C
O
O
H
C
O
O
H
H
OH
RO
H
R
R
C
O
O
R
R
C
O
H
O
H
C
O
H
O
H
H
OH
RO
H
R
R
C
O
H
O
R
R
aldehyde
ketone
hemiketal ketal
hemiacetal acetal
Substitution of the Carbonyl Oxygen in Ketones and
Aldehydes with Two C–O Bonds: Acetals and Ketals
Addition of one molar equiv alcohol (R–OH) to aldehydes and
ketones gives hemiacetals and hemiketals, respectively.
Hemiacetals and hemiketals are not usually isolated.
Elimination of water followed by addition of a second molar
equiv of R-OH gives the corresponding acetals and ketals.
Acetal and ketal derivatives are isolable compounds. Note:
several [pt] steps assist the elimination of water.
addition
elimination
then addition
addition
elimination
then addition
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