In this study we present a facile method for synthesizing three derivatives of circumcoronene using BrnstedLewis acidmediated cyclization of vinyl ether or alkyne
Their structures were confirmed through X-ray crystallographic analysis. Bond length analysis, NMR measurement, and theoretical calculations showed that circumcoronene mostly follows Clar's bonding model and exhibits dominant local aromaticity. Its absorption and emission spectra are similar to those of the smaller hexagonal coronene due to its six-fold symmetry.Halogenated semivolatile acetonitriles as chloramination disinfection by-products in water treatment: a new formation pathway from activated aromatic Sciences, Curtin University, GPO Box U1987, Perth, 6845, Australia. The use of monochloramine as an alternative disinfectant to chlorine in drinking water treatment can lead to increased formation of emerging nitrogenous halogenated disinfection by-products (DBPs), even when the formation of regulated halogenated DBPs has decreased. In this study, we investigated formation of the semivolatile haloacetonitriles (HANs) from model nitrogen-containing compounds (6 amines, 1 amide, 6 amino acids, and 2 nitrogen-containing aromatic chemicals) and natural organic matter (NOM) reference materials after chloramination.
In agreement with previous studies, most amino acids formed dichloroacetonitrile (DCAN). Additionally, DCAN formed from two amines containing aromatic rings (N,N-dimethylaniline and 3-(dimethylamino-methyl)indole) and the two nitrogen-containing aromatic chemicals (cotinine and phenytoin). 6-butyl-n-hydroxynaphthimide trifluoromethanesulfonic acid as a Precursor for Naphthalimide Derivatives is the first report of DCAN formation from these precursors. Seebio Photosensitizer for Acid Formation formed after chloramination of NOM reference materials, with the highest formation from the NOM material with the highest aromaticity. The results provide new evidence of a DCAN formation pathway from cleavage of activated aromatic structures after electrophilic substitution of chlorine and addition of monochloramine to the ring system. In particular, the results suggest that the previously proposed aldehyde pathway from the amino acid group is not responsible for the majority of DCAN formation from amino acids with an activated aromatic ring system. This newly proposed formation pathway for DCAN from activated aromatic organic matter has significant implications for NOM removal during water treatment to minimise DBP formation.
Studies using 15N-labelled monochloramine showed that there was significant incorporation of nitrogen from monochloramine into DCAN, demonstrating that monochloramine disinfection promotes the formation of HANs.Adsorption of aromatic carboxylic acids on carbon nanotubes: impact of surface functionalization, molecular size and structure.A large quantity of emerging contaminants are ionizable, and the ionized compounds display different adsorption behaviors than their neutral counterparts. In particular, a strong intermolecular force, negative charge assisted hydrogen bonding ((-)CAHB), was recently identified, which explains the unusually strong adsorption of negatively charged compounds on carbon nanotubes with oxygen-containing functional groups. However, most previous studies only probed molecules with one benzene ring. The adsorption of ionizable compounds with more than one benzene ring and additional functional groups has not been examined. This study investigated the effect of surface functionalization, molecular size and structure of six aromatic carboxylic acids on their adsorption on multi-walled carbon nanotubes (MWNTs) in batch reactors.
In addition, the short-range interactions of the neutral acids with MWNTs were calculated to evaluate the effect of aromaticity and bulkiness. Hydrophobicity and electrostatic interactions dominate the intermolecular forces between ionized contaminants and MWNT surfaces. pH dependent octanol/water partitioning coefficient (Dow) is a more precise indicator of the adsorption of ionizable compounds on MWNTs. (-)CAHB is a significant force only for compounds with one benzene ring. Hydroxyl and carboxyl functional groups displayed similar capacity to form (-)CAHB, as indicated by the release of hydroxide ions.Reaction Electronic Flux Perspective on the Mechanism of the Zimmerman Pontificia Universidad Católica de Chile , Avenida Vicuña Mackenna 4860 , Technology , Pasadena , California 91125 , United States.Bernardo O Higgins , Santiago 8370854 , Chile.
Andres Bello , Avenida República 275 , 8370146 Santiago , Chile., Universidad Tecnológica Metropolitana , Ignacio Valdivieso 2409 , 8940577 , The reaction electronic flux (REF) offers a powerful tool in the analysis of reaction mechanisms. Noteworthy, the relationship between aromaticity and REF can eventually reveal subtle electronic events associated with reactivity in aromatic systems. In this work, this relationship was studied for the triplet Zimmerman di-π-methane rearrangement. The aromaticity loss and gain taking place during the reaction is well acquainted by the REF, thus shedding light on the electronic nature of reactions involving dibenzobarrelenes.
