Secondary product

The primary products of autoxidation, the mono-hydroperoxides, are odorless and tasteless (such as linoleic acid hydroperoxides cf. 3.7.2.4.1). Food quality is not affected until volatile compounds are formed. The latter are usually powerfully odorous compounds and, even in the very small amounts in which they occur, affect the odor and flavor of food. 

From the numerous volatile secondary products of lipid peroxidation the following compounds will be discussed in detail 

Odor-Active Monocarbonyl Compounds. Model expriments showed that the volatile fractions formed during the autoxidation of oleic, linoleic and linolenic acid contain mainly aldehydes and ketones (Table 3.31). Linoleic acid, a component of all lipids sensitive to autoxidation, is a precursor of hexanal that is predominant in 

A corr5)arison of the sensory properties (Table 3.32) shows that some carbonyl compounds, belonging to side components of the volatile fractions, may intensively contribute to an off-flavor due to their low threshold values. Food items containing linoleic acid, especially (E)-2-nonenal, trans-4,5-epoxy-(E)-2-decenal and l-octen-3-one, are very aroma active. 

The rapid deterioration of food containing linolenic acid should not be ascribed solely to the preferential oxidation of this acid but also to the low odor threshold values of the carbonyl compounds formed, such as (Z)-3-hexenal, (E,Z)-2,6-nonadienal and (Z)-l,5-octadien-3-one (Table 3.32). Aldehydes with exceptionally strong aromas can be released in food by the autoxidation of some fatty acids, even if they are present in low amounts. An example is octadeca-(Z,Z)-11, 15-dienoic acid (the precursor for 

Different levels of secondary products of oxidized fats and oils are formed depending on the conditions of heating. Kanazawa et al. (1985), for example, have shown that the secondary product fraction of per-oxidized methyl linoleate consisted of approximately 35% polymers, 25% endoperoxide-rich components and 40% low molecule weight compounds. Approximately 2.6% of the total amount of orally administered radioactive secondary oxidation products was found in the rat liver 12-24 h after administration. This deposition of the secondary products coupled with elevation of serum transaminase activities, an increase in hepatic TEARS and slight hepatic hypertrophy suggest that secondary products of methyl linoleate cause oxidative damage. 

Cyclic monomers, when fed at high levels to rats, have been shown to cause fatty livers (Poling et al., 1960 Weil, 1970 Iwaoka and Perkins, 1978). Levels of 0.02-0.15% of cycUc monomers have produced fatty livers associated with diffuse fatty degeneration, atrophy and necrosis, and the severity was positively correlated with monomeric concentrations (Iwaoka and Perkins, 1978). Non-cyclic dimers are less reactive than the cyclic counterpart (Michael et al., 1966 Perkins and Taubold, 1978). 

2 Low molecular weight products. Approximately 16% of the total low molecular weight fraction obtained from peroxidized methyl linoleate is identified as 8-hydroxy methyl octanoate, 41% as 4-hydroxy-2-nonenal and 4% as lO-formyl-9-decenoate (Oarada et al., 1986). Azelaldehydic acid, hexanal, azelaic, monocarboxylic acids (mainly hexa- 

Many secondary oxidation products of fatty acids have been shown to be more toxic to experimental animals. This is partly due to the fact that the low molecular weight products have shorter carbon chain lengths, and are more easily absorbed into the intestinal wall than lipid hydroperoxides or their polymeric materials. Oarada et al. (1986), for example, have shown that over 73% of radioactivity was found in the urine and CO2 of rats 12 h after receiving C-labeled low molecular compounds, compared to less than 25% for methyl linoleate hydroperoxides and the polymeric fraction. 

Among a diverse array of low molecular weight compounds, aldehydes of short and middle chain lengths, malondialdehyde (MDA), 4-hydroxynonenal and 4-hydroxhexenal, have received the most attention (Esterbauer et al., 1991). 

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Esters react with 2-aminothiazole and derivatives in the presence of catalysts the reaction between 3-ketoesters and 2-aminothiazole is. for example, realized in acidic medium (278. 279) and yields 2-aceto-acetamidothiazole (114) (Scheme 771. No secondary products are... 

The percentage of cyclohexylation is given in Fig. 1-20. (411,412). Hydrogen abstraction from the alkyl side-chain produces, in addition, secondary products resulting from the dimerization of thiazolylalkyl radicals or from their reaction with cyclohexyl radicals (Scheme 68) (411). 

