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110 Cards in this Set
- Front
- Back
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Delocalized Electrons
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Neither belong to a single atom or are confined to a bond
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Systems with Delocalized Electrons
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Pi Systems, Conjugated Systems, Double bonds with Adjacent p-orbitals, Double bonds with adjacent lone pairs of electrons
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The more resonance structures a molecule has:
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the more stable to molecule
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Electrons always move toward:
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an Sp2 carbon
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Mass Number
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protons + neutrons
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N
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principle shell (1, 2, 3...)
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L
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orbital (s, p, d, f)
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m(l)
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suborbital
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m(s)
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spin (-1/2, +1/2)
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Aufbau Principle
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lowest energy levels are always filled first
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Pauli Exclusion Principle
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No two electrons can have the same two quantum numbers
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Hund's Rule
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an electron will occupy an empty suborbital before it pairs with another electron
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Energy trends of Increasing Orbitals
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Energy increases with increasing shell and orbital
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Group # on the P-Table
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means the number of valence electrons
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Ionic Bond
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transfer of electrons (NaCl)
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Covalent Bond
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Sharing of Electrons (CH4)
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Polar Covalent Bond
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sharing of electrons with different electronegativity
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Electronegativity across the PTable
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Increases to the right and higher up on the table
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Electonegativity of 1.6 or less
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border line ionic, otherwise covalent
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Electronegativity of 3.0
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Ionic
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Electronegativity of 0
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Covalent
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Polar covalent Electronegativity
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Identical Electronegativies
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Like Dissolves:
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Like
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Bond Dipole
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U= e x d (charge x distance)
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Can non-polar solvents dissolve in water?
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no because water is polar
"like dissolves like" |
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The top row of the PTable Never:
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violates the octet rule
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Formal Charge
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group # -(non-bonding electrons+ 1/2 bonding electrons)
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Energy Level of antibonding level
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antibonding level is always higher in energy than bonding level
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Sigma Bond
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electron density lies along the internuclear axis
overlap of 2(s) orbitals |
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Pi Bond
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Electron density lies above and below the internuclear axis
overlap of 2 (p) orbitals |
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Single bonds have:
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1 sigma bond
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Double bonds have
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1 sigma and 1 pi bond
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Triple bonds have
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1 sigma and 2 pi bonds
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Methyl cation hybridization
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Sp2
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Methy anion hybridization
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Sp3
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Which has a stronger overlap? Sp2 or Sp3?
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Sp2
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Shorter bonds are ______ bonds
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stronger
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greater electron density in the overlap region creates a _______ bond.
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stronger
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more s character in a bond, the __________ the bond
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stronger
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Bond Angle of Sp3
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109.5
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Bond Angle of Sp2
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120.0
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Bond Angle of Sp
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180.0
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Acid
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proton donor
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Base
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proton acceptor
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Separated Charges in resonance create:
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a decrease in stability
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when charges are separated, the more stable molecule is:
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the molecule with the negative charge on the most electronegative atom
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Stability of Resonance Structures Decrease with:
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incomplete octet, negative charge on greater electronegative atom, and separate charges
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Which is stronger? Sp2-Sp3 overlap or Sp2-Sp3 overlap?
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Sp2-Sp2
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Allene
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Ch2== C == Ch2
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Allylic Cation
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has a positive charge on an allyic carbon
CH2= CHCHR + |
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Benzyic Cation
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has a positive charge on a benzylic carbon
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Carbocation Stability
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tertiary cc > benzylic cation = allylic cation > secondary cc > primary cc > methyl cation > vinyl cation
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Allylic Carbocation Stability
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3 > 2 > 1
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Benzylic Carbocation Stability
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3 > 2 > 1
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Double bonds to an oxygen _______ the pka
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decrease
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Larger number of resonance structures ______ the pka
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decrease
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delocalized electrons ______ pka
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decrease
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functional groups attached to an sp2 carbon are:
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more acidic than groups attached to sp3 carbons
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Pka protonated alcohol
(R3O+) |
<0
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pka protonated carboxylic acid
(RCOOH2) |
<0
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pka H3O+
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<0
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pka of (RCOOH)
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5
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pka of (benzene-NH3+)
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5
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pka of RNH3+
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10
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pka of (benzene-OH)
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10
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pka of an alcohol
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15
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pka of H2O
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15
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Conjugated Dienes can undergo:
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1, 2 additon and 1, 4 addition reactions
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Kinetic Product
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first and most rapid product formed
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Thermodynamic Product
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Most Stable product formed
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At low temperatures, there is _____________ energy to reverse the product.
