Question

Calculate the theoretical yield 2-step synthesis from trans-cinnamic acid to phenylpropynoic acid, using the trans-cinnamic as the limiting reagent in your calculations. pls show all the calculations.

Answer 1

Suppose if we take starting as 1g of trans-cinnamic acid , then the theoritical yield calculation as follows:

Step-1:

Number of moles of trans-cinnamic acid = 1/148 =0.0066moles

Here bromine taken as excess so trans-cinnamic acid is limiting reagent

From the balanced chemical equation we know that for every mole of trans-cinnamic acid and bromine one mole of “B” is produced.

Therefore # moles of trans-cinnamic acid = # moles of “B” is produced

Theoretical Yield = moles of “B” x molar mass of “B”

                         = 0.0066 mol x 308 g/mol

                         = 2.08 g

Step-2:

Number of moles of “B”= 2.08/308 =0.0066moles

Here “B”is limiting reagent

From the balanced chemical equation we know that for every mole of “B” produced one mole of phenylpropynoic acid.

Therefore # moles of “B” = # moles of phenylpropynoic acid is produced

Theoretical Yield = moles of phenylpropynoic acid x molar mass of phenylpropynoic acid

                         = 0.0066 mol x 148 g/mol

                         = 0.9636g