Question

In an experiment we used : thiophene (0.8 ml), n-butyllithium ( 3.125 ml), 2-chloropyrimidine ( 0.515 ml), DDQ (1.136 ml) to synthesize 2-chloro-4-(2-thienyl) pyrimidine

using this scheme

then H20 n-Bu-Li

we obtained 0.078 g of the pure product calculate the yield % ??

Answer 1

Starting material/product	Molecular weight	Amount taken	moles	Equivalent	Product obtained
Thiophene	84.14 (d=1.05)	0.8 ml (0.84 g)	0.0099 mol	1.73
2-chloropyrimidine	113.54 (d=1.2710)	0.515 ml (0.654 g )	0.0057 mol	1.00
2-chloro-4-(2-thienyl) pyrimidine	196.66				0.078 g

2-chloropyrimidine is the limiting reagent in the reaction

113.54 gm of 2-chloropyrimidine gives 196.66 gm of Product

Therefore 0.654 g of 2-chloropyrimidine will give x gm of product

Theoretical yield of the reaction = (0.654 g *196.66 g)/113.54 = 1.132 gm

Percent yield of the reaction = (0.078//1.132)*100 = 6.89%