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not enough energy
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Thermodynamic products have:
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common intermediates
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1,2 addition is a ________ transition state
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more stable
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Proximity effect o 1, 2 addition
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product forms 1, 2 addition because the carbons are closer together than 1, 4 addition
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low temperature yield __________ product
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kinetic
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high temperatures yield ______________ product
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thermodynamic
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which is irreversible; kinetic or thermodynamic products?
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thermodynamic products
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A Diels-Alder Reaction is a ___________ reaction
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1, 4 addition reaction
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Diels- alder reaction produces what:
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2 new carbon-carbon bonds (1 is a double bond)
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What can increase the rate of a Diels-Alder reaction?
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electron withdrawing groups (C=O, C = N)
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When forming diels-alder prodcuts, _________ substituents are the best product.
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adjacent substituent groups
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Are Diels-Alder Reactions Syn or Anti?
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syn addition
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Diels-Alder reactions can only undergo:
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cis-reactions
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Elimination reactions form:
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double bonds
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Sn2 Kinetics and stereochemistry
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kinetics: second order
Stereochem: inversion |
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Sn2 Stericity and LG ability
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Steric hinderance
Weak bases are good leaving groups |
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Sn2 Nucleophile
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Strong bases and highly polarizable groups are good nucleophiles
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Which does Sn2 form; intermediate or a transition state?
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transition states
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Sn2 uses ________ attack
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backside attack
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Weak Bases: Better LG
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I-> Br-> Cl-> F-
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Strong Bases are good Nucleophiles for Sn2 in Protic Solvents
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OH-, CH3O-, NH2-, CH3CH2NH-
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Polar Aprotic Solvent
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NO (H-O) or (H-N) bonds
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Examples of polar aprotic solvents
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DMSO, DMF, and HmPA
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Weak Bases do not:
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share electrons well, therefore they are not bonded strongly to a carbon
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Strong Bases in Aprotic Solvents
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CH3CH2NH-, NH2-, CH3O-, OH-
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Ionic compounds ____________ in polar aprotic solvents
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can dissolve
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Protic Solvents
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solvent with (H-O) and (H-N) bonding
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Nucleophile Stengths for Sn2 Reactions
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HS-> CN-> I-> CH3O-> OH-> Cl->NH3-> RCOO-> H2O
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Steric Hinderance in Sn2 reaction:
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decrease the rate of reactions
CH3> 1 > 2 > 3 |
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Tert-Butoxide
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very strong bulky base, but very poor nucleophile because of steric hinderance
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If the difference between the basicities of the nucleophile and the leaving group is large:
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the reaction can be reversable
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Sn1 Kinetics and Stereochem
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Kinetics: first order
Stereochem: partial racemization |
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Sn1 LG ability and Nucleophiles
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LG: weak bases
Nucleophile: not a factor in Sn1 |
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Methyl Cations and Primary CC:
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cannot undergo Sn1 Reactions
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Solvolysis
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solvent acts as the nucleophile
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Does an Sn1 reaction have a CC intermediate or a transition state?
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CC intermediate
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Sn1 Nucleophiles
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rate of reaction increases with:
3 > 2 > 1 > CH3 |
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Sn1 forms ___ product (s)
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2 one with relative configuration and one with inversion
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Complete Racemization
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equal amounts of both enantiomers
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Partial Racemization
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unequal amounts of both enantiomers
usually more of the inversion |
