Chem Post Lab

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Hello there, I need help on my post lab. It is for Elimination experiment.


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CHEM 308 Organic Chemistry 1 Lab Elimination Reaction Data Analysis The GC data will have a series of peaks labeled with retention time (RT) and peak area (MA). Some peaks can be ignored, but you should pay attention to all peaks that have retention times and areas given. The approximate retention times for the expected compounds are given below, but note that the exact retention time can vary. Just like with other types of chromatography, the order that compounds elute does not change when the conditions are altered. Approximate retention times (in min.) … 3.43 3.75 3.95 ~8.5-10.5 11.85 Most likely identity 1-heptene trans-2-heptene cis-2-heptene SN2 products (normally only observed for reactions with NaOMe or NaOEt) 2-bromoheptane Once the GC data for our class is posted, do the following: 1. Use all of the spectra to complete post-lab part 2 2. Use Part 2 of the post-lab to help you answer the questions in Part 1 Your Analysis: 1. Print the spectrum for your assigned base only. a. On the spectrum, clearly draw the compound structure that corresponds to each peak.  There may be some slight variation in retention time (e.g., a peak expected at 2.24 min might show up at 2.20 or 2.27 min). b. If a peak from the table is NOT present in your spectrum (e.g., an SN2 product), you should still draw the structure and indicate approximately where that peak would have been expected. 2. Fill out Part 2 of the Elimination Report Form (a Word document is provided on Blackboard if you would like to type your values in). a. For the ratio of 1-heptene to 2-heptene, you should sum the areas of the two 2-heptene peaks (e.g., 1-heptene : [trans-2-heptene + cis-2-heptene]). b. When writing ratios, the smallest component should be given the number “1”. All other numbers should be larger than 1 and reported with one decimal place.  For example: 2-Heptene trans : cis Ratio 4.6 : 1 (not 1 : 0.22) 1 : 8.7 (not 0.11 : 1) c. The amount of SN2 Products and/or Starting Material (SM) should be reported as follows:  “Lots” if the height of the SN2 Product/Starting Material peak is the same as the height of the tallest elimination product peak.  “Some” if the height of the SN2 Product/Starting Material peak is smaller than the height of the tallest elimination product peak.  “None” if there is no peak visible where one would be expected for these materials (based on the retention times provided above). Name: _________________________________ Student ID # _________________ CHEM 308 REPORT FORM: Dehydrobromination of 2-Bromoheptane Submit via Blackboard by 5 pm the day before your scheduled lab (must be a PDF file) 1. 1 Order the alkoxide bases in order of increasing steric demand (i.e., start with the least bulky and finish with the one with the most steric bulk near the O atom). 2. 3 How did the structure of the alcohol affect the ratio of 1-heptene to 2-heptenes (for this question, use the sum of cis- and trans-2-heptenes). Give a reason for this trend. Be specific and use numbers from the spreadsheet to support your answer. 3. 3 How did the structure of the alcohol affect the formation of SN2 products? Give a reason for this trend. Be specific and discuss the presence/absence of the SN2 product in the spectra of all of the alkoxide bases used in lab. Page 1 of 2 4. 2 5. 2 Comment on how the structure of the alkoxide base affects the ratio of trans-2-heptene to cis-2heptene. Is there a dramatic effect? Be specific and use numbers from the spreadsheet to support your answer. Did your reaction go to completion? Support your answer with evidence from the GC spectra. (Consider the group data for your alkoxide base to be representative of your reaction). One way of assessing whether the reaction has reached completion is to monitor the reaction by TLC. Suppose that when you TLC your reaction mixture (in a solvent system of 100% hexanes), both 2-bromoheptane and a mixture of heptene products are present. 6. 2 Assuming that all heptene products appear as a single spot (due to similar polarities)…  Draw in the spots you would expect to see on the TLC template below.  Label which spot corresponds to (a) 2-bromoheptane and (b) heptene isomers. (Make sure your relative polarities are correct!) Page 2 of 2 Name __________________________________ Student ID # ________________________ CHEM 308 REPORT FORM: Dehydrobromination of 2-Bromoheptane, Part 2 Submit at the beginning of next week’s scheduled lab Simple Ratio Alkoxide base (1-heptene : trans-2heptene : cis-2-heptene) Simple ratio calculation for ethoxide: Ratio of 1-Heptene : 2-Heptene (both isomers) 2-Heptene trans : cis Ratio 2-bromoheptane SN2 product (Lots, some, none; see instructions) (Lots, some, none; see instructions) Name __________________________________ Student ID # ________________________ CHEM 308 REPORT FORM: Dehydrobromination of 2-Bromoheptane, Part 2 Submit at the beginning of next week’s scheduled lab Simple Ratio Alkoxide base (1-heptene : trans-2heptene : cis-2-heptene) Simple ratio calculation for ethoxide: Ratio of 1-Heptene : 2-Heptene (both isomers) 2-Heptene trans : cis Ratio 2-bromoheptane SN2 product (Lots, some, none; see instructions) (Lots, some, none; see instructions) ...
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Robert__F
School: Boston College

included also an excel file wit...

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Anonymous
Tutor went the extra mile to help me with this essay. Citations were a bit shaky but I appreciated how well he handled APA styles and how ok he was to change them even though I didnt specify. Got a B+ which is believable and acceptable.

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