During distillation, which class of compounds tends to concentrate in the 'heads' fraction due to its relatively low boiling point?

During distillation, aldehydes and esters, along with methanol, tend to concentrate in the 'heads' fraction due to their relatively low boiling points. Distillation is a process that separates liquids based on their boiling points; substances with lower boiling points vaporize more readily and are collected earlier in the distillation run. The 'heads' fraction refers to the initial portion of the distillate collected during distillation. Aldehydes, such as acetaldehyde, are volatile organic compounds with low boiling points and often possess sharp, unpleasant aromas. Similarly, some esters, though contributing fruity or floral notes at lower concentrations, can be harsh and undesirable in higher concentrations within the heads. Methanol, a toxic alcohol, also has a significantly lower boiling point than ethanol (the desired alcohol) and concentrates in the heads. Because these compounds have lower boiling points than ethanol, they vaporize and condense first, making it critical to discard the heads fraction to avoid including unwanted or harmful substances in the final product. The removal of the heads is crucial for ensuring the quality and safety of the distilled spirit.