Bromothymol blue (BTB) is a pH indicator that changes color from yellow to blue in the presence of a basic solution. It is commonly used in science experiments and as a medical diagnostic tool.
| IUPAC Name | 3′,3”-dibromothymolsulfonphthalein |
| Molecular Formula | C27H28Br2O5S |
| CAS Number | 76-59-5 |
| Synonyms | bromothymol sulfonphthalein; 4,4′-(1,1-dioxido-3H-2,1-benzoxathiole-3,3-diyl)bis(2-bromo-3-methyl-6-(1-methylethyl)phenol) |
| InChI | InChI=1S/C27H28Br2O5S/c1-13(2)17-11-20(15(5)23(28)18(17)7-9-19(24(20)29)8-10-21(27)22(30)12-25(31)32)37(33,34)36-26-14(3)6-4-16(35-26)24-7-9-29-11-10-23(24)28/h4-7,9-12,31-32H,8H2,1-3H3 |
Bromothymol Blue Molar Mass
BTB has a molar mass of 624.38 g/mol. Molar mass is the mass of one mole of a substance, and it is commonly used in calculations involving chemical reactions. The molar mass of BTB is calculated by adding up the atomic weights of all the atoms in its chemical formula, which is C27H28Br2O5S. Knowing the molar mass of a substance is important in determining the amount of the substance needed for a given reaction, as well as for determining the amount of product produced in a reaction.
Bromothymol Blue Boiling Point
BTB has a boiling point of 636.3°C at 760 mmHg. The boiling point is the temperature at which a substance changes from its liquid state to its gaseous state at a given pressure. The high boiling point of BTB indicates that it is a stable compound that does not easily vaporize or decompose under normal conditions. The boiling point of a substance can be used to determine its purity, as impurities can cause the boiling point to change.
Bromothymol Blue Melting Point
BTB has a melting point of 165-170°C. The melting point is the temperature at which a solid substance changes from its solid state to its liquid state. The melting point of a substance is used to identify and characterize it, as different substances have different melting points. The melting point of BTB is relatively high, indicating that it is a stable compound that does not decompose easily.
Bromothymol Blue Density g/ml
BTB has a density of 1.36 g/mL. Density is the mass of a substance per unit volume, and it is a measure of how tightly packed the molecules are in a substance. The density of BTB indicates that it is a relatively dense compound, and it is commonly used as a standard in density measurements.
Bromothymol Blue Molecular Weight
The molecular weight of BTB is 624.38 g/mol. Molecular weight is the sum of the atomic weights of all the atoms in a molecule, and it is an important factor in chemical reactions. The molecular weight of BTB is used to determine the amount of the substance needed for a given reaction, as well as for determining the amount of product produced in a reaction.
Bromothymol Blue Structure
The structure of BTB is composed of two aromatic rings, each with a bromine atom attached to it. There is also a sulfonate group attached to one of the rings, which makes the molecule water-soluble. The structure of BTB is similar to other pH indicators, which are used to determine the acidity or basicity of a solution.
Bromothymol Blue Formula
The chemical formula for BTB is C27H28Br2O5S. The formula indicates the number and types of atoms in the molecule, and it is used in chemical reactions to determine the amount of the substance needed for a given reaction. The formula for BTB shows that it contains two bromine atoms, which give it its distinctive yellow-green color in acidic solutions, and a sulfonate group, which makes it water-soluble.
