Retinol Esters- Common retinyl esters include linoleate, propionate, and palmitate.  When compared to retinol, they have a more difficult time penetrating the skin and they demonstrate a lower clinical effectiveness. However they are more stable than retinol. Esters- Products resulting from the combination of organic acids and alcohols. They can be natural or synthetic and liquid or solid, depending on properties of the reacting substances. Insoluble in water, they replace oils and fats to provide a more uniform composition and preservation.