PCAT Organic Flashcards

Terms Definitions
Structural Isomer
have the same chemical formulas but different atomic connectivity
Stereoisomers
compounds that differ only in respect to the spatial arrangement of their atoms
Anti, gauche, eclipsed, totally eclipsed
conformation energy levels low to high
Chair, twisted boat, boat
cyclic hexane conformations energy levels
Achiral molecules
optically inactive
Dextrorotatory compounds
rotates polarized light to the right
Levorotatory compounds
rotates light to the left
Racemic mixture
contains equal amounts of both enantiomers
Diastereomers
stereoisomers that are not mirror images of each other
Chiral molecules
optically active
Meso compound
a molecule that possesses stereocenters but has a plane of symmetry
Covalent bond
involves the sharing of electrons
Ionic bond
involves the transfer of electrons
S orbitals
spherically shaped
p orbitals
bi-lobed shaped
Sigma bonds
single bonds
Pi bonds
formed by two overlapping p orbitals
1 sigma bond, 1 pi bond
compose a double bond
1 sigma bond, 2 pi ponds
compose a triple bond
109.5 degrees
sp3 bond angle
180 degrees
sp bond angle
120
sp2 bond angle
Increased molecular weight
results in increased boiling and melting points
Increased branching
lowers the boiling point
Strong base
strong nucleophile
SN1 reaction
1. the molecule dissociates into a carbocation and a leaving group
2. the nucleophile combines with the carbocation
Rate determining step
the first step/formation of the carbocation
Concentration of the original molecule
what the rate of an SN1 reaction is dependent upon, no the nucleophile
How an SN1 reaction rate can be increased
1. stabilize the carbocation by increasing substitution and using a highly polar solvent
2. use a better leaving group
How basicity effects the nature of the leaving group
the weaker the base the better the leaving group
Polar protic solvents, tertiary alkyl halides
favor SN1
Polar aprotic solvents, Methyl or primary alkyl halides
favor SN2
SN2 reactions
one step, rate is dependent on the concentration of both the substrate and the nucleophile
E1 elimination
2 steps, driven by the same factors (polar solvent, good leaving groups, highly branched chains) as SN1 reactions, uses carbocation intermediate
E2 elimation
1 step, favor the formation of a highly substituted double bonds
Cis
alkene form that has a higher boiling point
Trans
alkene form that has a higher melting point
Markovnikov's rule
protons will add to the less substituted carbon of a double bond to create a more stable carbocation intermediate
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