Question

A Grignard reaction was performed with the following: 30.5 g 1-bromopropane, 7.30 g magnesium, 255 mL diethyl ether (“Et2O”), 27.5 mL 4-methyl-2-pentanone (“methyl isobutyl ketone”). What is the theoretical yield, in grams, of the product of this reaction? Show your calculations

The product from the Grignard reaction in above undergoes an E1 elimination reaction. Draw all possible elimination products.

Answer 1

1. Bromopropane – 30.5 g

Molecular weight of 1-bromopropane - 123 g

Number of moles = weight / molecular weight = 30.5 / 123 = 0.248 moles

1. 4-methyl-2-pentanone = 27.5 ml

Density = 0.801 g/mL

D= M/V

Mass = volume x density = 27.5 x 0.801 = 22.03 g

molecular weight = 100.16

Number of moles = weight /molecular weight =22.03/100.16 = 0.22 moles

Here the limiting reactant is 4-methyl-2-pentanone with 0.22 moles

The product obtained is 2,4 dimethyl 4-heptanol

Its

Theorectical yield = number of moles of limiting reactant x product molecular weight=

= 0.22 x 144.255= 31.73 g = 100 %

The reaction is as follows