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CHEM-3002-21W

Extraction: A Separation and Isolation Technique Section 01 Quesnel, David Feb 08, 2021

Thais Moreira Gomes Nicolas Rey Ospina Cameron Armstrong

1. OBJECTIVES This report aimed to describe the separation of a three-component mixture by Extraction, a technique used to separate a desired organic product from a reaction mixture. Additionally, the melting point of the residue was determined to check if the separation steps were efficient. 2. PROCEDURE

All laboratory activities followed Experiment 4 – Extraction: A Separation and Isolation Technique, available on Lab Manual for organic chemistry – A short course 13th edition.

3. RESULTS Amount of naphthalene recovered = 0.4092g % recovery of naphthalene = 81.84% Melting point of purified naphthalene = 112-81℃ Accepted melting point of naphthalene = 80℃

Amount of m-nitroaniline recovered = 0.5647 g % recovery of m-nitroaniline = 112.94% Melting point of purified m-nitroaniline = 109 - 113 ℃ Accepted melting point for m-nitroaniline = 114℃

Mass of benzoic acid recovered = 0.3474 g %recovery of benzoic acid = 69.48% Melting point of recovered benzoic acid = 120 - 122 ℃ Accepted melting point for benzoic acid = 122℃

Total mass of products = 1.3213 g

4. CALCULATIONS

Since initial mixture of the three-component mixture is in a 1:1:1 ratio,

1.5 g / 3 = 0.5 g of naphthalene, Benzoic acid and m-nitroaniline

% recovery formula: extracted weight / initial weight * 100%

naphthalene % recovery using equation: 0.4092g / 0.5 g * 100% = 81.84% recovery

m-nitroaniline % recovery using equation: 0.5647 g / 0.5 g * 100% = 112.94% recovery

Benzoic acid % recovery using equation: 0.3474 g/ 0.5 g * 100% = 69.48% recovery

Total % recovery using equation: 1.3213 g / 1.500 g * 100% = 88.09% recovery

5. DISCUSSION AND CONCLUSION In this laboratory a mixture of three components solids was separated to their individual components by using the technique of isolation and extraction, managing the acid-base properties of the components. In this procedure, ether was used as an extraction solvent because it is highly soluble and low boiling point (35º C). The benzoic acid reacted with NaOH to give a salt that moved from the organic phase to aqueous phase, because the acid was deprotonated, and thus was removed from the mixture. After the extraction, the flask was immersed in a cold water bath to complete the crystallization process, and performed the vacuum filtration process. m-Nitroaniline being a base, reacted with HCl to give it’s anilinium salt which moved from the organic phase to the aqueous phase.

The component

remaining in the organic phase was the naphthalene. The naphthalene was removed from the top and the calcium chloride, drying agent, was added to remove the water from the organic layer. Both the acid and base extracts were neutralized to give benzoic acid, naphthalene

and

p-nitroaniline as solids. By adding up the weights of the

components without any loss, It should have recovered 1.500 g of starting material. The actual mass of the recovered products was 1.3213 g, or 88.09% of 1.500 g.

The structural formulas of three-components are shown in Figure 1.

Figure 01 - Structural formulas of m-nitroaniline, benzoic acid, and naphthalene.

Overall, the experiment was moderately successful. The percent recovery was calculated to be 112.94% for m-nitroaniline , 81.84% for naphthalene, 69.48% for Benzoic acid, and 88.09% overall. The experimental percent recovery is not 100% which could have been caused by an experimental error especially in the extraction of the m-nitroaniline %. The crystals were probably not dried sufficiently before weighing which could have introduced excess water weight. Also, when transferring the crystals from the vapor bath hood to weighing, the ether didn’t evaporate completely which could have increased the experimental weight of the crystals. The melting point for naphthalene was determined to be 112-81 ℃ which is not very different from the real melting point 80 ℃. Since the two are not largely different from each other and the experimental range is narrow like the literature value, the purity of the experimentally extracted naphthalene is fairly high. Similarly, the melting point range for m-nitroaniline was experimentally determined to be 109 – 113 ℃ which is not largely removed from the literature 114 ℃. Since the difference is approximately 2 ℃ and the experimental range is narrow instead of broad, it can be said that the purity of the extracted mnitroaniline is high as well. At last, the melting point range for Benzoic acid was experimentally determined to be 120 - 122 ℃ , and according to the literature the Accepted melting point for benzoic acid is 122 ℃, therefore the overall the purity of the extracted components is very high.

6.

REFERENCES

1. Structural formulas of m-nitroaniline, benzoic acid, and naphthalene. Available at https://pubchem.ncbi.nlm.nih.gov. 2. Melting point of naphthalene https://pubchem.ncbi.nlm.nih.gov/compound/Naphthalene#section=Melting-Point 3. Melting point of benzoic acid https://pubchem.ncbi.nlm.nih.gov/compound/Benzoicacid#section=Melting-Point 4. Melting point of m-nitroaniline https://pubchem.ncbi.nlm.nih.gov/compound/3Nitroaniline#section=Melting-Point...