For my OCHEM lab we did a chiral reduction of Ethyl Acetoacetate and optical rot
ID: 503724 • Letter: F
Question
For my OCHEM lab we did a chiral reduction of Ethyl Acetoacetate and optical rotation. 2 of the chiral molecules we used were menthol and limonene.The literature specific rotations for limonene and menthol are: (R)-Limonene= +98, (S)-Limonene= -98 and for (1R, 2S,5R)-Menthol= -50, (1S,2R, 5S)-Menthol= +50. The specific rotations that we calculated personally our (Samples) are Limonene= +102.5 and Menthol= +1.96.
A. Which isomer of Limonene did your sample contain, (R) or (S)? Explain your reasoning.
B. Which isomer of Menthol did your sample contain, (R) or (S)? Explain your reasoning.
(PLEASE EXPLAIN WHY IT IS THAT ISOMER I AM VERY CONFUSED)
Explanation / Answer
A) Answer: (R) -Limenone
you got experimentally for limenone =+102.5 by polarimeter. but you reported for (R) limenoe=+98, (S)Limenone=-98
your value is +102.5 is more than reported (R) limenone +98. that means your sample doenot have S isomer but contimanation of some other materials may be like other compounds, dust particles, cotton depend on what material used in the analysis. if in your sample is having S isomer your experimental value should be below +98, in between -98.0
Answer:nearly racemic 1:1 ratio of (1R, 2S,5R)-Menthol and (1S,2R, 5S)-Menthol
if you have pure (1R, 2S,5R)-Menthol you can get value= -50, in the same way other isomer with pure (1S,2R, 5S)-Menthol show the value = +50
but you got +1.96 this value is nearly zero means the two isomer s with 1:1 ratio that is called racemic.
your case (1S,2R, 5S)-Menthol is little bit more that is the reason you + value
like 52: 48 ratio of (1S,2R, 5S)-Menthol and (1R, 2S,5R)-Menthol
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