1. Gas Chromatography Refractive Index Polarimetry Next Lecture: Lecture Problem 8 Due Next Thursday: Quiz 7 in Lecture Next Week’s Office Hours: Tuesday from 3 to 5 pm! This week in lab: Ch 9 Final Report Due Synthetic #2 PreLab Due Next week in lab: Synthetic #1 Final Report Due Lecture 24

2. Nutmeg Oil GC-MS Data Mass Spectrum of A M + at 192 Compound is:

3. Chromatography TLC & Column Chromatography Stationary phase: silica gel (polar) Mobile phase: organic solvent(s) (varying polarity) Separation: based on differences in polarity of compounds Gas Chromatography Stationary phase: can be polar or nonpolar (choice of column) Instrument Room GC uses a nonpolar stationary phase Mobile phase: helium gas! Separation: based on boiling points and/or size of compounds Can vary the temperature - allows for better separation of complex mixtures (low-boiling vs high-boiling components) Flame ionization detector (FID) Chapter 18 in Lab Guide

4. Gas Chromatography FID Detector

5. Gas Chromatography Capillary column Injection site Control panel

6. Gas Chromatography Plotter

7. Gas Chromatography Info from chromatogram: # of components in sample Retention time of each component Area of each signal - calculate % of each component in sample

8. Refractive Index An intrinsic property of a liquid compound Defined as the ratio of the speed of light through a vacuum to the speed of light through the liquid Operational instructions are given in Chapter 20.

9. Refractive Index Figures taken from Williamson, Minard & Masters MMOE, 5th edition Ideal reading

10. Polarimetry To determine the optical activity of a compound. Watch video at http://www.colby.edu/chemistry/OChem/DEMOS/Chirality.html Calculate the specific rotation of a chiral compound; see Chapter 19 of the Lab Guide Cell for sample solution Digital display - results