[Arfem]

Good evening guys, I'm new to the forum but I should be in the right section, if this is not the case just let me know!

When piperine is treated with sulfuric acid its color goes from pale yellow to blood red, after a bit of research on the web I learned that the reaction is known and has been used as a way to determine piperine for a long time, but I couldn't find anything on the actual reaction. What's going on? What product of the reaction gives the bloodish red color?

Thank you very much!

[pgk]

Oxonium cation has a stronger bathochromic effect than oxygen. Thus, protonation of the carbonyl and the ether groups of piperine by concentrated sulfuric acid, causes stronger bathochromy that disappears by dilution with water.