3-Octanoylthiopropyltriethoxysilane: A Versatile Silane Coupling Agent

3-Octanoylthiopropyltriethoxysilane (CAS: 220727-26-4) is a silane coupling agent that contains both a thioester and a triethoxysilyl group. It has the molecular formula C 17 H 36 O 4 SSi and the molecular weight 364.62 g/mol. It is also known as 3-Triethoxysilyl-1-propyl thiooctanoate, A-Link 599, NXT, NXT Silane, or Silquest A-Link 599.

Synthesis and Properties

3-Octanoylthiopropyltriethoxysilane can be synthesized by the reaction of 3-mercaptopropyltriethoxysilane with octanoyl chloride in the presence of a base, such as triethylamine. The reaction can be carried out in an inert solvent, such as dichloromethane, at room temperature or under reflux.

The product is a clear, colorless to pale yellow liquid with a characteristic odor. It has a density of 0.972 g/mL and a boiling point of 140 °C at 0.5 mmHg. It is soluble in most organic solvents, such as alcohols, ethers, ketones, and hydrocarbons, but insoluble in water. It is stable under normal storage conditions, but it may hydrolyze slowly in the presence of moisture or acid. It should be handled with care, as it may cause skin and eye irritation and may be harmful if swallowed or inhaled.


3-Octanoylthiopropyltriethoxysilane has a wide range of applications in various fields of science and technology. It can be used as a coupling agent to improve the adhesion, compatibility, and durability of organic-inorganic hybrid materials, such as polymers, coatings, adhesives, sealants, composites, and nanomaterials. It can also be used as a surface modifier to impart hydrophobicity, oleophobicity, anti-corrosion, anti-fouling, and anti-bacterial properties to various substrates, such as metals, glass, ceramics, and textiles.

The mechanism of action of 3-Octanoylthiopropyltriethoxysilane involves two steps: hydrolysis and condensation. The hydrolysis step occurs when the triethoxysilyl group reacts with water or moisture to form silanol groups. The condensation step occurs when the silanol groups react with each other or with other silanol groups on the surface of the substrate to form siloxane bonds. The thioester group remains intact and provides a reactive site for further functionalization or cross-linking with organic molecules.

Some examples of the applications of 3-Octanoylthiopropyltriethoxysilane are:

– It can be used to modify the surface of silica nanoparticles to improve their dispersion and compatibility with polypropylene matrix for the preparation of nanocomposites with enhanced mechanical and thermal properties.
– It can be used to modify the surface of carbon nanotubes to improve their dispersion and compatibility with epoxy resin for the preparation of nanocomposites with improved electrical conductivity and fracture toughness.
– It can be used to modify the surface of titanium dioxide nanoparticles to improve their photocatalytic activity and stability for the degradation of organic pollutants under visible light irradiation.
– It can be used to modify the surface of cotton fabrics to impart water-repellency, oil-repellency, self-cleaning, and antibacterial properties without affecting their breathability and comfort.
– It can be used to modify the surface of stainless steel to enhance its corrosion resistance and biocompatibility for biomedical applications.


3-Octanoylthiopropyltriethoxysilane is a versatile silane coupling agent that can be used to modify the surfaces of various materials to improve their properties and performance. It has potential applications in many fields of science and technology, such as polymer science, nanotechnology, catalysis, textile engineering, and biomedicine.