(204i) Solid-Liquid Equilibria for Selected Binary Mixtures Containing Diphenyl Carbonate

Polycarbonate (PC) is a widely used engineering plastic which has excellent features, such as transparency, impact resistance, thermal stability, dimensional stability, and flame resistance. Most PC production has been via the phosgene process, which uses carbon monoxide and chloride as raw materials. However, this phosgene process has a number of environmental drawbacks. In particular, highly toxic phosgene is used as a monomer and a large quantity of the low-boiling-point solvent methylene chloride is required for polymerization. Also, a very large quantity of water must be used to remove phosgene and chlorine (from methylene chloride) from the product PC. To overcome these environmental problems, a new process for PC production starting from carbon dioxide and bisphenol-A has been developed [1], and has attracted much attention as it offers much greener and more sustainable chemistry. Diphenyl carbonate (DPC) is an important intermediate material in this new process. The purity of the DPC directly influences the downstream PC quality, with high-purity DPC being critical for PC optical media applications. One of the options for purification of DPC is a crystallization process [2-4]. In the design and development of this crystallization process, knowledge of solid-liquid equilibrium (SLE) data is important.

The objective of this work to determine the SLE data for binary systems containing DPC. In this study, we have focused on the transesterification reaction for production of DPC. This reaction is based on alcohol, dialkyl carbonate, phenol, and DPC. Thus, we have measured the SLE for tselected binary mixtures: ethanol or 1-propanol + DPC at atmospheric pressure by visually observing the melting points using the synthetic method. The experimental SLE data of the three binary mixtures were represented by a polynomial equation of the composition suggested by Ott and Goates [5] and the NRTL model [6].

References

[1] N. Miyake, Expected Material for the Future 5 (2010) 46-51 .

[2] S. Kuze, R. Okumura, Y. Suwabe, Preparation of Polycarbonate by Melt Method without Discoloration. Eur. Patent EP0561363, 1993.

[3] D. W. Wei, Y. H. Pei, Ind. Eng. Chem. Res. 47 (2008) 8953-8956.

[4] D. W. Wei, Y. H. Pei, J. Chem. Eng. Data 53 (2008) 2710-2711.

[5] J. B. Ott, J. R. Goates, J. Chem. Thermodyn. 15 (1983) 267-278.

[6] H. Renon, J. M. Prausnitz, AIChE J. 14 (1968) 135-144.