Lignin-based aryl formate and diaryl ether compounds and methods of synthesis thereof
Aryl carbamates and diaryl ethers were prepared by reacting lignin β-O-4 model compounds with diaryl iodonium, solving the problems of complex and environmentally unfriendly synthesis methods in existing technologies and realizing an efficient and green synthesis method.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2024-12-06
- Publication Date
- 2026-06-09
Smart Images
Figure BDA0005175385540000021 
Figure BDA0005175385540000022 
Figure BDA0005175385540000031
Abstract
Description
Technical Field
[0001] This invention belongs to the field of organic compound synthesis technology, specifically relating to a lignin-based aryl carbamate and diaryl ether compounds and their synthesis method. Background Technology
[0002] Aryl carbamates and diaryl ethers are a class of very important organic compounds with significant applications in polymers, life sciences, pesticides, pharmaceuticals, and hygiene (Tetrahedron Lett. 2007, 48, 8883). Currently, the synthesis of aryl carbamates involves the reaction of benzoic acid with phenolic compounds under acidic conditions (Shandong Chemical Industry, 2011, 40(10), 16-17); the classic synthesis method for diaryl ethers is the Ullmann coupling method, which uses a copper-based catalyst to catalyze the reaction of halobenzenes with phenol to prepare diphenyl ethers (Chemical Industry Friend, 2007, 03, 44-45).
[0003] Although several successful syntheses of these compounds have been reported, these methods suffer from drawbacks such as the need for non-renewable substrates and expensive metal catalysts, resulting in low atom economy. For compounds of this type, synthetic efficiency is paramount; furthermore, simplicity, safety, economy, and environmental friendliness must be considered to achieve the goals of "green organic synthesis."
[0004] With increasing attention paid to environmental and energy issues, there is an urgent need to develop a simple, efficient, environmentally friendly, and atom-economical method for synthesizing aryl carbamates and diaryl ethers. Summary of the Invention
[0005] In order to solve the problems existing in the prior art, the present invention aims to provide a lignin-based aryl carbamate and diaryl ether compounds and their synthesis method, which has the advantages of simple operation, mild reaction conditions and high product selectivity.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0007] A method for synthesizing lignin-based aryl carbamates and diaryl ether compounds involves adding lignin β-O-4 model compound 1 to a solvent, heating the resulting mixture under oxidant and alkaline conditions, then adding diaryliodonium 2 and stirring the mixture in air to obtain aryl carbamate 3 and diaryl ether compound 4.
[0008] The reaction formula is:
[0009]
[0010] In the formula: R 1 R 2R 4 Each group is independently selected from C1-C10 alkyl, C1-C10 alkoxy, aromatic, ester, nitrile, halogen, benzyl, ester, nitro, C6-C18 aryl, amino, hydroxyl, or hydrogen; preferably R 1 With R 2 Each is independently selected from methoxy, hydrogen, or hydroxyl; R 4 It is hydrogen.
[0011] R 3 It is hydrogen or hydroxymethyl, preferably R 3 The anion X in the diaryliodonium 2 is hydrogen; - Cl - ,Br - I - , trifluoromethanesulfonate (OTf) - ), tetrafluoroborate (BF4) - ) and hexafluorophosphate (PF6) - At least one of the following, preferably the anion X in diaryliodonium 2 is OTf - or Br - .
[0012] Optionally, lignin β-O-4 model compound 1 is one of the following compounds:
[0013]
[0014] Optionally, diaryliodonium 2 is one of the following compounds:
[0015]
[0016] Optionally, the lignin-based aryl carbamate and diaryl ether compounds are one of the following compounds:
[0017]
[0018] Optionally, the oxidant includes at least one of H2O2, 2,2,6,6-tetramethylpiperidine oxide (TEMPO), O2, and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ).
[0019] Optionally, when the oxidant includes at least one of H2O2, 2,2,6,6-tetramethylpiperidine oxide (TEMPO) and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), the ratio of the amount of oxidant to the lignin β-O-4 model compound is 1:(0.1 to 1).
[0020] Optionally, when the oxidant is O2, the amount of oxidant used is 1 to 20 bar.
[0021] Optionally, the solvent includes one or more of n-butanol, water, methanol, ethanol, tetrahydrofuran, 1,4-dioxane, n-hexane, dimethyl carbonate, dimethyl sulfoxide, dimethylformamide, benzene, toluene, and chlorobenzene.
[0022] Optionally, the reaction conditions are as follows: the heating reaction and the stirring reaction are both at a temperature of 20-200℃ and a reaction time of 0.5-24h.
[0023] Optionally, the alkali is one or more of NaOH, KOH, CsCO3, t-BuOK, and CH3CHONa.
[0024] Optionally, the molar ratio of the lignin β-O-4 model compound 1 to the alkali is 1:(0.1-10); the molar ratio of the lignin β-O-4 model compound 1 to diaryliodonium 2 is 1:(0.5-10), preferably the molar ratio of the lignin β-O-4 model compound 1 to the alkali is 1:(1-5); preferably the molar ratio of the lignin β-O-4 model compound 1 to diaryliodonium 2 is 1:(1-3).
