1 st semester Organic Chemistry Now in < 1 % the time! Peter - PowerPoint PPT Presentation

1 st semester Organic Chemistry… Now in < 1 % the time! Peter Zoogman Jacob Group, Harvard EPS Graduate Student Forum January 12, 2012

What is going on?  Will a molecule react?  What type of molecule will it react with?  What bonds are likely to be EARTH SURFACE created/destroyed?  What will the product look like?

Molecular Orbitals  2 atomic orbitals combine constructively and destructively to form 2 molecular orbitals Sigma orbital: Pi orbital: One region of overlap Two regions of overlap corresponds to single bond corresponds to double bond σ∗ antibonding π∗ antibonding σ bonding π bonding σ∗ antibonding σ bonding

Molecular Orbital Example –H 2 vs. He H 2 Molecule σ∗ antibonding H Atom H Atom σ bonding

Molecular Orbital Example –H 2 vs. He He 2 Molecule?? σ∗ antibonding He Atom He Atom σ bonding

Molecular Orbitals – Relative Energy σ∗ antibonding π∗ antibonding (lone pairs) π bonding σ bonding

Molecular Orbital Example -- Ethene C-C σ∗ antibonding Ethene: H H C-H σ∗ antibonding C C H H C-C π∗ antibonding C-C π bonding also written as: C-H σ bonding C-C σ bonding

Frontier Orbitals – HOMOs and LUMOs  Behaves as electron donor (i.e. Nucleophile, Lewis Base) at Highest Occupied Molecular Orbital (HOMO)  Lone pairs (or radicals)  π bonds  Behaves as electron acceptor (Electrophile, Lewis Acid) at Lowest Unoccupied Molecular Orbital (LUMO)  Empty atomic orb.  π * antibonding orb.  σ∗ antibonding orb.

Molecular Orbital Example -- Ethene C-C σ∗ antibonding Ethene: H H C-H σ∗ antibonding C C H H C-C π∗ antibonding LUMO C-C π bonding HOMO also written as: C-H σ bonding C-C σ bonding

Ethene Hydration  What is the HOMO? H O H H C H H C H  What is the LUMO?

Ethene Hydration  What is the HOMO? H  O 2 lone pair O H H C H H C  What is the LUMO? H  C-C π * antibonding orbital

Ethene Hydration  What is the HOMO? H  O 2 lone pair O H H C H H C  What is the LUMO? H  C-C π * antibonding orbital

Ethene Hydration H H H O O H H C H H C H H C H C H H

Ethene Hydration H H H O O H H C H H C H H C H C H H H H H O O H H C C H H H C C H H H H

Molecular Orbitals -- Formaldehyde C-H σ∗ antibonding C-O σ∗ antibonding O C-O π∗ antibonding C O Lone Pairs H H C-O π bonding C-O σ bonding C-H σ bonding

Molecular Orbitals -- Formaldehyde C-H σ∗ antibonding C-O σ∗ antibonding O C-O π∗ antibonding LUMO C HOMO O Lone Pairs H H C-O π bonding C-O σ bonding C-H σ bonding

SOA formation by Polymerization O OH H + C C H H H H O H H

SOA formation by Polymerization O OH O C C H H H H H H OH OH C H H C H OH H O H H

SOA formation by Polymerization O OH O C C H H H H H H OH OH OH C H H C H C OH H H H O H H

SOA formation by Polymerization O OH C C O H H H H H H OH OH C OH H H C H C OH H H H O H H OH C H H H H HO OH C C OH H H O C H OH H

SOA formation by Polymerization

SOA formation by Polymerization