Question

Which substance is less polar? (circle one) methyl benzoate methyl nitrobenzoate

b.compare and contrast the tlc of the starting material, the crude product and the pure product. what substances are present in each and why are they different? what differences do you see in the crude vs. pure product?

Answer 1

A)
Among the given compounds, Methyl benzoate is less polar than Methyl nitrobenzoate. This is because Methyl nitrobenzene contains an additional polar group (-NO₂) which increases its polarity. Therefore, Methyl benzoate having any additional polar group is less polar than Methyl nitrobenzoate.

B)
Below a developed TLC is shown. It contain three spots. A spot at left (blue) is for Methyl benzoate, the middle spot is of crude product (containing reactant and product) and the spot at right (red) is for Methyl Nitrobenzoate. It is clearly shown that the Methyl benzoate being less polar has traveled more while Methyl nitrobenzoate being polar interacts with the stationary phase has traveled less. The middle spot shows the presence of both, reactant and product.