5-Hydroxy-1,3-dihydrobenzimidazole-2-thione
[CAS# 92806-98-9]

Identification

• Classification: Organic raw materials >> Heterocyclic compound >> Imidazoles
• Name: 5-Hydroxy-1,3-dihydrobenzimidazole-2-thione
• Synonyms: 2-Mercapto-1H-benzo[d]imidazol-5-ol
• Molecular Formula: C₇H₆N₂OS
• Molecular Weight: 166.20
• CAS Registry Number: 92806-98-9
• SMILES: C1=CC2=C(C=C1O)NC(=S)N2

Properties

• Density: 1.6±0.1 g/cm³ Calc.^*
• Boiling point: 422.2±37.0 ºC 760 mmHg (Calc.)^*
• Flash point: 209.1±26.5 ºC (Calc.)^*
• Index of refraction: 1.832 (Calc.)^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H302-H315-H319-H335
• Precautionary Statements: P261-P305+P351+P338

Discovory and Applicatios

5-Hydroxy-1,3-dihydrobenzimidazole-2-thione is a sulfur- and nitrogen-containing heterocycle derived from the benzimidazole framework, a core structure extensively studied for its chemical versatility and biological relevance. This compound is distinguished by a hydroxy substituent at the 5-position of the aromatic ring and a thione group at the 2-position of the imidazole moiety. The benzimidazole system itself, composed of a fused benzene and imidazole ring, contributes to the molecule’s stability and potential for diverse reactivity. The thione functional group imparts nucleophilic and metal-binding properties, while the hydroxy group offers opportunities for hydrogen bonding and further chemical modifications.

The synthesis of 5-hydroxy-1,3-dihydrobenzimidazole-2-thione typically involves the condensation of 4-hydroxy-o-phenylenediamine with carbon disulfide or analogous thiocarbonyl compounds under acidic or basic conditions. This reaction forms the benzimidazole ring system with concurrent introduction of the thione group at the 2-position. The hydroxy group is either retained from the starting material or introduced via selective hydroxylation. The compound may exist in equilibrium with its thiol tautomer, although the thione form is more stable under neutral and mildly acidic conditions. This tautomeric behavior influences its chemical reactivity, particularly in metal chelation and nucleophilic substitution reactions.

As a member of the benzimidazole-2-thione class, 5-hydroxy-1,3-dihydrobenzimidazole-2-thione has been examined for its coordination chemistry. The compound acts as a bidentate ligand, coordinating through the thione sulfur and one of the benzimidazole nitrogens, with potential tridentate behavior if the hydroxy group is deprotonated under basic conditions. Metal complexes formed with this ligand have been investigated for their structural, spectroscopic, and thermal properties. The chelating ability of this compound allows it to form stable complexes with transition metals such as copper, cobalt, nickel, and zinc. These complexes have attracted attention in the context of bioinorganic modeling, catalysis, and potential therapeutic agents.

In medicinal chemistry, benzimidazole derivatives bearing thione and hydroxy functionalities have been studied for a range of biological activities. 5-Hydroxy-1,3-dihydrobenzimidazole-2-thione exhibits structural features that are commonly associated with antimicrobial, antioxidant, and anticancer activities. The hydroxy group enhances the molecule’s polarity and capacity for hydrogen bonding, contributing to interactions with biological macromolecules such as enzymes or DNA. The presence of the thione moiety allows for binding to metal centers in biological systems, which is a relevant mechanism in the inhibition of metalloenzymes. Although specific pharmacological profiles vary across substituted benzimidazole-2-thiones, the core structure of 5-hydroxy-1,3-dihydrobenzimidazole-2-thione provides a foundation for potential therapeutic applications.

Beyond its biological significance, this compound has also been explored in the context of synthetic chemistry and materials science. Its ability to undergo electrophilic and nucleophilic substitution reactions enables the preparation of a variety of functional derivatives. These derivatives serve as intermediates in the synthesis of more complex heterocycles or as ligands in the formation of coordination polymers and organometallic assemblies. The electron-rich nature of the hydroxy and thione groups also lends itself to studies in redox chemistry and spectroscopic applications.

In summary, 5-hydroxy-1,3-dihydrobenzimidazole-2-thione is a well-defined heterocyclic compound with notable applications in coordination chemistry and pharmaceutical research. Its structural features support its role as a ligand in metal complexes and as a potential scaffold for drug development. The compound exemplifies the chemical and functional diversity of benzimidazole derivatives, reinforcing their continued significance in scientific investigation.