3. The following solvent selection data were collected for an impure sample of s

Question

3. The following solvent selection data were collected for an impure sample of solid compound A (mp 68 °C). Solvent Solubility solubility at BP crystals upon cooling? C Insoluble at RT Methanol (bp 65 Chloroform (bp 61 Insoluble soluble Cyclohexane (bp 81 Insoluble soluble Very few Many Dichloromethane (bp 41 Insoluble slightly Soluble Soluble Toluene (bp 111 C) Tvery few Based on these results, what solvent would you choose for your recrystallization? E your answer. (6 4. The goal of recrystallization is to obtain a purified sample with minimal loss of yield. Explain why this goal would be adversely affected by the following: a. An unnecessarily large volume of recrystallizing solvent was used. (5 pts) b. The flask was shaken while cooling to accelerate crystallization. (5 pts) c. The flask was not put on ice prior to filtration/centrifuging. (5 pts) Page 919

Explanation / Answer

Hi

3. Chloroform (bp= 61 C) is a good choice for the recrystallization of of compound A (bp= 68 C) beacuse of the following reasons...

a) It has lower boiling point than compound A, so compond A can be dissolved in chloroform.

b) Upon recrystallization it forms very few crystals, which means the impurity in the solute after its recrystallization will be very less.

Thank you

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