Lab Report P Toluic Acid And P-Butylphenol Extraction

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Aim The purpose of this lab was to separate a mixture of carboxylic acid (p- toluic acid), a phenol (p-tert-butylphenol) and a neutral compound (acetanilide) using solvent extraction. Introduction Solvent extraction is a process that separates compounds from a mixture by a solvent. It involves the transfer of compounds from one liquid solvent to another liquid solvent. The two solvents used in this process should be immiscible to each other for the separation of compounds leading to an organic phase and an aqueous phase. The organic phase is composed of a solvent that is insoluble in water mainly consisting of non-polar compounds. Non-polar compounds such as hydrocarbons and ethers are soluble in the organic phase. Whereas, the aqueous phase…show more content…
In the separatory funnel, the top layer is the organic solvent and the bottom layer because the aqueous solvent has a higher density thus it sinks. The property of "like dissolves like" can be used to distinguish or to be certain which solvent is on the top or bottom. A few drops of water introduced through the top of the separatory funnel and if the water drops mix with the first layer, then the first layer is the aqueous solvent but if it passes the first layer and goes to the second layer then the bottom layer is the aqueous solvent. However, the aqueous solvent being the bottom layer is not always the case and this can be seen when halogenated solvents such as dichloromethane are mixed with water. Halogenated solvents are denser than aqueous solvents and thus halogenated solvents sink to the bottom. Therefore, the water drop test should be conducted to be sure which layer is aqueous. Additionally, to transfer a compound from the organic layer to the aqueous layer the compound can be converted to an ionic form as ionic compounds are polar, it will not dissolve in the organic layer and will pass through it to the aqueous layer from which it can be extracted while the other organic compound remains in the organic layer. To convert it to an ionic compound the compound needs to be reacted with either aqueous acid or…show more content…
To determine pKa, the Ka (ionization constant of an acid) of the acid needs to be determined first. The Ka of an acid is the quotient of the concentration of its conjugate base multiplied by the concentration of hydronium ions divided by the concentration of the acid; K_a=([A^- ][H^+])/([HA]). Once Ka is determined, the pKa value can also be determined as pK_a= -log⁡〖K_a 〗. Since pKa is the measure of the strength of an acid, the lower the pKa the stronger the acid and higher pKa corresponds to a strong base. Strong bases with higher pKa are able to deprotonate molecules that have lower pKa values such as acids to produce a salt and water. The conjugate acid of the strong base must be weaker than the acid it is trying to deprotonate. Weaker bases on the other hand which have lower pKa values are unable to deprotonate the same molecule as the strong base. Thus, NaHCO3 which has a pKa value of 6.4 is unable to deprotonate the phenol which has a higher pKa of 10.2. So, the HCO3- will not take the H+ from the phenol and no salt will be

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