Nitrogen-containing pyrrole derivatives

Pyrrole A nitrogen-containing, heterocyclic compound found at low concentrations in crude. Pyrrole can readily polymerize in the presence of light to form dark-brown compounds. Pyrrole derivatives, such as indole, have been identified as sources which can lead to darkening of fuel color and eventual deposit formation. 

The other nitrogen compounds which are nonbasic, and are not extracted from hydrocarbons by dilute acid, have not been investigated in detail, though there are indications that they contain pyrroles. In addition, it is possible that some part of the nitrogen in this material is present in the form of amides, derived from primary or secondary amines and petroleum acids. 

Thus, the hydrodesulfurization process is a very complex sequence of reactions due, no doubt, to the complexity of the feedstock. Furthermore, the fact that feedstocks usually contain nitrogen and oxygen compounds (in addition to metal compounds) increases the complexity of the reactions that occur as part of the hydrodesulfurization process. The nitrogen compounds that may be present are typified by pyridine derivatives, quinoline derivatives, carbazole derivatives, indole derivatives, and pyrrole derivatives. Oxygen may be present as phenols (Ar-OH, where Ar is an aromatic moiety) and carboxylic acids (-C02H). The most common metals to occur in petroleum are nickel (Ni) and vanadium (V) (Reynolds, 1997). 

Acetylenecarboxylic esters, reactions with nitrogen-containing heterocycles, 23, 263 Acetylenic derivatives of pyrazoles, synthesis and properties of, 82, 1 Acetylenic esters, synthesis of heterocycles through nucleophilic additions to, 19,297 Acid-catalyzed polymerization of pyrroles and indoles, 2, 287... 

A,B-Diheteropentalenes have only limited solubility in water. The hydrogen donor properties of the NH site of pyrrole and the hydrogen acceptor property of the oxygen atom of the furan ring can increase the solubility of the compounds containing these heteroatoms relative to the systems with only sulfur or selenium atoms in their structure. Alkylation at the nitrogen of furo[3,2-6]pyrrole derivatives increases the solubility in ethanol and other organic solvents. 

The direct synthesis by anodic oxidation of a new series of electrically conducting poljnners is described.. Our polymers derive from sulfur and/or nitrogen containing hetero-cycles such as 2-(2-thienyl)pyrrole, thiazole, indole, and phthalazine. The anodic oxidation of these monomers is carried out in acetonitrile solutions containing tetrabu-tylammonium salts (TBA X ) ith X = BF, tetraethylammonium salt, TEA H C-C H -S0. Characterization of the materials by electrical conductivity, electron spin resonance, uv-visible spectroscopy, and cyclic voltammetry is discussed. 

Upon the reaction of 1,2,3-tris(methylsulfanyl)cyclopropenylium ion 30 with pyrrole or indole compounds, the substitution of one methylsulfanyl group by the nitrogen-containing aromatic ring occurred to give the cyclopropenylium derivatives 31, which can be regarded as derivatives of protonated azacalicene. ... 

Nitrogen-containing heterocycles can pose problems that are not encountered in their homocyclic analogues. Obviously, heterocycles involving NH groups, such as pyrrol and its annellated and aza derivatives, will destroy an organomagnesium-halide reagent formed from their halo derivatives. Another example is that of... 

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