butenes - CHEM 267. Week 8. Alkenes From Alcohols. Labnotes...

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CHEM 267 . Week 8 . Alkenes From Alcohols. Labnotes (revised 7/10). Include the Prelab Exercise on p. 205 of the lab text in your prelab outline. Answer the same for 2-butanol. Review Chapter 15 on Molecular Mechanics, paying particular attention to the section on local vs global minima (p. 302, 303) and also p. 304, 305. Review Wade, Section 7-7 (A-C) and your previous Molecular Modeling handout and report. Although the lab experiment is short and straightforward, you will need to put additional effort into the report. It is expected that such additional effort will be expended. Note also that unlike previous experiments, in which the procedure was spelled out quite exactly in the handout, this experiment and others to follow will rely more on the procedures given in the lab text. Be sure to carefully read the section below on calculations before you carry them out. Experiment Notes : Be extremely careful in using conc sulfuric acid. Instead of the 10 cm column/collection tube described in the book, use the longer chromatography column to collect the product. Much of the first slow bubbling that occurs is simply air being displaced from the heated reaction tube. Once product formation begins, the bubbling becomes rapid. To ensure that the butenes and not just air is being collected, allow the reaction to proceed until the tube is at least about 3/4 full. Calculations : From the GC analysis, determine the relative amounts of the three isomers produced in the reaction. These will be used to compute energies which will be compared with calculated and other experimental values. Note that the assumption that peak area is directly proportional to molar amount is not necessarily correct. The detector responds differently to different compounds. Usually however, for structurally similar compounds, as in this case, the assumption is valid. Air will elute first, followed by the butenes in order of boiling point. For the equilibrium as drawn above, calculate
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This note was uploaded on 11/29/2011 for the course CHEM 267 taught by Professor Samal,p during the Fall '08 term at UMass (Amherst).

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butenes - CHEM 267. Week 8. Alkenes From Alcohols. Labnotes...

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