Fischer Esterification: synthesis of an ester So we began the experiment by addi

Question

Fischer Esterification: synthesis of an ester

So we began the experiment by adding 3.5ml of isopropanol and 3.7ml of acetic acid in a round bottom flask along with 1.0ml of sulfuric acid. This mixture went on the refluxing apparatus and was heated for 45 min. Once done it was then cooled and the extraction by the separatory funnel began. We rinsed the flask with 12ml of water and 16ml of diethyl ether and then transferred into the separatory funnel. We drained the aqueous layer. and the added 10ml of 5% sodium bicarbonate. We drained the aq layer again. The organic layer was then kept and a drying agent and then it was decanted for simple distillation. This organic layer was placed in a distilling flask in the distillation head. The first distilled fraction was diethyl ether. After the ether was collected we removed that flask and replaced it with a new one which would now contain the pure isopropyl acetate.

I have to do a product separation scheme but I'm not sure if its right this is what i have so far and I always have a hard time figuring out what goes in what layer.

Refluxing flask: isopropanol, acetic acid, and sulfuric acid

extraction by the separatory funnel, add 12ml of water, 16ml of diethyl ether

organic layer: contains diethyl ether and I don't know what else

aqueous layer: water, sulfuric acid

I don't know what else...

For the product separation discussion, I just need to know what compounds were insoluble/soluble in both the organic and aqueous layer

Explanation / Answer

You have excess acetic acid in your reaction mixture. According to LaChatelier’s principle entire isopropanol will be consumed. At the end of the reaction, you have a mixture of isopropyl acetate, unreacted acetic acid and excess sulfuric acid. Separation is done by water and ether followed by 5% sodium bicarbonate. Now try to understand which layer will contain what compound.

Refluxing flask (Before reaction): isopropanol, acetic acid and sulfuric acid

Refluxing flask (After reaction): isopropyl acetate, unreacted acetic acid and unreacted sulfuric acid

Extraction by separation funnel (12 ml water + 16 ml diethyl ether)

Organic layer contains: diethyl ether + isopropyl acetate + portion of acetic acid

Aqueous layer contains: water + unreacted sulfuric acid + portion of acetic acid

(Please pay attention acetic acid is both soluble in organic and aqueous layer)

Extraction by 5% sodium bicarbonate: any unreacted acetic acid in organic layer will react and be converted to sodium acetate and come to water layer

At this stage your organic layer has only diethyl ether and isopropyl acetate which separated by fractional distillation

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