[0025] Optionally, the concentration of the lignin β-O-4 model compound 1 in the mixture is 0.01 to 0.5 mol / L, and preferably the concentration of the lignin β-O-4 model compound 1 in the mixture is 0.1 to 0.2 mol / L.
[0026] This invention also discloses a lignin-based aryl carbamate and a diaryl ether compound, wherein the aryl carbamate 3 and the diaryl ether compound 4 are prepared by the above-described synthetic method, and their structural formulas are shown below:
[0027]
[0028] Among them, R 1 R 2 R 4 Each group is independently selected from C1 to C10 alkyl, C1 to C10 alkoxy, aromatic, ester, nitrile, halogen, benzyl, ester, nitro, C6 to C18 aryl, amino, hydroxyl or hydrogen.
[0029] The advantages of this invention over the prior art are as follows:
[0030] 1. The preparation method of the present invention has mild reaction conditions, short reaction time, and simple operation.
[0031] 2. The aryl carbamates and diaryl ethers prepared by this invention exhibit high selectivity, few byproducts, and high atom economy.
[0032] 3. This invention utilizes green biomass as raw material to provide a sustainable and green method for synthesizing aryl carbamates and diaryl ether compounds, offering a new approach for the full utilization of biomass. Detailed Implementation
[0033] The present invention will be described in detail below with reference to the embodiments. However, the implementation of the present invention is not limited thereto. Obviously, the embodiments described below are only some embodiments of the present invention. For those skilled in the art, other similar embodiments can be obtained without creative effort and all fall within the protection scope of the present invention.
[0034] Example 1:
[0035] 2-(2-methoxyphenoxy)-1-benzyl alcohol (1a, 0.2 mmol), synthesized in the literature (Green. Chem. 2020, 22, 248-255), and t-BuOK (0.8 mmol) were added to 2 mL of toluene. The mixture was heated to 120 °C under oxygen (1 bar) and stirred for 4 h. After the reaction was complete, Ph2IOTf2 (diaryliodonium trifluoromethanesulfonic acid) (2a, 0.8 mmol) was added, and the mixture was stirred at 120 °C for 4 h. After cooling to room temperature, aryl carbamate 3a and diaryl ether compound 4a were obtained, with 3a yielding 84% and 4a yielding 95%. The reaction equation is as follows:
[0036]
[0037] Examples 2-7:
[0038] Except for the different reaction temperature, the other process conditions and experimental steps of Examples 2-7 are the same as those of Example 1, and the results are shown in Table 1.
[0039] Table 1. Effect of different reaction temperatures on the reaction of aryl carbamate 3a and diaryl ether 4a
[0040]
[0041] As shown in Table 1, the yields of aryl carbamate 3a and diaryl ether 4a both increased significantly with increasing reaction temperature. At a reaction temperature of 130℃, the yields of both aryl carbamate 3a and diaryl ether 4a were above 80%.
[0042] Examples 8-17:
[0043] Except for the use of different solvents, the other process conditions and experimental steps of Examples 8-17 are the same as those of Example 1, and the results are shown in Table 2.
[0044] Table 2. Effects of different solvents on the synthesis of aryl carbamate 3a and diaryl ether 4a
[0045]
[0046] Examples 18-23:
[0047] Except for the reaction time, the other process conditions and experimental steps of Examples 18-23 are the same as those of Example 1, and the results are shown in Table 3.
[0048] Table 3. Effect of different reaction times on the synthesis of aryl carbamate 3a and diaryl ether 4a
[0049]
[0050] As shown in Table 3, the yields of aryl carbamate 3 and diaryl ether 4a both increased significantly with the extension of reaction time.
[0051] Examples 24-27:
[0052] Except for the different use of alkali, the other process conditions and experimental steps in Examples 24-27 are the same as in Example 1, and the results are shown in Table 4.
[0053] Table 4. Results of synthesis of p-arylcarbamate 3a and diaryl ether 4a under different alkaline conditions
[0054]
[0055] Examples 28-32:
[0056] Except for the different molar ratio of lignin β-O-4 model compound 1 to alkali, the other process conditions and experimental steps of Examples 28-32 are the same as those of Example 1, and the results are shown in Table 5.
[0057] Table 5. Effect of different substrate feed ratios on the synthesis of aryl carbamate 3a and diaryl ether 4a
[0058]
[0059] Examples 33-37:
[0060] Except for the different molar ratio of lignin β-O-4 model compound 1 and diaryliodonium 2, the other process conditions and experimental steps of Examples 33-37 are the same as those of Example 1, and the results are shown in Table 6.
