Compound Overview and Physicochemical Properties

Ethyl 4-Methoxycinnamate (CAS commonly associated with the trans/E isomer; Aladdin SKU E422824) is the ethyl ester of 4-methoxycinnamic acid, belonging to the cinnamate family of UV-absorbing compounds. Its molecular formula is C₁₂H₁₄O₃ with a molecular weight of approximately 206.24 g/mol.

The compound typically appears as a white to off-white crystalline solid at room temperature. It exhibits strong absorption in the UV-B region (~310 nm in ethanol solution), which underpins its widespread use as a model UV absorber and reference standard in photochemistry research. The para-methoxy group on the phenyl ring extends the conjugated system, red-shifting the absorption maximum relative to unsubstituted ethyl cinnamate.

Key physicochemical parameters (textbook-level estimates; verify against certificate of analysis):

• Molecular Formula: C₁₂H₁₄O₃
• Molecular Weight: 206.24 g/mol
• Appearance: White to off-white crystalline solid
• Solubility: Soluble in common organic solvents (ethanol, methanol, acetone, ethyl acetate, DMSO); poorly soluble in water
• Storage: Store in a cool, dry, well-ventilated area away from light

Laboratory Applications

Ethyl 4-Methoxycinnamate serves multiple roles in research and analytical laboratories:

1. UV-filter reference standard: Used as a model compound for evaluating and comparing the UV-absorption efficiency of cinnamate-based sunscreen actives. Researchers benchmark novel UV-filter candidates against its well-characterized absorption profile.
2. Photochemistry and photostability studies: The compound undergoes trans-to-cis photoisomerization upon UV irradiation, making it a classic substrate for studying photoisomerization kinetics and mechanisms in solution.
3. Synthesis intermediate: Serves as a starting material or intermediate for the synthesis of more complex cinnamate derivatives, including pharmaceutical and agrochemical candidates.
4. Cosmetic ingredient research: Used in formulation studies investigating UV protection, stability, and skin-penetration behavior of lipophilic UV absorbers.
5. Analytical calibration: Applied as an analytical standard in HPLC and UV-Vis spectrophotometry method development and validation.

Step-by-Step Laboratory Protocol

The following general protocol describes preparation of a stock solution and UV-absorption measurement for Ethyl 4-Methoxycinnamate. Adapt conditions to your specific experimental requirements.

Materials Required

• Ethyl 4-Methoxycinnamate (Aladdin SKU E422824)
• Spectroscopic-grade ethanol (or appropriate solvent)
• Analytical balance (±0.01 mg sensitivity)
• Volumetric flasks (10 mL, 100 mL)
• UV-Vis spectrophotometer with 1 cm quartz cuvettes
• Amber vials for light-sensitive stock storage
• PPE: lab coat, nitrile gloves, safety glasses

Procedure

1. Preparation of stock solution (1 mM): Accurately weigh approximately 2.06 mg of Ethyl 4-Methoxycinnamate into a 10 mL amber volumetric flask. Dissolve in spectroscopic-grade ethanol, sonicating briefly if needed. Dilute to the mark with ethanol and mix thoroughly. Store at 4 °C protected from light.
2. Preparation of working solution (10 µM): Transfer 100 µL of the 1 mM stock solution into a 10 mL volumetric flask and dilute to the mark with ethanol. Mix well.
3. Blank measurement: Fill a clean quartz cuvette with pure ethanol. Record the baseline absorbance spectrum from 250 nm to 400 nm.
4. Sample measurement: Fill a second cuvette with the 10 µM working solution. Record the absorbance spectrum from 250 nm to 400 nm. Note the wavelength of maximum absorbance (λ_max).
5. Data analysis: Confirm λ_max near 310 nm. Calculate the molar extinction coefficient (ε) using Beer–Lambert Law: A = ε × c × l, where A is absorbance, c is concentration (mol/L), and l is path length (cm).
6. Photoisomerization study (optional): Irradiate a portion of the working solution with a UV lamp (365 nm or broadband UV-B). Record UV-Vis spectra at defined time intervals to monitor the decrease in trans-isomer absorbance and appearance of cis-isomer peaks.

Expected Result

A strong absorbance peak near 310 nm confirms compound identity and solution integrity. Loss of this peak upon UV irradiation corresponds to photoisomerization to the cis form.

Safety, Handling, and Storage

Always consult the Safety Data Sheet (SDS) for Ethyl 4-Methoxycinnamate before use. The following represents general guidance for cinnamate ester compounds:

• Personal Protective Equipment: Wear appropriate PPE including lab coat, nitrile gloves, and safety glasses when handling. Work in a well-ventilated area or fume hood.
• Skin and Eye Contact: Avoid direct contact. In case of skin contact, wash thoroughly with soap and water. In case of eye contact, rinse immediately with plenty of water and seek medical attention.
• Inhalation: Avoid inhaling dust or vapors. Use appropriate respiratory protection if dust generation is unavoidable.
• Storage: Store in a tightly sealed container in a cool (2–8 °C recommended for long-term stability), dry, and well-ventilated area, protected from light to prevent photoisomerization of the bulk material.
• Disposal: Dispose of waste in accordance with local regulations for organic chemical waste. Do not pour down the drain.
• Stability: The compound is light-sensitive; extended exposure to UV or ambient light may induce isomerization. Prepare solutions fresh or store in amber vessels.

Troubleshooting and Quality Considerations

The following table summarizes common issues encountered when working with Ethyl 4-Methoxycinnamate and suggested remedies:

For product specification details, purity certificates, and SDS, contact Aladdin Scientific customer service and reference SKU E422824 or the related reference SKU E132897.