Vinyl Acetate CAS 108-05-4

The most widely adopted industrial process for vinyl acetate production relies on vapor-phase catalytic synthesis of ethylene, acetic acid and oxygen over noble metal catalysts.

Raw materials ethylene and glacial acetic acid are preheated and vaporized before mixing, then fed into a fixed-bed reactor loaded with palladium-gold supported silica catalysts. The reaction temperature is maintained at 140–180 °C under a pressure of 0.6–0.9 MPa, with potassium acetate added as a co-catalyst to boost reaction selectivity.

The core reaction involves oxidative addition of ethylene, acetic acid and O₂ to produce VAc and water. Side reactions generate impurities including carbon dioxide, acetaldehyde and ethyl acetate. This route features readily available raw materials and strong continuous mass-production capacity, accounting for over 90% of global production capacity.

The mixed gas discharged from the reactor is condensed to separate crude products, while unreacted ethylene is recycled for reuse. Crude VAc first undergoes rectification to remove acetic acid and water, followed by secondary rectification to eliminate light impurities such as acetaldehyde and ethyl acetate. Dehydration and drying are finally carried out to obtain finished products with purity exceeding 99.9%.

The reflux ratio is strictly controlled during rectification to avoid self-polymerization of VAc, and trace amounts of polymerization inhibitors are added to stabilize the product.

The early process adopts liquid-phase addition reaction between acetylene and acetic acid over zinc acetate activated carbon catalysts at 170–220 °C.

Due to high storage and transportation costs of acetylene, significant safety hazards, rapid catalyst deactivation, excessive energy consumption and difficult separation of product impurities, this process has been fully replaced by the ethylene-based route. Only a small number of outdated small-scale production units remain in operation.

Vinyl acetate, a core vinyl monomer for modern polymer industry, was first isolated and systematically studied by German chemist Fritz Klatte in 1912, marking the origin of vinyl ester chemistry. Klatte worked at Griesheim-Elektron, a major German alkali manufacturer that generated massive acetylene as a byproduct from carbide production; his core task was developing high-value downstream derivatives for waste acetylene raw material.

Initially, Klatte focused on acetylene's addition reaction with hydrogen chloride to synthesize vinyl chloride. In parallel liquid-phase experiments, he bubbled acetylene into anhydrous acetic acid with mercuric sulfate as catalyst to prepare ethylidene diacetate. During product separation, he detected a volatile, unsaturated ester byproduct, later identified as vinile, formed via direct addition of acetic acid onto acetylene triple bonds. He confirmed its molecular structure and verified its unique reactivity: sealing vinile vapor in glass balloons and exposing to sunlight triggered spontaneous polymerization, yielding white solid polyvinyl acetate (PVAc) for the first time.

Between 1912 and 1914, Klatte filed five patents covering vinile synthesis, photopolymerization and polyvinyl acetate preparation, laying the theoretical and technical foundation for industrialization. Yet early development faced severe bottlenecks: mercury catalysts were highly toxic, liquid-phase batch processes delivered low yields, and uncontrolled polymerization risked explosion. At that time, macromolecular theory was not widely recognized, so industrial players deemed vinile a lab curiosity with limited commercial value, halting large-scale investment for nearly a decade.

In 1921, W. Haehnel from Germany's Electrochemical Consortium optimized the route, developing a gas-phase catalytic method using zinc acetate supported on activated carbon, eliminating mercury toxicity and boosting continuous production efficiency.

By the 1930s, Erich Rabald refined the acetylene-based process to target vinile as the main product instead of byproduct, enabling Germany to build the world's first dedicated production lines. Before 1970, acetylene vapor-phase technology dominated global supply chains.

The second revolutionary shift arrived in the mid-20th century: ethylene-based palladium catalytic oxidation technology replaced acetylene routes. Cheaper petroleum-derived ethylene replaced carbide acetylene, drastically cutting manufacturing costs.

This breakthrough turned vinile from a niche fine chemical into a mass commodity, driving rapid expansion of adhesives, latex coatings and polyvinyl alcohol industries. From accidental lab byproduct to foundational polymer feedstock, vinile's century-long discovery and evolution reflects the mutual promotion of basic organic chemistry and industrial material demands.