Extremely small pieces of PET were necessary to ensure a successful hydrolysis i
ID: 842183 • Letter: E
Question
Extremely small pieces of PET were necessary to ensure a successful hydrolysis in the allotted time. A 100mL round-bottom flask was charged with a prepared 2M pentanolic KOH solution (40mL), PET shavings (5.0g) and a stirring bar. It was imperative to maintain a stirring solution at all times. The mixture was heated to a gentle reflux and maintained for 2 hours. Shortly into the reflux period a thick white suspension forms. The reaction mixture was cooled and water (25mL) was added, which dissolves the white terephthalate salt. The solution was filtered in a Buchner funnel to remove undissolved PET. The filtrate was placed in a separatory funnel, and the bottom aqueous layer was removed. The pentanolic layer was washed with an additional 25mL of water. Again, the bottom layer was removed, and the aqueous layers were combined. HCl (2M) was added to the aqueous layer with stirring to acidify the solution. The solid was collected by suction filtration and then air-dried.
What is the overall reaction and what is the mechanism of this reaction?
Explanation / Answer
ALKALINE HYDROLYSIS OF POLYETHYLENE TEREPHTHALATE(PET)
(C10H8O4)x + 2x KOH --------> x K2C8H4O4 (Di-potassium terephthalate) + x C2H6O2 (Ethyleneglycol)
PET
Di-potassium terephthalate is soluble in water and is collected in aqueous layer during the work up.
after work up, acidified this aqeous layer and solid is collected.
K2C8H4O4 + HCl --------------> H6C8O4 + 2KCl
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