Eosin is a fluorescent red dye used in histology and microscopy to stain tissues and cells. It binds to acidic components and highlights cellular structures.
| IUPAC Name | Acid Red 87 |
| Molecular Formula | C20H6Br4Na2O5 |
| CAS Number | 17372-87-1 |
| Synonyms | Acid Red 87; C.I. 45380; Eosin Y; Eosin B; Eosin bluish; Fluorescein disodium salt; Eosin extra bluish; Eosin extra pure; tetrabromo-fluorescein disodium salt; Eosin scarlet; Eosin yellowish; |
| InChI | InChI=1S/C20H8Br4O5.2Na/c21-9-1-3-11(25)7-5-13(27)17(19(31)15(7)29)23-16-8(4-2-10(22)12(26)6-14(16)28)18(30)20(32)24-17;;/h1-6,27-28H,(H,23,29)(H,24,32);;/q;2*+1/p-2 |
Eosin Molar Mass
Eosin has a molar mass of approximately 691.86 g/mol. This means that one mole of Eosin weighs approximately 691.86 grams. The molar mass is calculated by adding up the atomic masses of all the atoms present in the compound. Eosine contains carbon, hydrogen, oxygen, sodium, and bromine atoms in its chemical structure, and their atomic masses are taken into account when calculating its molar mass.
Eosin Boiling Point
Eosin does not have a boiling point as it undergoes thermal decomposition before boiling. When heated, Eosin decomposes at temperatures above 300°C, which can produce toxic fumes. Therefore, Eosin is not suitable for use in applications that require high-temperature stability.
Eosin Melting Point
Eosin has a melting point range of 220-230°C. The melting point is the temperature at which a solid substance transitions into a liquid state. The melting point of Eosin is relatively high, which means that it is a stable compound that is solid at room temperature.
Eosine Density g/ml
Eosine has a density of approximately 2.06 g/mL. Density is a measure of the amount of mass per unit volume of a substance. Eosin is a relatively dense compound due to its molecular weight and the presence of heavy bromine atoms in its structure.
Eosine Molecular Weight
Eosine has a molecular weight of approximately 691.86 g/mol. Molecular weight is the sum of the atomic weights of all atoms in a molecule. It is an important parameter that affects the physical and chemical properties of a compound.
Eosin Structure
Eosin has a tetrabrominated fluorescein structure, which is a derivative of fluorescein. The molecule contains two sodium ions and five oxygen atoms, which provide its acidic character. The bromine atoms in its structure give Eosine its red color and are responsible for its ability to bind to acidic components in tissues and cells.
Eosine Formula
Eosine has a chemical formula C20H6Br4Na2O5. Its formula shows that it contains 20 carbon atoms, 6 hydrogen atoms, 4 sodium atoms, 4 oxygen atoms, and 10 bromine atoms. The formula of Eosine is used to calculate its molar mass and other physical and chemical properties.
| Appearance | Red powder |
| Specific Gravity | 2.06 g/mL |
| Color | Red |
| Odor | Odorless |
| Molar Mass | 691.86 g/mol |
| Density | 2.06 g/mL |
| Melting Point | 220-230°C |
| Boiling Point | Decomposes above 300°C |
| Flash Point | Not applicable |
| Water Solubility | Slightly soluble |
| Solubility | Soluble in alcohol, ether |
| Vapour Pressure | Not applicable |
| Vapour Density | Not applicable |
| pKa | 2.6, 4.4, 6.0, 7.9, 9.7, 11.5 |
| pH | 6.8 – 7.2 (0.1% aqueous solution) |
Eosine Safety and Hazards
Eosine is generally considered to be safe for use in laboratory settings when handled and stored properly. However, it can be irritating to the eyes, skin, and respiratory system, so proper protective equipment, such as gloves and goggles, should be worn when handling the substance. Eosine should also be kept away from sources of heat and flames, as it can decompose at high temperatures and release toxic fumes. In case of ingestion, seek medical attention immediately. Spills should be cleaned up promptly, and the area should be well-ventilated to prevent inhalation of any fumes.
