The lab begins with reflux of the reaction to form an ester followed by several extractions from an organic layer. To purify the ester the compound is dried by gravity filtration with a drying agent, distilled using simple distillation, and recrystallized. The aldol condensation is reacted in a test tube and the solute is collected via vacuum filtration and recrystallized. The esterification procedure was performed first. To begin the lab, the heating mantle was set at the 6 setting, and the hot plate heat was turned on to low. In a round bottom flask, 6.1 g of benzoic acid and 21 mL of MeOH were added into the flask. Once this was added to the flask, 2 mL of sulfuric acid was added and poured carefully down the side of the flask. It was noted that after the addition of the sulfuric acid there was heat production in the flask. The contents were swirled and a boiling chip was added into the flask. The flask was connected to the hood by a clamp. Water was then ran through the condenser and connected to the round bottom flask to begin refluxing the contents in the flask. The mixture was gently heated at reflux for one hour. While the esterification reaction was under reflux, the aldol condensation procedure was performed. The hot plate was turned to The washes needed to be performed and during this lab it was important to make sure that no aqueous layer remained in the organic layer. This is important for when the final product is distilled in an air tight condenser (with no water flow). The temperature would have gotten fairly high that the water either would’ve distilled out before the final product or would have caused the glassware to break due to temperature difference occurring in the setup. A better yield could have been achieved during the drying of the product, which facilitated some loss of product if there would have been some aqueous layer remaining in the organic
Perhaps, a different drying agent may also be used like MgSO4. Another improvement may be to use a curved Pasteur pipette to remove the appropriate liquid. Using a test tube to add anhydrous sodium sulfate resulted in the drying agent being on the sides of the tube. Hence, to improve this error, a glass with a flat bottom may be used.
Step 6: The ethyl ester on (20) is hydrolysed using concentrated sulphuric acid in a refluxing 1:1 acetic acid/water mixture.
The most classic and standard procedure for producing esters is the Fisher-esterification reaction. Discovered in 1895 by German chemists Emil Fischer and Arthur Speier 4, this reaction involves refluxing a carboxylic acid and an alcohol in the presence of an acid catalyst. In order to drive the equilibrium towards the products, the water from the dehydration process must be removed and there must be an excess amount of alcohol. A vast range of carboxylic acids may be used for this reaction however the type of alcohols are limited. Primary and secondary alcohols are most frequently used in esterification reactions, tertiary alcohols are steric ally hindered usually resulting in poor yields5 and tend to undergo elimination reactions instead. In this rea...
The solvent should be easily removed from the purified product, not react with the target substances, and should only dissolve the target substance near it’s boiling point, but none at freezing. A successful recrystallization uses minimum amount of solvent, and cools the solution slowly, if done to fast, many impurities will be left in the crystals. Using the correct solvent, in this case ice water and ethyl acetate, the impurities in the compound can be dissolved to obtain just the pure compound. A mixed solvent was used to control the solubility of the product. The product is soluble in ethanol an insoluble in water. Adding water reduced solubility and saturates the solution and then the crystals
As a final point, the unknown secondary alcohol α-methyl-2-naphthalenemethanol had the R-configuration since it reacted the fastest with S-HBTM and much slower with R-HBTM. TLC was a qualitative method and ImageJ served as a quantitative method for determining which reaction was the faster esterification. Finally, 1H NMR assisted in identifying the unknown from a finite list of possible alcohols by labeling the hydrogens to the corresponding peaks.
Fischer Esterification is a unique type of esterification first discovered by Emil Fischer and A Speier in 1895. Fischer Esterification is a mechanism of which an ester is formed as a product when a carboxylic acid is treated with an alcohol and an acid catalyst. Together with ester, water is also liberated on this reaction. The key bonds formed in this reaction is C-OR, of which the oxygen bonded to carbon is the oxygen from the alcohol, not the oxygen originally bonded to it from the starting carboxylic acid. The key bonds broken is C-OH, the oxygen from the carboxylic acid bonds with the hydrogens that will then form water. So, the reaction does not simply just break the H and the R but rather -OH and -OR. This reaction is an equilibrium reaction. Applying Le Chatelier’s principle, if alcohol is used as a solvent to carboxylic acid and have a small amount of water (product), then the reaction would favor the product. On the other hand, if the reaction is to go backwards, whereas the reaction would start from an ester going to a carboxylic acid, then the water would be used as a solvent. Common acid catalyst are sulfuric acid, tosylic acid, and Lewis acids such that of scandium(III) triflate. Tertiary alcohols are prone to elimination whereas phenols
In biology class, we were learning about enzymes. Enzymes are proteins that help catalyze chemical reactions in our bodies. In the lab, we were testing the relationship between the enzyme catalase and the rate of a chemical reaction. We predicted that if there was a higher percentage of enzyme concentration, then the rate of chemical reaction would increase or it would take less time. We placed 1 ml of hydrogen peroxide into four depressions. Underneath the first depression, we place 1 ml of 100% catalase and make 50% dilution with 0.5 ml of water. We take 50% of that solution and dilute with 0.5 ml of water and we repeat it two more times. there were four depressions filled with catalase: 100%, 50%, 25% , 12.5 % with the last three diluted
