1,2-Benzenediol,4,4'-(1,1-dioxido-3H-2,1-benzoxathiol-3-ylidene)bis- (115-41-3)

The IUPAC name of Pyrocatechol Violet is 4-[3-(3,4-dihydroxyphenyl)-1,1-dioxo-2,1λ6-benzoxathiol-3-yl]benzene-1,2-diol. With the CAS registry number 115-41-3, it is also named as 3H-2,1-Benzoxathiole, 3,3-bis(3,4-dihydroxyphenyl)-, 1,1-dioxide. It is greenish yellow powder which is soluble in water, slightly soluble in cold ethanol, not soluble in non-polar organic solvents such as ether, benzene and xylene. The water solution is yellow. When the acidity increases th color changes from yellow to red. In addition, this chemical is stable and incompatible with strong oxidizing agents. It is used as complexometry indicator. Furthermore, Pyrocatechol Violet is obtained by the reaction of benzoic sulfimide and catechol.

The other characteristics of this product can be summarized as: (1)ACD/LogP: 1.82; (2)# of Rule of 5 Violations: 0; (3)ACD/LogD (pH 5.5): 1.82; (4)ACD/LogD (pH 7.4): 1.79; (5)ACD/BCF (pH 5.5): 14.12; (6)ACD/BCF (pH 7.4): 13.28; (7)ACD/KOC (pH 5.5): 231.53; (8)ACD/KOC (pH 7.4): 217.81; (9)#H bond acceptors: 7; (10)#H bond donors: 4; (11)#Freely Rotating Bonds: 6; (12)Index of Refraction: 1.739; (13)Molar Refractivity: 95.43 cm³; (14)Molar Volume: 236.6 cm³; (15)Polarizability: 37.83×10^-24 cm³; (16)Surface Tension: 86.5 dyne/cm; (17)Enthalpy of Vaporization: 100.58 kJ/mol; (18)Vapour Pressure: 5.32E-18 mmHg at 25°C; (19)Rotatable Bond Count: 2; (20)Tautomer Count: 27; (21)Exact Mass: 386.046023; (22)MonoIsotopic Mass: 386.046023; (23)Topological Polar Surface Area: 133; (24)Heavy Atom Count: 27; (25)Complexity: 619.

When you are using this chemical, please be cautious about it as the following:
It is irritating to eyes, respiratory system and skin, so people should avoid contact with skin and eyes. In case of fire, use water, dry chemical, chemical foam, or alcohol-resistant foam. And wash thoroughly after handling. Remove contaminated clothing and wash before reuse.

People can use the following data to convert to the molecule structure. 
1 SMILES: O=S2(=O)OC(c1ccccc12)(c3ccc(O)c(O)c3)c4ccc(O)c(O)c4;
2. InChI: InChI=1/C19H14O7S/c20-14-7-5-11(9-16(14)22)19(12-6-8-15(21)17(23)10-12)13-3-1-2-4-18(13)27(24,25)26-19/h1-10,20-23H.