3-Methoxybutyl 3-Mercaptopropionate
[CAS# 27431-40-9]

Identification

• Classification: Organic raw materials >> Carboxylic compounds and derivatives >> Carboxylic esters and their derivatives
• Name: 3-Methoxybutyl 3-Mercaptopropionate
• Synonyms: 3-Methoxybutyl 3-sulfanylpropanoate
• Molecular Formula: C₈H₁₆O₃S
• Molecular Weight: 192.28
• CAS Registry Number: 27431-40-9
• EC Number: 608-098-2
• SMILES: CC(CCOC(=O)CCS)OC

Properties

• Density: 1.0±0.1 g/cm³ Calc.^*
• Boiling point: 269.7±25.0 ºC 760 mmHg (Calc.)^*
• Flash point: 150.4±11.1 ºC (Calc.)^*
• Index of refraction: 1.458 (Calc.)^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H315-H319
• Precautionary Statements: P264-P264+P265-P280-P302+P352-P305+P351+P338-P321-P332+P317-P337+P317-P362+P364

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319

Discovory and Applicatios

3-Methoxybutyl 3-mercaptopropionate is an organic compound belonging to the class of alkyl mercaptopropionates, characterized by the presence of both ester and thiol functional groups. Its molecular formula is C₈H₁₆O₃S, and it has a molecular weight of approximately 192.28 g/mol. Structurally, the compound consists of a 3-mercaptopropionate group esterified with a 3-methoxybutanol moiety, combining hydrophilic and hydrophobic domains that influence its solubility and reactivity in organic and polymeric systems. The compound is typically a colorless to pale yellow liquid with a characteristic sulfur odor, similar to that of related mercaptoesters.

This compound is known primarily as a reactive intermediate and as a specialty monomer in the synthesis of polymeric materials. The thiol (-SH) group in the 3-mercaptopropionate segment is capable of undergoing addition reactions with alkenes, alkynes, and epoxy groups, making 3-methoxybutyl 3-mercaptopropionate valuable in thiol-ene and thiol-epoxy polymerization processes. These reactions are commonly used in the production of UV-curable coatings, adhesives, and sealants. The compound’s reactivity allows for efficient crosslinking, resulting in polymers with enhanced flexibility, adhesion, and chemical resistance. Because of its dual functionality as both a thiol donor and an ester component, it serves as a versatile building block in the formulation of advanced polymer networks and resins.

In industrial applications, 3-methoxybutyl 3-mercaptopropionate is employed as a chain transfer agent or a crosslinking modifier in the manufacture of acrylic and polyurethane polymers. Its controlled reactivity helps regulate molecular weight distribution and terminal group chemistry in polymer chains, influencing properties such as toughness, viscosity, and thermal stability. The compound’s use in UV-curable coatings, for instance, improves substrate adhesion and surface flexibility while maintaining transparency and resistance to environmental degradation. It is also used in specialty coatings for electronics, automotive finishes, and protective films, where low odor, low volatility, and compatibility with various resin systems are advantageous.

The synthesis of 3-methoxybutyl 3-mercaptopropionate typically involves the esterification of 3-mercaptopropionic acid with 3-methoxybutanol in the presence of an acid catalyst. This reaction proceeds under controlled temperature and vacuum conditions to drive the equilibrium toward ester formation, followed by purification steps to remove unreacted starting materials and by-products. The resulting compound is relatively stable under ambient conditions but should be stored in airtight containers away from oxidizing agents, as thiols are susceptible to oxidation forming disulfides, which can alter reactivity and odor characteristics.

Environmental and safety considerations for this compound are consistent with those of other low-molecular-weight mercaptoesters. It may cause irritation to the skin and eyes upon direct contact, and adequate ventilation is recommended when handling to minimize inhalation of vapors. Because of the presence of the thiol group, the compound may emit a strong odor even at low concentrations, which can be managed through proper containment and ventilation during industrial use. Biodegradability data for 3-methoxybutyl 3-mercaptopropionate are limited, but similar mercaptoesters are known to undergo slow environmental degradation via oxidation and hydrolysis.

Although the compound is not widely cited in academic literature as a subject of pharmacological or biochemical research, its significance lies in its role as a specialty chemical used in polymer chemistry and industrial synthesis. Its inclusion in chemical inventories such as those maintained by industrial safety databases and regulatory agencies confirms its relevance as a functional monomer and intermediate in the chemical manufacturing sector.

In summary, 3-methoxybutyl 3-mercaptopropionate is an important industrial chemical used primarily in polymer modification, coating formulations, and resin chemistry. Its unique combination of a thiol and ester functional group provides both reactivity and compatibility with a wide range of chemical systems, making it a useful component in advanced material design. While it does not appear to have direct pharmaceutical or biological applications, its utility in materials science underscores its value as a multifunctional intermediate in the synthesis of flexible, durable, and high-performance coatings and polymers.