Optical Activity Rotation of plane-polarized light ● Enantiomers rotate light in opposite directions, but same number of degrees. -0 => Chapter 5 11
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) +50-5 sodium monochromator polarizing sample cell analyzing detector lamp 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●/ 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. =>