Organic Chemistry Lab 315 Fall, 2016

DUE DATES Today Next Week At beginning of lab – Distillation of a Mixture Report At end of lab - copy of laboratory notebook pages for today's experiment Next Week GC of Distillate Report – see my web page for instructions. Be prepared to calculate a theoretical and percent yield for a synthesis reaction. Review significant figures. Be prepared to give a complete and correct literature citation for physical properties of compounds used in next week’s experiment.

In Lab Today Last week for the Distillation experiment: you distilled a mixture of ethyl and butyl acetate by two different methods (simple and fractional distillation). from the graphs of volume distillate vs. temperature, you deduced the mole % of the two components of the unknown mixture. presumably, this was easier for the fractional distillation, which should have shown a better separation of vol. vs. temp.

In Lab Today GC Analysis – Unknown acetate mixture Now you will compare that analysis with the results from today’s GC analysis. Inject a sample of your unknown mixture (A or B). Assuming the components elute according to b.pt., you can identify the two components. (You also have the retention times from the GC-acetates experiment to compare.) By calculating the peak areas, you can directly determine the ~mole % composition of the unknown. Compare this % result with your conclusions derived by graphing the distillation data from last week (simple and fractional).

In Lab Today GC Analysis – Distillation Efficiency Inject the three saved distillate fractions for the simple and fractional distillations: “pure” EtOAc, “pure” BuOAC, and a middle fraction. Six fractions altogether from Simple and Fractional Data shared among 4 students Compare the GC results with what you hypothesized on the basis of the distillation temp. vs. volume results. For example, is the “pure” EtOAC fraction as seen on the chromatogram really pure, or is there a bit of BuOAc?

Notes Work at the GC in the same group of 4 as for the distillation experiment. Each student should inject at least once. No one may leave the lab until all students have finished using the GC’s. For Report on this GC: please pay attention to the corrections and remarks that appear on the GC of Acetates Report that I have returned to you.

Lab Clean-up Goodman, Emily E.