99% Purity Orcinol​ CAS 504-15-4

CAS Number:​ 504-15-4

Molecular Formula:​ C₇H₈O₂

Molecular Weight:​ 124.14 g/mol

Structural Formula:​ 5-Methylbenzene-1,3-diol

IUPAC Name:​ 5-Methylbenzene-1,3-diol

Common Names:​ Orcinol; Orcin; 3,5-Dihydroxytoluene

Appearance:​ White to pale pink crystalline solid.

Melting Point:​ 107 - 110 °C

Boiling Point:​ Decomposes upon boiling at atmospheric pressure.

Solubility:​ Moderately soluble in water (more soluble in hot water). Freely soluble in ethanol, ether, pyridine, and other polar organic solvents. Also soluble in alkalis, forming water-soluble phenolate salts.

Stability:​ Stable under normal conditions but may discolor upon prolonged exposure to air and light due to oxidation. It is sensitive to strong oxidizing agents.

Odor:​ Characteristic sweet, earthy odor.

Chemical Behavior:​ Exhibits typical phenolic properties: weakly acidic (can form salts with bases), undergoes electrophilic aromatic substitution (e.g., halogenation, nitration) readily due to the activating hydroxyl groups.

Natural Role:​ In nature, orcinol and its derivatives (e.g., orsellinic acid, lecanoric acid) are secondary metabolites produced by lichens​ and some fungi. They are thought to play roles in defense against microorganisms, herbivores, and UV radiation.

Antimicrobial Activity:​ Demonstrates modest antibacterial and antifungal properties, contributing to the ecological advantage of the lichens that produce it.

Enzyme Inhibition:​ Can act as a weak inhibitor for certain enzymes, such as tyrosinase and polyphenol oxidase, due to its structural similarity to substrate molecules.

Toxicity Profile:​ Generally considered low in acute toxicity but can be irritating to skin, eyes, and mucous membranes. It may cause sensitization upon prolonged or repeated exposure.

Natural Biosynthesis:​ In lichens and fungi, orcinol is biosynthesized via the polyketide pathway. The core skeleton is assembled by the sequential condensation of acetyl-CoA and malonyl-CoA units by a polyketide synthase (PKS), followed by cyclization and modification (reduction, decarboxylation). Orsellinic acid is a common direct precursor, which undergoes decarboxylation to form orcinol.

Industrial/ Laboratory Synthesis:

1.Classic Synthesis:​ Involves the fusion of diketene​ or other acetoacetate derivatives with resorcinol in the presence of a condensing agent like zinc chloride.

2.From Toluene Derivatives:​ Can be synthesized via the diazotization and hydrolysis of 3,5-diaminotoluene or through the selective demethylation of more complex methoxy derivatives.

3.Modern Methods:​ May involve catalytic hydroxylation of m-cresol or other regioselective functionalization techniques.

​🌟 Key Advantages & Benefits​

Dual-Functionality from a Single, Inexpensive Source:​​ Orcinol provides both a ​strongly electron-donating dihydroxy (resorcinol) moiety​ and a modifiable ​methyl group​ on the same aromatic ring. This allows for sequential or simultaneous derivatization (e.g., oxidation of the methyl to a carboxylic acid, substitution on the ring) from a single, low-cost starting material, enabling efficient synthesis of complex molecules.

​Natural Origin with Synthetic Versatility:​​ As a ​naturally occurring compound​ (found in lichens and certain plants), it is perceived favorably in consumer products (e.g., hair dyes labeled "natural origin"). Synthetically, it is produced at scale, ensuring consistent purity, ample supply, and low cost, bridging the natural and synthetic worlds effectively.

​Superior Stability & Performance in Key Applications:​​ Compared to its cousin resorcinol, the methyl group in orcinol enhances ​lipophilicity and stability. In hair dye formulations, this translates to better penetration and more durable color. In analytical chemistry (e.g., Bial's test for pentoses), orcinol's specific reactivity provides a more stable colored complex.

