Benzaldehyde,which occurs naturally in almond,makes a characteristic almond-like odor.It is commonly used as a flavor in foods and drinks,and as a fragrance in cosmetics and household chemicals.As the second largest flavor and fragrance in the world,with global demand about 7000 tons annually,it was synthesized by different routes.Preparation of benzaldehyde by Swern oxidation of benzyl alcohol was carried out in a continuous flow microreactor system.Dimethyl sulfoxide(Me2SO)was used as oxidizing agent,oxalyl chloride or p-toluenesulfonyl chloride was used as the activating agent.Benzyl alcohol was oxidized to benzaldehyde by the Me2SO-activating agent mixture in the microreactor system.