Synthesis of Terephthalic Acid from coke bottles

Synthesis of terePhthalic Acid from coke bottles

C₁₀H₈O₄ + 2 NaOH -> C₈H₄O₄Na₂ + C₂H₆O₂
PET + Sodium hydroxide -> Sodium terephthalate + Ethylene Glycol

1: Obtain a coke bottle with the recycling symbol number 1 on it... Should say PET also in small writing under it... Wash the bottle and cut it up into small bits (smaller the better to get more surface area)

2: weight out the appropriate amount of each chemical and place it in a beaker (or non reactive container ie... steel can).

3: Place on a heat source and start to apply heat.. the Sodium hydroxide will start to boil and react with the PET very slowly... the solution may turn white but that's OK.

4: Once all the plastic has dissolved and it now just looks like a solution, you can then take it off heat.

5: Filter off any insoluble material (i happened to have a white precipitate, don't know what it is)... you can add some water if you want... it isn't actually needed)

6: Once fully filtered you can then move onto adding the acid... SLOWLY add some HCl to the solution... it will first neutralize any Sodium hydroxide that hasn't reacted... one there isn't any Sodium hydroxide left, the acid will start attacking the sodium terephthalate forming terePhthalic Acid... this will be insoluble in water and will precipitate out... this is a very exothermic reaction (not enough to boil the water but enough i couldn't touch it for more then 2 seconds)

C₈H₄O₄Na₂ + 2 HCl -> C₈H₆O₄ + 2 NaCl

7: Boil down or evaporate until dryness... may not dry fully because of the Ethylene glycol but that wont matter for the next step... Now add some acetone to the terephthalic acid... terephthalic acid is really soluble in acetone but Sodium chloride is barely soluble in it (less then 0.00...)

8: Give it a mix around and then let it settle... you should be able to just decant off the acetone, leaving the sodium chloride behind... or you could just filter it off.

9: Let the acetone evaporate to get the terephthalic acid back... you may still of the ethylene glycol present so just wash it with a fair amounts of water to get rid of the ethylene glycol.

10: for extra purity, heat the acid up until it starts to form the anhydrous and collect it with a cold round bottom flask