Question

Discuss the purpose of the reaction. Discuss the function of the reagents used and what you are monitoring in that reaction.

JVCUDDL/64/1/649?response-content-dispositioninline Introduction: It is estimated that approximately 150 million metric tons of plastics are currently circulating in our global system of oceans and waterways. This seems like a fairly generic "big! number", and it's difficult to understand the scale of the problem without converting it to something more relatable. A standard empty plastic water bottle weighs approximately 12.7 g. The conversion of units from metric tons to number of empty water bottles is provided below: 1.5 x 10 metric tons 1x 10kg )/_1x10 1 matrie fon/ 1 kg Y 1 1 empty bottle 12.79 e) - 1.18 x 10" empty bottles This is the equivalent of 11,800,000,000,000 empty plastic bottles already present in the oceans and associated waterways (making the erroneous assumption that all plastic waste is from beverage bottles). Again, this is a hard number to grasp, but if you lined up this many bottles end-to-end, they would form a chain that would circle the earth 60,000 times. In addition to the plastics already present, approximately 8 million metric tons of new plastic waste are entering our oceans every year. If you perform another unit conversion, this equates to about 35,000 pounds of new plastic waste in the oceans PER MINUTE. Clearly, this is a very significant problem, and thousands of concerned scientists around the world are working on various kinds of potential solutions. Plastics are wonderfully versatile and useful, so they aren't going to disappear. But there are several possible strategies that can help avoid total destruction of our ecosystem, and one of these is recycling. https://oceanconservancy.org/trash-free-scas plastics in the ocean 2 http://www.bottled water org/news/ Though this is far from a perfect remedy (please look online and read for yourselves; plastics recycling is fraught with all sorts of problems), it is a step in the right direction. One method of doing so involves breaking down the polymers into the fundamental building blocks and, whenever possible, re-polymerizing them into "new" plastics for reuse. In this experiment, you will be hydrolyzing (breaking down) a common plastic often used for bottles containing water and other beverages called polyethylene terephthalate (abbreviated as PET or PETE). You will also isolate one of the hydrolysis products: terephthalic acid (shown below). The starting polymer is classified as a polyester and results from the copolymerization of two molecules (monomers): terephthalic acid and ethylene.

Answer 1

Solution:

1) Purpose of the reaction:

Purpose of this reaction is to recover a starting materials used for the synthesis of PET bottels through depolymerisation of the waste PET bottels into a monomers such as terephthalic acid and ethylene glycocl. This reaction is hydrolysis of ester functionality present into the PET polymer uisng KOH to monomers such as terephthalic acid and ethylene glycol.

2. Function of reagents used in this reaction:

In this reaction KOH, 1-Pentanol, and H3O+ [acid, eg. HCl or H2SO4] is used.

Role of KOH: This is strong base which provide -OH- [hydroxide ion] in the polar solvent. This -OH- will acts as a nucleophile to break ester bond [a bond between -C=O and O-alkyl] and form new acid bond [a bond between -C=O and -OH]. The overall process is hydrolysis of ester to acid and alcohol.

Role of 1-Pentanol: This is polar protic solvent to provide a space for collision between reactants and reagents.

Role of acid: Role of acid is to change pH of reaction from basic to acidic. At acidic pH a potasium salt of terephthalic acid is converted into terephtahalic acid.

Over all mechanism of this reaction is provided below to better understanding.

KOH К* ОН K+ OH KOH (her birhe ) — or een КОН Terephthalic acid has acid proton it will be abstracted by potassium alkoxide acid work up KCI + HCI HTCI OH + KCI