3-(Benzyloxy)phenol: Properties, Synthesis & Applications

3-(Benzyloxy)phenol is a difunctional aromatic compound serving as the monoprotected benzyl ether of resorcinol, widely employed as a selective hydroxyl-protecting-group intermediate in multistep organic synthesis.

IUPAC Name

3-(benzyloxy)phenol

CAS Number

3019-26-9

Molecular Formula

C₁₃H₁₂O₂

Molecular Weight

200.23 g/mol

Appearance

White to off-white crystalline solid

Key Functional Groups

Free phenolic –OH and benzyl aryl ether –OBn

Solubility

Soluble in common organic solvents (ethanol, acetone, ethyl acetate, DCM); sparingly soluble in water

Chemical Identity and Physical Properties

3-(Benzyloxy)phenol (CAS 3019-26-9) is the monoselectivly benzyl-protected form of resorcinol (1,3-benzenediol). Its molecular formula is C₁₃H₁₂O₂ with a molecular weight of 200.23 g/mol. The compound features two distinct oxygen functionalities: a free phenolic hydroxyl group at the 1-position and a benzyl aryl ether linkage at the 3-position.

The molecule typically presents as a white to off-white crystalline solid at room temperature. It is readily soluble in polar aprotic and protic organic solvents such as dichloromethane, ethyl acetate, acetone, and ethanol, but shows only limited solubility in water, consistent with its moderately lipophilic character. The free phenolic –OH group confers mild acidity (pKa broadly comparable to substituted phenols, approximately 9–10) and provides a handle for further functionalization. Storage under cool, dry conditions away from light and strong oxidizing agents is recommended to maintain purity.

Synthesis and Preparation

3-(Benzyloxy)phenol is most commonly prepared by selective mono-benzylation of resorcinol. The standard approach employs resorcinol with benzyl bromide or benzyl chloride in the presence of a mild base such as potassium carbonate in an aprotic solvent (e.g., acetone or DMF) under controlled temperature. Careful control of stoichiometry—using approximately one equivalent of the benzylating agent—favors mono-alkylation at one of the two phenolic oxygens, yielding 3-(benzyloxy)phenol as the primary product alongside recoverable starting material and the dibenzylated byproduct.

Phase-transfer catalysis conditions have also been described as an alternative approach to improve selectivity and yield. Purification is typically achieved by recrystallization or column chromatography. The regioselectivity between the two equivalent hydroxyl positions of resorcinol is statistical under symmetry, but reaction conditions and temperature can be optimized to maximize the mono-ether product. Researchers requiring high-purity material for sensitive downstream reactions typically source this compound directly from suppliers such as Aladdin Scientific to avoid the burden of optimization and purification.

Research Applications and Reactivity

3-(Benzyloxy)phenol occupies an important niche in synthetic organic chemistry primarily because it presents two orthogonally addressable oxygen functionalities. The free phenolic hydroxyl can be selectively alkylated, acylated, sulfonylated, or subjected to Mitsunobu reactions, while the benzyl ether remains intact under a wide range of reaction conditions. Conversely, the benzyl ether can be cleanly removed by catalytic hydrogenolysis (e.g., Pd/C under H₂ atmosphere) to regenerate the second free hydroxyl group, revealing resorcinol or an asymmetrically substituted diol depending on prior manipulation of the free –OH.

This orthogonal protection strategy makes the compound valuable in the synthesis of natural products, pharmaceutically active molecules, and functional materials that contain a 1,3-dioxybenzene motif—a structural element found in numerous bioactive compounds and ligands. It is also used as a building block for asymmetric aryl ether synthesis, as a precursor to catechol- and resorcinol-based pharmacophores, and in the preparation of dendrimers and supramolecular architectures. Additionally, the free phenol can serve as a nucleophile in copper- or palladium-catalyzed O-arylation reactions, enabling rapid access to unsymmetrical diaryl ethers.

Handling, Safety, and Storage

As with most phenolic compounds, 3-(benzyloxy)phenol should be handled with appropriate personal protective equipment including nitrile gloves, safety glasses, and a laboratory coat. Operations generating dust or aerosols should be conducted in a well-ventilated area or fume hood. The compound is not classified as a highly acute hazard, but phenolic compounds in general can cause skin and eye irritation and should not be ingested or inhaled.

For storage, the compound should be kept in a tightly sealed container at room temperature or under refrigeration (2–8 °C) in a cool, dry, and dark environment to prevent degradation. It should be stored away from strong oxidizers and bases. Users should consult the Safety Data Sheet (SDS) provided by Aladdin Scientific for complete hazard classification, first-aid measures, and disposal guidance in accordance with local regulations. Standard laboratory waste-disposal procedures for organic compounds apply.

Frequently asked questions

What is 3-(Benzyloxy)phenol used for in organic synthesis?

3-(Benzyloxy)phenol is primarily used as a versatile bifunctional building block in multistep organic synthesis. Its free phenolic –OH can be selectively functionalized while the benzyl ether acts as a removable protecting group, enabling the orthogonal elaboration of both oxygen atoms of the resorcinol scaffold. This makes it valuable for constructing natural product analogs, pharmaceutical intermediates, and functionalized aryl ethers.

How is the benzyl ether group removed from 3-(Benzyloxy)phenol?

The benzyl ether protecting group in 3-(benzyloxy)phenol is most commonly removed by catalytic hydrogenolysis using palladium on carbon (Pd/C) as the catalyst under a hydrogen atmosphere (H₂ gas or a hydrogen-transfer reagent such as ammonium formate). These conditions are mild and chemoselective, cleaving the benzyl–oxygen bond cleanly to regenerate the free phenol without affecting most other functional groups present in the molecule.

How should 3-(Benzyloxy)phenol be stored to maintain its quality?

3-(Benzyloxy)phenol should be stored in a tightly sealed container in a cool, dry, and dark location, ideally at room temperature or under refrigeration at 2–8 °C. It should be kept away from strong oxidizing agents, direct light, and moisture. Under these conditions the compound retains its purity over extended periods. Always refer to the product SDS and certificate of analysis for specific storage recommendations from Aladdin Scientific.

What is the difference between 3-(Benzyloxy)phenol and resorcinol?

Resorcinol (1,3-benzenediol) has two free hydroxyl groups on the benzene ring, making it highly symmetric and reactive at both positions. 3-(Benzyloxy)phenol is the monoprotected derivative of resorcinol in which one –OH has been converted to a benzyl ether (–OBn), leaving the other –OH free. This differentiation of the two oxygens allows chemists to manipulate each position independently, something that is very difficult to achieve with unprotected resorcinol.

References

1. Greene, T. W.; Wuts, P. G. M. Protective Groups in Organic Synthesis, 4th ed.; Wiley-Interscience: Hoboken, NJ, 2007.
2. March, J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 4th ed.; Wiley: New York, 1992.
3. Aladdin Scientific. Product page: 3-(Benzyloxy)phenol, SKU B152817. Aladdin Scientific Corp.

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