Lab Report 10 - Dehydrohalogenation of 2-Bromoheptane PDF

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Summary

Dehydrohalogenation of 2-Bromoheptane...

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Megan Matney Lab Partner - Annie Hilbun 11.10.2020, CHEM 3105-301 Lab 10 Dehydrohalogenation of 2-Bromoheptane Purpose The purpose of this experiment is to perform and describe E1 and E2 sections and mechanisms, dehydrohalogenation of alkyl halides, and to predict and validate the major elimination products based on Zaitsev’s Rule. Reaction and Physical Properties Table

Safety Make sure to wear proper personal protection equipment to the lab. This includes face shield, face mask, thick lab coat, pants that cover the entire leg, and shoes that cover the entire foot. Wear gloves for the entire duration of the lab. 2-bromoheptane (Flammable, Irritant) Risk Statement: Flammable liquid and vapor. Causes skin irritation. Causes serious eye irritation. Harmful if inhaled. May cause respiratory infection. Safety Statement: Avoid breathing dust/fume/gas/mist/vapors/spray. Use only outdoors or in a well-ventilated area. Wash face, hands and any exposed skin thoroughly after handling. Wear protective gloves/ protective clothing/eye protection/face protection. Keep away from heat/sparks/open flames/hot surfaces. - No smoking. Keep container tightly closed. Ground/bond container and receiving equipment. Use explosion-proof electrical/ventilating/lighting/equipment. Use only non-sparking tools. Take precautionary measures against static discharge. Keep cool. If inhaled, Remove

victim to fresh air and keep at rest in a position comfortable for breathing. Call a POISON CENTER or doctor/physician if you feel unwell. sodium methoxide in methanol (Flammable, Acute Toxic, Carcinogen, Corrosive) Risk Statement: May be corrosive to metals. Causes severe skin burns and eye damage. May cause respiratory irritation. May cause drowsiness or dizziness. Causes damage to organs. Causes damage to organs through prolonged or repeated exposure. Toxic if swallowed, in contact with skin or if inhaled. Safety Statement: Wash face, hands and any exposed skin thoroughly after handling. Do not eat, drink or smoke when using this product. Wear protective gloves/protective clothing/eye protection/face protection. Use only outdoors or in a well-ventilated area. Do not breathe dust/fume/gas/mist/ vapors/spray. Keep away from heat/sparks/open flames/hot surfaces. - No smoking. Keep container tightly closed. Ground/bond container and receiving equipment. Use explosion-proof electrical/ventilating/lighting/equipment. Use only non-sparking tools. Take precautionary measures against static discharge. Keep only in original container. Keep cool. If exposed, immediately call a poison control center or physician. potassium tert-butoxide (Flammable, Toxic, Corrosive) Risk Statement: Flammable solid. Self-heating in large quantities; may catch fire. Causes severe skin burns and eye damage. May cause respiratory irritation. Safety Statement: Do not breathe dust/fume/gas/mist/vapors/spray. Wash face, hands and any exposed skin thoroughly after handling. Wear protective gloves/protective clothing/eye protection/face protection. Use only outdoors or in a well-ventilated area. Keep away from heat/sparks/open flames/hot surfaces. - No smoking. Ground/bond container and receiving equipment. Use explosion-proof electrical/ventilating/lighting/equipment. Keep cool. Protect from sunlight. If exposed, immediately call a poison control center or physician. tert-butanol (Flammable, Irritant) Risk Statement: Highly flammable liquid and vapor. Causes serious eye irritation.May cause respiratory irritation. Safety Statement: If medical advice is needed, have product container or label at hand. Keep out of reach of children. Read label before use. Keep away from heat/sparks/open flames/hot surfaces. No smoking. Wear protective gloves/protective clothing/eye protection/face protection. Keep container tightly closed. Ground/bond container and receiving equipment. Use explosion-proof electrical/ventilating/light/equipment. Use only non-sparking tools. Take precautionary measures against static discharge. Avoid breathing dust/fume/gas/mist/vapours/spray. Wash skin thoroughly after handling. Use only outdoors or in a well-ventilated area.

