Terephthalic acid esters formation
The present disclosure relates to the formation of terephthalate esters. The present invention also relates to the depolymerization of polyethylene terephthalate (PET) or poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate) and the recovery of terephthalate esters
1. A process for the transformation of a polyester selected from polyethylene terephthalate and poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate) into dimethyl terephthalate, the process comprising admixing the polyester with a mixture comprising an alcohol and a sub-stoichiometric amount of methoxide, wherein the methoxide is included in the mixture at a ratio between about 20:1 and about 125:1 (w/w) of the polyester to the methoxide, wherein the process achieves at least about 70% yield of dimethyl terephthalate within about 2 hours, and wherein the process is conducted at a pressure below 120 psi.
2. The process of claim 1 , wherein the polyester and/or the mixture comprises a polar aprotic solvent.
3. The process of claim 1 , wherein the methoxide is selected from the group consisting of calcium methoxide, potassium methoxide, sodium methoxide, and any combination thereof.
4. The process of claim 3 , wherein the methoxide is sodium methoxide.
5. The process of claim 1 , wherein the ratio of the polyester to the methoxide is between about 40:1 and about 125:1 (w/w).
6. The process of claim 5 , wherein the ratio of the polyester to the methoxide is between about 60:1 and about 125:1 (w/w).
7. The process of claim 1 , wherein the process achieves at least about 80% yield of dimethyl terephthalate.
8. The process of claim 7 , wherein the process achieves at least about 90% yield of dimethyl terephthalate.
9. The process of claim 1 , further comprising pre-treating the polyester with a solvent for swelling.
10. The process of claim 9 , wherein the solvent for swelling is selected from the group consisting of a non-polar solvent, a polar aprotic solvent, a polar protic solvent, and any combination thereof.
11. The process of claim 10 , wherein the solvent for swelling comprises a combination of a polar protic solvent and a polar aprotic solvent.
12. The process of claim 9 . wherein the solvent for swelling is selected from the group consisting of DMSO, DMF, acetone, a halogenated solvent, n-hexane, nitrobenzene, methanol, benzyl alcohol, benzaldehyde, and any combination thereof.
13. The process of claim 12 , wherein the solvent for swelling is methanol.
14. The process of claim 1 , wherein the alcohol is methanol.
15. The process of claim 8 , wherein the process achieves at least about 95% yield of dimethyl terephthalate.
16. The process of claim 1 , wherein the process is conducted at a pressure below 100 psi.
17. The process of claim 1 , wherein the process is conducted at a pressure between atmospheric pressure and 50 psi.
18. The process of claim 1 , wherein the process is conducted at a pressure between 50 and 100 psi.
19. The process of claim 5 , wherein the ratio of the polyester to the methoxide is between about 80:1 and about 125:1 (w/w).