| Appearance | Dark green powder |
| Specific Gravity | 1.36 |
| Color | Yellow-green |
| Odor | Odorless |
| Molar Mass | 624.38 g/mol |
| Density | 1.36 g/mL |
| Melting Point | 165-170°C |
| Boiling Point | 636.3°C at 760 mmHg |
| Flash Point | Not applicable |
| Water Solubility | Soluble |
| Solubility | Soluble in ethanol, slightly soluble in ether and chloroform |
| Vapour Pressure | Not applicable |
| Vapour Density | Not applicable |
| pKa | 6.3 |
| pH | Yellow at pH 6.0, green at pH 7.6, blue at pH 7.9 |
Bromothymol Blue Safety and Hazards
BTB may be harmful if ingested, inhaled, or absorbed through the skin. It can cause irritation to the eyes, skin, and respiratory system. Ingestion may cause gastrointestinal irritation, nausea, vomiting, and abdominal pain. Inhalation of BTB dust or vapors may cause respiratory irritation, coughing, and difficulty breathing. The substance may also be harmful to aquatic life, and should not be disposed of in water sources. Proper personal protective equipment, such as gloves and eye protection, should be worn when handling BTB, and it should be used and disposed of in accordance with proper laboratory procedures and regulations.
| Hazard Symbols | None |
| Safety Description | S22: Do not breathe dust. S24/25: Avoid contact with skin and eyes. S36/37/39: Wear suitable protective clothing, gloves and eye/face protection. |
| UN Ids | Not regulated |
| HS Code | 2921.59.90 |
| Hazard Class | Not classified |
| Packing Group | Not applicable |
| Toxicity | LD50 (oral, rat) = 4500 mg/kg |
Bromothymol Blue Synthesis Methods
There are various methods to synthesize BTB.
One common method is the reaction between thymol blue and bromine in the presence of a strong acid catalyst, such as hydrochloric acid. The reaction proceeds through the electrophilic addition of bromine to the thymol blue molecule, followed by the substitution of a hydrogen atom with a bromine atom. The resulting compound is BTB.
Another method involves the reaction between 2,6-dibromoindophenol and cresol red in the presence of a strong acid catalyst. The reaction proceeds through the electrophilic substitution of a hydrogen atom in the cresol red molecule with a bromine atom from the 2,6-dibromoindophenol molecule. The resulting compound is BTB.
A third method involves the reaction between thymol blue and sodium bromide in the presence of sodium hydroxide. The reaction proceeds through the substitution of a hydrogen atom in the thymol blue molecule with a bromine atom from the sodium bromide molecule. The resulting compound is BTB.
Regardless of the method used, the resulting product must be purified through recrystallization or column chromatography to obtain pure BTB.
Bromothymol Blue Uses
BTB has several applications in various fields. Some of the uses of BTB include:
- Indicator: Used as an acid-base indicator, with a pH range between 6.0 and 7.6. At pH 6.0, it is yellow, at pH 7.6, it is green, and at pH 7.9, it is blue.
- Laboratory experiments: Used in various laboratory experiments to test the presence of carbon dioxide and other gases, and to determine the respiratory quotient.
- Aquaculture: Used in aquaculture to monitor the pH levels of water in fish tanks and ponds.
- Medical field: Used to test for the presence of bile in urine samples and to detect the presence of fungal infections.
- Education: Used in education as a visual aid to demonstrate the principles of acid-base reactions and to teach students about pH levels.
- Agricultural industry: Used to measure the pH levels of soil, which is an important factor in determining the health and growth of plants.
- Environmental testing: Used in environmental testing to measure the pH levels of water sources, such as lakes and rivers, to ensure their suitability for aquatic life.
Overall, BTB is a versatile compound with numerous applications in various fields.
Questions:
Q: What is bromothymol blue?
A: BTB is a pH indicator that is commonly used in laboratory experiments and various other applications. It is a chemical compound that changes color depending on the acidity or alkalinity of a solution.
Q: What is the pH range of bromothymol blue?
A: The pH range of BTB is between 6.0 and 7.6. At pH 6.0, it is yellow, at pH 7.6, it is green, and at pH 7.9, it is blue.
Q: What is the color change of bromothymol blue?
A: The color change of BTB depends on the pH of the solution. At pH 6.0, it is yellow, at pH 7.6, it is green, and at pH 7.9, it is blue.
Q: Is bromothymol blue an acid or base? A: BTB is neither an acid nor a base. It is an indicator that changes color depending on the acidity or alkalinity of a solution.