Lignins and lignin models

R = H, CH3CO, dimer fragment, or lignin Figure 1. The reaction of PEG-mesylate with lignin and lignin model compounds. 

Crestini, C., Saladino, R., Tagliatesta, P., and Boschi, T., Biomimetic degradation of lignin and lignin model compounds by synthetic anionic and cationic water soluble manganese and iron porphyrins. Bioorganic Medicinal Chem 1999, 7 (9), 1897-1905. 

Bozell, J. J., Hoberg, J. O., and Dimmel, D. R., Heteropolyacid catalyzed oxidation of lignin and lignin models to benzoquinones. J Wood Chem Technol 2000, 20 (1), 19-41. 

Table 5.1.2. Solvents for use in the ultraviolet spectroscopic measurement of lignin and lignin model compounds ...

Dissolve the lignin and lignin model compounds in a good solvent at room temperature do not heat the solution to dissolve the sample. 

Electron spin resonance (ESR) or electron paramagnetic resonance (EPR) spectroscopy has developed at an outstanding pace since its discovery in 1945 (Zavoiskii 1945), so that at present the technique is very well understood in its many aspects. In wood chemistry, ESR has become an essential tool for the study of the structure and dynamics of molecular systems containing one or more unpaired electrons, i.e., free radicals. ESR has found applications as a highly sensitive tool for the detection and identification of free radical species in lignin and lignin model compounds (Steelink 1966, Kringstad and Lin 1970). A recent literature review of free radicals in wood chemistry is available (Simkovic 1986). 

Leopold B (1952c) Lignin XI The alkaline nitrobenzene oxidation of lignin and lignin models Sven Kem Tidskr 64 18-26... 

In the analysis of isolated lignins and lignin model compounds, the experimental procedure starts directly with the alkylation step. 

Kratzl K, Claus P, Reichel G (1976) Reactions of lignin and lignin model compounds with ozone TAPPI 59(11) 86-87... 

The principles and methodology relevant to the UV spectrophotometric determination of lignin and lignin model compounds have been discussed by Goldschmid 1954, Browning 1967b, and by Lin in Chapter 5.1. 

Acidic condition. Acidic hydroxymethylation occurs mainly at the C2 or C6 position of aromatic nuclei which may be phenolic or etherified units. It is used in the preparation of wood adhesives. The influence of lignin structure on reactivity and performance of the resulting resin product is still not entirely understood, as discussed by Nimz [3951. Van der Klashorst [396-398] reported the acidic condensation of alkali lignin and lignin model compounds with formaldehyde. Initial hydroxymethylation was faster with syringyl units... 

Pareek S., Azuma J. I., Matsui S., and Shimizu Y. (2(X)1) Degradation of lignin and lignin model compound under sulfate-reducing condition. Water Sci. Technol. 44, 351-358. 

This section deals primarily with the spectra of excited states and short-lived intermediates of lignin and lignin model compounds. More detailed discussion of reaction mechanisms is contained in Chapter 16, Photochemistry of Lignin and Lignans. 

SY Lin. Derivative Ultraviolet Spectroscopy of Lignin and Lignin Model Compounds A New Analytical Technique. Svensk. Papperstidn. 85 R162-R171, 1982. 

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