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An acetal is a molecule with two single-bonded oxygen atoms attached to the same carbon atom.

Acetal is a highly flammable chemical. There is the risk of explosion from peroxide formation. It can be slightly toxic by ingestion and skin contact and is an irritant. Acetal is also known as Diethyl Acetal. There is no confirmed human disease-related or reproductive hazard data that has been reported and there is also no reported data on the toxicity of acetal to water organisms. Acetals are used as protecting groups for carbonyl groups in organic synthesis as they are stable with respect to hydrolysis by bases and with respect to many oxidizing and reducing agents. The formation of acetals occurs when the hydroxyl group of a hemiacetal becomes protonated and is lost as water. The carbocation ion that is produced is then rapidly attacked by a molecule of alcohol. Loss of the proton from the attached alcohol gives the acetal.

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More commonly Acetal is known as an engineering plastic widely used for machined parts, has high hardness and stiffness and also very good mechanical properties. It lends itself to turning, milling and most other plastic machining processes. Some production benefits of using Acetal in industry are as follows:

  • High stiffness and hardness
  • Very high mechanical properties
  • Excellent dialectical properties
  • High mechanical strength
  • Excellent creep resistance and dimensional stability
  • Low co-efficient of friction
  • Excellent machinability
  • Dimensional stability
  • Very low stick-slip
  • Physiologically inert for food and medical applications
  • low moisture absorption
  • Continuous use at a temperature of 115°

Also, here is a small list of production uses of Acetal:

  • Bearings with close tolerances
  • Electrical engineering insulators
  • Snap fit assemblies
  • Parts which operate in water between 60° to 90°C
  • Wear parts
  • Thrust washers
  • Slideways



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Formation of an acetal occurs when the hydroxyl group of a hemiacetal becomes protonated and is lost as water. The carbocation ion that is produced is then rapidly attacked by a molecule of alcohol. Loss of the proton from the attached alcohol gives the acetal.

Acetals are stable compared to hemiacetals but their formation is a reversible equilibrium as with esters.