| Hazard Symbols | Xi, N |
| Safety Description | Irritant, Harmful, Environmentally Hazardous |
| UN IDs | UN3077, UN2811 |
| HS Code | 3204.12 |
| Hazard Class | 9, 6.1 |
| Packing Group | III |
| Toxicity | Eosine is considered to have low toxicity. However, ingestion can cause abdominal pain, vomiting, and diarrhea. Prolonged exposure may cause irritation to the skin and eyes. |
Eosine Synthesis Methods
Eosine can be synthesized through several methods. One common method involves the reaction of fluorescein with bromine and sodium bromide in the presence of acetic acid. To yield Eosine, treat the resulting product with sodium hydroxide.
Another method involves the reaction of fluorescein with bromine in the presence of glacial acetic acid, followed by the addition of sodium bromide. To yield Eosine, heat the resulting mixture.
A third method involves the reaction of 2,4-dibromo-3-hydroxybenzaldehyde with phthalic anhydride in the presence of zinc chloride. To yield Eosine, treat the resulting product with sodium hydroxide.
All of these methods promote the formation of Eosin by heating and stirring the reaction mixture under specific conditions. Chemists can achieve purification of the product through a variety of techniques, such as recrystallization or column chromatography.
It is important to note that Eosine is a highly water-soluble substance, and therefore, the synthesis should be carried out in a well-ventilated area with appropriate safety measures in place.
Eosin Uses
Eosin has various uses across a range of industries due to its properties and characteristics. Some of the primary uses of Eosin are:
- Staining agent: Used as a staining agent in histology and cytology to enhance the visualization of cell structures under a microscope. Its ability to stain cellular structures such as red blood cells and muscle fibers makes it an essential tool in many medical and scientific fields.
- Dyeing agent: Used as a dyeing agent in the textile industry.
- Photographic processing: Used in photographic processing as a red filter dye, which helps to improve the contrast and color balance of photographs.
- Biological research: Used as a fluorescent tracer in biological research to track the movement of molecules and cells within living organisms.
- Medical applications: Used as a disinfectant in wound healing and in the treatment of minor skin irritations.
- Ink production: Used in the production of various types of ink, such as stamp pad ink and fountain pen ink.
Overall, the versatility and unique properties of Eosin make it a valuable substance in a wide range of applications, from scientific research to medical treatments and beyond.
Questions:
Q: What does eosin stain?
Eosine is a histological stain that is commonly used to stain cellular structures such as red blood cells and muscle fibers. It stains acidic structures pink or red, and is often used in combination with hematoxylin, which stains basic structures blue or purple, to provide a contrast in histological samples.
Q: What is eosin?
A: In histology, cytology, and other fields of science, researchers commonly use eosin as a biological dye to improve the visualization of cellular structures under a microscope. Eosin, which is a water-soluble red or pink dye, is often combined with other dyes, such as hematoxylin, to create a contrast in histological samples.
Q: What is hematoxylin and eosin staining used for?
A: Hematoxylin and Eosine staining, also known as H&E staining, is a widely used histological staining technique that is used to enhance the visualization of cellular structures in tissue samples. Hematoxylin stains basic structures, such as nuclei and mitochondria, blue or purple, while Eosine stains acidic structures, such as cytoplasm and connective tissue, pink or red. H&E staining is commonly used in medical and scientific research to examine tissue samples and diagnose various diseases and conditions.
Q: Eosin-methylene blue agar (emb) can be used to determine which of the following?
A: Eosine-methylene blue agar (EMB) is a selective and differential agar used for the detection of enteric bacteria, such as Escherichia coli and other coliforms. It is commonly used in microbiology to isolate and identify these bacteria in clinical and environmental samples. EMB agar contains lactose, which is fermented by enteric bacteria, causing the formation of characteristic dark purple or green colonies on the agar.