We then added 10cm3 ethanoic anhydride to the salicylic acid and swirled the contents, this mixes together the two chemicals. We then added 5 drops of concentrated sulphuric acid to the flask and thoroughly swirled the mixture, this creates the solution that makes the aspirin. We then warmed the flask for 20 minutes in a 400cm3 beaker of hot water which was approximately 60°C, we made sure the flask did not go above 65°C because this could have caused the contents to evaporate. Part 2: Using a 25cm3 measuring cylinder we measured out 15cm3 of ethanol into a boiling tube and then prepared a beaker half filled with hot water at approx. 75°C, we got this temperature by filling the beaker with cold water and slowly adding boiling water from a kettle until we reached the right temperature.
In the round-bottom flask (100 mL), we placed p-aminobenzoic acid (1.2 g) and ethanol (12 mL). We swirled the mixture until the solid dissolved completely. We used Pasteur pipet to add concentrated sulfuric acid (1.0 mL) to the flask. We added boiling stone and assembled the reflux. Then, we did reflux for 75 minutes.
The experiment began by setting up the LabQuest and preparing a 2M solution of HCl and a 2M solution of NaOH. This was called “Part A”. Two general rules were noted throughout the experiment: add acid to water and pour stock solution into beaker before graduated cylinder. This prevented flash-boiling of the solution, chemical burns, and spills. To make the 2M HCl solution, 200mL deionized water was added to a 600mL beaker labelled “2M HCl” by using a graduated cylinder.
Once a prevalent color change had been observed at approximately 4 minutes (blue green color) the crucible was set on the counter using the tongs to cool for approximately 5 minutes. The appearance after this period resulted in another color change back to white. The crucible, lid, and hydrated copper sulfate was weighed again to calculate the mass of water lost by dehydration (described in table 1.3). This was done by subtracting the final mass by the initial mass of the crucible, lid, and compound. The mass of the crucible would remain unchanged while the mass of the compound would be altered.
Throughout the mixing process, the clear red solution slowly changes to a denser red solution (Appendix figure 23). A thermometer was used for temperature checking. The beaker was removed from the hot plate when the temperature was found to be higher than 50 ℃. This was done to prevent a sudden gelation happen before all the active dissolved in the ethylene glycol. Moderate heating of the solution for a period of time is allowed to obtain a wet gel (Appendix figure 24).
25 mL of a 1 M phenyl magnesium bromide in tetrahydrofuran was dispensed into the beaker by using a syringe. The resulting mixture was stirred for about 15 minutes when the purple color turned into a brown color permanently. It was then extracted first with 20 mL of dichloromethane and the bottom DCM layer containing the product was reextracted with 10 mL of dichloromethane. The final bottom layer was retained and dried with MgSO4. The drying agent was discarded when the mixture was filtered.
The volumetric flask was then filled up to its 100 mL mark with deionized water. The buret was washed out with dionized water and then with the strong base NaOH before being filled up with NaOH. About 20 mL of the unknown weak acid was pipetted into a beaker. The starting volume of the NaOH in the buret was recorded before about 4 mL of the strong base was titrated into the weak acid solution. The final volume was recorded.
when the pH is 7, allow the solution to cool to room temperature. f. Add about 50 ml water to the solution and stir it. Filter the pale blue precipitate in a Buchner funnel.it is observed that the mixture filters slowly, the way to solve the little problem is to stir the precipitate with 50 ml more water. Wash the precipitate with water followed with alcohol. Place the mixture in a petri dish and let it dry in an oven at 140 ˚C for six hours.
The solvents DMF and methanol were distilled for purification. Other chemicals were used as obtained. 2.2 Preparation of polystyrene (PS) Polystyrene prepared by free radical polymerization of styrene monomer. Styrene (1 mole) was taken in a round bottom flask (RBF) fitted with a reflux condenser. DMF was used as a solvent and AIBN (0.5% w/w of total monomer) as free radical initiator .The reaction was carried out at 70±2° C for 6 hour with constant stirring.