​A Privileged Scaffold for Bioactive Molecules:​​ The orcinol scaffold is a core structure in many ​pharmaceutically relevant compounds, including certain antibiotics, antioxidants, and enzyme inhibitors. Its structure serves as an ideal starting point for medicinal chemistry, allowing for easy generation of diverse libraries for drug discovery.

​🎯 Specific Application Scenarios​

For a Cosmetic Chemist Developing a "Plant-Based" Hair Dye:​​ Formulating a permanent oxidative hair color, the chemist uses ​orcinol as a primary coupler. Its natural origin supports "botanical" marketing claims, while its methyl group ensures the resulting dye molecules have optimal solubility and binding to keratin, providing a ​long-lasting, vibrant auburn or brown shade​ with improved gray coverage compared to some pure resorcinol-based couplers.

​For a Pharmaceutical Researcher Discovering New Antibiotics:​​ Screening for novel antifungal agents, the researcher uses ​orcinol as the core scaffold. They perform selective ​oxidation of the methyl group​ to create a carboxylic acid library, then screen these derivatives. One derivative shows potent activity against Candida albicansby inhibiting a novel fungal enzyme pathway, leading to a new lead compound.

​For an Analytical Lab Manager:​​ Running quality control for a carbohydrate-based supplement, the lab uses the ​orcinol-based Bial's test​ to qualitatively and quantitatively check for pentose contamination (like xylose or ribose). The test provides a ​specific colorimetric change (blue-green) for pentoses, distinct from hexoses, offering a simple, cost-effective method for routine screening.

​Orcinol is the strategically methylated derivative of resorcinol that punches above its weight.​​ It delivers ​nearly all the desirable reactivity of resorcinol​ while adding the ​crucial benefits of a modifiable methyl group, slightly enhanced stability/lipophilicity, and a natural origin story—all at a minimal price premium. For chemists and formulators, it represents a smarter, more versatile starting point than resorcinol for creating dyes, pharmaceuticals, and fine chemicals, and a far more economical one than phloroglucinol. It is the ​optimal choice for value-driven innovation​ where an extra functional handle or a natural connotation is required.

Q1: What is the most common laboratory use of orcinol?

A1: Its most defining application is in Bial's test​ to detect the presence of pentose sugars (like ribose in RNA) and deoxy sugars. The formation of a blue-green complex is a classic diagnostic tool in biochemistry and carbohydrate chemistry.

Q2: Is orcinol a natural or synthetic compound?

A2: It is both. It is naturally produced by lichens​ (where it was first discovered) and some fungi. However, for commercial and laboratory use, it is almost exclusively produced via chemical synthesis​ to ensure consistent quality and supply.

Q3: How should orcinol be stored?

A3: Store in a tightly closed container, in a cool, dry, and dark place. Protect from light and air to prevent oxidation and discoloration. It is hygroscopic and may absorb moisture.

Q4: What are the main safety hazards?

A4: It is harmful if swallowed​ and causes skin and serious eye irritation. It may also cause respiratory irritation. Always use personal protective equipment (gloves, safety glasses) and handle in a well-ventilated area or fume hood.

Q5: What is the difference between orcinol and resorcinol?

A5: They are structural analogs. Resorcinol​ is m-dihydroxybenzene (C₆H₆O₂). Orcinol​ is 5-methylresorcinol (C₇H₈O₂) – it has an additional methyl group on the ring. This small difference alters their physical properties (e.g., solubility, melting point) and reactivity.

Q6: Can it be used in cosmetics?

A6: While it has historical use and is studied for UV absorption, its use in modern cosmetics is limited due to its potential as a skin irritant and sensitizer, and the availability of more effective and specialized alternatives. It is not a common active ingredient in mainstream formulations.

Q7: What purity grades are available?

A7: Common grades include:

Technical Grade:​ For industrial dye synthesis.

Reagent Grade / ACS Grade:​ For general laboratory use and analytical applications (like Bial's test).

High Purity Grade (>99%):​ For research and synthetic chemistry.

Disclaimer:​ This information is for educational and scientific purposes only. Orcinol is a chemical substance that requires careful handling. Always consult the Safety Data Sheet (SDS) for the specific product you are using and adhere to all local safety and environmental regulations.