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
An enzyme is a biomolecule that acts as a catalyst in biochemical reactions (1). Enzymes are commonly used in many products and medications. Enzymes function by flexibly binding to active sites in substrates (reactants). This binding is weak non-covalent interactions. The Michaelis Menten model is used to show the relationship between velocity and substrate concentration, such as in figures four and five.
Lipase catalysed synthesis of sucrose erucate on different enzyme concentration was investigated over the range from 2% to 14%. It is obvious that effective mixing of reactants and enzyme is important to provide good contact of substrates. The optimum enzyme concentration highly depends on stirring speed also. With increasing lipase concentration the percentage esterification of sucrose erucate increased (Figure). It was found that when the lipase concentration was---, the conversion reached---.
While the primary active transporters of the ABC superfamily utilize ATP hydrolysis for energy, the RND family (and the other superfamilies) derive their required energy for by proton motive force. It is this energy that is used in the extrusion of compounds (15). 2.1 Efflux pumps in P. aeruginosa (MexAB-OprM efflux system) The RND efflux pumps are most commonly found in Gram negative bacteria like P. aeruginosa. There are several
Alkaline phosphatases (ALP), members of the phosphomonoesterase family, hydrolyze the oxygen-phosphorus bond of organophosphates using metal ions to release an inorganic phosphate under alkaline conditions.1,2 These enzymes are dimeric metalloenzymes containing two Zn2+, one Mg2+, and a serine residue in the active site of each monomeric subunit, in both prokaryotes and higher eukaryotes.2,3 Studies have shown that the three divalent cations are essential for enzymatic activity to catalyze the formation of an alcohol and an inorganic phosphate (Figure 1). In E. coli, the zinc ions are positioned to activate the serine and water for nucleophilic attack and ultimate cleavage of the bond, in addition to holding the phosphate moiety of the substrate. The magnesium ion has been suggested to stabilize the transferred phosphoryl group by a water molecule, using a separate mechanism by which the zinc ions function.3 Although ALPs are found widely in nature and function similarly on the biochemical level, there are locational
o For all three trails the H202 solution in water increase by 10˚C in terms of before and after yeast is added. o The third trial has the same trend of increase as the first two but begins and ends with a 1˚C higher than the previous trials. Data processing: Number of moles for the hydrogen peroxide (H202) 34.02 = Mr Mass = 20g x 0.03 = 0.6 0.6÷34.02 = 0.017 moles Conclusion: What was learned in this lab is temperature rises when a hydrogen peroxide solution in water is activated by yeast. The hypothesis is supported by the data. Referring to what was stated, the Hydrogen peroxide solution did change based yeast that activated the solution, many were similar in temperature.
• Serine, threonine and cysteine proteases use a nucleophilic residue (usually in a catalytic triad). That residue performs a nucleophilic attack to covalently link the protease to the substrate protein, releasing the first half of the product. This covalent acyl-enzyme intermediate is then hydrolysed by activated water to complete catalysis by releasing the second half of the product and regenerating the free enzyme. A comparison of the two hydrolytic mechanisms used for proteolysis. enzyme is shown in black, substrate protein in red and water in blue.The top panel shows 1-step hydrolysis where the enzyme uses an acid to polarise water which then hydrolyses the substrate.
The data also describes that as the catalyst quantity increases, the solubility of the product in MTO decreased. The 5 increasing trend of hydroxyl value and decreasing trend in product solubility indicates that the degree of polymerization increases with catalyst loading. As the catalyst concentration increases, the decrement was observed for iodine values of the products. 3.5 FTIR analysis of the cyclohexanone monomer and product sample Functional group in a polymer is an important characteristic to play a vital role on film formation properties of a resin. To confirm the presence of hydroxyl group in the product sample, FTIR analysis was performed for both monomer and product samples.
5a). The silanol thus formed on the silane undergo condensation reaction with hydroxyl groups on the fiber surface and silanol on nano-silica forming a crosslinked network structure (Fig. 5b). In the case of APS, the NH2 group of APS interacts with the -OH groups on silica forming a polyaminosiloxane network containing more than two APS units. The peak observed in FTIR at 1560 cm-1, which is attributed to the deformation mode of amino group in APS forming hydrogen bond with silanol, confirm this observation.
As the concentration increases from 0.1 to 0.3% enrichment ratio and percentage removal too increases from 76.13823 to 89.19364 and 0.97202 to 2.07789. Surfactant concentration of 0.3% was finalized as the optimum surfactant concentration as further increase blows off the entire volume of aqueous solution out of the foam separation column. As the surfactant CTAB concentration increases percentage removal too increases and this is because aqueous phenol is slightly acidic and cationic surfactant attracts anionic phenolate and hence an increased surface activity too. Subsequently as the surface is saturated, further increase in CTAB concentration significantly slow down the rate of drainage of the foam and surplus surfactant can form the micelles. Therefore, the phenol percentage removal reduced to 80.03291 and 1.19199 with increase in the surfactant concentration after a certain level