Spruce lignin, milled wood

Comparisons made between unpurified spruce milled-wood lignin fractions and unfractionated poljrmers made from coniferjd alcohol alone already revealed the great qualitative similarity between natural and biosynthetically duplicated lignins [see, for example, K. Freudenberg in 94), pp, 125—126]. When a purified lignin fraction is compared tvith an identical fraction made from a mixture of all three -coumaryl alcohols, the resemblance is of course much greater. 

Okay, A. Hydrogenation Products of Spruce Milled-Wood Lignin and of Related Model Compounds. Holzforschung J7, 105—110 (1963) J. Org. Chem. 27, 1783-1786 (1962). 

Softwood kraft lignin, 2) NaBH -reduced softwood kraft ligniny (3) Bjorkman spruce milled wood lignin... 

The ionization — Ae curve for untreated Bjorkman spruce milled wood lignin has a maximum at 357 m/z (Figure 5) which is attributed to phenolic a-carbonyl structures (31). Kraft-cooked Bjorkman lignin, however, has... 

Kraft-cooked Bjorkman spruce milled wood lignin, (2) Bjorkman spruce milled wood lignin. Solvents methylcellosolve-ethanol, 1 4 and IN NaOH in methylcello-solve-ethanol-water, 2 3 5. Curves recorded within 2 minutes after mixing the solutions. 

Colorimetric analysis based on the above indophenol sequence indicates the presence of 0.12-0.14 and 0.07-0.10 p-hydroxybenzyl alcohol units/C6-C3 in spruce Brauns native lignin and spruce milled wood lignin, respectively (Gierer 1954, 1956). 

To eliminate interfering side reactions caused by units having carbonyl and hydroxyl groups at the a-position, the lignin is reduced with borohydride and alkylated with methanolic hydrochloric acid prior to oxidation to convert these groups to o-quinones. Following a procedure based on the above reaction, spruce milled-wood lignin was found to contain 15-18% of uncondensed phenolic units (Adler and Lundquist 1961). 

Table 5.1.5. Estimation of various conjugated carbonyl groups in spruce milled wood lignin (MWL) (Adler and Marton 1959) and kraft lignin (KL) (Marton 1964) by NaBH4 reduction difference spectroscopy...

Table 5.4.5. Number of carbon atoms in chemical shift ranges in the C NMR spectrum of spruce milled wood lignin (MWL) (Fig 5 4 8a)...

Unit weight of spruce milled wood lignin = 185 (Marton 1971)... 

Spruce milled wood lignin (MWL) 21.9 Harden etal. 1980... 

Extractive-free wood flour of Acer saccharum Marsh, (sugar maple), a-cellulose, birch acetyl-4-O-methylglucuronoxylan, and spruce-milled wood lignin were treated with 40% HNO3 and the resulting products were investigated by IR and UV spectroscopy in... 

Adler and Marton [39] nsed a combination of ionization difference spectra and NaBH4 reduction to estimate the amounts of the four conjugated carbonyl groups shown in Table 3.5 in spruce milled-wood lignin. Note that, although the difference... 

Carbonyl Groups in Spruce Milled-Wood Lignin, Estimated by Borobydride Reduction... 

These same authors also used difference spectroscopy to estimate the number of phenylcoumaran units in spruce milled-wood lignin at 9 per 100 Cg units [42]. 

Imsgard et al. [62] determined that spruce milled-wood lignin contained 0.7%... 

Imsgard et al. [62] noted that spruce milled-wood lignin contained, in addition to 0.7 quinone groups, 1% catechol groups. Lignin-like catechols form complexes with ferric ions that have a broad absorption from 470-700 nm with around 560-800 nm and s in the range of 1-2 x 10 L mol cm. ... 

Lundquist et al. [162,165,166] reported that the peak shapes and positions in emission spectra of spruce milled-wood lignin in dioxane/water were independent of excitation wavelength. The emission maximnm occurred at 358 nm. The excitation spec-trnm was consistent with the absorption spectrum of milled-wood lignin, indicating... 

FIGURE 4.3 Near-infrared (NIR) spectrum, obtained in authors laboratory, of black spruce milled wood lignin (MWL). Most peaks in the spectrum are annotated. The spectrum is similar to that of aspen (see Figure 4.4). 

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