[0061] Table 6. Effect of different substrate feed ratios on the synthesis of aryl carbamate 3a and diaryl ether 4a
[0062]
[0063]
[0064] Examples 38-55:
[0065] Except for the use of different types of lignin model compounds and diaryliodonium raw materials, the other process conditions and experimental procedures in Examples 38-55 were the same as in Example 1, and the results are shown in Table 5. To more clearly illustrate the synthesized arylformate 3a and diaryl ether 4a compounds, the results are shown in Table 7.
[0066] Table 7. Effects of different lignin model compounds and different diaryliodonium compounds on the synthesis of aryl carbamate 3a and diaryl ether 4a
[0067]
[0068]
[0069]
[0070] Examples 56-59:
[0071] Except for using different lignin concentrations, the other process conditions and experimental steps in Examples 56-59 are the same as in Example 1, and the results are shown in Table 8.
[0072] Table 8. Effects of different lignin concentrations on the synthesis of aryl carbamate 3a and diaryl ether 4a
[0073]
[0074]
[0075] Examples 60-62:
[0076] Except for the use of different oxidants, the other process conditions and experimental steps of Examples 60-62 are the same as those of Example 1, and the results are shown in Table 9.
[0077] Table 9. Effects of different oxidants on the synthesis of aryl carbamate 3a and diaryl ether 4a
[0078]
[0079] Examples 63-66:
[0080] Except for the use of different amounts of oxidant, the other process conditions and experimental steps of Examples 63-66 are the same as those of Example 60, and the results are shown in Table 10.
[0081] Table 10. Effect of different oxidant dosages on the synthesis of aryl carbamate 3a and diaryl ether 4a
[0082]
[0083] Examples 67-69
[0084] Except for using different amounts of O2, the other process conditions and experimental steps of Examples 67-69 are the same as those of Example 1, and the results are shown in Table 11.
[0085] Table 11. Effect of different oxygen amounts on the synthesis of aryl carbamate 3a and diaryl ether 4a
[0086]
[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for synthesizing lignin-based aryl carbamates and diaryl ether compounds, characterized in that, The lignin β-O-4 model compound 1 was added to a solvent, and the resulting mixture was heated and reacted under oxidant and alkaline conditions. Then, diaryliodonium 2 was added and the mixture was stirred and reacted under an air atmosphere to obtain aryl carbamate 3 and diaryl ether compound 4. The reaction formula is: In the formula: R 1 R 2 R 4 Each group is independently selected from C1-C10 alkyl, C1-C10 alkoxy, aromatic, ester, nitrile, halogen, benzyl, ester, nitro, C6-C18 aryl, amino, hydroxyl, or hydrogen; R 3 It is hydrogen or hydroxymethyl; the anion X in the diaryliodonium 2 is F - Cl - ,Br - I - , trifluoromethanesulfonate (OTf) - ), tetrafluoroborate (BF4) - ) and hexafluorophosphate (PF6) - At least one of the following.
2. The synthesis method according to claim 1, characterized in that, The oxidant includes at least one of H2O2, 2,2,6,6-tetramethylpiperidine oxide (TEMPO), O2, and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ).
3. The synthesis method according to claim 2, characterized in that, When the oxidant includes at least one of H2O2, 2,2,6,6-tetramethylpiperidine oxide (TEMPO) and 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ), the ratio of the amount of oxidant to the lignin β-O-4 model compound is 1:(0.1 to 1). When the oxidant is O2, the amount of oxidant used is 1 to 20 bar.
4. The synthesis method according to claim 1, characterized in that, The solvent includes one or more of the following: n-butanol, water, methanol, ethanol, tetrahydrofuran, 1,4-dioxane, n-hexane, dimethyl carbonate, dimethyl sulfoxide, dimethylformamide, benzene, toluene, and chlorobenzene.
5. The synthesis method according to claim 1, characterized in that, The conditions for both the heating reaction and the stirring reaction are: temperature of 20-200℃ and reaction time of 0.5-24h.
6. The synthesis method according to claim 1, characterized in that, The alkali is one or more of NaOH, KOH, CsCO3, t-BuOK, and CH3CHONa.
7. The synthesis method according to claim 1, characterized in that, The molar ratio of the lignin β-O-4 model compound 1 to the base is 1:(0.1-10); the molar ratio of the lignin β-O-4 model compound 1 to diaryliodonium 2 is 1:(0.5-10).
8. The synthesis method according to claim 1, characterized in that, The concentration of the lignin β-O-4 model compound 1 in the mixture is 0.01–0.5 mol / L.
9. A lignin-based aryl carboxylate and diaryl ether compound, characterized in that, The aryl carbamate 3 and the diaryl ether compound 4 are prepared by the synthetic method according to any one of claims 1-8, and their structural formulas are shown below: Among them, R 1 R 2 R 4 Each group is independently selected from C1 to C10 alkyl groups, C1 to C10 alkoxy groups, aromatic groups, ester groups, nitrile groups, halogen groups, benzyl groups, ester groups, nitro groups, C6 to C18 aryl groups, amino groups, hydroxyl groups, or hydrogen groups.