Question

Product	Amount recovered /g	% yield	Appearance of purified product	Literature MP /oC	Experimental MP /oC
2’-bromo-4’-methylacetanilide	0.43	43%	Crystal white	118 - 121	117.9 – 118.0

1) Comment on the purity and percentage yield of your isolated product. Use direct comparison to expected values to support your analysis and discuss plausible impurities. Include both methods used in the laboratory: melting point and TLC.

2) While performing the recrystallization, your colleague used pure ethanol instead of the 50/50 ethanol/DI water solution. Although the solution was put on ice for over 10 minutes and they tried to agitate, no crystals are formed. What would you suggest they do in order to recover their 2’-bromo-4’-methylacetanilide?

Answer 1

1. i) Melting point of compound is 118 - 121°C by litretulit and we got melting point 117.9 - 118°C which is indicating our product melting point is matching with standard melting point so our compound is pure.

ii) 1 g is 100% yield but we got 0.43 g so we got 43% yield.

iii) If we have authentic of 2-bromo-4-methylacetanilide just compare TLC OR just check TLC of our copound if it is singal spot after elution of TLC which is indicating that our product is pure.

2. Colleague has dissolved the compound in ethanol instead of 50/50 ethanol and water, so to recover the material just evaporate the ethanol to get our compound back, solvent (ethanol) will get evaporated because it's Boling point is 78°C and our compound will remain in the flask because it's heigh boiling so we can recover our compound by evaporation of ethanol.