Optical Activi Rotation of plane-polarized light Enantiomers rotate light in opposite directions, but same number of degrees 鲁鲁 Chapter 5
Chapter 5 11 Optical Activity • Rotation of plane-polarized light • Enantiomers rotate light in opposite directions, but same number of degrees. =>
Polarimetry Use monochromatic light, usually sodium D Movable polarizing filter to measure angle Clockwise =dextrorotatory= d or(+) Counterclockwise= levorotatory=/or(- Not related to(R) and(s) +15°0-15° 0=9 sodium monochromator polarizing sample cell analyzing dete mp filter filter filter Chapter 5 12
Chapter 5 12 Polarimetry • Use monochromatic light, usually sodium D • Movable polarizing filter to measure angle • Clockwise = dextrorotatory = d or (+) • Counterclockwise = levorotatory = l or (-) • Not related to (R) and (S) =>
Specific Rotation Observed rotation depends on the length of the cell and concentration as well as the strength of optical activity temperature, and wavelength of light a]=a(observed c is concentration in g/mL is length of path in decimeters Chapter 5 13
Chapter 5 13 Specific Rotation Observed rotation depends on the length of the cell and concentration, as well as the strength of optical activity, temperature, and wavelength of light. [] = (observed) c • l c is concentration in g/mL l is length of path in decimeters. =>