scholarly journals Site-selective covalent functionalization at interior carbon atoms and on the rim of circumtrindene, a C36H12 open geodesic polyarene

2014 ◽  
Vol 10 ◽  
pp. 956-968 ◽  
Author(s):  
Hee Yeon Cho ◽  
Ronald B M Ansems ◽  
Lawrence T Scott
Keyword(s):  
Aromatic Hydrocarbons ◽  
Electrophilic Aromatic Substitution ◽  
Coupling Reactions ◽  
Computational Results ◽  
Aromatic Substitution ◽  
Covalent Functionalization ◽  
Polycyclic Aromatic ◽  
Site Selective ◽  
Geodesic Polyarenes ◽  
Derivatives Of

Circumtrindene (6, C36H12), one of the largest open geodesic polyarenes ever reported, exhibits fullerene-like reactivity at its interior carbon atoms, whereas its edge carbons react like those of planar polycyclic aromatic hydrocarbons (PAHs). The Bingel–Hirsch and Prato reactions – two traditional methods for fullerene functionalization – afford derivatives of circumtrindene with one of the interior 6:6 C=C bonds modified. On the other hand, functionalization on the rim of circumtrindene can be achieved by normal electrophilic aromatic substitution, the most common reaction of planar PAHs. This peripheral functionalization has been used to extend the π-system of the polyarene by subsequent coupling reactions and to probe the magnetic environment of the concave/convex space around the hydrocarbon bowl. For both classes of functionalization, computational results are reported to complement the experimental observations.

Potential Contribution of Nutrients and Polycyclic Aromatic Hydrocarbons from the Creeks of Cootes Paradise Marsh

1996 ◽  
Vol 31 (3) ◽  
pp. 485-504 ◽  
Author(s):  
Patricia Chow-Fraser ◽  
Barb Crosbie ◽  
Douglas Bryant ◽  
Brian McCarry
Keyword(s):  
Aromatic Hydrocarbons ◽  
Laboratory Experiments ◽  
Dry Weight ◽  
Common Source ◽  
Potential Contribution ◽  
Nitrogen And Phosphorus ◽  
Engine Combustion ◽  
Polycyclic Aromatic ◽  
High Concentrations ◽  
Derivatives Of

Abstract During the summer of 1994, we compared the physical and nutrient characteristics of the three main tributaries of Cootes Paradise: Spencer, Chedoke and Borer’s creeks. On all sampling occasions, concentrations of CHL α and nutrients were always lowest in Borer’s Creek and highest in Chedoke Creek. There were generally 10-fold higher CHL α concentrations and 2 to 10 times higher levels of nitrogen and phosphorus in Chedoke Creek compared with Spencer Creek. Despite this, the light environment did not differ significantly between Spencer and Chedoke creeks because the low algal biomass in Spencer Creek was balanced by a relatively high loading of inorganic sediments from the watershed. Laboratory experiments indicated that sediments from Chedoke Creek released up to 10 µg/g of soluble phosphorus per gram (dry weight) of sediment, compared with only 2 µg/g from Spencer Creek. By contrast, sediment samples from Spencer Creek contained levels of polycyclic aromatic hydrocarbon that were as high as or higher than those from Chedoke Creek, and much higher than those found in Borer’s Creek. The distribution of normalized PAH concentrations suggests a common source of PAHs in all three tributaries, most likely automobile exhaust, since there were high concentrations of fluoranthene and pyrene, both of which are derivatives of engine combustion.

scholarly journals Site-Selective [2+2+n] Cycloadditions for Rapid, Scalable Access to Alkynylated Polycyclic Aromatic Hydrocarbons

2019 ◽  
Author(s):  
Gavin R. Kiel ◽  
Harrison Bergman ◽  
T. Don Tilley
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Structural Complexity ◽  
Building Blocks ◽  
Synthetic Methods ◽  
Proof Of Concept ◽  
Site Selectivity ◽  
Polycyclic Aromatic ◽  
Site Selective ◽  
Nanometer Regime

Polycyclic aromatic hydrocarbons (PAHs) are attractive synthetic building blocks for more complex conjugated nanocarbons, but their use for this purpose requires appreciable quantities of a PAH with reactive functional groups. Despite tremendous recent advances, most synthetic methods cannot satisfy these demands. Here we present a general and scalable [2+2+n] (n = 1 or 2) cycloaddition strategy to access PAHs that are decorated with synthetically versatile alkynyl groups and its application to seven structurally diverse PAH ring systems (thirteen new alkynylated PAHs in total). The critical discovery is the site-selectivity of an Ir-catalyzed [2+2+2] cycloaddition, which preferentially cyclizes tethered diyne units with preservation of other (peripheral) alkynyl groups. The potential for generalization of the site-selectivity to other [2+2+n] reactions is demonstrated by identification of a Cp<sub>2</sub>Zr-mediated [2+2+1] / metallacycle transfer sequence for synthesis of an alkynylated, selenophene-annulated PAH. The new PAHs are excellent synthons for macrocyclic conjugated nanocarbons. As a proof of concept, four were subjected to Mo catalysis to afford large, PAH-containing arylene ethylene macrocycles, which possess a range of cavity sizes reaching well into the nanometer regime. More generally, this work is a demonstration of how site-selective reactions can be harnessed to rapidly build up structural complexity in a practical, scalable fashion.

scholarly journals On the effects of some carcinogenic hydrocarbons on the growth of sporelings of marine red algae

1962 ◽  
Vol 42 (3) ◽  
pp. 579-585 ◽  
Author(s):  
A. D. Boney ◽  
E. D. S. Corner
Keyword(s):  
Aromatic Hydrocarbons ◽  
Red Algae ◽  
Considerable Increase ◽  
Rapid Screening ◽  
Cell Production ◽  
Low Concentrations ◽  
Rapid Screening Test ◽  
Polycyclic Aromatic ◽  
Carcinogenic Hydrocarbons ◽  
Derivatives Of

Low concentrations of various carcinogenic polycyclic aromatic hydrocarbons cause a considerable increase in cell production when applied to sporelings of certain marine red algae.Whereas low concentrations of carcinogenic derivatives of benzanthracene stimulate cell production, similar concentrations of structurally related non-carcinogens inhibit it.The applicability of the method as a rapid screening test for carcinogens is discussed.

Homolytic aromatic substitution. VIII. Phenylation of polycyclic aromatic hydrocarbons

1973 ◽  
Vol 95 (14) ◽  
pp. 4624-4632 ◽  
Author(s):  
S. Carlton. Dickerman ◽  
William M. Feigenbaum ◽  
Michael. Fryd ◽  
Norman. Milstein ◽  
George B. Vermont ◽  
...  
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Aromatic Substitution ◽  
Homolytic Aromatic Substitution ◽  
Polycyclic Aromatic
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