WebA substituent is one or a group of atoms that replaces (one or more) atoms, thereby becoming a moiety in the resultant (new) molecule. ( In organic chemistry and biochemistry, the terms substituent and functional group, as well as side chain and pendant group, are used almost interchangeably to describe those branches from the parent structure, …

Web1) Consider para-disubstituted benzene p-F-C 6 H 4 -Z, where Z is a substituent such as NH 2 , NO 2 , etc. The fluorine atom is para with respect to the substituent Z in the benzene ring. The image on the right shows four distinguished ring carbon atoms, C1(ipso), C2(ortho), C3(meta), C4(para) in p-F-C 6 H 4 -Z molecule. The carbon with Z is defined …

WebIn organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula CH 3.In formulas, the group is often abbreviated as Me.This hydrocarbon group occurs in many organic compounds.It is a very stable group in most molecules. While the methyl group is …

WebHunter et al. applied a more sophisticated chemical double mutant cycle with a hydrogen-bonded "zipper" to the issue of substituent effects in pi stacking interactions. This technique has been used to study a multitude of noncovalent interactions. The single mutation, in this case changing a substituent on an aromatic ring, results in secondary effects such as a …

WebUne institution sociale désigne une structure sociale dotée d'une certaine stabilité et durabilité, dans le temps. Il s'agit d'un mode de régulation d'interactions sociales vouées à se reproduire; les interactions vouées à se reproduire tendent à faire émerger des institutions sociales telles que le mariage, chômage, l'école ou la famille, afin d'y réguler …

WebA-values are numerical values used in the determination of the most stable orientation of atoms in a molecule (conformational analysis), as well as a general representation of steric bulk.A-values are derived from energy measurements of the different cyclohexane conformations of a monosubstituted cyclohexane chemical. Substituents on a …

WebKathryn D. Sullivan (born 1951) is an American geologist and oceanographer, and a former government official and NASA astronaut, who flew on three Space Shuttle missions. Sullivan was one of six women selected in NASA Astronaut Group 8, the first group to include women.During her first mission, STS-41-G, Sullivan performed the first spacewalk by an …

WebThe Madelung synthesis is a chemical reaction that produces (substituted or unsubstituted) indoles by the intramolecular cyclization of N-phenylamides using strong base at high temperature. The Madelung synthesis was reported in 1912 by Walter Madelung, when he observed that 2-phenylindole was synthesized using N-benzoyl-o-toluidine and two …

WebIn chemistry, the inductive effect in a molecule is a local change in the electron density due to electron-withdrawing or electron-donating groups elsewhere in the molecule, resulting in a permanent dipole in a bond. It is present in a σ (sigma) bond, unlike the electromeric effect which is present in a π (pi) bond.. The halogen atoms in an alkyl halide are electron …

WebBromothymol blue (also known as bromothymol sulfone phthalein and BTB) is a pH indicator.It is mostly used in applications that require measuring substances that would have a relatively neutral pH (near 7). A common use is for measuring the presence of carbonic acid in a liquid. It is typically sold in solid form as the sodium salt of the acid indicator.