-some of you made red-colored Co(salen), while others made brown-colored Co(sale
ID: 563886 • Letter: #
Question
-some of you made red-colored Co(salen), while others made brown-colored Co(salen). The difference is due to different amount of O2 incorporated into the reaction to make (salen)Co-O-O-Co(salen). The red compound has less O2 and usually forms when the temperature is higher. (1) Why you did not see the same phenomenon last week for the synthesis of Ni(salen)? (2) Why higher temperatures favor the product with less O2 incorporated? (3) Assuming you made pure (salen)Co-O-O-Co(salen), how would that affect your calculated isolated yield?
Experiments:
1)
In an Erlenmeyer flask, stir 5 mmol H2salen (1.34 g) in 30 mL of methanol under reflux (boiling).
Add 5 mmol nickel(II) acetate tetrahydrate [NiII(OAc)2•4H2O, 1.24 g] slowly.
After stirring for 10 min, let the solution cool to near room temperature.
Recover the solid product by suction filtration through filter paper in a Buchner
funnel on a filter flask. Rinse with diethyl ether.
Determine the yield of the dry solid.
2)
In a 250 mL Erlenmeyer flask, stir 5 mmol H2salen (1.34 g) in 40 mL of ethanol under reflux (boiling).
Add 5 mmol cobalt(II) acetate tetrahydrate [CoII(OAc)2•4H2O, 1.24 g] slowly.
After stirring for 30 min, let the solution cool to near room temperature. Pay
attention to the color change during this step.
Recover the solid product by suction filtration through filter paper in a Buchner
funnel on a filter flask. Rinse with diethyl ether.
Determine the yield of the dry solid.
Explanation / Answer
Yield can be calculated by above formula but product yield has not given. Hence you can also calculate product yield by predicting product structure and mass. At high temperature gas molecules has high kinetic energy, there fore incorporation will be less.
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