Esterification reactions involve the condensation of carboxylic acids and alcoho

Question

Esterification reactions involve the condensation of carboxylic acids and alcohols to generate esters. If 16 mL of isopentyl alcohol ((CH3)2CH(CH2)2OH, density 0.81 g/mL) is condensed with 22 mL acetic acid, CH3COOH, (density = 1.05 g/mL), what is the expected yield (in grams) of the product, isopentyl acetate? 3. If, under the reaction conditions listed in question #2, the amount of isopentyl acetate obtained were found to be 5.47 grams, what is the % yield? 4. Benzoic acid has a melting point of 122degreeC while salicylic acid's mp is i58degreeC; suggest a reason for the difference in melting points despite the structural similarity.

Explanation / Answer

2)

Acetic acid: 22 ml, molar mass- 60.05 g/ml, moles taken-0.4213, density-1.15 g/ml, weight - 25.3 g

Salicylic acid: 16 ml, molar mass - 88.14 g/ml, moles taken - 0.147, density - 0.81 g/ml, weight - 12.96 g

Here, isopentyl alcohol is the limiting reagent. If the conversion is 100%, then the ester formed will have 0.147 moles.

Molar mass of ester (C7H14O2) = 130.1 g/mol

So, weight of the ester = molar mass * number of moles = 130.1 * 0.147 = 19.129 g

3. In the above reaction condition if, the yield obtained is 5.47 g.

% yield = (isolate yield/theoritical yield) * 100 = (5.14/19.29) * 100 = 28.59%

4. Melting point of salicylic acid is 158 oC, where as for benzoic acid is 122 oC. They are isostructural, but molecular weight of salicylic acid is 138.1 g/mol, where as for benzoic acid it is 122.1 g/mol. Being heavier than benzoic acid, salicylic acid posses higher melting point.

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