and R 2 form a doubly bonded oxygen atom (carbonyl oxygen); and
[0036] R 3 , R 6 is independently selected from the group comprising H, C1-C3 alkyl and / or C2-C3 alkenyl.
[0037] Preferred substituted or unsubstituted oxolan-2-ones are selected from the group of compounds according to the following formulas (25) to (38):
[0038] A particularly preferred oxolan-2-one is gamma-butyrolactone according to formula (25).
[0039] In embodiments of the process, an oxolan-2-one of formula (VI) is reacted with serinol to form a pyrrolidone-substituted diol of formula (VII): where: R 1 , R 2 is independently selected from the group comprising H, and C1-C3 alkyl, or R 1and R 2 a doubly bonded oxygen atom (carbonyl oxygen); and
[0040] R 3 , R 6 is independently selected from the group comprising H, Ci-Cs-alkyl and / or C2-C3-alkenyl.
[0041] Using serinol and an oxolan-2-one of formula (VI), high yields were achieved in the reaction. Preferably, R 1 , R 2 , R 3 , R 6 independently selected from hydrogen and Ci-Cs-alkyl or R 1 and R 2 are carbonyl oxygen and R 3 and R 6 are hydrogen.
[0042] In preferred embodiments, gamma-butyrolactone is reacted with serinol to form a pyrrolidone-substituted diol of formula (40):
[0043] The oxolan-2-one can be used in stoichiometric amounts relative to the amino alcohol or, preferably, in excess. The oxolan-2-one can be present in the range of > 1 equivalent (eq.) to < 2 equivalents (eq.), relative to the amino alcohol. In embodiments, the reaction is carried out with an excess of oxolan-2-one to form amino alcohol in the range of > 1.2 eq. to < 1.5 eq. With such a slight excess of oxolan-2-one relative to the amino alcohol, better yields could be achieved.
[0044] In embodiments, the reaction is carried out in aqueous solution or solvent-free. For example, gamma-butyrolactone is liquid at room temperature (corresponding to 20±2°C), and a reaction can be carried out with serinol, which is solid at room temperature, without further addition of a solvent. Preferably, the reaction is carried out with the addition of small amounts of water in aqueous solution. This has been shown to increase the yield of the reaction. The amount of solvent is preferably as small as possible, for example an amount sufficient to dissolve one solid reactant, or several solid reactants. For example, the amount of water per gram of solid reactant, in particular serinol, can be in the range from > 1.5 mL / g to < 2 mL / g, in particular in the range from > 1.5 mL / g to < 1.8 mL / g.
[0045] In preferred embodiments, the reaction is carried out at a temperature in the range of >150°C to <220°C, preferably at a temperature in the range of >180°C to <200°C. Good yields were obtained particularly in these temperature ranges. At lower temperatures, the yield decreased, while at higher temperatures, decomposition of the product may occur. The reaction time can be in the range of >2 hours to <20 hours, preferably in the range of >12 hours to <16 hours.
[0046] The process can in principle be carried out continuously or batchwise, for example in stirred tanks, synthesis reactors such as stirred reactors, or autoclaves. It is preferred that the reaction be carried out under a nitrogen atmosphere. For this purpose, an autoclave can be purged with nitrogen before the reaction.
[0047] In a preferred embodiment, 10 mmol (1 eq) of serinol dissolved in 1.5 mL of deionized water is reacted with 12-15 mmol (1.2 - 1.5 eq) of gamma-butyrolactone at a temperature of 180-200°C for 16-20 hours.
[0048] The reaction mixtures resulting from the process can be purified by conventional methods, for example, thermally by distillation or rectification. In preferred embodiments, the pyrrolidone-substituted polyol is purified by extraction with ethyl acetate at a temperature in the range of > 85°C to < 95°C. For example, the temperature can be approximately 10 degrees above the boiling point of ethyl acetate (at about 87°C). Hot extraction with ethyl acetate yielded the products in the form of pure white crystals. It is preferred that any water added as a solvent or formed during the reaction be removed prior to such purification.
[0049] Overall, a process can be provided that allows the production of pyrrolidone-substituted diol-based polyols in a one-step reaction in good yield using readily available, resource-saving starting materials.
