Investigation of the Aspirin Oily Phase

Student Author(s)

Joshua Dykstra

Faculty Mentor(s)

Dr. Renata van der Weijden and Dr. Justin Shorb

Document Type


Event Date



Aspirin, or acetylsalicylic acid, is one of the most commonly used medications in the world and was first synthesized in 1897. The synthesis of aspirin is quite simple, involving the mixing of salicylic acid, acetic anhydride, and an acid catalyst. This reaction mixture is heated in a hot water bath before being quenched with water, resulting in aspirin forming as a white precipitant. However, occasionally during the synthesis of aspirin, an “oily phase” forms beneath the water layer after quenching. Although aspirin and the components used in its synthesis have been thoroughly studied, there is little to no information on this temporary “oily phase”. This research examines the chemical composition of the aspirin oily phase, how it affects the crystallization of aspirin, and whether crystal size and shape could be manipulated from the oily phase to give greater control over the pill manufacturing process. The chemical composition of the oily phase was determined using GC-MS, 1H-NMR spectroscopy, and 2D-NMR spectroscopy. Crystals precipitated from the oil using various methods were analyzed through XRD, SEM, and light microscopy.


This research was supported by previous work conducted by Dr. van Rossum and Lottee van Andel at the University College Roosevelt, Netherlands, and the Holleman Geology/ Environmental Science Student Research Fund.

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