Question

Construct a flow chart that follows the separation of a mixture of 2-nitrophenol (an organic acid not used in this experiment with a pKa = 7.26) and anthracene (neutral organic). Use scheme 1 as a template. Your reagents available are the same ones used in this lab.

Scheme 1 is shown below!

Scheme 1. The acid-base extraction of p-cresol (an acidic phenol) and para-nitrotoluene (a neutral organic compound). O 1. dissolve in TBME 2. Add NaOH/H, less dense TBME layer Remove bottom layer. Place into new, labeled tube. more dense water layer ON Oo H2O H20 Na Na 4-nitrotoluene p-cresol (acid) (neutral organic) - both soluble in ether - both water insoluble og New, labeled tube (AE1) Original tube (OLI) 1. Wash with NaOH(aq) 2. Remove aq layer to waste 3. Backwash with sat'd, aq, NaCl 1. Add HCl to make pH acidic 2. Cool and collect precipiate 3. recrystallize o H2O Pipet out liquid to tared vessel 4. Remove organic layer into new vessel ("OL 1 Dry") 5. Add CaCl, let rest ONI p-cresol (pure) 08. AE1 OL1 1. remove TBME O, NO 2. recrystallize 4-nitrotoluene (pure) This is an EXAMPLE chart. You are using a carboxylic acid, not a phenol as depicted here, and NaHCO3 as your base, NOT NaOH!

Answer 1

Given compounds are 2-nitrophenol (a weak acid) and anthracene (neutral, non polar organic compound)

Both these compounds are soluble in non polar solvents while ortho-nitrophenol is sparingly soluble in water.

So, for separation of these compounds, following steps can be followed:

1. a) Add the mixture in organic solvent such as tetrabutyl methyl ether (TBME) and stir to form clear solution.

At this point, both the compounds will be soluble in ether.

1. b) Add dilute aqueous NaOH solution to the ether solution.

o-nitrophenol being acidic, will react with base to form o-nitrophenoxide. This anion pulls it in the aqueous layer which being dense is at the bottom.

2. Separate the two layers and collect them in labeled tubes.

Organic layer will contain anthracene while aqueous layer will have o-nitrophenoxide anion.

3. Add HCl to aqueous layer.

This will convert o-nitrophenoxide back to o-nitrophenol. This being insoluble in water will precipitate as solid.

Filter the solid residue and recrystallize.

4. Wash the organic layer with NaOH solution 2 to 3 times. Discard the aqueous layer.

This will remove the o-nitrophenol, if any, present in organic layer.

Wash with saturated aqueous NaCl solution and collect organic layer in a separate tube marked as OL 1.

Add anhydrous CaCl₂ to OL1 and let it remain for about 30 minutes.

Saturated NaCl solution will remove water from organic layer. Anhydrous CaCl₂ will remove traces of water present in organic layer and will make it dry.

5. Pipette out organic layer in separate tube.

6. Then remove TBME to get anthracene. Recrystallize it to get pure compound.

The required scheme is as below:

Xa Ether Ho trol 71. Add TBME trololo Too boli То що 2. Add aq. o-ritopherol Anthracene осой – both soluble in TBME - both in soluble in water One Nat Remone bottom I laya in another luse OH o Addtice No to AEL Xe Recrystallize, to get Cool and collect ppt ho Na one Р o-nitro phenol (ppt) combound, AE1 (Aqueous Extract) 041 touginal bayer)

- Wash with Noи(4) Remore and discard aq. Layers Wash with satinatéet Nal Add Cally not after renwung wached &qunic OE1 (fue from o-nitrophenol) O 000 layer OE1 a OL1 Pipette out organic lagu in tased reset Remove TBME Recuptaltize loto Pure anthracene