Cassia, cinnamon, cinnamon bark: the distinctive character of cinnamon products comes from this aldehyde. Powerful and versatile it's particularly good in air-care where it's potential for irritating the skin isn't a problem. According to Arctander the odour is: "Warm-spicy -balsamic odor, suggestive of Cassia-cinnamon. Good tenacity and lasting sweetness." He goes on to say that it is: "Used in perfumery as a sweetener and powerful spicy ingredient in low-cost fragrances mainly for household products, in masking odors and in detergents and soaps where discoloration is not visible (Cinnamic aldehyde will discolor white soaps). Trace amounts are used as a warm-spicy and sweet note in floral balsamic fragrance types, heavy florals and oriental fragrance types. It introduces interesting notes when used discretely in Rose, Hyacinth or in woody fragrances, etc. Note that this material, normally a yellow liquid, can solidify in cold conditions, such as winter transport.  It is also exceptionally sensitive to light and should not be exposed to UV.