5,5'-Dichloro-4,4',7,7'-tetramethyl-2,2'-bibenzo[b]thiophene-3,3'-diol bis(sulfuric acid sodium) salt

Preparation

(a) in the presence of Pyridine , with Chlorosulfonic acid treatment C.I. Vat Violet 3 leuco; (b) in the Pyridine with metal (such as copper, iron, zinc, etc) and Sulfur trioxide source (such as Sulfur trioxide, Chlorosulfonic acid or Methyl chlorosulfonate, etc.) processing C.I. Vat Violet 3. The above two kinds of situation after alkaline, filter out insolubles, remove Pyridine and salting out.

Properties and Applications

brilliant red light purple. Purple red powder. Soluble in water for red light purple. Used for dyeing cotton fabric for brilliant red light purple, and also can be used for cotton fabric direct printing, resist printing. Also can be used for silk and wool dyeing and polyester/cotton blended fabric dyeing.

Standard	Ironing Fastness	Chlorine bleach	Light Fastness	Mercerized	Oxygen bleach	Soaping
						Fading	Stain
ISO	4	5	5	3	4	4-5	5
AATCC	5	5	5	3-4	4