4-[(4-Chlorobenzyl)oxy]-3-methoxybenzenecarbaldehyde: Properties & Uses

4-[(4-Chlorobenzyl)oxy]-3-methoxybenzenecarbaldehyde is a functionalized aromatic aldehyde derived from the vanillin scaffold, featuring a 4-chlorobenzyl ether at the para-hydroxyl position, and serves as a versatile electrophilic building block in medicinal chemistry and organic synthesis.

IUPAC Name

4-[(4-Chlorobenzyl)oxy]-3-methoxybenzaldehyde

SKU

C1369288

Molecular Formula

C₁₅H₁₃ClO₃

Molecular Weight

276.72 g/mol

Functional Groups

Aromatic aldehyde, aryl methoxy ether, aryl benzyl ether, aryl chloride

Core Scaffold

Vanillin (4-hydroxy-3-methoxybenzaldehyde) derivative

Primary Application

Electrophilic building block for Schiff bases, reductive aminations, and heterocycle synthesis

Chemical Structure and Physicochemical Properties

4-[(4-Chlorobenzyl)oxy]-3-methoxybenzenecarbaldehyde (C₁₅H₁₃ClO₃; MW 276.72 g/mol) belongs to the benzaldehyde family and is formally a protected vanillin derivative. The molecule retains the electron-rich methoxyphenyl aldehyde core of vanillin while the free phenolic hydroxyl group is masked as a 4-chlorobenzyl ether, dramatically altering solubility and reactivity relative to the parent compound.

The aromatic aldehyde carbonyl (C=O) at the 1-position of the ring is the primary reactive site, presenting a polarized electrophilic carbon susceptible to nucleophilic addition. The 3-methoxy substituent donates electron density through resonance, moderating electrophilicity. The 4-chlorobenzyl protecting group introduces a pendant aryl chloride, which may participate in further cross-coupling chemistry under appropriate palladium or copper catalysis.

As a solid aromatic aldehyde, the compound is expected to exhibit moderate lipophilicity (log P estimated >2) consistent with the introduction of the hydrophobic chlorobenzyl group, improving organic-solvent solubility compared with free vanillin. Common laboratory solvents including dichloromethane, ethyl acetate, tetrahydrofuran, dimethylformamide, and dimethyl sulfoxide are anticipated to dissolve the compound readily.

Synthesis and Preparation

The most straightforward route to 4-[(4-Chlorobenzyl)oxy]-3-methoxybenzenecarbaldehyde is O-benzylation of vanillin (4-hydroxy-3-methoxybenzaldehyde) using 4-chlorobenzyl chloride or 4-chlorobenzyl bromide under basic conditions. A typical protocol involves dissolving vanillin in an aprotic polar solvent (e.g., acetone or DMF), adding a mild inorganic base such as potassium carbonate, and treating with the 4-chlorobenzyl halide at temperatures ranging from ambient to 60 °C. The reaction generally proceeds via an S_N2 mechanism at the benzylic carbon, selectively etherifying the phenolic oxygen rather than the aldehyde.

Purification is routinely achieved by recrystallization from a suitable solvent system or by silica-gel column chromatography using hexane/ethyl acetate gradients. The aldehyde functionality is preserved under these mild etherification conditions because potassium carbonate does not catalyze aldol or Cannizzaro side reactions appreciably at the reaction temperature.

Alternatively, a retrosynthetic approach using 4-chlorobenzyl alcohol with the pre-protected 4-hydroxy-3-methoxybenzaldehyde via Mitsunobu conditions (DIAD/PPh₃) is feasible but is less atom-economical. Researchers requiring multi-gram quantities of high-purity material may find procurement of the commercial reagent (SKU C1369288, Aladdin Scientific) more efficient than in-house synthesis.

Research Applications

Schiff Base and Imine Formation: The aldehyde group reacts readily with primary amines under mild conditions—often without additional catalyst—to produce imines (Schiff bases). This condensation is widely exploited in the preparation of ligands for transition-metal coordination chemistry, in bioactive molecule screening, and in the construction of dynamic covalent frameworks.

Reductive Amination: Treatment with primary or secondary amines in the presence of a reducing agent such as sodium cyanoborohydride or sodium triacetoxyborohydride converts the aldehyde to a secondary or tertiary amine, enabling efficient introduction of the 4-[(4-chlorobenzyl)oxy]-3-methoxybenzyl pharmacophore into amine-containing drug candidates.

