Allocinnamic acid
Allocinnamic acid is a cis-isomer of cinnamic acid, into which the cinnamic acid is easily converted.
Synthesis
Allocinnamic acid was first discovered by Carl Liebermann in 1890 in coca leaves, then Liebermann found that this acid is formed during the reduction of β-dibromopropiolic acid.Physical properties
Allocinnamic acid crystallizes in the form of three crystalline modifications with melting points of 68 °C, 58 °C, and 42 °C. It is hardly soluble in water and cold ligroin, easily soluble in alcohol and ether, and does not change in dim light.Chemical properties
When heated briefly with concentrated sulfuric acid, the compound turns into cinnamic acid.It forms liquid anhydride with acetic anhydride, which turns into cinnamic acid anhydride when heated.