Hardwood Extractives Utilization

Hardwood extractives are produced in minor amounts all over the world. Some, such as cinnamon and licorice, are familiar items of our diets. Others, such as crude medicinal extracts, are produced and consumed locally. Tkble 10.5.1 lists these extractives alphabetically. Production data on these items do not exist. 

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Research in modern times has identified many thousands of compounds in extractives research. These extractives are produced in varying quantities depending on the demand and their natures. Many classes of wood extractives are covered in other sections of this book natural exudates in Chap. 1.1 tail-oil constituents as extractives from softwoods by kraft pulping liquor in Sect. 10.1 and pharmaceuticals such as cascara extract in Sect. 10.6. In this section I will discuss successful softwood and hardwood extractives utilization and prospects for their continued and expanded uses. 

The Utilization of Wood Extractives 10.5.3 Utilization of Hardwood Extractives... 

The above examples are a few of the many instances where the presenee of extractives and their influenee are to a large extent out of all proportion to the comparatively small amounts present. On the other hand in tropical hardwoods the amounts of tannins and related eompounds may be as much as 20% of oven-dry wood and here the potential for problems is more apparent. Overall the important role that extraetives may play in wood utilization must not be underestimated. 

Formation.— The greater part of acetic acid used in commerce is obtained b destructive distillation of wood. Hardwood, such as oak, birch, beech, maple, and elm give the best yields of acid and wood alcohol. A full description is given in H, Taylor s book on Fuel Production and Utilization of this series, from which the following extracts are taken —... 

Even if, in the first instance, it might seem that this material does not vary a lot, the different amounts and differing chemical composition of the polyoses (see Section 9.4.2.3) and the lignins (see Section 9.4.2.4) in hardwood and softwood strongly affect the manufacturing processes. This applies for the extractives too, which due to their large chemical diversity influence some of the properties of wood and behave respectively different with regard to the chemical utilization of the wood. 

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