Prelab 7

docx

School

University at Buffalo *

*We aren’t endorsed by this school

Course

113

Subject

Chemistry

Date

Jan 9, 2024

Type

docx

Pages

Uploaded by JudgeExplorationGorilla39

University at Buffalo Organic Chemistry Lab CHE 205 Fall 2023 Dr. K. Ahsan “Pre-Lab Procedure – Dehydration of Alcohol” on Labflow. Before your recitation start time Fall 2023 - Answer all questions (3 points) Name: TA: Lab Day & time: Answer the following questions on this sheet using words, chemical structures and reaction equations as required. 1) Using chemical structures draw the complete chemical reaction of cyclohexanol with 85 % phosphoric acid and catalytic conc. sulfuric acid, provide all the products and intermediates involved (1 point) 2) For reaction drawn above, calculate the theoretical yield if you started with 1.50 mL of 85% phosphoric acid and 1.50 mL of cyclohexanol (density 0.96 g/mL) to produce the product? 1 pt To calculate the theoretical yield, first, identify the limiting reactant, which determines the amount of product that can be formed. Assuming the reaction is producing cyclohexyl phosphate from phosphoric acid and cyclohexanol, follow these steps: 1. Determine the moles of phosphoric acid: Moles of H3PO4 = (1.50 mL / 1000 mL) * (0.85 g/mL) = 0.001275 moles 2. Calculate the mass of cyclohexanol: Mass = Volume * Density Mass of C6H11OH = 1.50 mL * 0.96 g/mL = 1.44 grams 3. Find the moles of cyclohexanol using its molar mass: Molar mass of C6H11OH = 100.17 g/mol Moles of C6H11OH = Mass / Molar mass = 1.44 g / 100.17 g/mol = 0.0144 moles 4. Determine the limiting reactant based on the 1:1 stoichiometric ratio: - Moles of H3PO4: 0.001275 moles - Moles of C6H11OH: 0.0144 moles

The limiting reactant is H3PO4 because it would require 0.0144 moles to react completely with the available moles of C6H11OH. 5. Calculate the theoretical yield based on the limiting reactant (H3PO4): - The molar mass of C6H11O4P (cyclohexyl phosphate) is 214.2 g/mol. - Mass of theoretical yield = Moles of H3PO4 * Molar mass = 0.001275 moles * 214.2 g/mol = 0.273 g So, the theoretical yield of cyclohexyl phosphate is 0.273 grams. 3) Using your own words, provide the procedure for the synthesis and purification of cyclohexene via a dehydration reaction. 1 point Here's a condensed version of the synthesis and purification procedure for cyclohexene via a dehydration reaction: **Procedure Summary:** 1. **Setup and Safety:** - Wear safety goggles and use a fume hood. - Gather equipment (e.g., round bottom flask, Pasteur pipet, distillation apparatus) and chemicals (85% phosphoric acid, cyclohexanol, concentrated sulfuric acid, anhydrous sodium sulfate). 2. **Reaction Setup:** - Combine 1.50 mL of 85% phosphoric acid and 1.50 mL of cyclohexanol in a 10 mL round bottom flask. - Add 3 drops of concentrated sulfuric acid and a few boiling chips. 3. **Distillation:** - Assemble the distillation setup with heating. - Heat the mixture until the product vaporizes (above 85°C). 4. **Cooling and Separation:** - Allow the apparatus to cool. - Transfer the product to a test tube to separate it from water. 5. **Layer Separation:** - Identify the organic (cyclohexene) and aqueous layers. - Transfer the aqueous layer to a separate flask. 6. **Drying the Organic Layer:** - Add anhydrous sodium sulfate to the organic layer and let it sit for 5 minutes. 7. **Weighing the Product:** - Weigh an empty conical vial. - Transfer the cyclohexene product to the vial, leaving behind the drying agent. - Weigh the vial with the product. 8. **Cleanup:** - Show the product to the TA. - Rinse glassware with ethanol. - Dispose of waste properly. - Wash glassware, lock your drawer, and leave the lab.

This procedure involves the synthesis of cyclohexene through acid-catalyzed dehydration of cyclohexanol, with subsequent separation, drying, and weighing of the product. The percent yield is calculated based on the product's mass.

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version