Ketones and aldehydes are activated towards nucleophilic attack via protonation; proton transfer reactions then occur so water may leave. This generic description applies to many reactions in organic chemistry and biochemistry. For instance, ketones and aldehydes can be activated towards nucleophilic attack via protonation; proton transfer reactions then occur so water may leave. This generic description applies to many reactions in organic chemistry and biochemistry. Consequently, reversible acetal and ketal formation is an essential mechanism for introductory organic chemistry. The key biomolecules for all life processes are: (i) carbohydrates; (ii) nucleic acids (DNA and RNA); (iii) amino acids, peptides, and proteins (these can be considered together); and (iv) lipids. Carbohydrate chemistry may be the first to learn because it mostly involves mostly alcohols and aldehydes or ketones in making and breaking hemi-acetals and ketals, and acetals and ketals. The arrow pushing part is quite easy for most carbohydrate chemistry, but putting the stereochemistry that you already know (from earlier parts of this series) into practice, sometimes concomitantly with forming or hydrolyzing those hemi-acetals and ketals, and acetals and ketals, is more difficult. That advanced practice of stereochemistry applied to carbohydrates will be dealt with later in this series. Understanding carbohydrates is empowering because these are extremely important molecules in all branches of biology, medicine, and related fields like nutrition. Moreover, understanding carbohydrate chemistry is a significant step to understanding nucleic acids (DNA and RNA have carbohydrate components), glycopeptides and glycoproteins (which also contain them). All students studying branches of biology, medicine, and related fields like nutrition do too. Organic chemists also need to understand aldehyde / ketone hydration, acetals, and ketals for their applications in syntheses, particularly of heterocycles, and as protecting groups and as fragments of natural products. Thus the chemistry learned here is extremely valuable.
