Definition: Diphenic acid, systematically known as 2,2'-biphenyldicarboxylic acid, is an organic compound with the molecular formula C₁₄H₁₀O₄. It consists of a biphenyl backbone with a carboxylic acid group attached to each of the two phenyl rings at the 2- and 2'-positions.
Overview: Diphenic acid is a member of the biphenyl dicarboxylic acid family. It is isomeric with other biphenyldicarboxylic acids such as 3,3'- and 4,4'-biphenyldicarboxylic acid. This compound is primarily used in research contexts, particularly in the study of coordination chemistry, polymer science, and crystal engineering due to its ability to act as a bridging ligand in metal-organic frameworks (MOFs). It may also serve as a precursor or building block in the synthesis of more complex organic molecules.
Etymology/Origin: The name "diphenic acid" is derived from "diphenyl," indicating the presence of two phenyl rings, and the suffix "-ic acid," denoting its carboxylic acid functionality. The term reflects the compound’s structural composition and functional groups.
Characteristics:
- Molecular formula: C₁₄H₁₀O₄
- Molecular weight: 242.23 g/mol
- Appearance: Typically a white to off-white crystalline solid
- Solubility: Sparingly soluble in water; more soluble in polar organic solvents such as ethanol, dimethylformamide (DMF), and dimethyl sulfoxide (DMSO)
- Melting point: Reported values vary; approximately 240–245°C (with decomposition)
- Structure: Features two ortho-substituted carboxylic acid groups on a biphenyl core, which can influence conformational flexibility due to steric hindrance
Related Topics:
- Biphenyl compounds
- Dicarboxylic acids
- Metal-organic frameworks (MOFs)
- Organic synthesis precursors
- Crystal engineering
- Ligand design in coordination chemistry
Diphenic acid is distinct from structurally similar compounds such as phthalic acid (benzene-1,2-dicarboxylic acid), although both contain ortho-positioned carboxyl groups. Its use in materials science stems from its rigid aromatic framework and bifunctional reactivity.