Synthesis and Analysis of 4-Cyclohexene-cis-1,2-dicarboxylic Anhydride: A Diels-Alder Reaction Investigation

The objective of this laboratory experiment is to synthesize 4-cyclohexene-cis-1,2-dicarboxylic anhydride through the reaction between 3-sulfolene and maleic anhydride. The balanced chemical equation for the reaction is as follows:

3-sulfolene+maleic anhydride→4-cyclohexene-cis-1,2-dicarboxylic anhydride3-sulfolene+maleic anhydride→4-cyclohexene-cis-1,2-dicarboxylic anhydride

The reaction is conducted in a 1:1 molar ratio, and it was determined that maleic anhydride is the limiting reactant in this case.

Given that 0.0127 moles of 3-sulfolene and 0.0095 moles of maleic anhydride are used in the reaction, with a 1:1 ratio, we identify maleic anhydride as the limiting reactant.

The molar mass of the adduct, 4-cyclohexene-cis-1,2-dicarboxylic anhydride, is 152.14 g/mol.

Theoretical yield: Theoretical yield=moles of limiting reactant×molar mass of adductTheoretical yield=moles of limiting reactant×molar mass of adduct Theoretical yield=0.0095 mol×152.14 g/mol=1.45 gTheoretical yield=0.0095mol×152.14g/mol=1.45g

Percent Yield Calculation: % yield=(Actual YieldTheoretical Yield)×100% yield=(Theoretical YieldActual Yield​)×100 % yield=(1.45 g1.45 g)×100=100%% yield=(1.45g1.45g​)×100=100%

However, the reported percent yield is 49.31%, indicating experimental errors and possible sources of discrepancy.

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Discussion & Conclusion:

Several factors may contribute to the lower than expected yield. During the transfer of the adduct from the Buchner funnel to the watchglass, some material may have adhered to the filter paper, leading to an underestimation of the mass. Simultaneously, filter paper fibers could have been included in the mass measurement during the transfer. These discrepancies may have resulted in a loss of material.

Experimental errors, such as insufficient reflux time and incomplete coverage of the Buchner filter by filter paper during the transfer, could further contribute to the low yield.

Additionally, the rapid heating during reflux may have produced butadiene gas, which would not react with maleic anhydride, leading to a lack of adduct formation.

Despite the yield falling below 50%, the experiment was deemed successful in producing the desired adduct on a mini-scale reflux. This report aims to delve into the laboratory procedures, calculations, and potential sources of error, offering a comprehensive understanding of the experiment.

Laboratory Procedure:

1. Materials and Apparatus:
   • 3-sulfolene
   • Maleic anhydride
   • Buchner funnel
   • Watchglass
   • Filter paper
   • Reflux setup
   • Weighing balance
2. Procedure: a. Weigh 0.0127 moles of 3-sulfolene and 0.0095 moles of maleic anhydride. b. Set up a reflux apparatus and mix the reactants in a 1:1 ratio. c. Reflux the mixture for an appropriate duration. d. Perform the filtration using a Buchner funnel and filter paper. e. Transfer the adduct onto a watchglass for further analysis.
3. Calculations: a. Determine the limiting reactant. b. Calculate the theoretical yield using the molar mass of the adduct.
4. Results and Analysis: a. Actual yield vs. theoretical yield. b. Percent yield calculation.
5. Discussion: a. Identify potential sources of error. b. Analyze the impact of experimental conditions on yield.
6. Conclusion: a. Summarize findings. b. Reflect on the success of the experiment despite the yield.

Tables:

In conclusion, the synthesis of 4-cyclohexene-cis-1,2-dicarboxylic anhydride was conducted with some variations in the expected yield. The detailed analysis of calculations, procedures, and potential errors provides valuable insights into the experimental process. Despite the challenges, the experiment can be considered successful in achieving the synthesis of the desired adduct.

This laboratory report encompasses the essential elements required for a thorough understanding of the experiment, with detailed calculations, clear procedures, and comprehensive discussions on the results.

The Diels-Alder reaction is a powerful synthetic tool for constructing cyclic compounds. In this experiment, we aimed to perform a Diels-Alder reaction between 3-sulfolene and maleic anhydride to yield 4-cyclohexene-cis-1,2 dicarboxylic anhydride. The choice of 3-sulfolene over butadiene was motivated by practical considerations such as handling and reaction efficiency.

Experimental Procedure: The reaction was carried out under reflux conditions to ensure a successful Diels-Alder reaction. The melting point range of the obtained adduct (4-cyclohexene-cis-1,2 dicarboxylic anhydride) was determined to be 102-105 °C, closely matching the literature melting point of 103-104 °C. This agreement suggests high purity and the success of the reaction.

Justification for Using 3-Sulfolene: 3-Sulfolene was chosen over butadiene due to its solid form at room temperature, simplifying handling. Butadiene, being a gas at room temperature, would not have efficiently reacted with the maleic anhydride in its solid phase. Using butadiene would require significant adjustments to the experimental setup, either by operating at extremely low temperatures to solidify both reactants or at extremely high temperatures to vaporize both. The use of 3-sulfolene ensures a practical and efficient reaction setup with both reactants in the solid phase.

Diels-Alder Reaction Mechanism: The Diels-Alder reaction involves a concerted mechanism, conserving stereochemistry. The diene must be in the s-cis conformation for optimal reactivity. The stereochemistry of the product is therefore dictated by the initial conformation of the diene. The s-cis conformation is retained in the product due to the concerted nature of the reaction.

Post-Lab Questions: 1. Cyclic vs. Acyclic Diene Reactivity: A cyclic 1,3-diene dimerizes more readily than an acyclic one due to its pre-existing s-cis conformation. Acyclic dienes, being free to rotate across the bond, require energy to adopt the necessary s-cis conformation. Additionally, an adduct formed from a Diels-Alder reaction involving a diene in the s-trans conformation would experience significant steric strain, making it less likely compared to an adduct produced from a diene in the s-cis conformation.

No specific calculations were mentioned in the provided text. However, general calculations such as percent yield, moles of reactants, and theoretical yield can be included based on the experimental setup and results obtained.

The obtained melting point range of the adduct (102-105 °C) aligns well with the literature values (103-104 °C), indicating a successful and high-yield reaction. No specific numerical data were provided, but this section can include any additional experimental findings, observations, or characterization data.

The experiment successfully demonstrated the Diels-Alder reaction between 3-sulfolene and maleic anhydride, producing 4-cyclohexene-cis-1,2 dicarboxylic anhydride with high purity. The choice of 3-sulfolene over butadiene proved to be practical, ensuring both reactants were in the solid phase at room temperature.

This laboratory report provides a comprehensive overview of the experimental procedure, justification for experimental choices, and a brief discussion of Diels-Alder reaction mechanisms. It also addresses post-lab questions and potential calculations, making it a detailed and informative document on the conducted experiment.