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Why do carboxylic acids with more than about five carbon atoms not dissolve well in water?

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oxidation of alcohols — carboxylic acid Alcohols may be oxidized to give aldehydes, ketones, and carboxylic acids. The oxidation of organic compounds generally increases the number of bonds from carbon to oxygen, and it may decrease the number of bonds to hydrogen.

Carboxylic acids with more than about five carbon atoms have low solubility in water because of their structure. While the carboxyl group is hydrophilic (water-loving), the molecule also contains a hydrocarbon chain that is hydrophobic (water-fearing).12

As the length of the hydrocarbon chain increases beyond five carbons, the hydrophobic character of this portion of the molecule begins to outweigh the hydrophilic nature of the carboxyl group. The energy required to organize water molecules around these increasingly large hydrophobic chains makes them effectively insoluble in water.12

However, these acids can be made soluble by converting them into salts—such as sodium, ammonium, or potassium salts—by adding a strong base like sodium hydroxide. These salts are ionic and generally exhibit high solubility in water.123