[0050] A further subject matter are pyrrolidone-substituted polyols, in particular prepared by the process described herein, according to the following general formula (IV): wherein:
[0051] R 1 , R 2 independently selected from the group comprising H, C1-C5-
[0052] Alkyl, C2-Cs-alkenyl, Cl, Br, I, F and / or OH, or
[0053] R 1 and R 2 form a doubly bonded oxygen atom (carbonyl oxygen);
[0054] R 3 , R 6 independently selected from the group comprising H, C1-C5-
[0055] Alkyl, C2-Cs-alkenyl, Cl, Br, I, F and / or OH; and
[0056] R 4 , R 5 independently selected from the group comprising H, C1-C5-
[0057] Alkyl, C2-Cs-alkenyl, Cl, Br, I, F and / or OH, or
[0058] R 4 and R 5 form a double bond;
[0059] R 7 is selected from the group comprising H, -(CH2) q -OH and Ci-Cs-alkyl; and m, n, q are independently an integer selected from 0, 1, 2, 3, 4, 5, 6, 7.
[0060] Preferably, R 1 and R 2 independently selected from hydrogen and Ci-Cs-alkyl, in particular methyl, or R 1 and R 2 form a doubly bonded oxygen atom (carbonyl oxygen). Preferably, R 3 and R 6independently selected from hydrogen, C1-C5-alkyl, in particular methyl, or C2-C5-alkenyl. In the case of C2-C5 alkenyl groups, it is preferred that the unsaturated bond is not located directly on the ring. In embodiments in which R 3 or R 6 a C2-Cs alkenyl group, R 4 and R 5 preferably hydrogen. Preferably, R 4 and R 5 independently selected from hydrogen, Ci-Cs-alkyl, in particular methyl, or C2-Cs-alkenyl, or R 4 and R 5 form a double bond. In embodiments where R 4 and R 5 form a double bond, R 3 and R 6 preferably hydrogen.
[0061] Preferred are pyrrolidone-substituted diols of the following formula (VII): wherein:
[0062] R 1 , R 2is independently selected from the group comprising H, and Ci-Cs-alkyl, or R 1 and R 2 form a doubly bonded oxygen atom (carbonyl oxygen); and
[0063] R 3 , R 6 is independently selected from the group comprising H, C1-C3 alkyl and / or C2-C3 alkenyl.
[0064] Preferably, R 1 , R 2 , R 3 , R 6 independently selected from hydrogen and Ci-Cs-alkyl or R 1 and R 2 are carbonyl oxygen and R 3 and R 6 are hydrogen. Particularly preferred are pyrrolidone-substituted diols of the following formulas (40), (41) and (42):
[0065] Unless otherwise specified, the technical and scientific terms used have the meaning commonly understood by one of ordinary skill in the art to which this invention belongs.
[0066] Examples and figures illustrating the present invention are given below.
[0067] This shows:
[0068] Figure 1 shows the yields of the reaction of succinic anhydride with serinol at different temperatures and reaction times.
[0069] Chemicals:
[0070] The reactants used were purchased from Sigma-Aldrich, Fluorochem, or Aldrich. Solvents were purchased from Chemsolute GmbH.
[0071] 'H nuclear magnetic resonance (NMR):
[0072] The reaction products were 1H-NMR was measured using a Bruker DPX-400 FT-NMR spectrometer at 400 MHz and room temperature. 2D spectra (COSY, HMBC, HSQC) were measured for some products to identify the product. The signals and chemical shifts in 5 units were referenced to the residual proton signals of the deuterated solvent: 1H: DMSO-d6 (5H = 2.50 ppm); DMSO-d6 (5C = 39.52 ppm). Quantitative analysis was performed using mesitylene as a standard. Example 1
[0073] Determination of the yield of the reaction of gamma-butyrolactone with serinol at varied
[0074] Temperature and reaction time
[0075] Serinol GBL
[0076] A 50 mL autoclave (homemade) was charged with 1.14 mL of gamma-butyrolactone (GBL) (15 mmol, 1.5 eq), 0.9111 g of serinol (10 mmol, 1 eq), and 1.5 mL of water. The autoclave was then purged with nitrogen three times for 2 minutes while stirring. The autoclave was then sealed, and the reaction was carried out at 180°C, 200°C, or 220°C for 4, 8, 12, 16, or 20 hours. The crude yields were determined by 'H NMR.