Heterocycle Synthesis: The bifunctional nature of the compound—aldehyde electrophile combined with electron-rich aromatic ring—makes it useful in multicomponent reactions (MCRs) such as the Biginelli reaction, Hantzsch synthesis, and Doebner modification of the Knoevenagel condensation, producing dihydropyrimidinones, dihydropyridines, and cinnamic acid derivatives respectively.

Medicinal Chemistry: Vanillin-derived aldehydes have attracted sustained interest as pharmacophore precursors due to reported bioactivities in the vanillin scaffold (antimicrobial, antioxidant, anti-inflammatory). The chlorobenzyl ether modification modulates lipophilicity and metabolic stability, making C1369288 a useful starting material for structure–activity relationship (SAR) studies.

Cross-Coupling Chemistry: The aryl chloride embedded in the 4-chlorobenzyl group can be engaged in palladium-catalyzed Suzuki–Miyaura, Negishi, or Buchwald–Hartwig reactions, enabling further structural elaboration of compounds derived from this aldehyde.

Handling, Storage, and Safety Considerations

As an aromatic aldehyde bearing a reactive electrophilic carbonyl, 4-[(4-Chlorobenzyl)oxy]-3-methoxybenzenecarbaldehyde should be handled with standard laboratory precautions. Nitrile or latex gloves, safety spectacles, and a laboratory coat are recommended to prevent skin and eye contact. Operations generating dust or aerosols should be conducted in a well-ventilated fume hood.

The compound should be stored in a tightly sealed container, away from strong oxidizing agents, strong bases, and reactive amines that could condense with the aldehyde. Cool, dry storage conditions (typically 2–8 °C or as indicated on the product label) in an amber vial or foil-sealed container will help minimize oxidation and photo-degradation of the aldehyde functionality. For long-term storage, an inert atmosphere (nitrogen or argon) is advisable.

Disposal should comply with local regulations for halogenated organic waste. Users should consult the Safety Data Sheet (SDS) supplied by Aladdin Scientific for specific hazard classifications, first-aid measures, and regulatory information before use.

Frequently asked questions

What is the recommended solvent for dissolving C1369288 in solution-phase reactions?

Dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) provide excellent solubility for this compound and are suitable for most condensation and coupling reactions. Dichloromethane and ethyl acetate are preferred for extraction and chromatographic purification steps.

Can the aryl chloride in the chlorobenzyl group be used for palladium-catalyzed cross-coupling?

Yes. The aryl chloride within the 4-chlorobenzyl moiety is in principle reactive toward palladium-catalyzed Suzuki–Miyaura and related cross-coupling reactions, particularly with electron-rich or bulky phosphine ligands that activate less-reactive aryl chloride substrates. Reaction conditions should be optimized to avoid competing reactions at the aldehyde.

How does 4-[(4-Chlorobenzyl)oxy]-3-methoxybenzenecarbaldehyde differ from vanillin?

Vanillin possesses a free phenolic hydroxyl group at the 4-position, which confers hydrogen-bond donor capacity and limited lipophilicity. In C1369288, this hydroxyl is protected as a 4-chlorobenzyl ether, eliminating the phenolic proton, increasing log P, and introducing a handle for further cross-coupling chemistry while maintaining the reactive aldehyde for downstream functionalization.

What reaction conditions are suitable for Schiff base formation with this aldehyde?

Schiff bases are typically formed by stirring equimolar amounts of the aldehyde and a primary amine in ethanol or methanol at room temperature to 70 °C, often with a catalytic amount of acetic acid. The imine product generally precipitates or can be isolated by evaporation and recrystallization. Molecular sieves may be added to drive equilibrium toward product formation.

Is this compound suitable for use in high-throughput screening (HTS) compound libraries?

The compound's drug-like physicochemical profile—moderate molecular weight (276.72 g/mol), lipophilicity conferred by the chlorobenzyl group, and single reactive aldehyde—makes it a useful electrophilic building block for generating focused libraries via condensation chemistry. However, free aldehydes can react non-specifically with biological nucleophiles, so researchers should consider masking or converting the aldehyde before biological evaluation.

References

1. March, J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 4th ed.; Wiley-Interscience: New York, 1992.
2. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed.; Oxford University Press: Oxford, 2012.
3. Aladdin Scientific Product Page: 4-[(4-Chlorobenzyl)oxy]-3-methoxybenzenecarbaldehyde, SKU C1369288. https://www.aladdin-e.com

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.