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A topic from the subject of Contributions of Famous Chemists in Chemistry.

  • 11 months ago
  • 6 min read
Emil Fischer and Fischer Projection
Introduction

Emil Fischer was a German chemist who made significant contributions to the field of organic chemistry. He is best known for his work on the structure of sugars and for developing the Fischer projection, a method for representing the three-dimensional structure of a molecule in two dimensions.

Basic Concepts

A Fischer projection is a two-dimensional representation of a molecule that shows the relative positions of atoms and groups of atoms in space. It depicts carbon atoms at the intersections of vertical and horizontal lines. Horizontal lines represent bonds projecting out of the plane (towards the viewer), and vertical lines represent bonds projecting into the plane (away from the viewer). The hydrogen atoms are often omitted for clarity.

Drawing a Fischer Projection

To draw a Fischer projection, you need to know:

  • The number of carbon atoms
  • The connectivity of the carbon atoms
  • The stereochemistry of the molecule (arrangement of groups around each carbon)
  1. Draw a vertical line to represent the carbon chain.
  2. Add horizontal lines to represent bonds to substituents.
  3. Attach the appropriate substituents to the horizontal lines.
  4. Number the carbon atoms.
Applications of Fischer Projections

Fischer projections are used to:

  • Determine the structure of molecules
  • Predict the reactivity of molecules
  • Design new molecules
  • Analyze NMR, IR, and mass spectra
  • Identify organic compounds
  • Design new drugs
  • Understand reaction mechanisms
Conclusion

Emil Fischer's work on sugars and the development of the Fischer projection remain fundamental tools in organic chemistry. Fischer projections provide a simple yet powerful way to visualize and analyze the three-dimensional structures of molecules, significantly contributing to our understanding of chemical processes.

Emil Fischer and Fischer Projection

Emil Fischer (1852-1919) was a German chemist and Nobel laureate who made significant contributions to organic chemistry, particularly in the fields of carbohydrates and proteins. He developed a method for representing the three-dimensional structure of molecules on a two-dimensional plane, now known as the Fischer projection.

Fischer Projection: A Fischer projection is a two-dimensional representation of a three-dimensional organic molecule, particularly useful for depicting chiral centers. In a Fischer projection:

  • The carbon chain is drawn vertically.
  • Horizontal lines represent bonds projecting out of the plane (towards the viewer).
  • Vertical lines represent bonds projecting into the plane (away from the viewer).
  • The chiral center (asymmetric carbon) is represented by the intersection of the vertical and horizontal lines.

Importance of Fischer Projections: Fischer projections are crucial for:

  • Clearly representing the stereochemistry of molecules, especially sugars and amino acids.
  • Easily visualizing and comparing the configurations of different isomers.
  • Simplifying the depiction of complex molecules for easier understanding and analysis.
  • Facilitating the understanding of reactions involving chiral molecules.

Example: The Fischer projection of D-glyceraldehyde, a simple sugar, clearly shows the arrangement of its atoms around the chiral center, allowing for easy comparison with other isomers like L-glyceraldehyde.

Limitations: While Fischer projections are helpful, they do have limitations. They don't accurately represent the true bond angles and spatial arrangement of atoms, which can be crucial for understanding certain aspects of molecular behavior. More sophisticated methods, such as perspective formulas and ball-and-stick models, are often used for a more realistic depiction of 3D structures.

In Summary: Emil Fischer's contribution to chemistry through the development of the Fischer projection remains invaluable. This method provides a simplified yet effective way to represent the stereochemistry of important organic molecules, aiding in the understanding and advancement of organic chemistry.

Emil Fischer and Fischer Projections Experiment

Step-by-Step Details

Materials:

  • 3D molecular model kit
  • Screen or projector
  • Pointer (optional)

Key Procedure:

  1. Build a Tetrahedral Carbon Atom:
    • Connect four straws or sticks to form a tetrahedron. Use different colored balls to represent different atoms (e.g., red for oxygen, black for carbon, green for chlorine, white for hydrogen).
  2. Represent Atoms and Bonds:
    • Use different colored balls to represent different atoms (e.g., red for oxygen, black for carbon, green for chlorine, white for hydrogen).
    • Use springs or pipe cleaners to represent single, double, or triple bonds.
  3. Orient the Carbon Atom Vertically:
    • Hold the carbon atom vertically, with one bond pointing up (vertical) and one pointing down (vertical). Two bonds will be pointing horizontally.
  4. Draw a Fischer Projection:
    • On the screen or paper, draw a vertical line representing the vertical bonds and horizontal lines representing the horizontal bonds.
    • Place the symbols representing atoms on the lines, according to their positions on the 3D model. (e.g., using the colors or standard abbreviations like O, Cl, H, C)

Showcase:

  • Project the Fischer projection onto a screen or draw it on a whiteboard.
  • Use a pointer to highlight the bonds and atoms.
  • Discuss how the Fischer projection shows the 3D arrangement of atoms in the compound, specifically focusing on the limitations and conventions of the projection (e.g., horizontal bonds projecting forward and backward).

Variations:

  • Use different compounds to explore the diversity of Fischer projections.
  • Introduce chirality by creating molecules with asymmetric carbon atoms and demonstrating how Fischer projections represent enantiomers.
  • Build and project molecules with different conformations to demonstrate the effect on Fischer projections (and their limitations in representing conformations).

Educational Benefits:

  • Visualizing the 3D structure of molecules
  • Developing spatial understanding
  • Comprehending the principles of organic chemistry
  • Appreciating the contributions of Emil Fischer

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