Chemistry Homework Help

Question

A reaction was performed in which 0.500 mLof p-anisaldwhyde was reacted with a slight excess of benzyltriphenylposphonium chloride to make 0.573 g of p-methoxystilbene. Calculate the theoretical yield and percent yield of this reaction

Answer 1

Hi Andrea!

Looks like we have a lab-style question on our hands! For a question like this, there's a few things that we're going to need -- particularly some physical properties of the reagents we're using. These all came from the Sigma-Aldrich website.

p-anisaldehyde: (abbrev. p-A)

density: 1.119 g/mL

MW: 136.15 g/mol

p-methoxystilbene: (abbrev p-MS)

MW: 210.27 g/mol

So in order to calculate a theoretical yield, we would have to do so by starting with the limiting reagent, the p-anisaldehyde, and work our way to the final amount of p-methoxystilbene we could produce. So let's start with the .500mL and work our way to the end!

0.500 mL p-A * (1.119 g p-A / 1 mL p-A) * (1 mol p-A / 136.15 g p-A) * (1 mol p-MS / 1 mol p-A) * (210.27 g p-MS / 1 mol p-MS) = g p-MS (theoretical)

Which works out to be...0.864g p-methoxystilbene, theoretically.

Finally, we get to do a simple calculation for yield!

% Yield = (Actual yield / theoretical yield) * 100

% Yield = (0.573 g p-MS / 0.864 g p-MS) * 100 = 66.3% yield

Not great, but good enough! Hope that helps!

Niral