丙二酸二乙酯（DEM）是丙二酸的二乙醇酯，无色有苹果味的液体，天然存在于葡萄和草莓中。属于β-二羰基化合物，用作有机合成和药物合成的中间体，可以合成巴比妥酸、维生素B1、维生素B6和人工香料等。类似的化合物还有乙酰乙酸乙酯、丙二酸二甲酯、乙酸乙酯、乙酰丙酮等。

丙二酸二乙酯可通过用氯乙酸为原料，用氰离子增碳生成氰乙酸，再与乙醇酯化制得：

丙二酸二乙酯或取代的丙二酸二乙酯经过“酮式分解”或“酸式分解”，可以得到乙酸或乙酸的衍生物。

Diethyl malonate, also known as DEM, is the diethyl ester of malonic acid. It occurs naturally in grapes and strawberries as a colourless liquid with an apple-like odour, and is used in perfumes. It is also used to synthesize other compounds such as barbiturates, artificial flavourings, vitamin B₁, and vitamin B₆.