+ +

Hydrogen cyanide adds to acetaldehyde to give the cyanohydrin which is subsequently dehydrated (at 650°C) to acrylonitrile.

Industrial Organic Chemistry, 3rd. Ed. K. Weissermel, H.-J. Arpe, VCH (1997)

Reaction defined as:
Addition: Electrophilic Protonation
Elimination: Second Order
Industrial Process: Organic