Question

reaction of propanal with methanol

Answer 1

I highly suggest you use the English website "Brainly" next time, instead of the Russian one.

Now, propanal reacts with methanol forming either hemiacetals or acetals in the presence of extra quantities of methanol.

Hemiacetal:
CH3CH2CHO+CH3OH-->CH3CH2CH(OH)-OCH3

Acetal:
CH3CH2CHO+2CH3OH-->CH3CH2CH(OCH3)2

Both reactions occur in the acidic environment and are reversable.