The Acetylation of Para-Aminophenol. Aim To make para-hydoxyacetanilide as pure as possible, through acetylation of Para- aminophenol.

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The Acetylation of Para-Aminophenol

Aim

To make para-hydoxyacetanilide as pure as possible, through acetylation of Para- aminophenol.

(Pal, S n.d, online)

Experimental

Laboratory safety precautions which were taken during this experiment were safety goggles and lab coats were worn. The effect of acetic anhydride causing eyes to water meant it is a necessity to wear goggles. It is important to ensure to avoid contact, inhalation, and ignition sources around this chemical as it is flammable.

Part1
15cm³ of water was added to a 100cm³ conical flask. This was then added to a suspension (mixture) of para-aminophenol (5.5g). The result of adding water meant the product became cloudy and fizzed. With the addition of ethanoic (acetic) anhydride (6.0 cm³) the solution changed from a cloudy white to a yellowy/brown colour which was only slightly transparent. The mixture was vigorously stirred and left to warm in a water bath (hot plate). Within the first few minutes of the product being on a hot plate, it began to dissolve slowly. After the product had dissolved it was a pale yellow transparent colour. Once it had fully dissolved, the product was left to cool down. After a period of time the product became a cream colour and small crystals were forming. The conical flask was placed into an ice bath so it could cool down further. Observations showed that the crystals had become white, and more of them had formed, in addition to this a clear liquid was left over. The crude solid was filtered off using vacuum filtration. White crystals were visible on the filter paper. Whilst the solid was still in the Buchner funnel, 10 cm³ of water was added to give the solid a quick wash, the vacuum filtration was left on until no more liquid could be drained from it. The product was transferred onto a watch glass and placed it in a vacuum oven at 70⁰C to dry. Once it was complete the product was weighed, it was found that there was 22.62g of the product minus 17.2304g for the watch glass.

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Part 2

To re-crystallise the crude product it was dissolved in a minimum amount of boiling water. Once the water was added it only took a few minutes for the compound to dissolve, thus leaving the solution looking transparent. The product was left to cool down in an ice bath for a while, it was noticed that crystals formed and a layer of liquid was left. Therefore the product was vacuum filtered, resulting in white crystals. The sample was then placed in the vacuum oven at 70⁰C to dry.

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