Sodium methylparaben
[CAS# 5026-62-0]

Identification

• Classification: Organic raw materials >> Organometallic salt
• Name: Sodium methylparaben
• Synonyms: p-Hydroxybenzoic acid methyl ester sodium salt; Sodium (p-carboxyphenoxy)-methyl ester; 4-Hydroxybenzoic acid methyl ester sodium salt; Methyl 4-hydroxybenzoate sodium salt; Methyl p-hydroxybenzoate sodium salt; Methylparaben sodium; Sodium 4-(methoxycarbonyl)phenoxide; Sodium 4-carbomethoxyphenolate; Sodium methyl p-hydroxybenzoate; Sodium p-methoxycarbonylphenoxide
• Molecular Formula: C₈H₇NaO₃
• Molecular Weight: 174.13
• CAS Registry Number: 5026-62-0
• EC Number: 225-714-1
• SMILES: COC(=O)C1=CC=C(C=C1)[O-].[Na+]

Properties

• Density: 1.42 g/mL (20 °C) (Expl.)
• Melting point: >125 °C (Expl.)

Safety Data

• Hazard Symbols: GHS05;GHS07;GHS09 Danger
• Risk Statements: H302-H315-H318-H411-H412
• Safety Statements: P264-P264+P265-P270-P273-P280-P301+P317-P302+P352-P305+P354+P338-P317-P321-P330-P332+P317-P362+P364-P391-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Serious eye damage	Eye Dam.	1	H318
Skin irritation	Skin Irrit.	2	H315
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Acute toxicity	Acute Tox.	4	H302
Eye irritation	Eye Irrit.	2	H319
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411
Specific target organ toxicity - repeated exposure	STOT RE	1	H372
Specific target organ toxicity - single exposure	STOT SE	3	H335
Acute toxicity	Acute Tox.	4	H312
Eye irritation	Eye Irrit.	2	H320

Discovery and Applications

Sodium methylparaben is the sodium salt form of methylparaben, a member of the paraben family widely used as preservatives in various industries. Chemically, sodium methylparaben is derived from methylparaben by neutralization with sodium hydroxide, resulting in a water-soluble compound. Its chemical formula is C₈H₇NaO₃, and it typically appears as a white to off-white powder that dissolves readily in water, which enhances its utility in aqueous formulations.

The discovery of parabens dates back to the early 20th century when methylparaben and related compounds were first introduced as antimicrobial agents due to their effectiveness in inhibiting mold, yeast, and bacterial growth. Their widespread adoption followed as the need for safe and effective preservatives in food, cosmetics, and pharmaceuticals grew. Sodium methylparaben was developed to improve the solubility of methylparaben in water, facilitating its use in a broader range of products where water-based formulations are common.

In pharmaceutical applications, sodium methylparaben is used as a preservative in various formulations, including topical creams, ointments, oral suspensions, and injectables. Its role is to prevent microbial contamination and prolong the shelf life of these products. The compound is effective against a broad spectrum of microorganisms and is particularly valued for its low toxicity and minimal irritation to skin and mucous membranes.

Cosmetic and personal care products frequently incorporate sodium methylparaben as a preservative to maintain product integrity. It is found in lotions, shampoos, conditioners, deodorants, and makeup products. The compound’s ability to prevent microbial spoilage helps ensure product safety and consistency over time, especially in water-based formulations. It also contributes to consumer confidence by reducing the risk of infection or adverse reactions associated with microbial contamination.

In the food industry, sodium methylparaben is approved as a food preservative in some countries, used to inhibit fungal growth and extend the shelf life of products such as baked goods, beverages, and processed foods. Its antimicrobial properties help maintain food quality and safety during storage and distribution.

From a chemical standpoint, sodium methylparaben exhibits good stability under normal storage conditions. It is resistant to hydrolysis and oxidation, which allows it to retain its preservative effectiveness over extended periods. Its pH range of efficacy typically lies between 4 and 8, making it compatible with many formulations without compromising stability.

Safety assessments have established that sodium methylparaben has low acute toxicity and is generally recognized as safe for use in cosmetics, pharmaceuticals, and food when applied within regulatory limits. It has been extensively studied and is considered non-carcinogenic and non-sensitizing in typical use concentrations. However, regulatory agencies monitor allowable levels to ensure consumer safety, and products containing parabens are subject to continuous evaluation.

Sodium methylparaben’s advantages include its broad-spectrum antimicrobial activity, water solubility, and compatibility with many formulation types. It also offers cost-effectiveness and ease of incorporation into manufacturing processes. These attributes have contributed to its continued popularity as a preservative.

In summary, sodium methylparaben is a water-soluble preservative derived from methylparaben that plays a crucial role in protecting pharmaceutical, cosmetic, and food products from microbial contamination. Its discovery as part of the paraben family marked a significant advancement in preservative technology, and its solubility and safety profile have ensured its wide acceptance and use in modern formulations.

References

1964. INTERACTION OF SOME PHARMACEUTICALS WITH MACROMOLECULES. I. EFFECT OF TEMPERATURE ON THE BINDING OF PARABENS AND PHENOLS BY POLYSORBATE 80 AND POLYETHYLENE GLYCOL 4000. Journal of Pharmaceutical Sciences, 53(1).
DOI: 10.1002/jps.2600530119

2024. Simultaneous and sensitive detection of methylparaben and its metabolites by using molecularly imprinted solid-phase microextraction fiber array technique. Analytica Chimica Acta, 1312.
DOI: 10.1016/j.aca.2024.342676

2024. Deciphering trends in replacing preservatives in cosmetics intended for infants and sensitive population. Scientific Reports, 14(1).
DOI: 10.1038/s41598-024-69624-9