Question

Calculate the overall percent yield of the synthesis to produce lidocaine. The initial weight 6.652g (alpha-chloro-2 6 dimethylacetanilide), final weight 4.064g (crude lidocaine). 7.6mL Diethylamine and30.2mL toluene were added to synthesize the crude lidocaine. Show step by step.

Answer 1

Toluene is used as a solvent and will not appear in the calculation of percent yield.

Diethylamine has density of 0.707 gm/mL.

7.6 mL of diethylamine

Diethylamine has molar mass of 73.1 g/mol

5.37 g of diethylamine

6.652g of alpha-chloro-2 6 dimethylacetanilide (molar mass 197.66 g/mol)

0.0735 moles of diethylamine are present for 0.03365 moles of alpha-chloro-2 6 dimethylacetanilide which corresponds to mole ratio of alpha-chloro-2 6 dimethylacetanilide : diethylamine= 1:2.2

Thus, alpha-chloro-2 6 dimethylacetanilide is limiting reagent and diethylamine is excess reagent.

0.03365 moles of alpha-chloro-2 6 dimethylacetanilide will give 0.03365 moles of lidocaine (Molecular Weight: 234.34 g/mol). The theoretical yield of lidocaine

The final weight of crude lidocaine is 4.064 g.

The overall percent yield of the synthesis to produce lidocaine is