Enantiocats and Diastereocats
- “Initial Tails” and “Final Heads”
- 3 Ways To Make OH A Better Leaving Group
- A Simple Formula For 7 Important Aldehyde/Ketone Reactions
- Acetoacetic
- Acids (Again!)
- Activating and Deactivating
- Actors In Every Acid Base Reaction
- Addition – Elimination
- Addition Pattern 1 – Carbocations
- Addition pattern 2 – 3 membered rings
- Addition Reactions
- Aldehydes And Ketones – Addition
- Alkene Pattern #3 – The “Concerted” Pathway
- Alkyl Rearrangements
- Alkynes – 3 Patterns
- Alkynes: Deprotonation and SN2
- Amines
- Aromaticity: Lone Pairs
- Avoid These Resonance Mistakes
- Best Way To Form Amines
- Bulky Bases
- Carbocation Stability
- Carbocation Stability Revisited
- Carboxylic Acids are Acids
- Chair Flips
- Cis and Trans
- Conformations
- Conjugate Addition
- Curved Arrow Refresher
- Curved Arrows
- Decarboxylation
- Determining Aromaticity
- Diels Alder Reaction – 1
- Dipoles: Polar vs. Covalent Bonding
- E2 Reactions
- Electronegativity Is Greed For Electrons
- Electrophilic Aromatic Substitution – Directing Groups
- Elimination Reactions
- Enantiocats and Diastereocats
- Enolates
- Epoxides – Basic and Acidic
- Evaluating Resonance Forms
- Figuring Out The Fischer
- Find That Which Is Hidden
- Formal Charge
- Frost Circles
- Gabriel Synthesis
- Grignards
- Hofmann Elimination
- How Acidity and Basicity Are Related
- How Are These Molecules Related?
- How Stereochemistry matters
- How To Stabilize Negative Charge
- How To Tell Enantiomers From Diastereomers
- Hybridization
- Hybridization Shortcut
- Hydroboration
- Imines and Enamines
- Importance of Stereochemistry
- Intermolecular Forces
- Intro to Resonance
- Ketones on Acid
- Kinetic Thermodynamic
- Making Alcohols Into Good Leaving Groups
- Markovnikov’s rule
- Mechanisms Like Chords
- Mish Mashamine
- More On The E2
- Newman Projections
- Nucleophiles & Electrophiles
- Nucleophilic Aromatic Substitution
- Nucleophilic Aromatic Substitution 2
- Order of Operations!
- Oxidation And Reduction
- Oxidative Cleavage
- Paped
- Pi Donation
- Pointers on Free Radical Reactions
- Protecting Groups
- Protecting Groups
- Proton Transfer
- Putting it together (1)
- Putting it together (2)
- Putting it together (3)
- Putting the Newman into ACTION
- Reaction Maps
- Rearrangements
- Recognizing Endo and Exo
- Redraw / Modify
- Robinson Annulation
- Robinson Annulation Mech
- Sigma and Pi Bonding
- SN1 vs SN2
- sn1/sn2 – Putting It Together
- sn1/sn2/e1/e2 – Exceptions
- sn1/sn2/e1/e2 – Nucleophile
- sn1/sn2/e1/e2 – Solvent
- sn1/sn2/e1/e2 – Substrate
- sn1/sn2/e1/e2 – Temperature
- Stereochemistry
- Strong Acid Strong Base
- Strong And Weak Oxidants
- Strong and Weak Reductants
- Stronger Donor Wins
- Substitution
- Sugars (2)
- Synthesis (1) – “What’s Different?”
- Synthesis (2) – What Reactions?
- Synthesis (3) – Figuring Out The Order
- Synthesis Part 1
- Synthesis Study Buddy
- Synthesis: Walkthrough of A Sample Problem
- Synthesis: Working Backwards
- t-butyl
- Tautomerism
- The 4 Actors In Every Acid-Base Reaction
- The Claisen Condensation
- The E1 Reaction
- The Inflection Point
- The Meso Trap
- The Michael Reaction
- The Nucleophile Adds Twice (to the ester)
- The One-Sentence Summary Of Chemistry
- The Second Most Important Carbonyl Mechanism
- The Single Swap Rule
- The SN1 Reaction
- The SN2 Reaction
- The Wittig Reaction
- Three Exam Tips
- Tips On Building Molecular Orbitals
- Top 10 Skills
- Try The Acid-Base Reaction First
- Two Key Reactions of Enolates
- What makes a good leaving group?
- What Makes A Good Nucleophile?
- What to expect in Org 2
- Work Backwards
- Zaitsev’s Rule
Let’s do a thought experiment. It involves cats. It’s a good thing it’s a thought experiment because doing this on a real cat might involve dodging some angry claws.
Imagine I’ve got a pet cat, “Whitey” – a totally albino cat, completely devoid of other colors. If I put Whitey in front of a mirror, I will see his mirror image reflected there. And since Whitey is completely symmetrical in his coloring, I think you’d agree that we’d have a hard time distinguishing Whitey and his mirror image. In fact, for our purposes, they are the same.
However, if you took out a can of red paint and bravely put a dollop on Whitey’s front right (FR) forepaw, something interesting happens when you look in the mirror. Whitey’s mirror image appears to have a dollop of red paint on his front left paw (FL). So he’s no longer superimposable on his mirror image!
What does this have to do with chemistry?
In chemistry, two molecules that are superimposable on their mirror images (like original Whitey) are the same molecule. They have exactly the same properties in every way.
Now – it’s also possible to have molecules which are mirror images of each other, but those mirror images are not superimposable, like Whitey (FR) and Whitey (FL) These molecules are not exactly the same. We have a name to describe them – they’re called enantiomers. They have identical physical properties, except for how they interact with polarized light (that’s another story).
It’s important to realize that to call molecules “enantiomers” implies that we’re analyzing the relationship between two molecules.
Let’s go back to Whitey. Now let’s pretend we have Whitey (FR) and Whitey (FL) standing in front of us. On the first cat (FR) we put a dollop of red paint on the back left paw (BL). And on the second cat (FL) we also put an identical dollop of red paint on the back left paw (BL).
So now we have (FR, BL) and (FL, BL).
These cats are certainly not superimposable, and they are no longer mirror images of each other. But they’re clearly closely related.
In chemistry there’s a different word we have for molecules that are stereoisomers but not mirror images. These are called diastereomers. Unlike enantiomers, these molecules have different physical properties (like boiling points, melting points, etc.).
I should just stop here! A picture says a thousand words.
Don’t forget that these are *relationships*. The terms “diastereomer” or “enantiomer” only have meaning when you are comparing molecules to each other. No molecule can be an “enantiomer” or “diastereomer” in a vacuum, just like no single child can be a “brother” or “sister”.
Tomorrow – a handy little trick for how to draw the enantiomer of any molecule.
Thanks for reading! James
P.S. Everything I learned about stereochemistry I learned from cats.