U.S. primary and secondary production plus imports minus exports plus adjustments for government and industry stock changes. 

An excess of phosgene is used during the initial reaction of amine and phosgene to retard the formation of substituted ureas. Ureas are undesirable because they serve as a source for secondary product formation which adversely affects isocyanate stabiUty and performance. By-products, such as biurets (23) and triurets (24), are formed via the reaction of the labile hydrogens of the urea with excess isocyanate. Isocyanurates (25, R = phenyl, toluyl) may subsequendy be formed from the urea oligomers via ring closure. 

Fig. 19. Trends in the lead industry in the United States (—), total consumption (-), total production and (-), secondary production. The...

Ammonia reacts vigorously with phosgene. The products are urea, biuret, ammeUde (a polymer of urea), cyanuric acid, and sometimes cyameUde (a polymer of cyanic acid). The secondary products probably arise through the very reactive intermediate carbamyl chloride [463-72-9] NH2COCI (see... 

Approximately 4500 tons of sodium hypophosphite [7681-53-0] NaH2P02, was produced in 1990. This material is used principally in electroless nickel plating of plastic objects. Of the secondary products made from primary phosphoms compounds, phosphoms oxychloride is manufactured in the largest volume. Phosphoms pentachloride and phosphoms sulfochloride are made from phosphoms trichloride. 

There are over 65 known vanadium-bearing minerals, some of the more important are Hsted in Table 1. Patronite, bravoite, sulvanite, davidite, and roscoehte are classified as primary minerals, whereas all of the others are secondary products which form in the oxidizing zone of the upper Hthosphere. 

Secondary Timber Products. Secondary timber products are products manufactured from primary timber products. Secondary products can be sold directly to the final consumer or can requite additional processing before reaching the final consumer. The wide diversity of products manufactured from primary timber products makes it difficult to precisely define secondary products. Lumber, for example, is clearly a secondary product because it is manufactured from roundwood and typically requites further processing before reaching its final use. Wooden furniture is considered a final product, not a secondary product because it is made from lumber or other secondary timber products. In general, products made from secondary timber products were not included in this analysis. 

In 1991, timber-related secondary products manufacturing industries added an estimated 40,128 million of value to primary timber products (Table 11). Most of the timber-related value added (63%) originated in the paper and aUied products industry. The lumber and wood products industry added nearly 37% of total timber-related value added. Less than 1% was from chemicals and aUied products. 

The South and North were the two largest timber-related secondary products manufacturing regions, adding 16,350 million (41%) and 15,549 million (30%) of value, respectively, in 1991 (Table 10). The Rocky Mountain and Pacific Coast regions combined added the remaining 20%. 

Yeast (qv) metabolize maltose and glucose sugars via the Embden-Meyerhof pathway to pymvate, and via acetaldehyde to ethanol. AH distiUers yeast strains can be expected to produce 6% (v/v) ethanol from a mash containing 11% (w/v) starch. Ethanol concentration up to 18% can be tolerated by some yeasts. Secondary products (congeners) arise during fermentation and are retained in the distiUation of whiskey. These include aldehydes, esters, and higher alcohols (fusel oHs). NaturaHy occurring lactic acid bacteria may simultaneously ferment within the mash and contribute to the whiskey flavor profile. 

Photochemical Reactions. The photochemistry of chlorine dioxide is complex and has been extensively studied (29—32). In the gas phase, the primary photochemical reaction is the homolytic fission of the chlorine—oxygen bond to form CIO and O. These products then generate secondary products such as chlorine peroxide, ClOO, chlorine, CI2, oxygen, O2, chlorine trioxide [17496-59-2] CI2O2, chlorine hexoxide [12442-63-6] and... 

Production in Target Elements. Tritium is produced on a large scale by neutron irradiation of Li. The principal U.S. site of production is the Savaimah River plant near Aiken, South Carolina where tritium is produced in large heavy-water moderated, uranium-fueled reactors. The tritium may be produced either as a primary product by placing target elements of Li—A1 alloy in the reactor, or as a secondary product by using Li—A1 elements as an absorber for control of the neutron flux. 

With Alcohols. These reactions parallel those of ethylene oxide with water. The primary products are monoethers of ethylene glycol secondary products are monoethers of poly(ethylene glycol) (42). Most are appreciably water-soluble. 

