Hydrochloric Acid → 4,4'-Dds dhp

Participants

Reaction Steps

Under nitrogen inside a resin kettle, placed 2.48 g of 4,4'-DDS (fw 248.3, 10.0 mmoles) and 40.0 mL of anhydrous THF. The diamine did not go into solution. While stirring with a high-torque mechanical stirrer, added 4.66 g of 6FDA (fw 444.2, 10.5 mmoles) and 10.0 mL more THF. Everything went into solution within 5 minutes. After 2 hours of stirring at room temperature added 16.0 g of dihydropyran and 0.2 g of pyr-HCl polymer. The reaction was then stirred for 60 hours at 35° C. under nitrogen with stirring. 1H NMR of crude reaction product shows 90+% conversion to the acetal ester. The catalyst was filtered off and the filtrate was added dropwise to a stirring blender containing 500 mL of hexane. The white precipitate was filtered, washed with hexane, dried under high vacuum to give 6.52 g of product. GPC analysis showed Mw =4730, Mn =2380, and Mw /Mn =1.99.

Provenance & Evidence