5-Cyclohexadecenone is a macrocyclic synthetic musk with the chemical formula C<sub>16</sub>H<sub>28</sub>O. It is an unsaturated analog of cyclohexadecanone. It is also similar in chemical structure to the natural musk scents civetone and muscone.
5-Cyclohexadecenone has a strong musk scent with floral, amber, and civet tones. It is used as a substitute for natural musk in perfumes, cosmetics, and soaps. Trade names include Ambretone, Velvione, and TM-II.
5-Cyclohexadecenone can exist as either of two cis/trans isomers and the commercial product is typically a mixture of the two. It can be synthesized in a four-step sequence from cyclododecanone.