A New Index for the Estimation of the Aromatic Character – VII

2015 ◽  
Vol 12 (6) ◽  
pp. 402-406 ◽  
Author(s):  
Maurizio D’Auria
Keyword(s):  
Aromatic Character

Reactions of an Aluminium(I) Reagent with 1,2-, 1,3- and 1,5-Dienes: Dearomatisation, Reversibility, and a Pericyclic Mechanism

2019 ◽  
Author(s):  
Clare Bakewell ◽  
Martí Garçon ◽  
Richard Y Kong ◽  
Louisa O'Hare ◽  
Andrew J. P. White ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Dft Calculations ◽  
Transition State ◽  
Reaction Pathways ◽  
Aromatic Rings ◽  
Aromatic Character ◽  
Pericyclic Reaction

The reactions of an aluminium(I) reagent with a series of 1,2-, 1,3- and 1,5-dienes are reported. In the case of 1,3-dienes the reaction occurs by a pericyclic reaction mechanism, specifically a cheletropic cycloaddition, to form aluminocyclopentene containing products. This mechanism has been interrogated by stereochemical experiments and DFT calculations. The stereochemical experiments show that the (4+1) cycloaddition follows a suprafacial topology, while calculations support a concerted albeit asynchronous pathway in which the transition state demonstrates aromatic character. Remarkably, the substrate scope of the (4+1) cycloaddition includes dienes that are either in part, or entirely, contained within aromatic rings. In these cases, reactions occur with dearomatisation of the substrate and can be reversible. In the case of 1,2- or 1,5-dienes complementary reactivity is observed; the orthogonal nature of the C=C π-bonds (1,2-diene) and the homoconjugated system (1,5-diene) both disfavour a (4+1) cycloaddition. Rather, reaction pathways are determined by an initial (2+1) cycloaddition to form an aluminocyclopropane intermediate which can in turn undergo insertion of a further C=C π-bond leading to complex organometallic products that incorporate fused hydrocarbon rings.

Switching Aromatic Character by Complexation: π to π* Change Seen in Molecular Rotation Spectra

2021 ◽  
pp. 5150-5155
Author(s):  
Hao Wang ◽  
Junhua Chen ◽  
Chunguo Duan ◽  
Xuefang Xu ◽  
Yang Zheng ◽  
...  
Keyword(s):  
Molecular Rotation ◽  
Aromatic Character

scholarly journals Amethyrin-type expanded porphyrins that display anti-aromatic character upon protonation

2020 ◽  
Vol 56 (69) ◽  
pp. 9994-9997 ◽  
Author(s):  
Harrison D. Root ◽  
Daniel N. Mangel ◽  
James T. Brewster ◽  
Hadiqa Zafar ◽  
Adam Samia ◽  
...  
Keyword(s):  
Aromatic Character ◽  
Expanded Porphyrins

The use of protonation to switch nonaromatic expanded porphyrins to their corresponding anti-aromatic forms is shown.

Aromatic Character of [n]Helicenes and [n]Phenacenes

1999 ◽  
Vol 103 (33) ◽  
pp. 6669-6672 ◽  
Author(s):  
Jerome M. Schulman ◽  
Raymond L. Disch
Keyword(s):  
Aromatic Character

Aromatic character of annelated dimethyldihydropyrenes

2004 ◽  
Vol 17 (5) ◽  
pp. 393-398 ◽  
Author(s):  
Jun-ichi Aihara ◽  
Toshimasa Ishida
Keyword(s):  
Aromatic Character

The effects of ultraviolet/H2O2 advanced oxidation on the content and characteristics of groundwater natural organic matter

2014 ◽  
Vol 15 (1) ◽  
pp. 34-41 ◽  
Author(s):  
J. Molnar ◽  
J. Agbaba ◽  
A. Tubić ◽  
M. Watson ◽  
M. Kragulj ◽  
...  
Keyword(s):  
Organic Matter ◽  
Natural Organic Matter ◽  
Advanced Oxidation ◽  
Total Content ◽  
Process Conditions ◽  
Water Type ◽  
H2o2 Treatment ◽  
Trihalomethane Formation Potential ◽  
Aromatic Character ◽  
A Minor

This work investigates the effects of ultraviolet (UV)/H2O2 advanced oxidation on the content and characteristics of natural organic matter (NOM) originating from two different groundwaters (3.03–9.69 mg/L total organic carbon (TOC), 2.71–4.31 Lmg−1m−1 specific ultraviolet absorbance (SUVA)). Application of UV irradiation resulted in a minor reduction in the total content of NOM. Using UV/H2O2 advanced oxidation led to a significant reduction of the aromatic character of NOM (SUVA was reduced by up to 80%) and an increase in the hydrophilic character of the residual NOM, with the optimal UV/H2O2 treatment conditions depending on the water type. In addition, fluctuations in trihalomethane formation potential (THMFP) were observed depending on the UV/H2O2 process conditions, with a maximal reduction of about 40% achieved for both waters.

scholarly journals Nucleus-independent chemical shift profiles along the intrinsic distortion path for Jahn-Teller active molecules. Study on cyclopentadienyl radical and cobaltocene

2015 ◽  
Vol 80 (7) ◽  
pp. 877-888 ◽  
Author(s):  
Ljubica Andjelkovic ◽  
Marko Peric ◽  
Matija Zlatar ◽  
Maja Gruden-Pavlovic
Keyword(s):  
Density Functional ◽  
Chemical Shifts ◽  
High Symmetry ◽  
Functional Theory ◽  
Aromatic Character ◽  
Nucleus Independent Chemical Shift ◽  
Jahn Teller ◽  
Cyclopentadienyl Radical ◽  
Cyclopentadienyl Anion ◽  
Low Symmetry

The aromatic/antiaromatic behavior of the cyclopentadienyl anion (Cp-), bis(?5-cyclopentadienyl)iron(II) (Fe(Cp)2), as well as of the Jahn-Teller (JT) active cyclopentadienyl radical (Cp?) and bis(?5-cyclopentadienyl)cobalt(II) (Co(Cp)2) has been investigated using Density Functional Theory (DFT) calculations of the Nuclear Independent Chemical Shifts (NICS). According to the NICS values, pentagon ring in Fe(Cp)2 is more aromatic than isolated Cp-. The NICS parameters have been scanned along the Intrinsic Distortion Path (IDP) for Cp? and Co(Cp)2 showing antiaromaticity, which decreases with increasing deviation from high symmetry D5h to low symmetry (LS) C2v. Changes in the NICS values along the IDP revealed that Co(Cp)2 in the LS nuclear arrangement has aromatic character, in contrast to the case of Cp?

Sign in / Sign up

Export Citation Format

Share Document