Purification of Highly Insoluble Squarylium Dyes
Original Publication Date: 1982-Jul-01
Included in the Prior Art Database: 2005-Feb-09
Squarylium dyes can be purified by simply refluxing slurries of the materials for brief time periods in certain high-boiling ether solvents. The process is not a classical recrystallization because the highly insoluble squarylium dyes are only partially dissolved at any one instant of the reflux. However, during the course of the reflux, it is clear that enough squarylium (solid) (see original) squarylium (soln) exchange takes place to clean effectively both the exterior and interior of the squarylium crystals of impurities.