Discuss the mechanisms of all reactions you have performed in this synthesis. Determine the yield for each step, and the overall yield (from benzoic acid).
Draw mechanisms for the two most important reactions:
Fischer Esterification, which converted benzoic acid into methyl benzoate.
Grignard addition/substitution, which converted methyl benzoate and phenylmagnesium bromide into triphenylmethanol (remember to include protonation, which was a separate reaction step!
Include curly arrows in your reaction mechanisms as appropriate.
Remember that yield calculations involve mole ratios, not simply mass ratios!
To determine the yield of each step, ask yourself:
What was the starting material (limiting reagent)?
What was the product?
How many moles of the starting material become part of each mole of product?
To calculate the overall yield, multiply the yield of the first step by that of the second step. For example, if your first step had a yield of 50% and your second step had a yield of 40%, your overall yield is 50% × 40% = 20%.
One way to think of it is this: you got 50% of the expected initial product, so only 50% of your starting material was recovered. You got 40% in the second step, so the amount of your initial starting material recovered was 40% of 50%, or 20%.
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