Cool the filtrate to room temperature, add 1.5 g of sodium nitrite, and stir until reaction is complete. 5. Pour this mixture, while stirring, into a beaker containing 25 mL of ice water to which 5 mL of concentrated hydrochloric acid have been added. The diazonium salt of sulfanilic acid should soon separate as a finely divided white precipitate. Keep this suspension cooled in an ice bath until it is to be used.
It is to prevent the cell from washing away during the staining and washing process. Then, it is air dried and followed by fixing it with flame from Bunsen burner. After fixing the smear, it must be stained using Gram staining solution, firstly crystal violet solution was flood onto it, and allowed for 1 minute, then wash off with tap water. Then, flood the slide with iodine solution for 1 minute and wash it off with tap water again. The formation of a dye-iodine complex will occur in the cytoplasm.
22.5 g of plate count agar powder was dissolved in a litre of sterile distilled water on the hot plate 2. pH of the solution was adjusted to 7.0 ± 0.2 by adding NaOH or HCl and was immediately transferred into the Schott bottle to be autoclaved at 121 ° C for 15 minutes 3. Prepared medium was stored in 4° C chiller Lauryl Sulphate Broth
After completion of the solubility tests, the appropriate solvent, cyclohexane, was selected for large-scale recrystallization. The unknown was weighed for the large-scale recrystallization then the same process was repeated to test the solubility. The solute dissolved after adding of about 60 mL of solvent, it was set aside to cool to induce crystal reformation. The solution was then seeded and set alone once more. When the process was complete, the crystals
Upon finding the actual concentrations of salicylic acid, concentration of aspirin in the flask at various times can be found using the equation [aspirin]t = [aspirin]0 – [salicylic acid], since at constant volume, number of moles of initial aspirin decrease to form salicylic acid. Initial concentration of aspirin formed as follows: [aspirin]0 = 0.212g / (180.157gmol-1 * 50/1000 L) = 0.0235 mol L-1. Thus using the first test as sample, [aspirin]t = 0.0235 – 9.981*10-4 = 0.0225 mol L-1. To find the rate constant, we will need to log the value of [aspirin]t and plot it against time to find the rate constant. Figure 1 shows the diluted and actual concentrations of salicylic acid, the concentration and log value of aspirin at various times.
1 “substrate” and another “ enzyme.” Instead of using the distilled water, this time you are going to use different pH buffer in the enzyme test tube. In the substrate tube, add 7 mL of distilled water, 0.3 mL of hydrogen peroxide, and 0.2 mL of guaiacol for a total volume of 7.5 mL. For the enzyme tube, instead of distilled water add the pH solution (3) and 1.5 mL of peroxidase which equals a total volume of 7.5 mL. Use the dH2O syringe for our pH solution. To clean the syringe, flush it by drawing 6 mL of distilled water.
Once cool to touch the squeeze out all the tea bags carefully without tearing them apart. Using a separatory funnel extract three times with 15.0ml of dichloromethane gently rocking bath and forth the funnel venting the funnel often each time. Carefully decant into a pre-weighed 125ml flask and add the drying agent-calcium chloride pellets- and the organic layer was evaporated off in a warm water bath. Using aluminum foil as support around the mouth of the flask place test tube in the flask and heat the flask on a hot plate whilst adding water into the tube without letting it boil. Once the caffeine forms crystals around the test tube scrape off all the sublimed product and weigh the dried product 0.1grams of caffeine and had a melting point range of 175-230
V. Results and Discussion One of the objectives of this exercise is to synthesize acetylsalicylic acid (aspirin) from salicylic acid. The mechanism for this synthesis is through nucleophilic acyl substitution. Acetic anhydride was the acetylation reagent used with the salicylic acid. The mechanisms and the reaction involved in the synthesis are seen in the following figure. 1.00 gram of fine white salicylic acid powder was weighed in a clean, dry 125mL Erlenmeyer flask.
2) Purification of caffeine by sublimation The crude caffeine was transferred to Petri dish. Petri dish was placed on a hot plate and covered with three disks of filter paper. Another petri dish filled with ice was placed just on the top of petri dish covered with filter papers. The heat was turned on and sublimation was performed for 5 minutes. The purified caffeine was scraped from the filter papers and its weigh was measured.
The residual biomass was separated by filtration and washed with distilled water. For alginate extraction, the acidified algal biomass was suspended in 3% Na2CO3 solution at different alkali: alga ratio (20, 40, and 60 mL/g). The different extraction temperatures ranged from 25 to 45º C, and lasted for 1 to 3 h. For each experimental run, sodium alginate was collected by filtration and precipitated with absolute ethanol (1:2 v/v). The mixture was maintained at 4º C overnight. The precipitate was collected by vacuum filtration and allowed to dry at room temperature.