a Specific rotation polarimeter a [a] = c.l Sample cell t temperature Observed rotation [a] = a c.l t D l = 589 nm D-line length of tube (dm) Concentration (g/ml)
การหมุนระนาบของแสงโพลาไรซ์มี 2ทิศทาง dextrorotatory clockwise d or + levorotatory counterclockwise ℓ or - OH COOH CH3 H COOH OH CH3 H ℓ or (-)-lactic acid d or (+)-lactic acid [a]D = +3.28 o 25 mp. = 53 C [a]D = -3.28 o 25 mp. = 53 C
(+)-cavone (-)-cavone * caraway spearmint
[a] = 0 o + Racemic mixture 50 % + 50% of enantiomer pair 1 mol of (+)-enatiomer 1 mol of (-)-enatiomer + 50 % + 50% of enantiomer pair Racemic mixture [a] = 0 o