Halogen

About: Halogen is a research topic. Over the lifetime, 6789 publications have been published within this topic receiving 110903 citations. The topic is also known as: group 17 elements & halogens.

Halogen-Substituted Mesoionic-Carbene/Palladium Complexes for Catalytic Arylation of Aldehydes

Abstract: Various halogenated mesoionic-carbene-coordinated palladium complexes (denoted as TAPs and e-TAPs) were prepared using triazolylidene precursors that were synthesized in only two steps via a click reaction. Among the prepared complexes, Br-e-TAP showed optimal catalytic activity for the arylation of aldehydes with arylboronic compounds. Additionally, the Br-e-TAP catalyst assisted in synthesizing a wide range of functionalized diarylmethanols and arylmethanols in 29%95% yields with loadings of 0.2–0.6 mol% Pd.

Synthesis and styrene copolymerization of halogen ring-disubstituted 2-methoxyethyl phenylcyanoacrylates

Abstract: Novel halogen ring-disubstituted 2-methoxyethyl phenylcyanoacrylates, RPhCH=C(CN)CO2CH2CH2OCH3 (where R is 2,5-dibromo, 3,5-dibromo, 2,3-dichloro, 2,4-dichloro, 2,6-dichloro, 3,4-dichloro, 3,5-dichloro, 2,4-difluoro, 2,5-difluoro, 2,6-difluoro, 3,4-difluoro, 3,5-difluoro, 2-chloro-6-fluoro, 3-chloro-4-fluoro, 2-chloro-5-nitro, 4-chloro-3-nitro, 2-fluoro-5-iodo) were prepared and copolymerized with styrene. The acrylates were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-disubstituted benzaldehydes and 2-methoxyethyl cyanoacetate, and characterized by CHN analysis, IR, 1H and 13C NMR. All the acrylates were copolymerized with styrene in solution with radical initiation (ABCN) at 70C. The compositions of the copolymers were calculated from nitrogen analysis.

Correlation Between Halogens Atoms Elements, Their Positions on the Main Chain of Organic Compounds, and Corrosion Inhibition Performance

Abstract: In this book chapter, the authors focus on the comparative study of some benzimidazole-substituted compounds used as corrosion inhibitors for mild steel in molar Hydrochloric acid solution. It has been determined that the quinazolinone studied compounds exhibit a very good performance as corrosion inhibitors for mild steel in molar Hydrochloric acid solution, as the halogen-substituted compounds show better inhibitive performance than the non-halogen-substituted one. Correspondence between inhibition property, molecular structure, and halogen substitution of benzimidazole-substituted compounds is investigated, using chemical, electrochemical, and theoretical methods. Halogen substitution effect on the inhibition performance has also been explored by quantum chemical computations and obvious correlations were observed. The binding energies of tested compounds on Fe(110) surfaces were calculated using Monte Carlo simulation. Bromide-substituted compound shows better inhibitive performance than the chloride-substituted one.

Stimuli Responsive Materials Supported by Orthogonal Hydrogen and Halogen Bonding or I···Alkene Interaction

Abstract: Smart materials represent an elegant class of (macro)-molecules endowed with the ability to react to chemical/physical changes in the environment. Herein, we prepared new photo responsive azobenzenes possessing halogen bond donor groups. The X-ray structures of two molecules highlight supramolecular organizations governed by unusual noncovalent bonds. In azo dye I-azo-NO2, the nitro group is engaged in orthogonal H···O···I halogen and hydrogen bonding, linking the units in parallel undulating chains. As far as compound I-azo-NH-MMA is concerned, a non-centrosymmetric pattern is formed due to a very rare I···π interaction involving the alkene group supplemented by hydrogen bonds. The Cambridge Structural Database contains only four structures showing the same I···CH2=C contact. For all compounds, an 19F NMR spectroscopic analysis confirms the formation of halogen bonds in solution through a recognition process with chloride anion, and the reversible photo-responsiveness is demonstrated upon exposing a solution to UV light irradiation. Finally, the intermediate I-azo-NH2 also shows a pronounced color change due to pH variation. These azobenzenes are thereby attractive building blocks to design future multi-stimuli responsive materials for highly functional devices.