Investigation of lignin models of the biphenyl type by X-ray crystallography and NMR spectroscopy |
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| Authors: | Gösta Brunow Pirkko Karhunen Knut Lundquist Solveig Olson Rolf Stomberg |
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| Institution: | (1) Department of Chemistry, University of Helsinki, FIN-000140, Finland;(2) Department of Organic Chemistry, Chalmers University of Technology and University of Göteborg, S-412 96 Göteborg, Sweden;(3) Department of Inorganic Chemistry, Chalmers University of Technology and University of Göteborg, S-412 96 Göteborg, Sweden |
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| Abstract: | Lignin models of the biphenyl type have been synthesized and crystal structures of two of them have been determined. The tetraacetate of 5,5 -bis(hydroxymethyl)-3,3-dimethoxy-2,2-biphenyldiol crystallizes in space group
witha=11.319(2),b=12.232(6),c=9.242(3) Å,  =101.66(3)°,  =108.14(2)°,  =79.08(2)° andZ=2.R=0.036 (2720 observed I>3 (I)] reflections). The acetate of 5,5-di-tert-butyl-2,3,3-trimethoxy-2-biphenylol crystallizes in space group
witha=11.972(2),b=21.621(3),c=9.834(1) Å, =91.18(1)°, =113.13(1)°. =98.42(1)°, andZ=4.R=0.050 (8129 observed I>3(I)] reflections).1H NMR and13C NMR data for the above-mentioned compounds and a third model, the diacetate of 5,5-bis(1-hydroxyethyl)-2,2,3,3-tetramethoxybiphenyl, are reported. Observed signal positions are compared with those calculated on the basis of crystal structure data. The possibilities to obtain structural information about biphenyl structures in lignins from NMR spectra are discussed. |
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| Keywords: | Lignin model biphenyl X-ray crystallography conformation nuclear magnetic resonance |
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