Editing Aldehyde (section)

===Naturally occurring aldehydes===
Traces of many aldehydes are found in [[essential oil]]s and often contribute to their pleasant odours, including [[cinnamaldehyde]], [[cilantro]], and [[vanillin]]. Possibly due to the high reactivity of the formyl group, aldehydes are not commonly found in organic "building block" molecules, such as amino acids, nucleic acids, and lipids. However, most sugars are derivatives of aldehydes. These [[aldose]]s exist as [[hemiacetal]]s, a sort of masked form of the parent aldehyde. For example, in aqueous solution only a tiny fraction of glucose exists as the aldehyde.