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30 Cards in this Set
- Front
- Back
SN2 reactions always occur with what type of configuration? |
Inversion. Substrate is attacked by the nucleophile from the back side |
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What is the free energy of activation or Delta G Prime? |
The difference in energy between the reactants and the transition state |
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This is the difference in energy between reactants and the products. |
The free energy change for the reaction or Delta G |
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What is the transition state on the reaction graph? |
The top of the energy curve |
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What type of nucleophile results in a neutral product? |
Negatively charged nucleophile such as hydroxide |
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Is a nucleophile an acid or a base and what type of charge does it have to have? |
It's always a Lewis base which is an electron-pair donor and it can be negatively charged or neutral |
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Which group is always a species that takes a pair of electrons with it when it departs? |
The leaving group which is usually an electronegative atom such as the halide family |
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As you go down the periodic table how does that affect bond strength and bond length? |
Bond length increases and the carbon halogen bond strength decreases |
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What is a Bronsted-Lowry base? |
Accepts a proton |
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How can you compare the relative stabilities of carbo cations? |
Look at the number of alkyl groups attached to the positively charged carbon. Tertiary carbo cations are the most stable and methyl carbo cations are the least stable. |
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What are the best types of leaving groups? |
Ones that become weak bases |
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SN2 reactions are favored by which solvents? |
Polar aprotic solvents |
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SN1 reactions are favored by which solvents? |
Polar PROTIC solvents ie EtOH, MeOH, H2O |
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What is the trend in nucleophilicity among halide anions in a PROTIC solvent? |
I>Br>Cl>F |
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What is the trend in nucleophilicity among halide anions in an APROTIC solvent? |
F>Cl>Br>I |
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A substrate with a relatively unhindered leaving group favors_____ |
An SN2 reaction |
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Tertiary halides do not react by an _____mechanism |
SN2 |
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A substrate that can form a stable carbocation favors a _____ reaction. The substrate would have a _____ in the tertiary position |
SN1; leaving group |
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Which mechanism is important in solvolysis reactions? |
SN1 |
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Which type of solvents hinder the nucleophile in sn2 reactions? Why? |
PROTIC because hydrogen bonding encumbers it's reactivity in substitution reactions |
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How do smaller more concentrated anions affect solvation? |
They are more strongly solvated and are not as effective of a nucleophile. Iodide is strongest compared to F |
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Rate constant k , is dependent on which 3 factors? |
Catalyst, temperature, energy of activation or Ea |
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The RATE of a reaction is dependent on what? |
Reactants, k, temp, Ea |
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True or false. Activation energy is dependent on temperature? |
False |
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SN1 reactions have _____ kinetics and are _______, which means the rate depends on concentration of ______. |
First order, unimolecular, the substrate only |
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The rate of a SN2 reaction depends on what? |
Concentration AND identity of attacking nucleophile |
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SN1 reaction rates are increased in what type of solvent? |
Polar PROTIC or ionizing solvent |
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In which type of solvent does nucleophilicity correlate with basicity? |
Polar aprotic |
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Secondary , allylic, and and benzylic substrates can proceed though which mechanism? |
SN1 or sn2 Vinyl and aryl substrates can NOT undergo either |
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Rank the stabilities of carbocations |
Benzylic/allylic, 3°,2°,1°, Me |