Question

What reactions do aldehydes undergo?

Answer 1

Aldehydes are very versatile compounds for many chemical syntheses.

Explanation:

Their combination with other types of molecules produces the so-called aldehyde condensation polymers, which have been used in plastics such as Bakelite and in the laminate tabletop material Formica.

Aldehydes are also useful as solvents and perfume ingredients and as intermediates in the production of dyes and pharmaceuticals. Certain aldehydes are involved in physiological processes.

Examples are retinal (vitamin A aldehyde), important in human vision, and pyridoxal phosphate, one of the forms of vitamin B6. Glucose and other so-called reducing sugars are aldehydes, as are several natural and synthetic hormones.
https://www.britannica.com/science/aldehyde

http://crab.rutgers.edu/~alroche/Ch18.pdf

http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch17/ch17-3-0-2.html