In step one, a 0.1 grams of 4-t-butylcyclohexanone and 0.2 mL of methanol was placed into a long-neck round-bottom flask. The contents were swirled and a boiling chip was placed. 0.023 grams of NaBH4 was weighed to prepare the sodium borohydride solution. Once ready, 0.6 mL of the sodium borohydride solution was added to the apparatus. The reaction was allowed to proceed for about ten minutes. During this time, 0.5 mL of 1 N HCL was chilled in a small dram vial. Once the reaction was complete, using a pipette the cold hydrochloric acid was added to the flask. In step nine, the solution was extracted three times using 0.5 mL increments of methylene chloride. To do this the contents from the flask were washed with one 0.5 mL increment
Ø Then pour the catalyst into a test tube along with the H O and
Ensure gloves are worn at all times when handling strong acids and bases within the experiment of the preparation of benzocaine. 4-aminobenzoic acid (3.0g, 0.022 moles) was suspended into a dry round-bottomed flask (100cm3) followed by methylated sprits (20 cm3). Taking extra care the concentrated sulphuric acid of (3.0 cm3, 0.031 moles) was added. Immediately after the condenser was fitted on, and the components in the flask were swirled gently to mix components. It should be ensured that the reactants of the concentrated sulphuric acid and the 4-aminobenzoic acid were not clustered in the ground glass joint between the condenser itself and the flask. In order to heat the mixture to a boiling point, a heating mantle was used and then further left for gently refluxing for a constituent time of forty minutes. After the duration of the consistent forty minutes the rou...
In this lab, it was determined how the rate of an enzyme-catalyzed reaction is affected by physical factors such as enzyme concentration, temperature, and substrate concentration affect. The question of what factors influence enzyme activity can be answered by the results of peroxidase activity and its relation to temperature and whether or not hydroxylamine causes a reaction change with enzyme activity. An enzyme is a protein produced by a living organism that serves as a biological catalyst. A catalyst is a substance that speeds up the rate of a chemical reaction and does so by lowering the activation energy of a reaction. With that energy reactants are brought together so that products can be formed.
A condensation reaction is a reaction where two molecules react to form a larger and smaller molecule (Boundless 2016). A type of condensation reaction is an esterification reaction generally when an alcohol reacts with a carboxylic acid. However, esters can also be created from phenols but requires a vigorous ethanoylating agent such as an anhydride (York, 2000). In the synthesis of aspirin, the phenol mentioned is salicylic acid. The structure of a basic phenol is shown in figure 3 and figure 4 shows the structure of salicylic acid where the phenol group can easily be seen. The required anhydride for the reaction is acetic anhydride. Similarly, figure 6 shows the general structure of an anhydride and figure 5 shows the structure of acetic anhydride. It can be clearly seen that the basic structure of an anhydride is present in acetic anhydride. Therefore, the phenol molecule of the reaction is salicylic acid and the anhydride is acetic anhydride, reacting together to produce the ester of acetylsalicylic acid. The structure of acetylsalicylic acid is shown in figure 7, a combination of a phenol and one side of the anhydride. The other side of the anhydride is the second product which is acetic acid; a by-product of the
Base catalysts are highly sensitive to water content due to soap formation which makes separation difficult. Acid catalyst are used when the acid values of the non-edible oils are higher than the performance range of base catalysts. The acid value represents the number of acidic functional groups and is measured in terms of the quantity of potassium hydroxide required to neutralize the acidic characteristics of the sample. The protonation of the carbonyl group of the ester promotes the formation of a carbocation, which after nucleophilic attack of the alcohol produces a tetrahedral intermediate. This intermediate will eliminate glycerol to form a new ester and to reform the catalyst. Acid-catalyzed transesterification are carried out in the absence of water. The problems with the use of these catalysts are: the requirement for more alcohol; slower reaction rates; higher reaction temperatures and pressures; reactor corrosion and environmental issues. Both homogeneous and heterogonous acid catalysts can be used for transesterification. The acid catalysts more commonly used include, sulfuric acid, hydrochloric acid, phosphoric acid, and sulfonated organic acids. Due to the fact that the FFA content of neat edible oils is normally low but these oils are costly and conversion of too much edible oil into biodiesel may cause food crises, use
The aim of this experiment was to investigate the affect of the use of a catalyst and temperature on the rate of reaction while keeping all the other factors that affect the reaction rate constant.
The process need toluene and hydrogen as a main reactor. Then, toluene and hydrogen are converted in a reactor packed with catalyst to produce benzene and methane. This reaction is exothermic and the operating conditions are 500 0C to 660 0C, and 20 to 60 bar of pressure. This process begins with mixing fresh toluene with a stream of recycle unreacted toluene, and the mixing is achieved in a storage tank. Then, the toluene is pumped to combine it with a stream of mixed hydrogen and fresh hydrogen gas. The mixture of toluene and hydrogen is preheated before it is introduce to the heater or furnace. In the furnace, the stream is heated to 600 0C, then introduced into the reactor. Basically, the main reactions occurs in the reactor.