Electrophilic Aromatic Cation Lab Report

The objective of this lab was to create a ketone through an oxidation reaction using a using a secondary alcohol and oxidizing agent in order to use that ketone in a reduction reaction with a specific reducing agent to determine the affect of that reducing agent on the diastereoselectivity of the product. In the first part of this experiment, 4-tert-butylcyclohexanol was reacted with NaOCl, an oxidizing agent, and acetic acid to form 4-tert-butylcyclohexanone. In the second part of this experiment, 4-tert-butylcyclohexanone was reacted with a reducing agent, either NaBH4 in EtOH or Al(OiPr)3 in iPrOH, to form the product 4-tert-butylcyclohexanol. 1H NMR spectroscopy was used to determine the cis:trans ratio of the OH relative to the tert-butyl group in the product formed from the reduction reaction with each reducing agent. Thin-layer chromatography was used in both the oxidation and reduction steps to ensure that each reaction ran to completion.

group. The location of this hydroxyl functional group will impact the molecular structure of the

Grignard reagents also react with the least hindered carbon on an epoxide to break the ring in order to relieve ring strain.

The objective of this laboratory experiment is to study both SN1 and SN2 reactions. The first part of the lab focuses on synthesizing 1-bromobutane from 1-butanol by using an SN2 mechanism. The obtained product will then be analyzed using infrared spectroscopy and refractive index. The second part of the lab concentrates on how different factors influence the rate of SN1 reactions. The factors that will be examined are the leaving group, Br – versus Cl-; the structure of the alkyl group, 3◦ versus 2◦; and the polarity of the solvent, 40 percent 2-propanol versus 60 percent 2-propanol.

The solvolysis of t-butyl bromide is an SN1 reaction, or a first order nucleophilic substitution reaction. An SN1 reaction involves a nucleophilic attack on an electrophilic substrate. The reaction is SN1 because there is steric obstruction on the electrophile, bromine is a good leaving group due to its large size and low electronegativity, a stable tertiary carbocation is formed, and a weak nucleophile is formed. Since a strong acid, HBr, is formed as a byproduct of this reaction, SN1 dominates over E1. The first step in an SN1 reaction is the formation of a highly reactive carbocation, in which a leaving group is ejected. The ionization to form a carbocation is the rate limiting step of an SN1 reaction, as it is highly endothermic and has a large activation energy. The subsequent nucleophilic attack by solvent and deprotonation is fast and does not contribute to the rate law for the reaction. The Hammond Postulate predicts that the transition state for any process is most similar to the higher energy species, and is more affected by changes to the free energy of the higher energy species. Thus, the reaction rate for the solvolysis of t-butyl bromide is unimolecular and entirely dependent on the initial concentration of t-butyl bromide.

A unimolecular nucleophilic substitution or SN1 is a two-step reaction that occurs with a first order reaction. The rate-limiting step, which is the first step, forms a carbocation. This would be the slowest step in the mechanism. The addition of the nucleophile speeds up the reaction and stabilizes the carbocation. This reaction is more favorable with tertiary and sometimes secondary alkyl halides under strong basic or acidic conditions with secondary or tertiary alcohols. In this experiment, the t-butyl halide underwent an SN1 reaction. Nucleophiles do not necessarily effect the reaction because the nucleophile is considered zero order, (which makes it a first order reaction.) The ion that should have the strongest effect in an SN1 reaction is the bromide ion. The bromide ion should be stronger because it has a lower electronegativity than chloride as well as a smaller radius.

