Nitrogen-containing compounds, evaluated

In addition to lipid oxidation and hydrolysis reactions, the rancid off-flavor results from interactions, particularly those between aldehydes and nitrogen-containing compounds. However, for some of these interactions, it is impossible to evaluate the off-flavor. 

We completed acute bioassays with Daphnia pulex for 35 representative and related chemicals from the following top-ranked classes for which available toxicity data were deemed inadequate to evaluate the hazard of the classes (National Fisheries Center - Great Lakes 1986 Perry 1985) polyaromatic hydrocarbons (PAHs), alkyl halides, mono- and polycyclic alkanes, heterocyclic nitrogen compounds, other nitrogen-containing compounds, and silicon-containing compounds (alkylether silanes). The acute bioassays with Daphnia pulex followed the methods of National Fisheries Center - Great Lakes (1986) with the temperature at 20° C. 

There have been kinetic investigations of the breakdown of four nitrogen-containing tetrahedral intermediates [ 124]—[ 127] (see Table 19). In addition, compound [28] was studied but the rate constants for individual steps were not evaluated (Rogers and Bruice, 1973, 1974). Compounds [124], [126] and... 

The composition of the carbonaceous species retained by sorption on sampling media has rarely been evaluated. Fung (59) reported that the carbonaceous materials retained by sorption on quartz-fiber filters were relatively polar organic compounds, including phthalate esters and nitrogen-containing heterocyclic compounds. Additional studies of this type would be very helpful. 

Lobert, J. M., D. H. Scharffe, W. M. Hao, T. A. Kuhlbusch, P. Warneck, and P. J. Crutzen. 1991. Experimental evaluation of biomass burning emissions Nitrogen and carbon containing compounds. In Global Biomass Burning Atmospheric, Climatic and Biospheric Implications (J. S. Levine, Ed.). MIT Press, Cambridge, MA. 

Similarly to the study on coal, of significant importance was the evaluation of polycyclic aromatic compounds generated from the pyrolysis of oil shale. This type of study included the evaluation of PAH in shale pyrolysates, and also of sulfur containing polycyclic aromatic compounds, and nitrogen containing polycyclic aromatic compounds [41 aj. 

The use of internal standards makes it unnecessary to analyse all of the components of a mixture when evaluating process parameters, as it is sufficient to establish relative concentrations of the components and the standard. However, the introduction of a standard into the mbcture being analysed by gravimetric techniques leads to serious difficulties in laboratory analyses, especially in the analysis of gases clearly, such a solution is inapplicable to automatic production control. The standard may be a compound inert to a given reaction and incorporated in both the raw materials and the end products. Naturally, such compounds can be found only for a limited number of processes. For example, nitrogen contained in the air used for oxidation has been used as a standard for the oxidation of butane in a fluidized bed of a catalyst [163]. 

An algae-derived oil was reported to be principally n-paraffins and olefins with oxygen- and nitrogen-containing straight-chain hydrocarbons (5 ). Polar compounds were reported to comprise 50-60 percent of the oil. Unfortunately, there is no indication of the type of analysis performed or detailed results of any kind therefore, it is difficult to evaluate the veracity of these reported results. 

Pyridine is considered as one of the commonest heterocycles among nitrogen-containing heterocychc compounds. Substituent effects in meta-and para-X-substituted pyridines (with X = OMe and Me) on their basicity have been studied in water and ionic hquid (IL, l-buthyl-3-methyl-imidazolium hexafluorophosphate) (2010JOC(75)3912). The equibbrimn constants were evaluated by spectrophotometric titration of pyridine solution with trifluoroacetic acid. The results of the Hammett approach (Eqn (1)), applied to aU studied systems, allow one to state that pyridine basicity is almost twice as less sensitive to the substituent effect in IL than in water (Figure 2). 

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