Carbocation

Substitution and Elimination Reactions Substitution reactions replace a functional group with a new group. These reactions compete with elimination reactions in which a group is eliminated and a π (pi) bond is formed. Substitution reactions occur when a nucleophile is added to an electrophile/substrate. Elimination reactions occur when a base is added to an electrophile/substrate. The electrophile must contain a leaving group to be considered a substrate. Alkyl Halides Alkyl Halides are the common

INTRODUCTION: The polymerization of sugar molecules, such as sucrose and fructose, involves the dehydration of two sugar monomers to produce a peptide C=O bond, and the release of water. This common biomolecular mechanism has been greatly studied within the science disciplines. For Biologists, they’ve studied how nature does it, and for Chemist, they’ve studied how we mimic, and manipulate it. Chemist refer to such chemical reactions, in which atoms or groups of atoms are removed from a molecule

Introduction Experiment 5 deals with the bromination of an alkene. It is considered an addition reaction in which bromine is added to an alkene. This breaks double bonds of alkene and forms an alkane. With the removal of the double bond, each bromine atom can now attach to a carbon. In the first part of this experiment, bromine is added to the π bond of trans-stilbene, which results in the formation of vicinal dibromide. Vicinal is a term used to describe two functional groups bonded to two neighboring

it needs aluminium chloride catalyst to make it strong electrophile. Aluminium chloride is a lewis acid. The chloride atom will be separated from t-butyl chloride and attached to the aluminium chloride to become AlCl4. So, the t-butyl will be a carbocation, and it will be good electrophile due to its ability to form carbon-carbon bond. ( The equation of AlCl3). ( The mechanism of AlCl3). The electrophile, t-butyl cation, reacts with benzene. One of the three pi bonds of the aromatic ring

involves the heterolytic fission of the X-X bond to give a carbocation intermediate.  In aqueous halogen, the water molecule can behave as a nucleophile as it also carries a lone pair.  In step 2, two nucleophiles are available to attack the carbocation intermediates i.e. the halide ions and the water molecules.  Since there are more water molecules than halide ions in the aqueous medium, there is a higher probability that the carbocation intermediate would be attacked by the water nucleophiles

1. In the four structures displayed, two of them are repetitive and identical. Generally, the placement of the hydrogen atom and the hydroxyl group on a designated carbon site after norbornene is hydrated is determined by Markovnikov's rule. Markovnikov's rule indicates the location of the hydrogen and hydroxyl group when the ends of the C=C double bond of an alkene are not identical. However, the substituents on the ends of the alkene are identical, as demonstrated by each structure. Thus, the placement

substituent groups are removed from a molecule via a two-step mechanism1. One feature of a E1 reaction is the carbocation intermediate. A carbocation is a carbon that has three bonds and a positive charge, but these carbons are very unstable and more reactive because they want to be stabilized. Carbocations can be stabilized with neighboring carbon atoms1. The stability of a carbocation increases as it changes from primary to secondary to tertiary carbons. The reason why is because of two

The more stable the resulting carbocation, the quicker this step occurs. After this rate-limiting step, rapid reaction with a weak nucleophile (e.g. ethanol) attacking from either side of the carbocation completes the substitution reaction. A racemic mixture forms with a slight favoring of the inverted molecule because of ion pair formation. A good leaving group capable of delocalizing a negative charge aids in the formation of the initial carbocation. Additionally, polar, protic solvents

attacks an alkene’s -bond, functioning as a nucleophile, to produce a carbocation. The resulting carbocation can then be attacked by a nucleophile from either side of the molecule. In this experiment, the -bond found in (E)-stilbene is considered as an electron source that can donate electrons to form a bond with a bromine atom from a diatomic bromine molecule. As a result of this bond formation (addition), an acyclic carbocation is produced. Additionally, the electrons that are found in the covalent

nucleophilic substitution mechanisms and are a first-order process. Meaning that the reaction forms a carbocation intermediate and that the concentration of the nucleophile does not play a role in the rate-determining step, which is the slowest step in the reaction. All of the SN1 reaction mechanisms in this procedure can react two different ways. The expected mechanism for these reactions would be that the carbocation would react with the weak nucleophile nitrate, attaching the nitrogen to the positively charged