P-Retin-15-yl-phosphonic Acid Diethyl Ester is an intermediate in synthesizing 9-cis-β-Carotene (C184230), which is the 9-cis isomer of β-Caroten (C184250). Carrots are one of the highest dietary sources of β-carotene and are naturally high in the (all-E)-β-carotene isomer, which has higher bioavailability, provitamin A activity, and antioxidant capacity compared to Z (cis) isomers. Molecular Formula: C24H39O3P Solubility: Chloroform, Ethyl Acetate Molecular Weight: 406.54