[0077] Figure 1 shows the crude yields from the screening of the reaction of gamma-butyrolactone and serinol under various reaction conditions. As can be seen from Figure 1, the best yields were obtained in the range of 12 to 20 hours for all temperatures tested. The best conditions in this screening were found for a reaction at 200°C for 12 hours.
[0078] Purification of the crude yield with ethyl acetate (87°C) resulted in pure, white crystals.
[0079] Example 2
[0080] Determination of the yield of the reaction of gamma-butyrolactone with serinol at varied reactant ratio and presence of solvent
[0081] The reaction of gamma-butyrolactone and serinol was carried out in a 50 mL autoclave according to
[0082] The reaction was carried out under nitrogen at a reaction temperature of 200°C for 16 hours. In four batches, an equimolar ratio of gamma-butyrolactone to serinol and a ratio of 20 mmol (2 eq) of gamma-butyrolactone to 10 mmol (1 eq) of serinol were used without solvent and 2 mL of water. The crude yields were determined by 'H NMR.
[0083] This showed that the yield was higher when using an excess (1.5 eq) of gamma-butyrolactone. Furthermore, the yield was higher when using water as the solvent. Further investigations of the reactants and solvent ratio showed that a serinol to gamma-butyrolactone ratio of 1:1.2 already showed a corresponding increase in yield. Furthermore, a solvent amount of 1.5 mL per 10 mmol of serinol already showed a corresponding increase in yield.
[0084] Example 3
[0085] Investigation of the reaction of serinol with succinic anhydride
[0086] Serinol succinic anhydride
[0087] The reaction of 12 mmol (1.2 eq) of succinic anhydride with 10 mmol (1 eq) of serinol was carried out using water as the solvent in a 50 mL autoclave after purging with nitrogen at a reaction temperature of 200°C for reaction times between 1 and 20 hours. The crude yields were determined by 'H-NMR. The following Table 1 summarizes the crude yields obtained:
[0088] Table 1 : Crude yields of the reaction of 1.2 eq succinic anhydride with 1 eq serinol
[0089] It is assumed that reaction times longer than 12 hours resulted in the formation of byproducts, which led to a reduction in product yield. Example 4
[0090] Investigation of the reaction of serinol with 4-valerolactone Serinol Valerolactone
[0091] The reaction of 12 mmol (1.2 eq) of 4-valerolactone with 10 mmol (1 eq) of serinol was carried out using water as the solvent in a 50 mL autoclave after purging with nitrogen at a reaction temperature of 200°C for reaction times between 1 and 20 hours. The crude yields were determined by 'H-NMR. The following Table 2 summarizes the crude yields obtained: Table 2: Crude yields of the reaction of valerolactone with serinol
[0092] It is believed that the methyl group resulted in a reduction in product yield.
[0093] Example 5
[0094] Investigation of the reaction of serinol with other lactones
[0095] The reactions of 12 mmol (1.2 eq) of alpha-valerolactone, 5-methyl-2-furanone or furaneol with 10 mmol (1 eq) of serinol were carried out using water as solvent in a 50 mL autoclave after gassing with nitrogen at a reaction temperature of 200°C for 16 hours.
[0096] The reaction with alpha-valerolactone was successful, whereas the reactions with 5-methyl-2-furanone and furaneol were unsuccessful.
[0097] Example 6
[0098] Investigation of the reaction of gamma-butyrolactone with other aminodiols or aminotriols
[0099] The reactions of 12 mmol (1.2 eq) of gamma-butyrolactone with 10 mmol (1 eq) of 3-aminopropane-1,2-diol or the triol 2-amino-2-(hydroxymethyl)propane-1,3-diol were carried out using water as the solvent in a 50 mL autoclave after purging with nitrogen at a reaction temperature of 200°C for 16 hours. Both the reactions of the diol and the triol yielded the desired product. Overall, the results demonstrate that pyrrolidone-substituted diols and triols can be prepared by reacting a substituted or unsubstituted oxolan-2-one with an aminodiol or aminotriol in a one-step reaction with good yield.
