Overview
Thymol Blue is a triphenylmethane dye belonging to the sulfonphthalein family of pH indicators. It exhibits a distinct color change from yellow (acidic) to blue (alkaline) across two transition ranges (pH 1.2-2.8 and 8.0-9.6). First synthesized in the early 20th century, it remains a staple in analytical chemistry due to its reliability and clear visual endpoints. The compound derives its name from thymol, a monoterpene phenol that forms part of its molecular structure. Its dual-range pH sensitivity makes it particularly valuable for titrations requiring multiple equivalence point detection.
Physical and Chemical Properties
As a crystalline powder, Thymol Blue demonstrates moderate solubility in polar organic solvents like ethanol (10 g/100 mL) but limited water solubility (0.04 g/100 mL). The dry powder is stable under normal conditions but may degrade when exposed to strong oxidizers or prolonged UV light. Its color transitions occur through protonation/deprotonation of sulfone groups. The first transition (pH 1.2-2.8) involves structural changes in the sulfonphthalein core, while the second (pH 8.0-9.6) reflects phenolic group ionization. The molar extinction coefficient reaches 38,000 L·mol⁻¹·cm⁻¹ at 596 nm in alkaline solutions.
Main Applications
In laboratory settings, Thymol Blue serves as a visual endpoint indicator for acid-base titrations, particularly for weak acid-strong base reactions. Its ability to function across wide pH ranges makes it suitable for multi-step titration procedures. The dye finds specialized use in microbiology for staining bacterial capsules and in histology for tissue pH monitoring. Industrial applications include water treatment process monitoring and quality control in pharmaceutical manufacturing where pH-sensitive reactions occur.
Safety and Storage
As a chemical substance, Thymol Blue requires proper handling to prevent exposure. Powdered form poses inhalation risks, and solutions may cause skin/eye irritation. Laboratories should store it in sealed containers with desiccants to prevent moisture absorption. For waste disposal, neutralization followed by incineration is recommended. Spills should be contained with absorbent materials and cleaned while wearing nitrile gloves and safety goggles. SDS sheets typically classify it as a Category 4 health hazard (low toxicity).
B2B Procurement Guide
When sourcing Thymol Blue commercially, buyers should specify technical grade (≥95% purity) or ACS reagent grade (≥98%) depending on application requirements. Bulk pharmaceutical applications may demand USP/EP compliance documentation. Leading manufacturers include Sigma-Aldrich, TCI Chemicals, and Alfa Aesar. Prices fluctuate based on market availability of thymol precursors. For large-scale orders (25kg+), direct contracts with specialty chemical producers often yield 15-30% cost reductions compared to laboratory supply distributors.
Related Manufacturers
- 主营：聚苯胺、脯氨酸甲酯盐酸盐、苄基三甲基氯化铵
- 主营：阻燃剂、拉那白、牛儿酮、麝香酮、海藻糖、热敏蓝、萘磺酸、氯菊酯、硫酸锌、催化剂、杨梅酯、檀香醚、聚醚胺、吸收剂、脂檀油、苍术素、羟钴胺、转移剂、溶剂绿、王浆酸、芬多精、纤维素、新戊酯、王冠醚、遮甜粉
- 主营：环戊酮、甲酸镍、阻燃剂、百里酚蓝、草酸镧、钼酸铵、催化剂、钒酸铋、溴氨酸、硝酸锆、碳酸镧、白僵菌、磷酸铁、钨酸酐、氟化镧、视黄醇、叔丁醇、杀螨剂、杀虫剂、醋酸钬、抗粘剂、氟化镥、肟菌酯、氢化钠、氯铂酸、氟化镁
- 主营：阻燃剂、乙酸镍、乙酸镝、麝香草酚蓝、硫酸锂、硫酸锶、溴氨酸、香茅醇、肌氨酸、锂电池、四氢萘、磷酸铬、碳酸镁、碳酸镍、防冻剂、磷酸铝、叔丁醇、氟苯基、浮选剂、稀释剂、羟乙基、去除剂、庚二酸、除磷剂、十八烯、蛋白酶
- 主营：乙二醇、甘油、防冻液、溴百里香酚蓝、丙三醇
- 主营：异丙醇、冰醋酸、化工原料、麝香草酚蓝、正庚烷、甲基环己烷、乙二醇、苯酚、江苏异丙醇、江苏化工原料、工业吡啶、工业苯酚、正丁醇、MIBK、无水乙醇、正己烷
- 主营：全氟三丁胺、木质素、吉氏色素
- 主营：全氟三丁胺、二苄叉山梨醇、六氟丙烯二聚体、溴百里酚蓝、六氟环氧丙烷二聚体、异丙醇铝、纳米勃姆石、二异戊基硫醚、隐色结晶紫、邻菲罗啉
- 主营：甘氨酸、水苏糖、阻燃剂、麝香酮、硫酸锌、硫酸锆、硫酸锂、硫酸锶、硫酸锰、铝酸锌、1680-21-3、牛磺酸、褪黑素、磷酸铁、丙酸铵、苏云金、碳酸镁、肉桂醛、磷酸铝、王浆酸、椰油胺、赖氨酸、增塑剂、浸膏粉、乙氧基
- 主营：有机原料、中间体、香精香料、催化剂、有机硅、表面活性剂
- 主营：叔碳酸、十八醛、溶菌酶、百里香酚蓝、海藻糖、癸二醇、氨基丙基、氢路噻嗪、邻苯二甲、乙基碳二、羟基癸酸、正十七烷、谷胱甘肽、烷二甲醇、松果体素、vc磷酸酯镁、2-甲基丁醛、朱栾倍半萜、丁烷四乙酸、表面活性剂、癸烷撑二醇、缩水甘油邻、10-羟基羊蜡酸、氢氯噻嗪杂质、盐酸邻菲罗啉、壳聚糖季铵盐
- 主营：透析袋、移液器、SIGMA、溴麝香草酚蓝指示剂、赛默飞、爱思进、康宁、离心管、巴氏吸管、保存管、封板膜、细胞爬片、滤器、ELISA试剂盒
- 主营：三硫代碳酸钠、红色素-16、聚乙烯亚胺、溴百里酚蓝钠盐、三乙二醇二异辛酸酯、巯基苯并噻唑钠、L-丙交酯、乙交酯、石油酯-T50、多元醇苯甲酸酯、热压敏染料、光稳定剂、高分子降解材料
- 主营：酸碱指示剂、指示剂、生物染色剂、溴百里香酚蓝、PH指示剂
- 主营：氯化镉分析纯、硝酸镉分析纯、碳酸镉试剂级、百里香酚蓝、乙酸镉分析纯、硫酸镉分析纯、氧化钙、甲酚红、苯酚红、间甲酚紫、氢氧化钙、氧化镉分析纯、乙二醇涤纶、丙二酸、轻质氧化钙、冰醋酸工业、丁二酮肟、铜试剂