The purpose of this experiment is to perform a Friedel-Crafts reaction of ferrocene. Friedel-Crafts reactions are examples of electrophilic aromatic substitution reactions in which the electrophile is a carbocation or an acylium ion. These reactions form a carbon-carbon bond and allows for either an alkyl or acyl group to be substituted onto an aromatic ring. Figure 1 shows the general mechanism for the Friedel-Crafts acylation of benzene. First, the alkyl halide reacts with a strong Lewis Acid catalyst, usually aluminum chloride, to form a complex, which will then lose the halide to the Lewis acid to give the electrophilic acylium ion.
The principal product in this case is R-Nuc. In such reactions, the nucleophile is usually electrically neutral or negatively charged, whereas the substrate is typically neutral or positively charged. An example of Nucleophilic substitution is the hydrolysis of an alkyl bromide, R-Br, under basic conditions, where the attacking nucleophile is the base OH− and the leaving group is Br−. R-Br + OH− → R-OH + Br− Nucleophilic substitution reactions are commonplace in organic chemistry, and they can be broadly categorized as taking place at a carbon of a saturated aliphatic compound carbon or (less often) at an aromatic or other
The Wittig reaction is valuable reaction. It has unique properties that allows for a carbon=carbon double bond to form from where a C=O double bond used to be located. Creating additional C=C double bonds is valuable due to its use in synthesis. The Wittig reaction will allow the synthesis of Stilbene (E and Z) from a Benzaldehyde (Ketcha, 141). 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).
Michael Bent Mohamed Mire CHEM 220-12 4/13/2016 Methyl Benzoate Labs The first part of the lab regarded an esterification leading to the formation of Methyl Benzoate (C8H8O2). The purpose of this lab was to convert benzoic acid to methyl benzoate by means of utilizing a reflux acid catalyzed reaction with methanol; purity of the final product was assessed by means of both proton and carbon NMR. The extent to which a reaction’s products are reverted back into the original reactants is denoted by the equilibrium constant. The esterification reaction that's taking place in this lab has a low equilibrium constant (about 2.3) which means that a very low yield of the methyl benzoate product would be generated. There are a couple of mechanisms that
TLC, NMR, and IR spectroscopy were used throughout the process to identify ferrocene and acetylferrocene in addition to evaluating the levels of purity. Evidence: The objective of our experiments was to prepare acetylferrocene from ferrocene. The overall reaction was carried out using 6.1 equivalents of liquid acetic anhydride to 1.8 equivalents of phosphoric acid and concluded with an aqueous workup with NaOH. The initial reaction mixture containing ferrocene, acetic anhydride, and phosphate acid was mixed on a hot stir plate. During this period, reflux was observed, and the mixture appeared dark brown in color.
Since alkenes are immiscible with concentrated HBr, tetrabutylammonium bromide is used as a phase-transfer catalyst. It forms a complex with HBr and extracts it from the aqueous phase into the organic phase where the alkene is. This dehydrates the acid, making it more reactive so that the addition reaction is possible. Rapid stirring is required in order to maximize the surface area
3. To purify and identify the product, recrystallization is used in order to purify the product, then melting point and TLC techniques are used to identify the product. Theory 4. In nucleophilic substitution reactions, there are two possibilities, either Sn1 or Sn2. In this particular experiment, an Sn2 reaction
The structure of benzocaine included an aromatic ring and amine group. The reaction to synthesize benzocaine was known as a Fisher esterification reaction. The Fisher esterification was reaction between alcohol and carboxylic acid in the presence of acid. The reaction was used to form an ester. In the experiment, sulfuric acid acted as a catalyst and necessary for this reaction to occur.
The first step is where the substrate enters the active site on the enzyme. It is held there by hydrophobic interactions between the exposed non-polar groups of the enzyme residues and the side chain of the substrate. The second step is where the hydroxyl group on Serine 195, aided by the histidine-serine hydrogen bonding, preforms its nucleophilic attack on the carbonyl carbon of an aromatic amino acid. While this happens, it also transfers the hydroxyl hydrogen to the histidine nitrogen. The nucleophilic attack pushes the carbonyl electrons onto the carbonyl oxygen, which forms a short-lived intermediate.