2-Phenylbenzimidazole-5-sulfonic acid CAS No.: 27503-81-7

May 20, 2026

2-Phenylbenzimidazole-5-sulfonic acid CAS No.: 27503-81-7, commonly known as the UV filter UV-T or Ensulizole, is an important water-soluble ultraviolet absorber. With its high-efficiency UVB protection capability and good hydrophilicity, it is widely used in cosmetics, advanced materials , and biochemical research..

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📋Basic information:

Chemical name: 2-Phenylbenzimidazole-5-sulfonic acid
CAS No.: 27503-81-7
Molecular Formula: C13H10N2O3S
Molecular Weight: 274.30

📌Specification:

Appearance:	White powder
Purity:	≥98%
Density :	1.3592 g/cm3
Package:	1KG/Bag, 25kg/Drum；or as per customer request
Storage:	Store in cool & dry place.

🧩Application of 2-Phenylbenzimidazole-5-sulfonic acid
CAS No.: 27503-81-7

1. Highly effective UV absorber for Sunscreen Cosmetics

It can efficiently absorbs UVB radiation (with a major absorption peak around 302 ± 2 nm) and also provides partial UVA protection. It is commonly used in combination with other ingredients such as avobenzone, titanium dioxide, zinc oxide and Tinosorb. Its UV protection efficacy and stability will not decline over time. To a certain extent, it can inhibit the photodegradation of other UVB filters in sunscreen products. It has the following advantage:

Excellent Skin Feel: Its most notable feature is being water-soluble rather than oil-soluble. Therefore, it is non-greasy in formulations and provides a light, refreshing skin feel. It is particularly suitable for sunscreens, BB creams, daily creams, and especially for oily or combination skin.
Good Photostability: Compared to certain other sunscreen agents, Ensulizole maintains good stability under light exposure, ensuring long-lasting protective effects.
High Safety Profile: It is approved for use in cosmetics by regulatory authorities such as the U.S. FDA, exhibiting low toxicity and minimal skin irritation.

2. Advanced Materials

It can be added to water-based coatings, polymers, and other coatings to impart weatherability, preventing degradation, yellowing, and performance loss caused by UV radiation.

3. Scientific Research Reagent

Analytical Chemistry: Used as a reagent or standard in chromatography or spectrophotometry.
Sensor Fabrication: Used in the production of biomimetic sensors to detect other UV filters (e.g., 4-methylbenzylidene camphor).
Pharmaceutical & Biochemical Research: Acts as an intermediate in drug synthesis and plays a role in biochemical studies such as enzyme activity and pollutant degradation.