Stereochemical Assignment Sheet

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Chirality Stereochemistry Cheat Sheet

Understanding chirality is important, not only to organic chemistry, but to understand the world around you in general. I like to think of chirality as ‘handedness’.

We have a right and left hand that are similar to each other, mirror images in fact. Yet our hands are not super-imposable. A right glove will not fit a left hand due to the opposite ‘handedness’.

Be sure to check out the Optical Activity Mini Series in Videos 8-10 below!

As you work through this series, pause and try each question and make sure you’ve mastered a topic before moving on.

Download my free Stereochemistry Cheat Sheet to follow along, and be sure to try the Stereochemistry Practice Quiz once you feel ready. Also, do you need a Model Kit? Watch How to Use Your Organic Chemistry Model Kit.

Video 1 – Introduction to Stereochemistry, Enantiomers and Chiral Molecules

Let’s start at the very beginning. WHAT is chirality? What does it mean for molecules? How can you identify a chiral carbon and what does that mean for its non-superimposable mirror image? All of this and more

 

Video 2 – R and S Configurations using Cahn-Ingold-Prelog rules

Now that you understand about chirality, how do you find it’s absolute configuration to see if it’s R or S? Learn how to rank substituents using the Cahn-Ingold-Prelog system and using priorities to differentiate between R and S stereoisomers.

 

 

Video 3 – Finding R and S When Group 4 is Forward

Finding R and S is easiest when priority group #4 is towards the back. But how do you find if a molecule is R or S when group #4 is facing forward? More importantly WITHOUT having to visualize a confusing 3-dimensional molecule? Learn how to use my ‘think backwards method’ and how I learned this in the military by watching video 3

 

Video 4 – Swap Method For Finding R&S Configurations

Swap Method Trick for quickly finding R and S configurations when group #4 not forward/back. Save time AND forget your model kit and mental molecule manipulations redrawing structures on your exam.

 

 

Video 5 – R & S Configuration for Lengthy Complex Substituents

This orgo tutorial video shows you how to approach lengthy and complex substituents so that you can quickly and easily determine R and S configurations.

 

 

Video 6 – Fischer Projection Stereochemistry Trick

This video shows you how to quickly and easily find R and S configurations directly on the Fischer Projection. Guaranteed to save you time on your next stereochemistry quiz/exam.

 

 

Video 7 – Newman Projection Stereochemistry R&S Trick

This video teaches you how to quickly find configurations of molecules presented in a Newman Projection. Learn how to view the molecule and quickly assign priority WITHOUT the need to redraw into a sawhorse projection.

 

 

◊ Optical Activity in Stereochemistry Mini-Series ◊

Video 8: Polarimetry

Each enantiomer of a chiral molecule has its own characteristic of light rotation! And not to be confused with R/S!!

This video introduces polarimetry, racemic mixtures vs pure solutions, +/- , dextrorotary (D) and levorotary (L), and more.

Video 9: Specific Rotation

This video details the factors influencing specific rotation such as observed rotation, g/mL, path-length, wavelength, and temperature. Along with test-level examples!

 

 

Video 10: Enantiomeric Excess Percentage and Optical Purity

This video shows the logic behind EE% or Enantiomeric Excess Percentage, also known as Optical Purity Percentage. Step by step example calculations are shown and more.

Additional Chirality Videos to Follow

Don’t forget to Download my free Stereochemistry Cheat Sheet to remember all the details and be sure to try the Stereochemistry Practice Quiz to test your skills!

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