Lower aldehydes and ketones (e.g., methanal, ethanal, propanone) are miscible with water due to hydrogen bonding. However, solubility decreases with increasing alkyl chain length.
What factors influence the solubility of lower aldehydes and ketones in water, and how does the solubility change with the length of the alkyl chain?
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The solubility of lower aldehydes and ketones in water is influenced by their ability to form hydrogen bonds. Aldehydes and ketones with smaller alkyl chains (e.g., formaldehyde, acetone) are more soluble in water due to the presence of the carbonyl group, allowing for hydrogen bonding with water molecules. As the alkyl chain length increases, the nonpolar nature dominates, reducing solubility. However, short-chain aldehydes and ketones (up to four carbons) remain somewhat soluble. Beyond that, the hydrophobic alkyl group prevails, decreasing water solubility. Overall, water solubility decreases with increasing alkyl chain length in aldehydes and ketones.