Separation of Nitrophenols
Using a micro scale steam distillation we separated ortho and para-nitrophenol from a mixture that was already made. After the para and ortho were separated we measured their melting points and compared it to the literature values for purity. For ortho-nitrophenol we had 60% recovery and for para 160% recovery. Our melting point ranges were ortho: 45-46°C and para 64-95°C. Introduction:
In phenols, -OH group strongly activates the ring system. As a result, phenols are susceptible to oxidation in the presence of concentrated nitric acid (HNO3). Thus, nitration of phenols is carried out with dilute nitric acid and results in the formation of o-nitrophenol and p-nitrophenol. The o-nitrophenol is steam volatile and the mixture of o-nitrophenol and p-nitrophenol is separated by steam distillation, in our case using micro scale measurements for safety and time consumption purposes.
(Electrophilic aromatic substitution)
We used steam distillation because we are distilling under 100°C; above 100°C is H2O. Looking at the volatility of o-nitrophenol compared to p-nitrophenol, the p-nitrophenol has intermolecular hydrogen bonding and it occurs due to a large number of molecules are associated together. This association in the p-isomer makes it less volatile. However in o-nitrophenol, intramolecular hydrogen bonding occurs and thus, it exists in a monomolecular state making it more volatile.
Using a sand bath for transferring of heat through the distillation which was sitting on a hot plate. Using a small round bottom flask which was attached to Hickman’s distillation head and then we attached water through the openings. Using 1.00g of the prepared mixture we placed it in the round bottom flask along with 1.00mL of ethanol and then filled it about 2/3 with water. We added a magnetic spin-vane to the flask as well. We collected the yellow waxy ortho-isomer from...
Please join StudyMode to read the full document