Procedure:
1. A 25 mL round bottom flask equipped with a stir bar is loadedwith 13 mg of CdO powder, 0.6 mL of oleic acid, and 10 mL of1-octadecene. The reaction flask is placed into a heating mantleand surrounded with aluminum foil so that the temperature can reach225 °C, which will take approximately 1 hr. Some hot plates mayheat up faster and the experiment can be performed sooner.
2. As the CdO solution is heating, the Se solution should beprepared. Five students can share the Se solution, since only 1 mLis required for each reaction. A 25 mL round-bottom flask equippedwith a stir bar is loaded with 30 mg of Se and 5 mL of 1-octadeceneand allowed to stir at room temperature. To this stirred solutionwas added 0.4 mL of trioctylphosphine via syringe. The mixture willturn homogeneous. At this point it is ready for the next step.
3. Once the CdO solution has reached a temperature of about 225°C, add 1 mL of the Se solution from step 2 in a rapid fashion. Assoon as you add the Se solution start collecting samples ofapproximately 1 mL into separate test tubes continuously as thereaction will be changing colors from yellow to orange to bloodred.
4. After allowing the quantum dot solutions to cool, add 1 mL ofpentane to the test tube containing ~1 mL of sample. Then, pipettethe samples into a glass cuvette to record their UV-Vis spectra.Use pentane as the blank. The solutions collected in test tubes canbe stored overnight in the hood or drawer without decomposition ifthere is not enough time to record UV-vis spectra.
What reaction is occurring when the selenium dissolves aftertrioctylphosphine is added?
