Process for preparing a phthalocyanine

A process for preparing vanadyl phthalocyanine particles for photoresponsive devices comprising reacting vanadium pentoxide with phthalonitrile and an alcohol at least at an exotherm temperature with agitation, said alcohol having a boiling point of at least 180.degree. C.;

• filtering the resulting reaction mixture to form a reaction product pigment cake;
• washing said reaction product pigment cake at lest once with a dipolar aprotic solvent to form a treated pigment cake;
• drying said treated pigment cake;
• leaching with agitation said treated pigment cake with a strong acid diluted with water;
• filtering the resulting mixture to form a leached pigment cake;
• washing said leached pigment cake at least once with a strong acid diluted with water to form a washed leached pigment cake;
• washing said leached pigment cake at least once with a solvent comprising water to form a water washed leached pigment cake;
• forming a strong base slurry by combining said washed leached pigment cake with a strong base diluted with water;
• heating said strong base slurry with agitation;
• filtering the resulting mixture to form a strong base treated pigment cake;
• forming a solvent slurry by combining said strong base treated pigment cake with a dipolar aprotic solvent, heating said solvent slurry with agitation;
• filtering the solvent slurry to obtain a solvent treated pigment cake;
• forming an aqueous slurry by combining said solvent treated pigment cake with a solvent comprising water;
• heating said aqueous slurry with agitation;
• filtering the aqueous slurry to obtain a washed pigment cake;
• drying said washed pigment cake;
• incrementally dissolving with agitation said washed pigment cake in a chilled concentrated strong acid to form a chilled concentrated strong acid solution of vanadyl phthalocyanine;
• incrementally combining with agitation said solution with chilled water to form a mixture comprising precipitated vanadyl phthalocyanine particles;
• filtering the resulting mixture to obtain a cake of precipitated vanadyl phthalocyanine particles;
• forming an aqueous slurry by combining said cake of precipitated vanadyl phthalocyanine particles with a solvent comprising water to form a vanadyl phthalocyanine particle water slurry;
• heating said vanadyl phthalocyanine particle water slurry;
• filtering the resulting mixture to obtain a cake of vanadyl phthalocyanine particles;
• forming a water slurry by combining said cake of vanadyl phthalocyanine particles with water;
• filtering said water slurry to form a purified pigment cake of vanadyl phthalocyanine;
• and drying said purified pigment cake of vanadyl phthalocyanine.