Ethylation, lignins

It has been shown that aromatic aldehydes including vanillin, syfingaldehyde, coniferaldehyde, siaapaldehyde, and ethyl lignin come from charred wood, the length of matufing directly affects the amount of aldehydes formed, the lower proof spirits have more aldehydes than higher proof spirits do, and the used and new uncharred barrels produce about one-third of the aromatic aldehydes found ia new charred barrels (Table 3) (8). 

It should be noted that results on blends prepared with the ethylated lignins are consistent with this view, as will become evident in later discussion. 

Figure 4. Variation in the polymer-polymer interaction parameter, B with hydroxy content of ethyl lignin (X), lignin acetate (O), unmodified lignin ( ), and hydroxypropyl lignin (—).

Vanilla flavoring in bakery goods, confectionery, and many fro2en desserts need not be natural vanilla. The artificial and synthetic vanilla flavors that are used include vanillin [121-33-5] from lignin (wood pulp), ethyl vanillin [121 -32-4] and vanitrope [94-86-0], the latter two are synthetics. Over 90% of the U.S. market for vanilla flavor contains vanillin. These synthetics continue to dominate the market because of availabiUty, quahty, and relatively low and stable prices. 

A polymeric composition for reducing fluid loss in drilling muds and well cement compositions is obtained by the free radical-initiated polymerization of a water-soluble vinyl monomer in an aqueous suspension of lignin, modified lignins, lignite, brown coal, and modified brown coal [705,1847]. The vinyl monomers can be methacrylic acid, methacrylamide, hydroxyethyl acrylate, hydroxypropyl acrylate, vinylacetate, methyl vinyl ether, ethyl vinyl ether, N-methylmethacrylamide, N,N-dimethylmethacrylamide, vinyl sulfonate, and additional AMPS. In this process a grafting process to the coals by chain transfer may occur. 

However, in 1939 this difficulty was obviated by Brauns extraction of about 3% lignin from spruce wood by means of the solvent, ethyl alcohol, at room temperature (9). He termed this preparation native lignin. It was found to be soluble in methanol, ethanol, dioxane, dilute sodium hydroxide and pyridine, and insoluble in water, ether, petroleum ether and benzene. Chemically it behaved the same as lignin as it exists in woody tissues. It also reduced Fehling s solution and gave a strong... 

Finally, in order to establish unequivocally the identity of the native and residual lignin of white Scots pine wood, the sound wood was first extracted with ethyl alcohol to remove the native lignin fraction. The extracted wood was then decayed by means of the brown rot fungi,... 

Bagasse Native Lignin in 95% Ethyl Alcohol Bagasse Native Lignin in 0 02 N Alkali — Acetate of Bagasse Native Lignin in 95% Ethyl Alcohol. 

More recently, Brauns and Seiler (12), (13) extracted native lignin from spruce wood and then homogenized the wood in a colloidal mill. A suspension of approximately one gram of colloidal wood per liter of water was obtained. After the colloidal wood was changed to a solid form, it was found that its cell structure was completely destroyed. However, extraction of this wood with ethyl alcohol at room temperature did not yield further quantities of native lignin. These investigators have also reported the isolation of a lignosulfonic acid-carbohydrate compound. 

That some of the lignin, undoubtedly, is present in a free state in wood, is concluded from the fact that up to 10% of the total native lignin in the wood can be extracted with ethyl alcohol at room temperature. Further support for the incrustation theory is given by Nord in that an additional 23% of the native lignin in white Scots pine wood... 

Figure 7. Preparation of synthetic lignin 16, ethylated copolymer of coniferyl alcohol 7 and arylglycerol-/ -syringaresinol ether 6. In 16, the rectangular enclosure represents an assumed structure of the moiety derived from 7.

Figure 8. Gel filtration of ethylated (/ -0-4)-(/ -/ )-DHP 16. Solid line Ethylated (/ -0-4)-(/ -/ )-DHP 16 after removal of low molecular weight fractions. The column was calibrated with (/ -0-4)-(/ -/ ) lignin substructure model trimer 6 (molecular weight 642) /3-0-4 lignin model dimer 1 (molecular weight 348) and polystyrenes of molecular weight 9000, 4000 (void), 2200 (indicated by A). Column Sephadex LH-20, 1.1 x 48 cm. Eluent DMF, 13.5-14.4 ml/hr. Detector Refractive index detector RI-2 (Japan Analytical Industry Co., Ltd.).

From this work it is evident, then, that the hydrolysis of glycol lignin with sodium hydroxide does yield a rather significant amount of catechol and its methyl and ethyl derivatives. A maximum quantity of these, which amounted to 9% of the original lignin, was obtained at the conditions cited above. 

The hydroxyl content of the lignin was incrementally eliminated by acetylation and ethylation according to previously described procedures (11). In addition, modification with propylene oxide was also used to alter the original lignin structure (12). Table I presents a summary of the hydroxy content, and pertinent physical properties, of the derivatized lignins. 

Table II. Summary of melting point depression analysis for blends of HPC and lignin modified by acetylation (Ac), ethylation (Et) and propoxylation (Pr)...

We have also made an attempt to prepare lignin-epoxy resin adhesives (21). However, in order to improve its reactivity, kraft lignin was first phenolated with bisphenol-A. For phenolation, a small amount of aqueous hydrochloric acid or BF3-ethyl etherate was used as catalyst, and thus two kinds of glycidylation methods were adopted (21). The phenolation with bisphenol-A was found to enhance the solubility of the lignin derivative. In fact, the lignin-epoxy resins obtained were found to be completely soluble in certain organic solvents, including acetone. 

Wood is a cellular substance chemically composed of roughly 70% holo cellulose. 25% lignin, and 5% water and ethyl alcohol-benzene soluble extractives. These percentages are based on oven-dry wood. 

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