Sep 12, 2023
Synthetic Procedure of 3,3'-dimethoxy-5,5'-dipropyl-2,2'-biphenyldiol
- Lisa.Stanley1,
- rui.katahira1,
- Gregg T. Beckham1
- 1National Renewable Energy Laboratory, Renewable Resources and Enabling Sciences Center
Protocol Citation: Lisa.Stanley, rui.katahira, Gregg T. Beckham 2023. Synthetic Procedure of 3,3'-dimethoxy-5,5'-dipropyl-2,2'-biphenyldiol. protocols.io https://dx.doi.org/10.17504/protocols.io.yxmvm2mr6g3p/v1
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
We use this protocol and it's working
Created: March 07, 2023
Last Modified: September 12, 2023
Protocol Integer ID: 78284
Keywords: lignin model compounds, dimers, nuclear magnetic resonance, lignin, synthesis, 5-5 linkage
Funders Acknowledgement:
U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Bioenergy Technologies Office
Grant ID: DE-AC36-08GO28308
Disclaimer
This work was authored by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Funding provided by U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Bioenergy Technologies Office. The views expressed herein do not necessarily represent the views of the DOE or the U.S. Government.
Abstract
A direct understanding of the degradation reaction pathways of lignin polymers in biomass is difficult due to the complexity of lignin’s structure. To overcome the difficulty, simple lignin dimeric and trimeric model compounds which include typical lignin interunit linkages are useful to clarify reaction mechanisms. The following protocol describes the synthetic procedure of a 5-5' dimeric lignin model compound: 3,3'-Dimethoxy-5,5'-dipropyl-2,2'-biphenyldiol. Lignin model compounds are useful for screening the effectiveness of catalysts and microoganisms. As well as determining the effect of a treatment on the lignin fraction, in particular the effect on the degree of depolymerization in the lignin polymer.
Materials
2-methoxy-4-propylphenolMerck MilliporeSigma (Sigma-Aldrich)Catalog #W359807 Step 1.1
AcetoneVWR InternationalCatalog #BDH2002 Step 1.1
Sodium AcetateMerck MilliporeSigma (Sigma-Aldrich)Catalog #241245 Step 1.1 [see Note 1]
Acetic AcidMerck MilliporeSigma (Sigma-Aldrich)Catalog #695092 Step 1.1 [see Note 1]
LaccaseMerck MilliporeSigma (Sigma-Aldrich)Catalog #38429 Step 1.1
Oxygen compressed gasCatalog #G2182101 Step 1.1
Silica gelSupelcoCatalog #60737 Step 2.1
Hexane mixture of isomersMerck MilliporeSigma (Sigma-Aldrich)Catalog #178918 Step 2.1
Ethyl acetateFisher ScientificCatalog #E145 Step 2.1
Chloroform-DCambridge Isotope Laboratories, Inc.Catalog #DLM-7-100 Step 3.1
Safety warnings
Almost all chemicals used for this procedure are hazardous. Read the Safety Data Sheet (SDS) for all chemicals and follow all applicable chemical handling and waste disposal procedures.
Before start
All glassware is dried in an oven set to 105ºC then cooled in a desiccator prior to use.
Synthetic Procedure
Synthetic Procedure
Figure 1. Reaction scheme for the synthesis of 3,3'-dimethoxy-5,5'-dipropyl-2,2'-biphenyldiol (5-5' dimer).
4-propylguaiacol (5.00 g , 0.03 mol) was dissolved in acetone (75 mL ) then diluted with 500 mL of acetic acid buffer (pH 5) [see Note 1]. Oxygen gas (O2) was bubbled through the buffer solution for 30 minutes. 75 mg of laccase (>0.5 U/mg) was then added to the solution. The reaction was stirred at room temperature for four hours while the product precipitated.1 The precipitated material was then collected via vacuum filtration using a Büchner funnel. The crude product was purified via flash chromatography to yield 3,3'-dimethoxy-5,5'-dipropyl-2,2'-biphenyldiol (1.5452g, 31.3%).
Note
Note 1. Preparation of acetic acid buffer: 5.52 g of sodium acetate and 1.961 g of acetic acid are added to 1 L of deionized (D.I.) water. Stir until materials are completely dissolved. Check pH is close to 5.
[1]
CITATION
Purification
Purification
Flash chromatography was performed using a Teledyne Isco Combiflash® NextGen 300+. Collected fractions were determined using a UV detector with wavelengths set at 254 and 280 nm. Samples were prepared by dissolving the crude material in the smallest amount of compatible solvent. Silica gel (mesh size 70-230) was then added to adsorb the material. Excess solvent was vacuum evaporated and the sample was loaded into a RediSep® Rf 25 g sample cartridge (catalog # 69-3873-240).
3,3'-Dimethoxy-5,5'-dipropyl-2,2'-biphenyldiol was purified via flash chromatography. Column used was a RediSep® Silver 80 g silica gel flash column (catalog # 69-2203-380). Solvent system was hexane (Solvent A) and ethyl acetate (Solvent B). 3,3'-Dimethoxy-5,5'-dipropyl-2,2'-biphenyldiol was separated from impurities using a ratio of 1:4 ethyl acetate:hexane for ten minutes then a ratio of 1:2 ethyl acetate: hexane.
Figure 2. Run program from Combiflash® NextGen 300+ of 3,3'-dimethoxy-5,5'-dipropyl-2,2'-biphenyldiol separation.
NMR Spectroscopy
NMR Spectroscopy
Nuclear magnetic resonance (NMR) spectra are acquired in a suitable deuterated NMR solvent at 25°C on a Bruker AVANCE 400 MHz spectrometer equipped with a 5 mm BBO probe. Chemical shifts (δ) are reported in ppm. 1H-NMR spectra are recorded with a relaxation delay of 1.0 s and an acquisition time of 4.09 s. The acquisition parameters for 13C-NMR include a 90˚ pulse width, a relaxation delay of 1.0 s, and an acquisition time of 1.36 s. Tetramethylsilane is used as a reference.
Figure 3. 1H NMR spectrum of 3,3'-dimethoxy-5,5'-dipropyl-2,2'-biphenyldiol.
1H NMR (400 MHz, CDCl3) δ 6.74 (d, J=8.7 Hz, 4H, 2&6), 6.06 (s, 2H, OH), 3.91 (s, 6H, OMe), 2.58 (t, J=7.5 Hz, 4H, α), 1.67 (q, J=7.5 Hz, 4H, β), 0.974 (t, J=7.3 Hz, 6H, γ).
Figure 4. 13C NMR spectrum of 3,3'-dimethoxy-5,5'-dipropyl-2,2'-biphenyldiol.
13C NMR (100 MHz, CDCl3) δ 147.12 (3), 140.47 (4), 134.68 (1), 124.46 (5), 122.95 (6), 110.61 (2), 56.04 (OMe), 37.87 (α), 24.78 (β), 13.90 (γ).
Citations
Step 1.1
Maarit Lahtinen, Kristiina Kruus, Petri Heinonen, and Jussi Sipilä. On the Reactions of Two Fungal Laccases Differing in Their Redox Potential with Lignin Model Compounds: Products and Their Rate of Formation
https://doi.org/10.1021/jf901511k