Aromaticity

There is no doubt that benzene is aromatic. Now we must ask: how can we insert a heteroatom into the ring and retain aromaticity? What kind of atom is needed? If we want to replace one of the carbon atoms of benzene with a heteroatom, we need an atom that can be trigonal to keep the flat hexagonal ring and that has a p orbital to keep the six delocalized electrons. Nitrogen is ideal so we can imagine replacing a CH group in benzene with a nitrogen atom. The orbitals in the ring have not changed in position or shape and we still have the six electrons from the three double bonds. One obvious difference is that nitrogen is trivalent and thus there is no NH bond. Instead, a lone pair of electrons occupies the space of the C–H bond in benzene.…

Background Benzo(a)pyrene (BaP), a polycyclic aromatic hydrocarbon(PAH) when infiltrated within the body of humans and animals undergoes a series of chemically modified changes to form a number of metabolites that are known to elicit portentous and toxic effects (4). Benzo(a)pyrene has a chemical formula of C20H12 and is considered a Group 1 Carcinogen by the International Agency for Research and Cancer (IARC) (7, 11). It is composed of a cyclic structure and crystals appear to be pale yellow…

Abstract This experiment involved an electrophilic aromatic substitution of bromobenzene. Two products were formed: 4-nitrobromobenzene (4-NBB) and 2-nitrobromobenzene (2-NBB). Utilizing column chromatography and recrystallization, separation and purification of the two products was obtained. The mass of 4-NBB, the para product, was 1.57 grams, while the mass of 2-NBB, the ortho product, was 0.80 grams. The para product was expected to have the higher yield, since it is more stable and…

The goal of this lab was to prepare methyl m-nitrobenzoate using electrophilic aromatic substitution. An example of electrophilic aromatic substitution is nitration where a hydrogen atom which is part of a aromatic ring is substituted by an electrophile. For benzene, aromaticity is a stabilizing feature. As such, instead of undergoing electrophilic additions, it undergoes electrophilic substitutions. The nitronium ion is the electrophile which gets attached to the electron rich aromatic…

examine its own gaps and goals" (Jogalekar 2013). His defense for psychology begins early on by confronting first against what he states is Berezow's largest argument against psychology; lack of adequate definitions and quantifiability. Jogalekar gives personal examples from his career and how his work involves highly scientific processes, yet there is "a longstanding debate in our field about how you define a "druglike" molecule..." which means many of the terms they use are subjective, but…

can inhibit the corrosion rate of metal alloys but cost effectiveness, toxicity, processibility and other factors limit the applications1. The need for new, eco-friendly and cost effective corrosion inhibitors have led to research in the field of polymer chemistry. Discussion The performance of a polymeric corrosion inhibitor is a function of its size and number of functional anchoring groups1. The anchoring groups allow the polymer to adsorb to the metal surface and assist in corrosion…

the melting point was 47-52.7 °C. Introduction1 This experiment was designed to practice working with electrophilic aromatic substitution reactions. Specifically, a Friedel-Craft reaction was used to synthesize 1,4-di-t-butyl-2,5-dimethyoxybenzene from p-dimethoxybenzene and t-butyl alcohol. These reactions are designed so that a substituent can be added to a benzene ring. This is significant due to the stability of the aromatic substance. For this reaction to occur, a carbocation must be…

performed in the hood. Second, we should wear gloves and do the addition of bromine in the hood, as bromine vapour can be irritating. When dealing with bromine solution, we should also avoid spilling toward our hand as bromine was a strong oxidising agent. Third, the combustion experiment must be performed in the hood. Last but not least, all the organic waste was disposed into an appropriate waste container in the hood rather than just pour it into the sink. CONCLUSION From this experiment,…

alkane standard was used to construct the Kovats index, it contained pentane, hexane, heptane, octane and nonane. The purpose of building such an index is to estimate the number of carbons of the compounds absent from the blank solutions according to their retention time. The retention time on the chromatograms were given in minutes but they needed to be converted to seconds to calculate the logarithm of the retention time in seconds. The Kovats index is a graph that represents a linear…

is an essential -amino acid found in humans and mammals. The structure of a fully protonated form of histidine is shown at right: As shown in the structure of the fully protonated histidine above, the side chain of the fully protonated histidine has two different N atoms, NA and NB. NB is protonated but not NA. Explain why NA atom cannot be protonated. Solution Both NA and NB atoms are sp2 hybridized. The lone pair of electrons on NA atom is not available to accept a proton because these are…