Week 8 Condensed Answer Key

1. a. 3

b. 6

c. 3

d. 0

2. a.

b.

c.

d.

3. absolute ethanol is essentially 100% ethanol and 95% ethanol has 5% water in it.

4. The rinse is to wash off impurities that adhere to the surface of the tetraphenylcyclopentadienone crystals (Analogy: like hosing off the dust (impurities) on your car after a smoggy day in Los Angeles). Ice-cold ethanol was used to minimize as much as possible the loss (rinsing through) of product.

5. Two equivalents of water are given off in this week's aldol reaction. Adding water to the reaction would shift equilibrium to the left.

6. 12.5 mL

7. The product is not that soluble in ethanol. Conversely, the product is very soluble in toluene at all temperatures. Either one is a poor choice of a solvent for recrystallization. [However, by combining the two solvents in a 1:1 mixture a steep solubility curve is obtained and thus an excellent solvent system of recrystallization.