Question

1.Caryophyllene is another component of the essential oil of cloves, however, it is present in a much smaller amount than eugenol. How could you use IR to determine whether the oil obtained is primarily eugenol or caryophyllene? What band(s) would you look for? (2 pts.)

Answer 1

Eugenol IR Spectrum 0.8 Transmitance O-H Stretch 3500cm 4000 3000 1000 2000 Wavenumber (cm-1) Eugenol Structure Caryophyllene IR Spectrum 0.6 4000 3000 2000 Wavenumber (cm-1) 1000 CH3 Ho Caryophyllene structure CH3 CH3 Explanation: As you can see marked peak in eugenol spectrum around 3500cm-1 is for -O-H stretch same is missing in the caryophyllene structure it is the main and primary easily depictable difference between two IR peaks and the basis of presence/ absence of this peak in the spectum you can say the compound is eugenol or caryophyllene. ar missing in the Caryophellene spectrum but for new student it is difficult to identify because there are lot of peaks present below 1500cm-1 hence best way to understand whether given compound is eugenol or cryophyllene is the the presence of absence of -OH stretch peak above 3500cm-1 (Broad peak)