Question

1. In the course of the filtration you washed the solid in the funnel with methanol to remove as much color as possible. Look at the compounds in the balanced equation and think about the solvent properties of methanol. What compounds would likely be removed from the product by means of washing with methanol? Explain.

E-stilbene + Pyridinium hydrobromide perbromide ----------> stilbene dibromide + Pyridinium bromide

Answer 1

The given reaction:

E-stilbene + Pyridinium hydrobromide perbromide ----------> stilbene dibromide + Pyridinium bromide

In this reaction, pyridinium hydrobromide ((pyridinium hydrobromide and pyridinium bromide are similar reagents only) used to brominate the stilbene. After rection complete also some amount of unreacted (not used) present in the product.

Filteration process:

Methanol used in during filtration process. Methanol is a highly polar solvent so more polar compounds and ionic salts are soluble in methanol.

pyridinium bromide is salt like compound so which is soluble in methanol. But stilbene dibromide is an aromatic less polar compound. Aromatic compounds are more soluble in an aromatic solvent like benzene or non-polar solvent.

I- ZO B13

So while filtration with methanol pyridinium bromide mostly removed from the product.