Synthesis of polycarbonate from dimethyl carbonate and bisphenol-a through a non-phosgene process

✍ Scribed by Osamu Haba; Isao Itakura; Mitsuru Ueda; Shigeki Kuze

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 141 KB
• Volume: 37
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(19990701)37:13<2087::aid-pola23>3.0.co;2-5

✦ Synopsis

A novel nonphosgene process for producing bisphenol-A polycarbonate (PC) was developed through a transesterification between bisphenol-A (BPA) and dimethyl carbonate (DMC) and a melt-polycondensation of the resulting bisphenol-A bismethylcarbonate (1). The transesterification was carried out by heating bisphenol A in dimethylcarbonate in the presence of Lewis acid catalysts, removing the by-producing methanol using molecular shieves 4A. Among various catalysts, a combination of (Bu 2 SnCl) 2 O and dimethylaminopyridine gave the best results to produce 1 in 22% yield for 48 h. Using a larger amount of the molecular sieves further improved the yield to 80% in 120 h. The resulting 1 was heated under reduced pressure in the presence of titanium catalysts to produce PC in good yields. The resulting PC had high weight average molecular weight (M w ) of 75,000.