Steam Distillation Lab

Introduction

• Objective: Steam distill cinnamaldehyde from ground cinnamon.
• Focus: Steam distillation technique and some NMR concepts.

Steam Distillation Technique

• Purpose: Separate volatile organic compounds from mixtures using water.
• Principle: Two immiscible compounds have additive vapor pressures.
  • Example: Cinnamaldehyde is immiscible with water.
  • Total vapor pressure = Sum of vapor pressures of each compound.
  • Allows co-distillation at temperatures lower than the boiling point of water.
• Advantage: Avoids decomposition and oxidation.
  • Cinnamaldehyde boiling point: 248°C (decomposes at this temp).
  • Co-distillation occurs at water's boiling point or lower.
• Applications:
  • Essential oils extraction (e.g., limonene from orange peels).

Experiment Overview

• Materials: 50 mL Erlenmeyer flask, Hickman still, ground cinnamon, water, Triton X-45 surfactant.
• Process:
  1. Add 10-15 mL of water & Triton X-45 to Erlenmeyer flask.
  2. Add ~2 grams ground cinnamon.
  3. Set up apparatus with Hickman still and water condenser.
  4. Heat mixture to boil.
  5. Collect milky distillate using a Pasture pipette.
  6. Extract cinnamaldehyde using methylene chloride.
  7. Dry extracts with sodium sulfate.
  8. Evaporate solvent to obtain pure cinnamaldehyde.
  9. Weigh product for percent recovery calculation.

Cleaning and Safety

• Clean apparatus to prevent burnt residue.
• Use sodium carbonate solution to clean burnt cinnamon residue.

Analyzing and Characterizing Product

• Characterization using IR spectroscopy.
• Notable IR peaks for cinnamaldehyde:
  • Aromatic hydrogen peak at 3335 cm⁻¹.
  • Aldehyde peaks at 2814 & 2742 cm⁻¹.
  • Carbonyl peak at 1677 cm⁻¹.
  • Carbon-carbon double bond peak at 1626 cm⁻¹.

NMR Concepts

• Resonance Structures:
  • Cinnamaldehyde is fully conjugated, affecting shielding.
  • Carbonyl group is electron-withdrawing.
• Splitting Patterns:
  • Deshielding occurs in carbons with partial positive charges.
  • Splitting complexity due to unique hydrogen neighbors.
  • Example: Hydrogen splitting into a doublet of doublets.
• Coupling Constants:
  • Trans coupling: 12-18 Hz.
  • Cis coupling: 6-12 Hz.
  • Calculations involve converting ppm to Hz (using spectrometer frequency).
  • Understanding these principles helps in analyzing cinnamaldehyde's NMR spectra.

Conclusion

• Successful extraction and characterization of cinnamaldehyde.
• Importance of understanding distillation and NMR for organic compound separation and analysis.