Other Biogenic Residues

Besides the lignoceUulosic residues described in Section 4.2.2.4 further biogenic residues accrue. 

The production of pulp and paper delivers by-products that can principally be recovered and utiHzed as renewable raw materials. The waste liquor of alkahne pulping, the so-caUed black Hquor contains inter alia acetates, degradation products, soluble alkali Hgnin as well as saponified rosin acids and fatty acids. Black liquor can be combusted to provide energy for the plant or alternatively yield crude tail oil (CTO) which contains between 15 and 55% fatty acids and 20-65% rosin aids [15]. World production of CTO can be estimated to be about 1.5 miUion tons [41]. 

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Figure 8.8 The bioliq plant at KIT In a multistage process, high-quality synthetic fuels are produced from straw and other biogenous residues. (Photograph KIT/Tom Zevaco.)...

The basic skeleton of isoprenoids may be modified by the introduction of a wide variety of chemical groups, by isomerization, shift of double bonds, methyl groups, etc. Hence a bewildering number of chemical structures arises. In addition compounds derived from other biogenic pathways may contain isoprene residues. For instance the K vitamins (D 8.1), ubiquinones (D 8.3), chlorophylls (D 10.1), plastoquinones, and tocopherylquinones (D 22.4) have isoprenoid side chains with up to ten isoprene units. Polyketides (D 3.3), alkaloids (D 8.4.2), and coumarins (D 22.2.2) may be substituted by dimethylallyl groups. The terpene residues are attached to nucleophilic sites, such as active methylene groups and phenolic oxygen atoms. 

The chemical weathering of crustal rock was discussed in Chapter 14 from the perspective of clay mineral formation. It was shown that acid attack of igneous silicates produces dissolved ions and a weathered solid residue, called a clay mineral. Examples of these weathering reactions were shown in Table 14.1 using CO2 + H2O as the acid (carbonic acid). Other minerals that undergo terrestrial weathering include the evaporites, biogenic carbonates, and sulfides. Their contributions to the major ion content of river water are shown in Table 21.1. 

Acyl residues are usually activated by transfer to coenzyme A (2). In coenzyme A (see p. 12), pantetheine is linked to 3 -phos-pho-ADP by a phosphoric acid anhydride bond. Pantetheine consists of three components connected by amide bonds—pantoic acid, alanine, and cysteamine. The latter two components are biogenic amines formed by the decarboxylation of aspartate and cysteine, respectively. The compound formed from pantoic acid and p-alanine (pantothenic acid) has vitamin-like characteristics for humans (see p. 368). Reactions between the thiol group of the cysteamine residue and carboxylic acids give rise to thioesters, such as acetyl CoA. This reaction is strongly endergonic, and it is therefore coupled to exergonic processes. Thioesters represent the activated form of carboxylic adds, because acyl residues of this type have a high chemical potential and are easily transferred to other molecules. This property is often exploited in metabolism. 

The problem with the silylation of different biogenic amines is that it is difficult to prepare uniform derivatives as these compounds usually contain amino groups of different reactivity, hydroxyl and other functional groups. Several procedures have been proposed for solving this problem. The determination of norepinephrine and dopamine in brain tissue was described by Maruyama and Takemori [90]. Dried residue from the extraction... 

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