Fischer Projections and R/S Configurations

Professor Dave explains Fischer projections, a notation used in organic chemistry to represent molecules, particularly sugars. He discusses how to interpret these projections, emphasizing the importance of understanding the implied stereochemistry. The tutorial covers how to assign R/S configurations using the Cahn-Ingold-Prelog convention, focusing on the orientation of bonds in Fischer projections. The video aims to help students visualize and understand the geometry of molecules in this notation.

What is the primary use of Fischer projections in biochemistry?

• To represent aromatic compounds

• To depict linear sugars and carbohydrates

• To illustrate protein structures

• To show the structure of lipids

In Fischer projections, what do horizontal bonds represent?

• Double bonds

• Triple bonds

• Wedge bonds

• Dash bonds

How are vertical bonds interpreted in Fischer projections?

• As wedge bonds

• As dash bonds

• As double bonds

• As single bonds

What is a key characteristic of molecules represented in Fischer projections?

• They are aromatic

• They are linear

• They are tetrahedral

• They are flat

What is the first step in assigning R/S configurations using Fischer projections?

• Determine the molecular weight

• Assign priority based on atomic number

• Count the number of hydrogen atoms

• Identify the longest carbon chain

When the lowest priority group is on a vertical bond in a Fischer projection, what should you do?

• Swap two groups

• Trace from lowest to highest priority

• Trace from highest to lowest priority

• Invert the configuration

If the lowest priority group is on a horizontal bond, what is the correct approach?

• Ignore the horizontal bond

• Invert the configuration after tracing

• Swap the highest and lowest priority groups

• Trace as usual without changes

What is the implication of a horizontal bond in a Fischer projection?

• It is a single bond

• It is a wedge bond

• It is a double bond

• It is a dash bond

What should be done if the lowest priority group is facing towards you in a Fischer projection?

• Change the priority order

• Swap all groups

• Leave the configuration as is

• Invert the stereochemistry

What is the easiest way to assign R/S configurations when the lowest priority group is on a horizontal bond?

• Ignore the horizontal bond

• Swap the horizontal and vertical bonds

• Trace without inverting

• Trace and invert the answer