"New" Compounds from Old Plastics: Recycling PET Plastics via Depolymerization. An Activity for the Undergraduate Organic Lab

Abstract

This paper describes work done to develop a meaningful undergraduate organic lab activity that illustrates chemistry of the real world while utilizing reactions typically included in the organic lecture and lab. We show how a common plastic can be converted into several compounds using ester hydrolysis and SN2 reactions.Contributing to the critical shortage of landfill space faced by many communities is the large quantity of plastic refuse. Thus, there is a real need to recycle plastic products. One way to recycle plastics such as polyethyleneterephthalate (PET), the polyester from which numerous consumer products such as 2-liter soda bottles are made, is to depolymerize them and then to use the resulting monomers to produce new products. PET is industrially depolymerized via an acid-catalyzed transesterification reaction conducted under conditions of high temperature and pressure that are not feasible in the undergraduate lab. Despite literature reports that PET is remarkably resistant to hydrolysis, we found that PET can be readily hydrolyzed by refluxing with potassium hydroxide or potassium tert-butoxide in amyl alcohol to give terephthalic acid in high yield. It is then possible to readily synthesize terephthalate diesters via SN2 reactions of ammonium terephthalate salts with alkyl halides. Fischer esterification can also be used to prepare the diesters, but yields are significantly lower.

Study of Polyurethane Formulations Containing Diols Obtained via Glycolysis of Poly(ethylene terephthalate) (PET) by Oligoesters Diols through a Reactive Extrusion Process

“…The indicator used during this titration was Bromothymol Blue. The acid value was calculated according to Equation (1).…”

Scientists' Perspective on Introducing Authentic Inquiry to High School Teachers During an Intensive Three‐Week Summer Professional Development Experience

“…On Day 11 and 12, participants examined the depolymerization of polyethylene terephthalate (PET) and polylactic acid (PLA), so‐called biodegradable and/or recyclable plastics (Figure 7 and 8, respectively) using combinations of various catalysts and solvents suited to each reaction (Donahue, Exline, & Warner, 2003; Kaufman, Wright, Kroemer, & Engel, 1999; Nakayama, Sato, Ishihara, & Yamamoto, 2004). The participants were asked to inspect and compare the various reactions using visual inspection to determine the conditions under which a successful depolymerization took place.…”

Sintesis Dibenzil Tereftalat Melalui Depolimerisasi Plastik Poli(etilena Tereftalate) Sebagai Alternatif Daur Ulang Plastik Bekas

“…Faktor kontribusi lain melibatkan problem pemilahan (sorting) produk limbah plastik menjadi katagori yang bervariasi. Jika pemilahan ini tidak dilakukan, produk yang dibuat dari campuran plastik yang digunakan akan rendah mutunya [1].…”

“…Penelitian depolimerisasi PET terakhir adalah hidrolisis PET dengan kalium tert-butoksida atau kalium hidroksida yang direfluks dalam pentanol untuk menghasilkan asam tereftalat [1].…”