Term
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Definition
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Term
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Definition
| Ag2O - reacts ONLY with aldehydes, turning them into carboxylic acids |
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Term
| aldehydes are more reactive than ketones; why? |
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Definition
- steric reasons - aldehydes are more open to nucleophilic attack (less substituent groups)
- electronic reasons - there are two R-groups on ketones, which are electron donating groups that stabilize the positive charge on C and makes it less polarized and therefore less reactive |
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Term
| if you add H2O to a ketone and to an aldehyde, creating in both cases a geminal diol, where will the equilibrium lie? |
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Definition
ketone: equilibrium will lie toward the ketone because it is less reactive due to steric and electronic reasons.
aldehyde: equilibrium will lie towards the geminal diol because an aldehyde is very reactive to nucleophilic substitution because of a lack of steric strain and fewer EDG to stabilize the partial positive charge on carbon |
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Term
| why does imine and enamine formation work best in acidic (but not TOO acidic) environments? |
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Definition
| need acid to donate a proton to make OH into OH2 to make it a good leaving group; but you also need a little base later on to abstract a proton. |
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Term
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Definition
| making a ketone or an aldehyde into a carbonyl using H2NNH2; has a hydrazone intermediate |
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Term
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Definition
| ketal is the general name for a carbon with two -OR groups attached; it's achieved by reacting a ketone with 2ROH and an acid catalyst, is reversible using large amounts of excess acid. "acetal" is the specific name used for when you started with an aldehyde. |
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Term
| would an imine/enamine be expected to undergo 1,2 or 1,4 addition preferentially? Why? |
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Definition
| 1,4 addition preferentially - because they are reversible reactions, they are at equilibrium and assume the more stable final product. |
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Term
| why will a 1,4 conjugate addition of (R)2CuLi not work on an aldehyde? |
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Definition
| if it's not sterically hindered enough, you'll also get 1,2 addition |
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Term
| which is more stable, RSH or RSSR? |
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Definition
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Term
| Williamson Ether Synthesis |
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Definition
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Term
| basically the only thing that doesn't react in alkoxymercuration of alkenes is a ditertiary ether. Why not? |
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Definition
| It's too sterically hindered. |
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Term
| how is base-catalyzed ring opening different from acid-catalyzed? |
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Definition
acid-catalyzed: if there's an option to form a tertiary carbocation, it will be formed. Otherwise, the less sterically-hindered site will form.
base-catalyzed: there is no carbocation intermediate, so you only consider steric strain when you look to see where attack will be. |
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Term
| why are dimethyl sulfides more reactive than ethers? |
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Definition
| sulfur is bigger and hence more reactive, so a good nucleophile |
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Term
| why does water force a micelle structure? |
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Definition
| to minimize the contact it has with the micelle, which forces it to be ordered (decrease entropy). |
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Term
| why are carboxylic acids more acidic than alcohols? |
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Definition
| because resonance stablizes their ion |
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Term
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Definition
| a mix of an acid and its conjugate base that resists change in pH |
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Term
| what is the Henderson-Hasselback equation? |
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Definition
| pH = pKa + log (base/acid) |
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Term
| what are the two things that determine the reactivity of carboxylic acids/derivatives? |
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Definition
1. steric factors - less substitution means more reactive.
2. -NH2 < -OR < -O-C=OR < X |
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