ATTN: answers to the below questions are due at the start of your second meeting (10/2 or 10/3); these answers should be part of your pre-lab write-up. The first quiz will be administered in lecture on Monday 10/8/2007 at 10 am. Please make sure that you arrive on time. Late arrivals will not be allowed into the class room since they disturb the rest of the class!!

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

a. The procedure mentions to crush the sodium hydroxide. Why is this done? What has to be kept in mind here?

b.Why is it imperative to seal off the flask carefully during the reaction?

c.Why is the mixture cooled down prior to adding the 36% formaldehyde solution? Which other precautions should be taken when working with formaldehyde?

d. After the reaction is completed, 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.

e. Why is hexane not a good solvent for extraction here?

f. After removing the solvent, student A observes a viscous liquid as their crude product, while student B obtains a pale yellow solid. Explain briefly. How should each of these students proceed?

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 (2:1)? What is the purpose of this step when performed on the crude product?

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

2. Theory of asymmetric synthesis

a. Asymmetric synthesis is a very active field in research. Explain briefly why and give two examples.

b. Many syntheses in this field utilize the chiral pool. What does this mean? Give two examples from the literature (not the reader!)

c. What is a chiral auxiliary and how is it used?

d. What is the difference between "Cram Rule" and "Cram's chelate model"?