Method of making soluble squaraine dyes

摘要

The present invention provides a novel process for the production of organic solvent soluble squaraine dyes. More specifically, the invention describes how a difficult to prepare tetrahydroxy squaraine intermediate can be prepared in an organic solvent system in the presence of water. This intermediate can then be esterified in pyridine to form the soluble squaraine dye which can then be easily isolated from the reaction mixture. The invention also provides the dyes prepared according to this method.