4''-(Pentyloxy)-[1,1':4',1''-terphenyl]-4-carboxylic acid
[CAS 158938-08-0]

Identification

• Classification: Organic raw materials >> Carboxylic compounds and derivatives
• Name: 4''-(Pentyloxy)-[1,1':4',1''-terphenyl]-4-carboxylic acid
• Synonyms: 4-[4-(4-pentoxyphenyl)phenyl]benzoic acid
• Molecular Formula: C₂₄H₂₄O₃
• Molecular Weight: 360.45
• CAS Registry Number: 158938-08-0
• EC Number: 691-410-4
• SMILES: CCCCCOC1=CC=C(C=C1)C2=CC=C(C=C2)C3=CC=C(C=C3)C(=O)O

Properties

• Density: 1.1±0.1 g/cm³ Calc.^*
• Boiling point: 557.9±43.0 °C 760 mmHg (Calc.)^*
• Flash point: 192.6±21.7 °C (Calc.)^*
• Index of refraction: 1.582 (Calc.)^*

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

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H312-H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P270-P271-P280-P301+P317-P302+P352-P304+P340-P305+P351+P338-P317-P319-P321-P330-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H312
Skin irritation	Skin Irrit.	2	H315
Acute toxicity	Acute Tox.	4	H302

chemBlink Chemical Story

4''-(Pentyloxy)-[1,1':4',1''-terphenyl]-4-carboxylic acid is a rigid aromatic acid with a specific pharmaceutical-process role. Patent and synthesis literature identify it as the lipophilic terphenyl side-chain intermediate used to manufacture the semisynthetic echinocandin antifungal anidulafungin. Published routes construct the extended terphenyl system by carbon-carbon cross-coupling, illustrating modular pharmaceutical synthesis. The pentoxy substituent contributes hydrophobic character, while the terminal carboxylic acid supplies the coupling handle. It is an engineered intermediate that becomes part of a much larger antifungal molecule, not an antifungal drug by itself.

The exact registry identity matters because related free forms, salts, hydrates, stereoisomers, process intermediates and finished medicines can have separate CAS numbers even when their names share a familiar stem. In pharmaceutical and fine-chemical work this distinction is practical: composition changes formula weight and can alter solubility, crystallization, analytical standards, manufacturing specifications and interpretation of physical-property data.

The molecule also illustrates how chemists use functional groups as deliberate handles. Aromatic rings and heterocycles establish shape and electronic character, while amines, alcohols, carbonyl groups, carboxylic acids, esters or ionic centers control reactivity and intermolecular interactions. In a multistep route, an intermediate may be valuable precisely because one group can be transformed selectively while another survives for a later operation.

Modern development is equally an analytical problem. Chemists must demonstrate identity and purity, control stereochemistry or salt composition where relevant, follow process-related impurities and establish reproducible specifications. Reference materials and isolated intermediates therefore have scientific importance even when they are never administered to a patient or sold as the final commercial product.

A careful Chemical Story must distinguish documented use from structural possibility. A familiar scaffold can suggest a biological hypothesis, but resemblance is not evidence that the exact CAS substance has been tested, approved or commercially adopted for that purpose. The account therefore emphasizes verified identity, development history and supported applications, and deliberately leaves unsupported claims out.

Seen more broadly, the compound shows that useful molecular design rarely depends on one functional group in isolation. Performance emerges from the whole structure, stereochemistry and physical form, the route used to make it, and the environment in which it operates. Connecting those molecular details to a real manufacturing, analytical or therapeutic role turns a technical registry entry into a meaningful chemical story.

The exact registry identity matters because related free forms, salts, hydrates, stereoisomers, process intermediates and finished medicines can have separate CAS numbers even when their names share a familiar stem. In pharmaceutical and fine-chemical work this distinction is practical: composition changes formula weight and can alter solubility, crystallization, analytical standards, manufacturing specifications and interpretation of physical-property data.

The molecule also illustrates how chemists use functional groups as deliberate handles. Aromatic rings and heterocycles establish shape and electronic character, while amines, alcohols, carbonyl groups, carboxylic acids, esters or ionic centers control reactivity and intermolecular interactions. In a multistep route, an intermediate may be valuable precisely because one group can be transformed selectively while another survives for a later operation.

Modern development is equally an analytical problem. Chemists must demonstrate identity and purity, control stereochemistry or salt composition where relevant, follow process-related impurities and establish reproducible specifications. Reference materials and isolated intermediates therefore have scientific importance even when they are never administered to a patient or sold as the final commercial product.

References:
1. European Patent EP1156997B1, anidulafungin side-chain chemistry.
2. Published biaryl cross-coupling literature relevant to terphenyl construction.
3. DailyMed. ERAXIS (anidulafungin).

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