Term
How do you calculate the acid dissociation constant?
pKa? |
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Definition
Ka = [H+][A-]/[HA]
pKa = -logKa |
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Term
| How do you tell acidity and basicity from pKa? |
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Definition
| more acidic molecules will have a smaller or even negative pKa; more basic molecules will have a larger pKa; a higher pKa molecule with have a weaker conjugate base and a lower pKa molecule will have a stronger conjugate base |
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Term
| How do you compare/determine nucleophilicity? |
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Definition
- charge: nucelophilicity increases with increasing electron density (more negative charge)
- electronegativity: nucleophilicity decreases as electronegativity increases because these atoms are less likely to share electron density
- steric hindrance: bulkier molecules are less nucleophilic
- solvent: protic solvents can hinder nucleophilicity by protonating the nucleophile or through hydrogen bonding
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Term
| What makes a solvent protic or aprotic? |
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Definition
| protic solvents can hydrogen bond, aprotic solvents can't |
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Term
| How does the solvent affect the nucleophilicity of a molecule? |
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Definition
| In an polar protic solvent nucleophilicity increases down the periodic table because the more electronegative atoms will form bonds with the protons making it harder for them to access the electrophile; in polar aprotic solvents nucleophilicity increases up the periodic table because because there are no protons to get in the way |
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Term
| What factors affect electrophilicity? |
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Definition
- the more positive charge the more electrophilic
- a molecule with empty orbitals (unhybridized) is a better electrophile because the nucleophiles can make a bond without displacing the leaving group
- a better leaving group makes for a better electrophile
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Term
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Definition
- molecular fragments that retain the electrons after heterolysis
- the best leaving groups can stabilize additional charge through resonance or induction
- weak bases (the conjugate bases of strong acids) make good leaving groups
- alkanes and hydrogen ions are almost never leaving groups because they form reactive anions
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Term
| nucleophilic substitution reactions |
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Definition
| a nucleophile forms a bond with a substrate carbon and a leaving group leaves |
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Term
| unimolecular nucleophilic substitution reactions |
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Definition
- 2 steps
- carbocation formation
- occurs at most substituted carbocation due to stability
- first order reaction
- product is racemic mixture due to planar carbocation
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Term
| biomolecular nucleophilic substitution reactions |
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Definition
- single step reaction
- backside attack
- concerted reaction
- must have strong nucleophile and substrate can't be sterically hindered
- less substituted carbons (primary carbons)
- second-order reaction
- if nucleophile and leaving group have same priorities in their respective molecules the absolute configuration changes from S to R and R to S
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Term
| What makes a good oxidizing agent? |
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Definition
- high affinity for electrons
- unusually high oxidiation states
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Term
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Definition
- primary alcohol to aldehyde
- secondary alcohol to ketone
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Term
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Definition
- primary alcohol to aldehyde
- secondary alcohol to ketone
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Term
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Definition
- aldehyde to carboxylic acid
- primary alcohol to carboxylic acid
- secondary alcohol to ketone
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Term
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Definition
- aldehyde to carboxylic acid
- primary alcohol to carboxylic acid
- secondary alcohol to ketone
- methylbenzene to benzoic acid
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Term
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Definition
| aldehyde to carboxylic acid |
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Term
| alkene to aldehyde/ketone |
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Definition
- O3, then Zn
- O3, then CH3SCH3
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Term
O3, then H2O2
KMnO4, heat, H3O+
What do both of these do? |
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Definition
- alkene to carboxylic acid/ketone
- alkyne to carboxylic acid
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Term
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Definition
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Term
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Definition
cis alkene to epoxide
ketone to ester |
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Term
NaIO4 or
Pb(OAc)4 or
HIO4
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Definition
| diol to an aldehydes and ketones |
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Term
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Definition
| strong reducing agent; reduces an aldehyde, ketone, carboxylic acid or amide down to an alcohol or amine; reduces an exter to two primary alcohols |
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Term
| Both nucleophile-electrophile and oxidation-reduction reactions tend to act at the highest priority (most oxidized) functional group |
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Definition
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