Density Functional Theory (DFT) can be used to calculate an accurate electronic structure, HOMO and LUMO energies, Mulliken charge of atoms, energetic orbital levels, global hardness, chemical potential and electrophilicity of systems, and finally chemical, physical properties of fullerene and fullerene derivatives. Delocalization of electron density between the filled (bond or lone pair) Lewis type NBOs and empty anti-bonding non-Lewis NBOs calculated by NBO (Natural Bond Orbital) analyzing by B3LYP/3-21G*
Introduction:- In organic chemistry the substitution reactions is the most important reactions, especially Nucleophilic aromatic substitution reactions where nucleophile attacks positive charge or partially positive charge As it does so, it replaces a weaker nucleophile which then becomes a leaving group. The remaining positive or partially positive atom becomes an electrophile. The general form of the reaction is: Nuc: + R-LG → R-Nuc + LG: The electron pair (:) from the nucleophile (Nuc :) attacks the substrate (R-LG) forming a new covalent bond Nuc-R-LG. The prior state of charge is restored when the leaving group (LG) departs with an electron pair. The principal product in this case is R-Nuc.
This reaction was able to happen during designated lab time due to the fact that a phenol was used. Phenols or more reactive than unsubstitued benzene rings due to the presence of the alcohol on the benzene ring. The alcohol is considered an activating group due to the oxygen’s ability to donate its lone pairs into the benzene ring thus giving it more electrons and thus making it more nucleophilic and more likely to react with the introduced electrophilic species. As aforementioned, there are various products formed in this reaction the two major products formed though are the ortho and para products. It is debatable which product is more prominent due to steric reasons and the capability of each product to conduct in hydrogen bonding.
It is classed as a [4πS+2πS] cycloaddition; progressing via a thermally allowed 4n+2 cycloaddition involving a suprafacial/suprafacial interaction between a 4π electron system with a 2π electron system. This can be explained using Molecular Orbital Theorem (MOT) as follows by considering the frontier molecular orbitals, FMO, of the reactants: For a ‘normal’
One purpose of a Wittig reaction is the formation of alkenes from aldehydes or ketones employing a carbo-phosphorous ylide, which is stabilized vie resonance to allow for the carbon bonded to phosphorus to be deprotonate from by a base (Ketcha, 142). The resonating ylide will react with the electrophilic carbonyl carbon of its aromatic aldehyde to produce a betaine intermediate, or a crystalized 4
Introduction: We have seen that the carbonyl group of aldehydes and ketones is highly immediate, and that accompaniments to this functionality are ordinary. Carbonyl functionality reactive but that it also activates to hand carbon-hydrogen bonds (particularly alpha hydrogen’s) to go through a variety of substitution reactions.1 Carbonyl compounds can be explained by just four fundamental reaction types: Nucleophilic additions Nucleophilic acyl substitutions α-Substitutions Carbonyl condensations2 α-Substitutions: Alpha-substitution reactions take place at the site next to the carbonyl group the α-position and occupy the substitution of an α hydrogen atom by an electrophile, E,
The pairs of electrons are called “shared pairs” or “bonding pairs.” The stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding. This only happens between atoms of the same or very similar elements. Ionic bonding is the transfer of valence electrons between atoms. This chemical bond produces two oppositely charged ions. Metal elements lose electrons to become a positively charged cation whereas nonmetal elements let the electrons in to become a negatively charged
Given the name endohedral fullerenes or endofullerenes, these trapped molecules have increased physical and electronic properties and open up a new world of applications in medicine, cosmetics and perhaps even superconductivity. There are two types of endohedral fullerenes in existence, which are endohedral metallofullerenes and non-metal doped fullerenes. Endohedral metallofullerenes are fullerenes that have been doped with electropositive metals through laser evaporation. These metallic atoms will transfer electrons to the surrounding cage and will also move off centre in the cage. There are usually 2 or 3 charge units in the fullerene cage, but this is difficult to determine accurately.
Non-polar: when the two atoms have identical or similar electro negativities so the charges are distributed equally. A covalent compound: it is a molecule formed by covalent bonds in which atoms share one or more pairs of valence electrons. Properties of Covalent compounds: • Hard • Good insulators • Transparent • Poor conductors of heat and electricity (specially in water) • Tend to be gases, liquids or soft