Experimental Organic Chemistry Experiment 5 - Lab Report

Purpose: An acylated Ferrocene is formed via Friedel-Crafts acylation.Ferrocene contains two cyclopentadienyl rings. Through this experiment the products of Friedel-Crafts acylation can be predicted while also understanding how to achieve optimum yield from this reaction. Reaction and physical properties: Mechanism: Figure 1 Friedel-craft’s acylation reaction and mechanism Table 1. Physical Properties Table Compound MWg/mol Amount mmol Mp (°C) Ferrocene 186.04 0.120g 0.65 172.5 AlCl3 133.34 0.170g 1.27 192.6 Acetyl Chloride 78.49 90µl 1.15 Dichlorome thane 84.93 4 mL bp (°C) Density g/ml 52 1.10 39.6 1.33 Safety: Ferrocene Risk statements: Flammable Injurious if swallowed Safety statements Must wear protective gloves and goggles when handling the chemical. If comes in direct contact with skin or eyes must rinse thoroughly. AlCl3 Risk statements: Can cause skin and eye damage if it comes in direct contact. Can cause respiratory irritation if inhaled. Safety statements Must wear protective gloves and goggles when handling the chemical. If comes in direct contact with skin or eyes must rinse thoroughly. Must not be inhaled. Must be measured in the hood otherwise can react with water and produce toxic HCL gas Acetyl Chloride Risk Statements Flammable Can cause skin burn and eye damage if comes in direct contact Safety statements Must wear protective gloves and goggles when handling the chemical. If comes in direct contact with skin or eyes must rinse thoroughly. Must not be inhaled and be stored away from flames and hot surfaces. Dichloromethane Risk statements Skin, eye and respiratory irritant Carcinogen Can cause drowsiness and dizziness Excessive exposure can cause organ damage Safety statement Must wear protective gloves and goggles when handling the chemical. If comes in direct contact with skin or eyes must rinse thoroughly. Must not be inhaled. Sodium Hydroxide solution Risk statements Corrosive Can cause eye and skin damage upon direct contact Can cause respiratory irritation Safety statement Must only be kept in the original container. Must wear protective gloves and goggles when handling the chemical. If comes in direct contact with skin or eyes must rinse thoroughly. Must not be inhaled. Acid chlorides and aluminium chloride must be handled in the hood due to its corrosiveness and reactivity with water. Procedure: 1. Add a spin vain to the 5 mL conical vial (long pointy end down). Weigh 0.170 g of anhydrous AlCl3 using the scale in the hood and transfer it to the 5 mL conical vial. Keep vial covered when not adding solvent. 2. Add ~2.5 mL of CH2Cl2 to the conical vial. 3. Add 90 microliters of acetyl chloride to the conical vial using a micropipette in the hood. 4. Dissolve 0.120 g of ferrocene in ~1.5 mL of CH2Cl2 and add the solution to the conical vial through the straight neck of the Claisen head adaptor. 5. Allow the reaction to proceed for 15 minutes 6. Carefully transfer the reaction mixture to a centrifuge tube containing 5 mL of ice water. Cool the tube in a beaker of ice water 7. Remove the organic layer and transfer it to a clean dry 50 mL Erlenmeyer flask or container of similar size. 8. Extract the aqueous mixture with CH2Cl2 (3 x 3 mL) in the tube with shaking and venting to encourage the mixing of the aqueous and organic phases. Remove the organic layer after each extraction using a pipet and combine it with the previous organic layers that are in the clean dry 50 mL Erlenmeyer flask or container of similar size. 9. Dry the organic solution using anhydrous MgSO4 by adding small amounts covering the tip of your spatula and swirling the solution. 10. Transfer the dried solution to a small dry container for solvent evaporation. 11. Use a hot plate and compressed air in the hood to evaporate all of the solvent. 12. Remove the solid material from the container and transfer to a shell vial. Get a weight of the crude product during this process. Data/Observation: When the ferrocene solution was added to the CH2Cl2 solution that contained the AlCl3 as well, the color changed from orange to a dark purple. After reaction for 15 minutes the solution cooled and the solution separated into an organic and aqueous layer. The denser layer is the organic layer with a deep orange color and the top layer is the aqueous layer which has a deep blue shade. The bottom layer is extracted using a pipet and put in a separate vial. Error was made when the organic layer was extracted with the acetyl chloride instead of the aqueous layer and acetyl chloride was used instead of dichloromethane. The crude product could not be extracted through drying as it was contaminated. The product distribution of the crude product, if found, would have been unknown. Conclusion/Discussion: The Friedel-Crafts reaction is an aromatic electrophilic substitution where one electrophile substitutes another electrophile. The electrophile is electron deficient and has a positive charge. The benzene formed from acylation is an acylated benzene which is basically a ketone. This is important because through this chemical process AlCl3 is being used as a catalyst so that a more reactive intermediate is formed compared to the starting material. This causes the stable aromatic benzene to react with the intermediate which would otherwise not. Two resonance structures intermediates with formal positive charge are formed. Benzene interacts with the intermediate which could possibly cause the color change. In the final product aromaticity is restored and AlCl3 is also regenerated. Post Lab Questions 1. A double bonded oxygen and an alkyl side chain. 2. 3. Presence of two reactive aromatic rings in the ferrocene yields two products. When the first ring is attacked, the aromatic system is deactivated. For the compound below, no regeneration of AlCl3 occurs via acylation.