[0100] The invention underlying this patent application was created in a project funded by the BMBF under the funding reference 031B1141 A.
Claims
Patent claims 1. A process for the preparation of pyrrolidone-substituted polyols, wherein a substituted or unsubstituted oxolan-2-one according to the following general formula (I) is reacted with an amino alcohol of the general formula NH2- C(R 7 )((CH2)m-OH)-(CH2)n-OH (II) or NH2-(CH2)o-CH(OH)-(CH2) P -OH (III) to a pyrrolidone-substituted polyol of the following general formula (IV) or (V): wherein: R 1 , R 2 is independently selected from the group comprising H, C1-C5 alkyl, C2-C5 alkenyl, Cl, Br, I, F and / or OH, or R 1 and R 2 form a doubly bonded oxygen atom; R 3 , R 6 is independently selected from the group comprising H, C1-C5 alkyl, C2-C5 alkenyl, Cl, Br, I, F and / or OH; and R 4 , R 5is independently selected from the group comprising H, C1-C5 alkyl, C2-C5 alkenyl, Cl, Br, I, F and / or OH, or R 4 and R 5 form a double bond; R 7 is selected from the group comprising H, -(CH2) q -OH and Ci-Cs-alkyl; and m, n, o, p, q are independently an integer selected from 0, 1, 2, 3, 4, 5, 6, 7.
2. Process according to claim 1, characterized in that the amino alcohol is a diol of the formula NH2-C(R 7 )((CH2) m -OH)-(CH2) n -OH (1) with R 7 is selected from H or Methyl and m = n selected from 0, 1, 2, 3, or m=0 and n=1 or 2, or m=1 and n=2, 3, 4, 5, 6 or 7, or the amino alcohol is a triol of the formula NH2-C(-(CH2) q - OH)((CH2)m-OH)-(CH2) n -OH (2) with m=n=q selected from 1, 2, 3.
3. Process according to claim 1 or 2, characterized in that an oxolan-2-one of formula (VI) is reacted with serinol to give a pyrrolidone-substituted diol of formula (VII): wherein: R 1 , R 2 is independently selected from the group comprising H, and Ci-Cs-alkyl, or R 1 and R 2 form a double-bonded oxygen atom; R 3 , R 6 is independently selected from the group comprising H, C1-C3 alkyl and / or C2-C3 alkenyl.
4. Process according to one of the preceding claims, characterized in that the reaction is carried out with an excess of oxolan-2-one to amino alcohol in the range from > 1.2 eq. to < 1.5 eq.
5. Process according to one of the preceding claims, characterized in that the reaction is carried out in aqueous solution or solvent-free.
6. Process according to one of the preceding claims, characterized in that the reaction is carried out at a temperature in the range from > 150°C to < 220°C, preferably at a temperature in the range from > 180°C to < 200°C.
7. Process according to one of the preceding claims, characterized in that the reaction time of the reaction is in the range from > 2 hours to < 20 hours, preferably in the range from > 12 hours to < 16 hours.
8. Process according to one of the preceding claims, characterized in that the pyrrolidone-substituted polyol is purified by extraction with ethyl acetate at a temperature in the range of > 85°C to < 95°C.
9. Pyrrolidone-substituted polyol according to the following general formula (IV), in particular prepared by a process according to claims 1 to 8: wherein: R 1 , R 2independently selected from the group comprising H, C1-C5- Alkyl, C2-Cs-alkenyl, Cl, Br, I, F and / or OH, or R 1 and R 2 form a doubly bonded oxygen atom; R 3 , R 6 independently selected from the group comprising H, C1-C5- Alkyl, C2-Cs-alkenyl, Cl, Br, I, F and / or OH; and R 4 , R 5 independently selected from the group comprising H, C1-C5- Alkyl, C2-Cs-alkenyl, Cl, Br, I, F and / or OH, or R 4 and R 5 form a double bond; R 7 is selected from the group comprising H, -(CH2) q -OH and Ci-Cs-alkyl; and m, n, q are independently an integer selected from 0, 1, 2, 3, 4, 5, 6, 7.