Question

Write the mechanism for the formation of Malachite Green from methyl benzoate. Be sure to show all steps, including the loss of water. 1. 2. Write the mechanism for the formation of Crystal violet from diethyl carbonate. 3. Methyl benzoate is an ester, but is technically a carboxylate ester. Diethyl carbonate is a 4. Why is the green dye in this experiment called "Malachite Green"? Hint: Try looking in a 5. Write the balanced equation for the reaction of hydrochloric acid with the excess magnesium 6. Write the equation for the reaction of the Grignard reagent used in this experiment with any 7. In both Malachite Green and Crystal Violet, the positive charge may be delocalized onto carbonate ester. Explain these terms. dictionary under "malachite." that remains after the reaction. water that may be present in the solvent or flask. different nitrogens. Draw one structure of Crystal Violet and then show the movement of electrons that allows you to draw two other resonance structures in which there is a positive charge on nitrogen. 8. Explain why Malachite Green and Crystal Violet are referred to as "triarylmethane dyes."

Answer 1

1. Malachite green is synthesised from methyl benzoate by treating the latter with the Grignard reagent prepared from 4-bromo-N,N-dimethylaniline. The mechanism of the reaction in detail is given below.

OMg Ph Ph Mg PhCOOMe CH3O Mg Br MgBr MgBr OMg H20 HC1 Ph Ph H2O Malachite Green N CI