Solvent Black 3, also recognized as Sudan Black B, is a compound that commands attention in the chemical industry due to its distinctive molecular structure and resulting properties. As an azo dye, its chemical makeup is key to its effectiveness as a colorant across a variety of demanding applications, from plastics to fuels and specialized staining. A thorough understanding of its chemistry is fundamental for its optimal utilization.

The molecular formula of Solvent Black 3 is C29H24N6. This structure, characterized by the presence of azo groups (-N=N-), is typical of azo dyes and is responsible for the compound's intense color. The molecule is designed to be soluble in organic solvents, a trait that defines it as a 'solvent dye.' This solubility ensures that it can be effectively dispersed and integrated into non-polar or weakly polar media, such as hydrocarbon fuels, oils, waxes, and many plastic resins. This inherent solubility is a critical factor when considering Solvent Black 3 properties for industrial use.

Physically, Solvent Black 3 typically appears as a deep black powder. Its density is approximately 1.45 g/cm³, and it exhibits a melting point range that can vary but is generally found to be around 115-140°C, though this can be influenced by purity and specific crystalline forms. The specification of residue on an 80-mesh sieve being less than or equal to 5.0% indicates a certain fineness and consistency of the powder.

Chemically, Solvent Black 3 is valued for its stability. Its light fastness of 6-7 signifies its ability to resist fading when exposed to light over time. This is a crucial characteristic for products that will be subjected to environmental exposure. Furthermore, its excellent heat resistance allows it to be processed at elevated temperatures commonly encountered in plastic manufacturing without significant degradation. This combination makes it a preferred choice for applications requiring robust color performance, distinguishing it as a high-performance black dye.

The chemical structure also allows Solvent Black 3 to function in more specialized roles, such as histochemical staining, where it is used to identify lipids. This affinity for specific organic molecules underscores the versatile nature of its chemical design. For professionals in material science and chemical engineering, comprehending the detailed chemical formula of Solvent Black 3 and its related physical and chemical properties is essential for successful application and product development.

In conclusion, the molecular structure of Solvent Black 3 underpins its valuable properties, including its deep black color, solubility in organic media, and exceptional heat and light fastness, making it a vital component in many industrial applications.