Organic Chemistry Exam 1

Alkyl Halide
Alkene
Alkyne
Alcohol
Ether
Thiol
Sulfide
Arene
Ketone
Aldehyde
Carboxylic Acid
Acyl Halide
Anhydride
Ester
Amide
Amine
Valence Bond Theory A covalent bond is formed from the overlap of atomic orbitals. It is also the sharing of electron density.
Atomic Orbital Theory Overlap of electron cloud
Molecular Orbital Theory Linear combination of atomic orbitals. Molecular Orbitals are associated with an entire molecule. Treats bonding electrons as being part of the entire molecule.
Antibonding Molecular orbital Destructive interference, higher energy orbital
Bonding Molecular Orbital Constructive Interference, lower energy orbital
Hybridization
Steric Number: 2, 3, 4 4-109.5, sp3, 1 sigma bond 3 pi bonds
3-120, sp2, 1 sigma bond 2 pi bonds
2-18-, sp, 1 sigma bond 1 pi bond
Hybridization Specific orbitals available for bonding
Bond Strength versus Length Strongest to Weakest: triple, double, and single
Longest to Shortest: single, double, and triple
Sigma Bonds Head to head over lap of s orbitals
Pi Bonds Side to Side overlap of p orbitals. They prevent bond axis from rotating, meaning double bonded carbons have no isomers involving rotation. Triple bonds also cannot rotate but it doesn't matter because of their linear geometry.
Molecular Formula No structure info, just lists the molecule number and their amount
Lewis Structure Draw all bonds
Partially Condensed Structure C-H bonds are not explicitly drawn, all other bonds and lone pairs are drawn
Condensed Structure Single bonds are not drawn. Groups of atoms are clustered together.
Heteroatoms Atoms other than carbon and oxygen
Formal Charge Number of valence electrons - (bonds + number of lone pairs)
Hydrocarbon Contains only C and H
Alkyl Group Straight branch chain of C and H atoms
R
x
Z R : Rest of molecule
X : Represents common halogen
Z Represents any group of atoms
Wedge
Dash
Curvy Line Wedge : Represents a group coming out of the page
Dash : Represents a group going behind the page
Curvy Line : 50% behind and 5-% in front
Acyclic
Cyclic
Bicyclic Acyclic : No rings
Cyclic : One ring
Bicyclic : two rings
Parent Chain Select the longest chain to be the parent chain. If two are the same, choose the on with more substituents.
Naming Substituents add -yl to parent name for substituent name.
Misconceptions -Prefixes are not used to alphabetize except for iso
-No formula for calculating possible isomers
Isopropyl 1-methylethyl
Sec-butyl 1-methylpropyl
isobutyl 2-methylpropyl
tert-butyl 1,1-Dimethylethyl
isopentyl or isoamyl 3-methylbutyl
neopentyl 2,2 - dimethylpropyl
Assembling Names -Number all carbon atoms
-First substituent receives lower number, with a tie, the 2nd should be as low as possible
-Further tie, assign alphabetically
Naming Bicyclic Bicycloalkane : two rings connected to one another
Identify two bridgeheads
Start numbering from bridgeheads, longest to shortest
Constitutional Isomers Must use all atoms, both structures must be real, must be different compounds. To check if you drew the same isomer twice, use IUPAC naming
Stability of Isomeric Alkanes Because branched alkanes have a larger heat of combustion their bonds are stronger and more stable
Newman Projections Achieved due to the rotation about the vertical axis of a c-c single bond
Stereoisomer Same connectivity but different spatial arrangement
Degenerate Same amount of energy
Staggered v. Eclipsed Staggered :

  • Possess favorable interactions between an occupied bonding and antibonding sigma orbitals(hyperconjugation)
      -60 degree bond angle
      -lowest in energy
      -Gauche interactions between methyl groups that are right by each other in the conformation (increased energy due to steric interaction)
      Eclipsed :
  • In the highest energy, the largest molecules are eclipsing each other (steric interaction)
      -Experience torsional strain due to the rotation
      Cycloalkanes Ideal angle 109.5. Anything that deviates from that is angle strain. Cyclopropane ( 60, severe angle strain that can be alleviated by orbitals bending but this increases energy due to inefficient overlap of orbitals. Torsional strain due to eclipsed conformation) Cyclobutene ( 90, less angle strain but more torsional bc four sets of eclipsing hydrogens, can adopt a puckered formation without gaining strain ). Cyclopentane ( 108, only slight angle strain, exhibits some torsional strain, envelope form relieves some torsional strain ). Cyclohexane ( 120, nearly strain free. Chair and boat conformation. ). Cycloheptane ( 129 ). Cyclooctane ( 135 ).
      Chair No angle strain, no torsional strain
      Half chair Some angle strain and some torsional strain
      Boat No angle strain, torsional strain and steric strain because of flagpole hydrogens.
      Axial v. equatorial Axial : parallel to vertical axis
      Equatorial : along the equator of the ring ( it is favorable to put large groups in equatorial positions because it lowers their potential energy)
      Wedge v Dash Wedge : Up
      Dash : Down
      Ring flip Conversion of one chair conformation to the other by rotating all C-C bonds
      Cis v trans Cis : same plane
      Trans : opposite plane
      Comparing stability Add up A-Values for axial positions
      Haloalkane Halogen as a substituent
      Organohalide Organic Compound Containing a hydrogen
  • Stereoisomers same molecular formula, same connection, different 3D arrangement. Cannot convert one to the other
  • Superimposable An object and its mirror image are identical
  • Chiral object An object that is not superimposable
  • Achiral object An object that is superimposable
  • A carbon is a chiral center when It is a tetrahedral bearing four different groups. In a ring it is when the paths around the ring are different
  • Enantiomer The non-superimposable mirror image to a chiral compound
  • Assign priority based on the atomic number of the substituents, with 4 being the largest priority. If there is a tie, keep moving outwards until something breaks the tie
  • If priority 4 is on a dash(S and R are what) R is clockwise and S is counterclockwise
  • If priority 4 is on a wedge(S and R are what) R is counterclockwise and S is clockwise
  • If priority 4 is on plane Swap 4 with the dashed substituent and then swap the other two
  • Chiral center on rings If each side of the carbon is the same (as in there is an internal mirror plane) then it is achiral. If each side is different then it is chiral.