Compare the appearance, mass and melting point ranges of your crude and recrysta

Question

Compare the appearance, mass and melting point ranges of your crude and recrystallized (final) product. Citing experimental and literature evidence, can you conclude that recrystallization increased the purity of your product? What can you attribute the change in mass from crude to recrystallized product if, in general, the crude product from this reaction contains few impurities? Do you think your product was pure after recrystallization? What evidence helps you make conclusions about the quality of your final product?

Explanation / Answer

Aldol reaction of 3,4-dimethoxybenzaldehyde and indan-1-one

3. From the given data for the crude and the recrystallized product,

the product purity was increased by recrytsallization. This is apparent from the melting point of the recrystallized product which is closer to the expected melting point from literature 178-181 oC. The appearence of of compound from dark brown (with impurity) to light yellow also confirms the purity of the material.

4. moles of 3,4-dimethoxybenzldehde = 0.250/166.176 g/mol = 0.0015 mol

moles Indan-1-one = 0.200 g/132.16 g/mol = 0.0015 mol

theoretical yield of the product = 0.0015 mol x 280.3 g/mol = 0.420 g

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