one acetyl group to an aromatic ring or add two acetyl groups to each of the

If air is admitted to the sample, that spectrum is replaced by one consisting of a quintet of quintets, which we assign, on the basis of the further experiments described below, to the radical anion (1). Two reasonable routes by which the reaction might occur are illustrated in equation A, where the two rings become linked either by the condensation of cyclo- pentadienyl-lithium with cyclopentadienone resulting from the autoxidation of cyclopentadienyl-lithium, or by the coupling of two cyclopentadienyl radicals. The same spectrum is obtained by the autoxidation of the dilithium salt of dihydrofulvalene (2) prepared by Doering and Matzner's method (equation B) ; the pink colour of the suspension of the dianion (2) in tetrahydrofuran changes first to deep green then to violet when the e.s.r. spectrum of the radical anion becomes apparent. Further autoxidation gives the characteristic orange colour of fulvalene? and reaction of this with a sodium mirror and subsequent photolysis restores the colour and the e.s.r. spectrum of the radical anion. Similarly, electrolytic reduction of the fulvalene shows the same 25- line spectrum(equation

Phenol is very oxidised and will react with dilute nitric acid/sodium nitrate at room temperature to produce a mixture of 2-nitrophenol and 4-nitrophenol. The nitration of phenol occurs in the presence of sulfuric acid as a dehydrating agent and remove a molecule of water as a by-product. Nitronium ion is produced when concentrated sulfuric acid is added to nitric acid. The nitronium ion attacks the benzene ring of phenol and the OH (hydroxyl) functional group of phenol activates the benzene ring at the 2- and 4- positions, which produce a mixture of 2-nitrophenol and 4-nitrophenol.

In an aromatic ring, a ring of delocalized π bonds extends above and below the plane of the molecule, which creates a strong electric current that stabilizes the ring more than what would be expected from either a double bond or a linear delocalized π system. The characteristics of an aromatic compound are:

The results are summarized in Table 2. Pleasingly, the results indicated that a range of arylmethyl chlorides with electron-neutral (H), electron-donating (Me and OMe) regardless of their position(s) on the aryl ring, afforded the desired products 2a–i in good to excellent yields. Unfortunately, benzyl chlorides including electron-deficient such as p-chloro and p- nitro groups did not participate in the cross-coupling reaction and desired products 2j and 2k were not detected in the reaction mixtures. Notably, 1,2-bis(chloromethyl)benzene reacted under the optimal conditions, and the corresponding product 3l was obtained in 79% yield. Furthermore, the fused-ring methyl chlorides 1m-o and heteroaromatic methyl chlorides 1p and 1q applied well under this conditions and gave corresponding anhydrides 2m–r in 75-86% yields. The (3-chloroprop-1-en-1-yl)benzene 1x was also smoothly converted to the corresponding carboxylic anhydrides 2x in good

Upon heating, 1,3,5-hexatriene will undergo an electrocyclic ring closure to give 1,3-cyclohexadiene (Scheme 2). 1.1. Stereospecificity of Electrocyclic Reactions Electrocyclic reactions are completely stereospecific. For example, ring closure of (2E,4Z,6E)-2,4,6-octatriene yields a single product with cis methyl groups on the ring. Ring opening of cis-3,4-dimethylcyclobutene forms a single conjugated diene with one Z alkene and one E alkene (Scheme 3).

The structure of pyridine e considerably resembles that of benzene. It may be formally derived from the structure of benzene through the exchange of one ring carbon for a nitrogen but, is pyridine which is structurally and electronically allied to benzene, also aromatic?.

b.Preliminary modification of the lead compound revealed that the introduction of an electron-withdrawing substituent and hydrogen bond acceptor such as NO2 or CF3 at the 3’-position of the phenyl ring or an electron-donating substituent such as OR or COOH at the 4’-position led to an increase of the inhibitory activity. Attempts to replace the nitro group with other electron-withdrawing substituents at the 3-position resulted in identification of the cyano group as the best substituent among other substituents examined. The final structure proposed was found to be febuxustat with high inhibitory activity.

The objective of this experiment was to perform experiment that would nitrate Acetanilide and produce Nitroacetanilide, then also separate the para-directing and ortho-directing products of Nitroacetanilide by an electrophilic aromatic substitution by means of filtration and recrystallization. This lab also demonstrated how electrophilic aromatic substitution works with activating and deactivating groups.