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
ABSTRACT The Diels-Alder reaction has been an area of great research interest with regards to enhancing enantioselectivity in the reaction by use of various catalysts and reaction conditions. INTRODUCTION In organic chemistry, a Diels-Alder reaction refers to a 4, 2 cycloaddition between a diene consisting of alternating double bonds and a substituted alkene (the dienophile) resulting in a substituted cyclohexene system. The reaction is often used to reliably control regioselective and enantioselective aspects in organic synthesis. If specific conditions are applied, these reactions can be reversible, with the reverse reaction referred to as the retro-Diels-Alder reaction. Mechanism, Regioselectivity and Enantioselectivity of the Diels-Alder Reaction
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
In the induced fit hypothesis the binding of the substrate changes the shape of the enzyme’s active site. For the lock and key hypothesis the substrate fits the enzymes active site. Then as the bond with the substrate becomes stressed it speeds up the reaction leading it into a chemical reaction with two end products as the
They found that carbon dioxide needed to be activated to build hydroxybenzoic acids with alkali metal phenoxide. They came to this realization by coordinating the alkali metal with the carbon dioxide. This caused the formation of the MOPh-CO2 complex. As the carboxylation reaction proceeded, a direct carboxylation of the benzene ring with another molecule of carbon dioxide did not take place, instead, the CO2 moiety of the MOPh-CO2 complex performed an electrophilic attack on the benzene ring in the ortho and para positions. It was shown that the intramolecular conversion of the MOPh-CO2 complex was the most responsible for the products distribution of the Kolbe-Schmitt reaction.
They are proteins that are complexly folded to allow smaller molecules to fit into them; this active site is where substrate molecules bind. Enzymes must collide with one another at a precise position with enough activation energy. The active site must bind to the reacting molecule, or the substrate (1). Enzyme-catalyzed reactions require lower activation energy. The activity of an enzyme is affected by its environmental factors, and any change results in an alteration in the rate of the reaction caused by the enzyme (2).
Enzymes are homogeneous biological catalyst that work by lowering the activation of a reaction pathway or providing a new pathway with a low activation energy. Enzymes are special biological polymers that contain an active site, which is responsible for binding the substrates, the reactants, and processing them into products. As is true of any catalyst, the active site returns to its original state after the products are released. Many enzymes consist primarily of proteins, some featuring organic or inorganic cofactors in their active sites. However, certain ribonucleic acid (RNA) molecules can also be biological catalysts, forming ribozymes.
pruriens seed extract and FeMPn were characterized with FTIR to determine the biomolecules contained in the extract that involved in the reaction to form FeMPn. The FTIR spectra of the extract and FeMPn are shown in Fig. 5. The FTIR spectrum of the extract showed a broad absorption band in an absorbance area of 3384.8 cm-1 that assigned to the overlapping of O-H stretching vibration of flavonoids, alkaloids, polyphenols, alcohols or water and N-H stretching vibration of amine compounds, due to the hydrogen bonding. The absorption band at 1627.8 cm-1 referred to C=C stretching vibration which is possible to be derived from aromatic ring in amino acid, while the absorption band in 1529.4 cm-1 referred to N-H bending vibration of amine which is possible to be derived from the L-dopa.
Introduction 1.1 Aim: To determine the kinetic parameters, Vmax and Km, of the alkaline phosphatase enzyme through the determination of the optimum pH and temperature. 1.2 Theory and Principles (General Background): Enzymes are highly specific protein catalysts that are utilised in chemical reactions in biological systems.1 Enzymes, being catalysts, decrease the activation energy required to convert substrates to products. They do this by attaching to the substrate to form an intermediate; the substrate binds to the active site of the enzyme. Then, another or the same enzyme reacts with the intermediate to form the final product.2 The rate of enzyme-catalysed reactions is influenced by different environmental conditions, such as: concentration
Additionally, there exists three domains of the enzyme namely C- terminal catalytic domain, an N- terminal regulatory domain and a tetramerization domain. Tetrahydrobiopterin (BH4) acts as a cofactor for the enzyme activity. Hence, the regulatory action by PAH enzyme involves activation by the presence of the amino acid phenylalanine, inhibition by the cofactor Tetrahydrobiopterin (BH4) and activation of the enzyme by phosphorylation. Cyclic adenosine monophosphate (cAMP) – dependent protein kinase helps in the phosphorylation of the amino acid serine that is present on the 16 position of the regulatory domain of the enzyme. This in turn helps in maintaining the activity of the enzyme by reducing the concentration of the phenylalanine