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25 Cards in this Set
- Front
- Back
*aldehydes and ketones* typically undergo *nucleophilic addition*,
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while *other carbonyls* undergo *nucleophilic substitution*
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aldehydes and ketones
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*** don't H-bond with any cmpd, including themselves***
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chemical properties of aldehydes and ketones
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will often act as nucleophilic substrates,
or as a Bronsted-Lowry acids, by **donating one of their alpha-hydrogens** aldehydes are more acidic than ketones |
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when the B-carbon of a carbonyl is also a carbonyl carbon,
(B-dicarbonyl) |
the alpha-H gets more acidic, pushing acidity of the aldehyde or ketone > water or alcohol
(normally, they are less acidic) |
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acetals and ketals are used as blocking groups
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to *prevent* an aldehyde or ketone from *reacting with a nucleophile*
(take an aldehyde, make it an acetal via catalyst, base eventually goes away, return the acetal into an aldehyde by acid) |
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**look for carboxylic acid to behave as either**
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an acid or a substrate in nucleophilic substitution rxns
look for water leaving |
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**physical properties of carboxylic acids**
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formation of *dimers* due to H-bonds between two mlcls
- **significantly increases the BP** Carboxylic acids with more than 10 carbons = insoluble in water |
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tautomerization favors
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the aldehyde or ketone form
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acyl chlorides:
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Bronsted-Lowry acids that donate an alpha-hydrogen
- significantly stronger acids than aldehydes ***most reactive of carboxylic acid derivatives***, because of the stability of Cl LG ***acid chlorides love nucleophiles*** |
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hydrolysis can occur under either
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acidic OR basic conditions
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determine which one is Beta and which is the main carbonyl by
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priority
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strong bases make poor
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leaving groups
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in all CA-derivative rxns, the carbonyl carbon acts as the
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substrate in nucleophilic substitution
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***all carboxylic acids and their derivatives undergo nucleophilic substitution;***
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***while all aldehydes and ketones prefer nucleophilic addition***
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***3 important things to consider when you see cmpds containing nitrogen:***
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1. they may act as Lewis bases, donating their lone pair of electrons
2. they may act as a nucleophile where the lone pair of electrons attacks a positive charge 3. Nitrogen can take on a fourth bond, becoming positively charged |
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when the functional groups are EDG, the trend of amine basicity is:
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2 > 1 > ammonia
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aromatic amines (amines directly attached to a benzene ring) are:
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much weaker Lewis bases than nonaromatic amines
because the electron pair delocalizes around the ring |
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amines tend to stabilize carbocations when
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they are part of the same mlcl, because they donate their electrons
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ammonia and amines H-bond,
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**raising the BP and increasing solubility**
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ammonium salt =
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NH4
an excellent leaving group |
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nitrous acid (HNO2) is a
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weak acid
nitric acid (HNO3) is a strong acid |
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aliphatic =
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non-aromatic
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**nitrous acid + primary, aromatic amine =
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diazonium salt
**only aromatic amines work** |
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amides can behave as
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weak acids or weak bases;
are hydrolyzed by strong acids or strong bases |
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cyclic amides are called
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lactams
Beta-lactam = a 4-membered ring - they are highly reactive due to ring strain - look for nucleophiles to react with B-lactams |