Exam 2 Flashcards
Methane
one carbon
Ethane
Two Carbons
Propane
Three Carbons
Butane
Four Carbons
Pentane
Five Carbons
Hexane
Six Carbons
Heptane
Seven Carbons
Octane
Eight Carbons
Nonane
Nine Carbons
Decane
Ten Carbons
Undecane
Eleven Carbons
Dodecane
Twelve Carbons
Stereochemistry
noted whether substituents are cis or trans
Newman Projection
orientation of atoms when looking down a specific C-C bond
Staggered projection
Most Stable and less energy
Eclipsed Projection
least stable and more energy
Conformational Analysis
determine energy given off of atoms being oriented next to one another
- H/H eclipsed= 1 kCal/mol
- CH3/H eclipsed = 1.3 kCal/mol
- CH3/CH3 Gauche = 0.9 kCal/mol
Lowest energy conformer
trans orientation
Torsional Strain
all eclipsing interactions
Cyclohexane
six member ring - Chair, no torsional or angle strain, Axial and equatorial bonds (3 up and 3 down)
Chair Flip
Axial and Equatorial bond switch, Front carbons stay in the front
Substituted cyclohexane
favored in the equatorial position
Bycyclic Alkanes
two rings share one or more carbons
- Spiro = 1 shared carbon
- Bicyclo = 2+ shared carbons
Spiro/Bicyclo [# of carbons to complete one side of the ring - # of carbons to complete the other side of the ring - # od carbons in the bridge] # of total Carbons
Molecular Chirality
Chirol - molecule can’t be placed upon its mirror image
Non-chirol - molecule can be placed upon its mirror image
Chirol
sp3 atom with 4 different substituted groups
Enantiomers
the R or S of the chirol center switches to the other
Determining R or S
- Rank groups 1-4 (H is always 4, atomic number - largest to smallest)
- orient so 4 priority is in the back plane
- Read groups 1-3 from highest to lowest - clockwise = R, Counter clockwise = S
Diastereoisomers
One chirol center in common, one different
Meso Compounds
- inner mirror plane
- 2 or more chirol center
- achirol, rotations cancel out
Naming with stereochemistry
R and S are added when there are wedges or dashes
Racemic
50/50 mixture of enantiomers
Fisher Projections
2-D representation of 3-D chirol centers
- horizontal lines = in the plane towards me
- vertical lines = in the flane away from me
