Question

Need help with number 2 and 3 on the postlab section.

Elimination Reactions Background The purpose of this lab is to prepare an alkene by dehydration of an alcohol in the presence of an acid catalyst Elimination reactions often result in the formation of multiple products. In this lab, 2-methylcyclohexanol is dehydrated to form an alkene. The product will be analyzed by GC-MS to determine the ratio of alkene isomers formed. You will need to determine the mechanism of the reaction, predict the major and minor products, and calculate the ratios formed. HAPO heat C7H12 Boiling Point 163-165°C Boiling Point 103-110°C Procedure Place 5 mL of 2-methylcyclohexanol into a 10 mL round bottom flask. Carefully add 1.5 mL of 85% phosphoric acid and a stir vane. Mount the flask for microscale distillation using a Hickman still (Zubrick p. 176). Slowly heat the mixture until it comes to a gently boil (Keep the rate of boiling slow enough that the distillation does not start.) After 10 minutes of gentle boiling. increase the heat sufficiently to cause distillation. The temperature of the distilling vapor should not exceed 115° C. Collect the distillate in a small vial. Part II: Washing (See Zubrick Ch.16) Add 1 mL of sodium carbonate solution to the distillate. Add 2 mL of cold water, swirl the mixture gently, and remove the lower aqueous layer using a pipet Dry the remaining organic layer with anhydrous calcium chloride. Let stand covered for 10 minutes. Decant the dried product from the calcium chloride. Filter the solution using a Pasteur filter pipet. Determine the weight of the product Analyze the product mixture by GC. Your gas chromatogram may show peaks for more than one alkene product, from the relative areas of these peaks, you can determine the % composition of the product mixture Post lab 1. Calculate your percent yield. 2. In your GC analysis, if you were to observe more than one peak, this would suggest an additional alkene product. Using the integration of your peaks, calculate the ratio of your product. Draw the structure of each product and write mechanisms showing the formation of each of your products. 3. Where would the starting material, 2-methylcyclohexanol, come out on a gas chromatogram relative to the alkene product if they were run at the same time? Explain.

Answer 1

Questions 283 There is the formation of two products, as shown below hydrogen transter A -au (Major product of G i Coor ( Methylcyclohexene) - 4 (Minor producted Methiferecycloberane a The peap at 25 RT corresponds to the minor Product i.e. methylenecyclobescane. Whereas the peak at 5.9 RT corresponds to the major produit, il L-Methylcyclobencie.