Sometimes the 1-phenylethylamine tartrate salt crystallizes as fine needles rather than the desired prisms. The 1-phenylethylamine recovered from these needles has been found to have a specific rotation of -20.1 degrees. What percent of (-)-1-phenylethylamine is this amine mixture? What is the percent of (+)-1-phenylethylamine?

Question

aaronq · Answer

do you have the data of the light rotation of the mixture?

anonymous · Answer

[a]D of pure (-) 1-phenylethylamine is -40.2 degrees

aaronq · Answer

actually 3/4
and 1/4

3/4  x -40 = - 30
1/4 x 40 = 10 

= -20

anonymous · Answer

okay that makes sense. thank you. do you think you can help me with another problem related to optical purity?

aaronq · Answer

il give it a try, but i don't promise anything

anonymous · Answer

ok

anonymous · Answer

after the formation and separation of diastereomers and treating the diastereomer salt with excess strong base,  what other experimental method can be used to yield (-)-1-phenylethylamine of higher optical purity?

anonymous · Answer

this is basically the lab : http://www.chem.ucla.edu/~bacher/Specialtopics/Resolution.html

aaronq · Answer

im not sure, but in the link you send me is says "The (1R,2R)-amine-(2R,3R)-acid salt crystallizes from hot water, while the (1S, 2S)-amine-(2R,3R)-acid and the cis salts stay in solution." have you figured out the stereochem of that you're separating