ATTN: answers to the below questions are due at the start of your second meeting (1/10 or 1/11); these answers should be part of your pre-lab write-up. The first quiz will be administered in lecture on Tuesday 1/15/2008 at 12 pm (covering step 2, step 3 and the introduction to asymmetric synthesis). Please make sure that you arrive on time. Late arrivals will not be allowed into the class room until the quiz is finished, which means that you will receive an automatic zero score for the quiz. If you do not place your name on the quiz to assume authorship, which happened twice last quarter, you will receive a zero score as well!

1. Referring to step 2 (Synthesis of 2,4-Di-tert.-butyl-6-hydroxymethylphenol), answer the following questions.

a. In the initial part of the reaction, the sodium hydroxide has to be dissolved in the solution of the phenol in methanol. How can the process be accelerated? Why should a small flask be used here that is sealed off?

b.The mixture has to be chilled prior addition of the 36% formaldehyde solution. Explain briefly why. Which precautions should be taken when working with formaldehyde?

c. After the reaction is deemed to be complete (~20-24 hr), the reaction mixture (usually a golden-brown solution) is poured into water and the mixture then acidified using 36% hydrochloric acid. Rationalize this step and provide pertinent chemical equations.

d. After extraction with dichloromethane, the combined organic layers are extracted with sodium bicarbonate and water. Explain briefly.

e. How is the solution dried during the workup?

f. Why is it important to remove the solvent at low heat using an air stream?

f. Sketch the TLC plate (SiO₂, CH₂Cl₂/hexane (1:1)) with the desired product in lane 1, the starting phenol in lane 2 and the salicylaldehyde (product from step 3) in lane 3. What would change if the solvent mixture used would be CH₂Cl₂/hexane (1:2)? What is the purpose of this step when performed on the crude product? How would the result change if the student would only use hexane for this step?

g. The crude product is recrystallized from hot hexane. Rationalize this choice.