Classes Of Nitrogen Compounds Research Articles

Conformationally Constrained 1,4‐DHPs. A Convenient Route to Bis‐1,4‐DHPs as a Novel Class of Nitrogen Compounds.

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Conformationally constrained 1,4-DHPs. A convenient route to bis-1,4-DHPs as a novel class of nitrogen compounds

2-Formyl-1,4-DHP derivatives 2 undergo the tandem Knoevenagel condensation/amino-nitrile cyclisation with activated methylene reagents to afford high functionalised indolizines. However, in the absence of this tandem, the Knoevenagel condensation intermediate leads to bis-1,4-DHPs as a new class of nitrogen compounds.

Analyses of degradation products from lipid and protein hydrolyses in the small intestine of broiler chickens fed on maize-based diets containing guar gum, or wheat-based diets

1. Three maize diets containing graded levels (0, 0.1, 0.3%) of guar gum and two wheat diets differing in their in vitro viscosities were fed to male broiler chickens (7 to 23 d) for measurements of growth performance and analyses of degradation products from lipid and protein hydrolyses in the small intestine of broiler chickens. Analyses of degradation products were conducted to define which step (hydrolysis or absorption) was most involved in the negative effects of the digesta viscosity on lipid and protein digestibilities. The experiment was also carried out to examine whether effects of wheats could be explained in terms of intestinal viscosity alone. 2. The intestinal viscosities with wheat diets were within the range of those observed with the three maize diets. The correlations between in vivo and in vitro viscosities were higher with real than with potential applied viscosity of diets, both in jejunum and ileum. 3. The mean gain : food ratio observed with wheat diets was lower ( P < 0.05) than with maize diets despite lower ( P < 0.05) mean intestinal viscosities in birds given the wheat than given the maize diets. This shows that factors different from intestinal viscosity were also involved in the negative effects of wheats. 4. Distributions of nitrogen compounds in digesta were characterised by low proportions of compounds with high molecular weight (> 12,000). For all classes of nitrogen compounds, the contents measured in digesta dry matter did not differ between chickens fed with or without guar gum. 5. Distributions of lipid classes in both jejunum and ileum were characterised by a large proportion of free fatty acids (FFA) and very few triglycerides (TG). In the ileum, FFA and TG contents were both positively correlated with supernatant viscosity, but the slope for FFA content was 35 times higher than for TG. In these relationships, there was no difference between maize and wheat diets. 6. It is concluded that absorption was the main step involved in the lipid digestibility reduction due to intestinal viscosity. For proteins, the most important step (hydrolysis or absorption) involved in decreased digestibility due to intestinal viscosity was not clearly identified.

Characterization of the nitrogen compounds released during yeast autolysis in a model wine system.

The nitrogen composition of wines aged with yeast for a long period of time, as in the case of sparkling wines, depends on the composition of the base wine and on the compounds released by the yeast. In this paper, the release of the different classes of nitrogen compounds during autolysis of one of the strains of yeast used in the manufacture of sparkling wines has been studied. The yeast, Saccharomyces bayanus, was suspended in a model wine buffer, pH 3.0 and 10% ethanol, and incubated at 30 degrees C. Samples of the autolysate were taken after 4, 24, 48, 72, 168, and 360 h of autolysis. An electrophoretic and chromatographic study was conducted of the proteins, peptides with molecular weights higher and lower than 700 Da, and amino acids released during the autolysis. Using SDS-PAGE, it was observed that it was predominantly polypeptides with molecular weights lower than 10 000 that were released. Through HPLC of the fraction lower than 10 000 Da, it was observed that it is polypeptides with molecular weights of between 10 000 and 700 Da that are released first and that these later break up to give rise to peptides with molecular weights lower than 700 Da, which in turn break down into amino acids. This indicates that the nature of the nitrogen compounds present in wines aged with yeast depends on the aging time, being less polymerized as the aging time increases.

Nitrogen compound distribution in a heating oil

A Number 1 fuel heating oil was studied for the organo‐nitrogen content. The organo‐nitrogen compounds were isolated by mild acid extraction followed by silica gel adsorption. Three extracts were studied ‐ a basic nitrogen extract in methylene chloride, a nonbasic nitrogen extract in methyl alcohol and a nonbasic nitrogen extract in methylene chloride. The major constituents of each extract were identified by GC/MS. There were seven major classes of nitrogen compounds detected in each extract. These compounds included alkyl‐substituted carbazoles, indoles, pyrazines, pyridines, pyrroles, quinolines and tetrahydroquinolines. The nitrogen content and distribution was compared to both tar‐sands and shale derived fuels.

Speciation of Nitrogen Compounds in Gasoline and Diesel Range Process Streams by Capillary Column Gas Chromatography with Chemiluminescence Detection

This paper describes the development of a gas chromatographic method that uses nitrogen-specific detection based on chemiluminescence. A highly sensitive nitrogen-specific detector (Antek 705D) coupled to a Hewlett-Packard gas chromatograph is optimized to speciate nitrogen compounds in gasoline and diesel range process streams. Under optimized conditions, the nitrogen-to-carbon selectivity is greater than 106. The nitrogen chemiluminescence detector (NCD) provides a uniform response to different classes of nitrogen compounds and can detect concentration of individual components down to 100 ppb nitrogen. The detector's linear response in a range of 0.2 to 54 ppm nitrogen for an individual nitrogen component is established using several aliphatic and aromatic nitrogen-containing compounds. Gasoline and diesel range streams containing any level of total nitrogen can be analyzed after appropriate dilution so that each nitrogen component is below 50 ppm. In addition to the nitrogen speciation, total nitrogen can simultaneously be determined with reasonable accuracy using the NCD system. The repeatability and accuracy of the nitrogen quantitation is found to be within 7% at the 95% confidence level based on six to seven measurements.