lab 2 pg 5 - at 40°C Since a major difference between...

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Unformatted text preview: at 40°C. Since- a major difference between enantiomers is the way that they reflect pure polarized light and theoretical pure rotation numbers are known, the purity of the extracted enanti‘omer can be measured. The polarimeter was used to gitie a rotation number for the sample collected through the above process. By comparing the collected number to'the theoretical purity of sautple' can be measm'ed. ' The observed optical rotation of'the final precinct was 85.953 degrees. The - ,1 negative sign signifies a counter clockwise direction The reported value of optical rotation for this enamiotner is 40.4 degrees ('3).- Our obtained Value is quite c1056 to this _ reported value; The optical purity obtained was 89.0% which is also quite close to the '-/ reported value of95% (3). Temperature, solvent, and the wavelength of the light all . - - affect the optical rotation (1). The observed rotation of a substance is dependent on the structure of the compound and the number of molecules, which .is a fiinction of the path [ g/é length and Concentration. Ihe'Concentra'tion of sample in our esperiment was not exaCt J potentially because the material may not have dissolved properly and evaporated when J the sample was boiling, although this is' highly-unlikely to have occurred. I Fer the crystallization part of this experiment, the percent yield that we obtained was 71.2%. Crystals were lost during transfer throughout some steps of the experiment, for. example when crystals were: transferred onto" the weighing paper. This partially explains the decline in yield. From the original 12 grams of crude material 7.69 g was L"- recovered in part B of the experiment. Also, with the addition of tartaric acid it is possible for the reaction to not react completely and for formation of incomplete salts. Further areas of contamination may occur with the addition of base and separating. of organic from non-organie material. This method of separation of enanfiomc'rs proved to: be quite effective with is ample yielded that was 89.0% pure, determined through-optical rotation. The crystal was yielded with an effectiveness of 71.2%. The amine was yielded with an effectiveness of 71.9%. The very close relationship of all three of these numbers shows how the theory and the experimental results preof one another. The logic is applied in the CalculatiOns of theoretical yield Which can be seen in the appendix. This lab was a good representation of the principles" of enanriomers and the d-ifiiculties that can arise in attempting to separate them. With enantiome'rs having often ...
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