o-Cresolphthalein

Reported in EPA TSCA Inventory.

The IUPAC name of o-Cresolphthalein is 3,3-bis(4-hydroxy-3-methylphenyl)-2-benzofuran-1-one. With the CAS registry number 596-27-0, it is also named as 3',3''-Dimethylphenolphthalein. The product's categories are analytical chemistry; indicator (pH); pH indicators; stains and dyes. It is white to pink or beige to tan powder which is soluble in alcohol, ether, acetic acid and dilute alkali, slightly soluble in water, and insoluble in benzene. In addition, o-Cresolphthalein is used as acid-base indicator. The color range is pH 8.2 (colorless) -9.8 (red).

The other characteristics of this product can be summarized as: (1)ACD/LogP: 3.55; (2)# of Rule of 5 Violations: 0; (3)ACD/LogD (pH 5.5): 3.55; (4)ACD/LogD (pH 7.4): 3.55; (5)ACD/BCF (pH 5.5): 294.05; (6)ACD/BCF (pH 7.4): 292.28; (7)ACD/KOC (pH 5.5): 2034.67; (8)ACD/KOC (pH 7.4): 2022.4; (9)#H bond acceptors: 4; (10)#H bond donors: 2; (11)#Freely Rotating Bonds: 4; (12)Index of Refraction: 1.668; (13)Molar Refractivity: 97.75 cm³; (14)Molar Volume: 262.2 cm³; (15)Polarizability: 38.75×10^-24 cm³; (16)Surface Tension: 59.6 dyne/cm; (17)Enthalpy of Vaporization: 86.75 kJ/mol; (18)Vapour Pressure: 6.29E-13 mmHg at 25°C; (19)Rotatable Bond Count: 2; (20)Tautomer Count: 5; (21)Exact Mass: 346.120509; (22)MonoIsotopic Mass: 346.120509; (23)Topological Polar Surface Area: 66.8; (24)Heavy Atom Count: 26.

Preparation of o-Cresolphthalein: It is obtained by the condensation of phthalic anhydride and o-cresol. Heating the mixture of phthalic anhydride and o-cresol mixture to melt, adding anhydrous zinc chloride at 110 °C and stirring 12-18h at 110-115 °C, then using steam to clean up the remaining o-cresol. The crude product is dissolved sodium hydroxide solution and filtered. Filtrate was neutralized with dilute hydrochloric acid, then we can get the white crystalline which is the end product.

When you are using this chemical, please be cautious about it as the following:
It is harmful by inhalation, in contact with skin and if swallowed. And it is also irritating to eyes, respiratory system and skin. In addition, o-Cresolphthalein has limited evidence of a carcinogenic effect. In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. If you want to contact this product, you must wear suitable protective clothing and gloves.

People can use the following data to convert to the molecule structure.
1. SMILES: O=C1OC(c2ccccc12)(c3ccc(O)c(c3)C)c4ccc(O)c(c4)C;
2. InChI: InChI=1/C22H18O4/c1-13-11-15(7-9-19(13)23)22(16-8-10-20(24)14(2)12-16)18-6-4-3-5-17(18)21(25)26-22/h3-12,23-24H,1-2H3.

The following are the toxicity data which has been tested.