Substances derived from wood. Woody plants comprise the greatest part of the organic materials produced by photosynthesis on a renewable basis, and were the precursors of the fossil coal deposits. The derivation of chemicals from wood is carried out wherever technical utility and economic conditions have combined to make it feasible.
Wood is a mixture of three natural polymers—cellulose, hemicelluloses, and lignin—in an approximate abundance of 50:25:25. In addition to these polymeric cell wall components which make up the major portion of the wood, different species contain varying amounts and kinds of extraneous materials called extractives. The nature of the chemicals derived from wood depends on the wood component involved. See also Cellulose; Hemicellulose.
Chemicals derived from wood include: bark products, cellulose, cellulose esters, cellulose ethers, charcoal, dimethyl sulfoxide, ethyl alcohol, fatty acids, furfural, hemicellulose extracts, kraft lignin, lignin sulfonates, pine oil, rayons, rosin, sugars, tall oil, turpentine, and vanillin. Most of these are either direct products or by-products of wood pulping, in which the lignin that cements the wood fibers together and stiffens them is dissolved away from the cellulose. High-purity chemical cellulose or dissolving pulp is the starting material for such polymeric cellulose derivatives as viscose rayon and cellophane, cellulose esters such as the acetate and butyrate for fiber, film, and molding applications, and cellulose ethers such as carboxymethylcellulose, ethylcellulose, and hydroxyethylcellulose for use as gums. See also Cellophane; Dimethyl sulfoxide; Ethyl alcohol; Rosin; Vanilla; Wax, animal and vegetable; Wood products.
