Volatile products from browning

FIGURE 8.1 Variation of coal strength with volatile matter production. (Adapted from Brown and Hioms, 1963, p. 131.)... 

Amadori compounds (N-substituted-l-amino-l-deoxy-2-ketoses) are potential precursors to the formation of many of these heterocyclic volatile products. The secondary nitrogen in most Amadori compounds is weakly basic and is therefore a likely site for rapid nitrosation reactions via normal reactions with nitrous acid, under mildly acidic conditions. However, purified Amadori compounds are usually obtained only after tedious isolation procedures are invoked to separate them from the complex mixtures of typical Maillard browning systems. Takeoka et al. ( 5) reported high performance liquid chromatographic (HPLC) procedures to separate Amadori compounds in highly purified form on a wide variety of columns, both of hydrophilic and hydrophobic nature. They were able to thus demonstrate that reaction products could be followed for kinetic measurements as well as to ensure purity of isolated products. 

Tar the volatile, brown to black, oily, viscous product from the destructive distillation (q.v.) of many bituminous or other organic materials, especially coal a name used for petroleum in ancient texts. 

Mulders (1973c) identified 1-furfurylpyrrole in a cysteine/cystine ribose browning system, Shibamoto et al. (1979) in a D-glucose/ammonia model system, Ho and Chen (1999) in a Maillard reaction of threonine with ribose as a main volatile product, Baltes and Bochmann (1987b) when heating serine and/ or threonine with sucrose (and in coffee). According to Tressl et al. (1981c), this compound was also formed from 4-hydroxyproline and 2-furaldehyde. 

Saita and Maenosono have reported the synthesis of FePt NPs using iron(ni) ethoxide [Fe(OEt)3] and platinum(II) acetylacetonate [Pt(acac)2] as precursors without any reducing agent. Fe(OEt)3 is a brown powder at room temperature (nonvolatile) and is a highly reactive late transition metal alkoxide [248]. In addition, decomposition products of Fe(OEt)3 are less toxic. For these reasons, the use of Fe(OEt)3 as a precursor is suitable for industrialization. An amount of 1 mmol of Fe(OEt)3, 0.5 mmol of Pt(acac)2, 17 mL of octyl ether, 1.6 mL of oleic acid, and 1.7 mL of oleylamine were placed in a three-necked flask at ambient air. The color of the resulting mixture was brown. The molar ratio of Fe to Pt in the mother reaction solution was adjusted to 2. The flask was then evacuated to remove oxygen and volatile components from the reaction solution. After evacuation, the flask was... 

Metallurgical (smelter) plants and spent acid decomposition plants usually produce acid of good (low) color because the SO2 feed gases ate extensively purified prior to use. In some cases, however, and particularly at lead smelters, sufficient amounts of organic flotation agents are volatilized from sulfide ores to form brown or black acid. Such acid can be used in many applications, particularly for fertilizer production, without significant problems arising. 

The first part of this paper has shown that Australian black and brown coals differ significantly in a number of respects from coals of similar ranks from North America and elsewhere in the northern hemisphere. The rest of the paper than proceeded to indicate the progress being made to determine how the characteristics of Australian coals influence their conversion to volatile and liquid products during pyrolysis and hydrogenation. 

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