The primary and secondary products of photolysis of common diazirines are collected in Table 4. According to the table secondary reactions include not only isomerization of alkenes and hydrogen elimination to alkynes, but also a retro-Diels-Alder reaction of vibrationally excited cyclohexene, as well as obvious radical reactions in the case of excited propene. 

Table 4 Primary and Secondary Products of Diazirine Photolysis...

The photolysis of chlorodiazirine was investigated in several cases. From chloromethyl-diazirine (232) vinyl chloride was formed as the stable primary product of stabilization of chloromethylcarbene, with acetylene and hydrogen chloride as secondary products. Some 1,1-dichloroethane was assumed to have been formed through a linear diazo compound by reaction with HCl. Added HBr yielded 1-bromo-l-chloroethane (76MI5Q800). 

The calcium salt of the principal product, d/-tartaric acid, crystallizes with four molecules of water, while the secondary product, meso-tartaric acid, forms a calcium salt which crystallizes with three molecules of water. The amount of sulfuric acid actually required may readily be calculated from the percentage of calcium found on analysis in the regular way or it may be estimated by igniting a sample, and titrating the residue with standard acid. 

Finally, atmospheric chemical transformations are classified in terms of whether they occur as a gas (homogeneous), on a surface, or in a liquid droplet (heterogeneous). An example of the last is the oxidation of dissolved sulfur dioxide in a liquid droplet. Thus, chemical transformations can occur in the gas phase, forming secondary products such as NO2 and O3 in the liquid phase, such as SO2 oxidation in liquid droplets or water films and as gas-to-particle conversion, in which the oxidized product condenses to form an aerosol. 

Steelmaking is a sophisticated and complex process, with many secondary production operations, each having unique air pollution problems to varying degrees. Figures 10, 11, and 12 provide some examples of common air pollution problems. 

The secondary production of lead begins with the recovery of old scrap from worn-out, damaged, or obsolete products and with new scrap. The chief source of old scrap is lead-acid batteries other sources include cable coverings, pipe, sheet, and other lead-bearing metals. Solder, a tin-based alloy, may be recovered from the processing of circuit boards for use as lead charge. 

Figure 10-4 shows the predicted X as a function of A j for the 30-1 reactor at 100 rpm. Decreasing A j slows the first reaction and increases the formation of the secondary product S. As a result, the predicted Xg decreases with increasing A j. It was found that A j = 0.08 gave the best predictions when compared to the experimental data from Middleton et al. [4] Figure 10-5 shows a comparison between the experimental data from Middleton et al. and the current model predictions for both the 30-1 and 600-1 reactors. Xg is plotted as a function... 

The SCOTT process uses an amine to remove the HjS. The acid gas off the amine still is recycled back to the Claus plant. Other types oi processes oxidize the sulfur compounds to SO2 and then convert ihc SO to a secondary product such as ammonium thiosulfate, a fertilizer. These plants can remove more than 99.5% of the sulfur in the inlet stream to the Claus plant and may eliminate the need for incineration. Costs of achieving this removal are high. 

Hydrolysis of the polymers yields H2SO4 and H2SO5 (p. 712), with H2O2 and O2 as secondary products. 

Blowing air through the hot, crude, liquid metal oxidizes traces of metals such as Fe, Cu, Zn and Pb which form an easily removable scum. Further purification is by distillation under reduced pressure. About 4000 tonnes of mercury are used annually but only half is from primary, mine production the other half being secondary production and sales from stockpiles. The main primary producer is now Spain, but several other countries, including the former Soviet Union, China and Algeria, have capacity for production. 

Recently, the cyclopenta[c]pyran (122) was obtained as a secondary product along with 1,2,3-tribenzoylcyclopropane from phenacyl-trimethylammonium hydroxide a complicated sequence was proposed involving a Michael addition to 1,2-dibenzoylethylene intermediately formed. 

The stable dicyanomethylides 274, made directly from the triazolopyridines and tetracyanoethylene oxide (TCNEO) reacts more slowly with MEP in acetonitrile to give mainly indolizines, with cyclazines as secondary products formed... 

The powerful nucleophilicity of enaimnes illows the dclthcion of rutro ilkenes to take place without the presence of Lewis acids The isolanon of secondary products, which can be explained by an initial Michael addition, suggests the participation of zwitlerionic intermediates m the mechanism of the reaction fEq 8 97i... 

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