10% potassium hydroxide solution (Irritant, Corrosive) Risk Statement: May be corrosive to metals. Harmful if swallowed. Causes severe skin burns and eye damage. Safety Statement: Wash face, hands and any exposed skin thoroughly after handling. Do not eat, drink or smoke when using this product. Do not breathe dust/fume/gas/mist/vapors/spray. Wear protective gloves/protective clothing/eye protection/face protection. Keep only in original container. If exposed, immediately call a poison control center or doctor/physician. magnesium sulfate Risk Statement: No risk statements. Safety Statement: For eye contact: Rinse immediately with plenty of water, also under the eyelids, for at least 15 minutes. Get medical attention. For skin contact: Wash off immediately with plenty of water for at least 15 minutes. Get medical attention immediately if symptoms occur. If inhaled, Remove to fresh air. Get medical attention immediately if symptoms occur. If not breathing, give artificial respiration. If ingested, do not induce vomiting. Procedure Procedure A: 1. With the lid tightly closed on the stock container gently swirl the 25% by weight solution/ mixture of sodium methoxide in methanol to suspend the solid sodium methoxide and then add 1.1 mL of the mixture to a 5 mL conical vial. 2. Add methanol (1.90 mL) and 2-bromoheptane (160 µL, using micropipette) to the 5 mL conical vial. Add a spin vain, long pointy end down. 3. Add a water cooled condenser equipped with a drying tube packed with a small amount of CaCl2 held in place with cotton. Stir the reaction mixture while heating it to reflux and continue to heat and stir the mixture for 30 minutes. 4. Turn off the heat and allow the vial to cool to room temperature. 5. Using a Pasteur pipet transfer the reaction mixture to a centrifuge tube. Add 2 mL of pentane to the conical vial to extract the remaining residues and transfer the solution to the centrifuge tube. Repeat this process one more time. 6. Add 1 mL of water to the centrifuge tube. Cap and gently mix, occasionally loosening the cap to vent. Continue to do this until all of the solid has dissolved, adding more water if required. 7. Carefully remove the aqueous layer (bottom). Extract the organic layer twice with 1 mL of water being sure to remove the aqueous layer (bottom) each time. At this point there are no more extractions to be done so try to remove all of the water in the bottom of the centrifuge tube with a Pasteur pipet with minimal loss of the organic layer. 8. Add small amounts of anhydrous MgSO4 (tip of a spatula or scoopula) to the centrifuge tube to dry (remove the water) until the added solid does not clump with swirling. See below about preparing GC sample.

Procedure B 1. Directly into a 5 mL conical vial containing a magnetic spin vane (long pointy end down) add t-BuOK (0.56 g) followed by t-butanol (3.00 mL) and 2-bromoheptane (160 µL, using micropipette). 2. Add a water cooled condenser equipped with a drying tube packed with a small amount of CaCl2 held in place with cotton. Stir the reaction mixture while heating it to reflux and continue to heat and stir the mixture for 30 minutes. 3. Turn off the heat and allow the vial to cool to room temperature. 4. Using a Pasteur pipet transfer the reaction mixture to a centrifuge tube. Add 2 mL of pentane to the conical vial to extract the remaining residues and transfer the solution to the centrifuge tube. Repeat this process one more time. 5. Add 1 mL of water to the centrifuge tube. Cap and gently mix, occasionally loosening the cap to vent. Continue to do this until all of the solid has dissolved, adding more water if required. Carefully remove the aqueous layer (bottom). 6. Extract the organic layer four times with 1 mL aliquots of KOH(aq) being sure to remove the aqueous layer (bottom) each time. Extract the organic layer twice with 1 mL of water being sure to remove the aqueous layer (bottom) each time. 7. At this point there are no more extractions to be done so try to remove all of the water in the bottom of the centrifuge tube with a Pasteur pipet with minimal loss of the organic layer. 8. Add small amounts anhydrous MgSO4 (tip of a spatula or scoopula) to the centrifuge tube to dry (remove the water) until the added solid does not clump with swirling. See below about preparing GC sample. GC Sample Preparation 1. Using a clean Pasteur pipet, transfer enough of the dried pentane solution to a provided GC vial, filling it ~3/4 full. A small space should be left at the top of the vial. Put the cap on the vial and record the number that is next to your names on the sign-up sheet on the side of the GC vial. Place the labeled GC vial in the well plate. 2. All samples from the section will be checked to confirm they are pentane solutions. Samples of water will not be run. GC data for the lab section will be emailed after the samples have been ran and will include a scanned copy of the sign-up sheet as well as all of the gas chromatograms for all samples ran for the section. Reference gas chromatograms for standard samples will also be included for peak identification.

Data/Observations • The base assigned was t-BuOK so "Procedures 2" were followed. 0.61 g of t-BuOK were used, about 3 mL of t-BuOH was used and 160 microliters of the starting material, 2bromoheptane were transferred into the reaction vial using a micropipette. • The Hotplate was originally set to 200 degrees, but after realizing the reaction mixture wasn't refluxing after 10 minutes had passed by, the temperature was increased to 300 degrees. The solvent started slowly bubbling and evaporating, and it could be seen

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condensing back into the reaction vial, indicating refluxing has started. Only then, the timer was started. The reaction mixture color did not change throughout the reaction, it remained mostly colorless. When extracting, the separation between the aqueous (water) layer and the organic (pentane) layer was clear in the centrifuge tube. The GC vial was filled up about 2/3 of the way up using the product solution in pentane. However, when filtering away the MgSO4 used for drying the pentane layer, much of the pentane was soaked into the filtering cotton, therefore, some additional pentane was added to push the product solution through the cotton filter. Based on this, the product solution might be more dilute than originally expected. Since the pentane solvent was never evaporated (our product would have evaporated along too), I didn't obtain the mass of the product for this experiment.

Calculations & Results

Conclusions/Discussions

Post Lab Questions 1. What is the major elimination product of the following reaction?

2. List all of the of the elimination products of the following reaction. Indicate which one is the most stable.

3. What is the SN2 product of the following reaction?

References https://www.fishersci.com/store/msds? partNumber=A65500&productDescription=BENZOIC+ACID+ACS+500G&vendorId=VN0003 3897&countryCode=US&language=en https://www.kovaintl.com/downloads/sodiumchloridesat.pdf...