Ubidecarenone: Yellow to orange, crystalline powder. Melts at about 48. Soluble in ether; very slightly soluble in dehydrated alcohol; practically insoluble in water.
Undecylenic Acid: Clear, colorless to pale yellow liquid having a characteristic odor. Practically insoluble in water. Miscible with alcohol, with chloroform, with ether, with benzene, and with fixed and volatile oils.
Urea: Colorless to white, prismatic crystals, or white, crystalline powder, or small white pellets. Is practically odorless, but may gradually develop a slight odor of ammonia upon long standing. Its solutions are neutral to litmus. Freely soluble in water and in boiling alcohol; practically insoluble in chloroform and in ether.
Urea C 13: See Urea.
Ursodiol: White or almost white, crystalline powder. Freely soluble in alcohol and in glacial acetic acid; sparingly soluble in chloroform; slightly soluble in ether; practically insoluble in water.