Carbonyls and Amines
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| carbonyl | carbon double bonded to an oxygen, found in aldehydes, ketones, carboxylic acids, amides, and esters
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| 2 important facts about carbonyls | (1) planar stereochemistry (2) partial negative charge on the oxygen with partial positive charge on the carbon
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| carbonyl carbons readily undergo ______ attack | nucleophillic
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| aldehydes and ketones typically undergo nucleophillic ______. | addition
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| carbonyls other than aldehydes and ketones typically undergo nucleophillic _______. | substitution
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| formaldehyde structure | O
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H-C-H
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| acetone structure | O
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CH3-C-CH3
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| physical properties of aldehydes and ketones | -more polar and higher bp than alkenes/alkynes of similar MW
-lower bp than corresponding alcohols (no H bonding)
-excellent solvents for molecules that H bond with water
-water soluble w/ up to 4 C's
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| enolate ion | C=O dbl bond in aldehydes or ketones stabilized by resonance to alkene btw carbonyl C and alpha carbon
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| what happens when beta-carbon is also a carbonyl? | enol form becomes more stable bc of internal H bonding and resonance (one carbonyl stays C=O and then the other is alkene form and the neg charged oxygen forms H bond)
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| the dicarbonyl ______ the acidity of the alpha hydrogen btw carbonyls | increases
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| which are more acidic - aldehydes or ketones, and why? | aldehydes are slightly more acidic than ketones bc it only has one e' donating group
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| how do e' donating groups on carbonyls affect acidity? | e' donating grps cannot help distribute negative charge on the conjugate bases, making them less stable --> less acidic
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| what groups attached to the alpha carbon of a carbonyl will increase acidity? | e' withdrawing groups (will help stabilize conjugate base and therefore increase acidity
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| tautomerization of ketone (keto-enol) | alpha hydrogen moves from alpha carbon to the carbonyl oxygen - RXN AT EQUILIBRIUM NOT RESONANCE (exist at RT)
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| aldehydes react with alcohols to form... | hemiacetals
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| ketones react with alcohols to form... | hemiketals
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| hemiacetal formation | catalyzed by acid or base where ROH acts as nucleophile and aldehyde undergos addition and can exist in equilibrium with ROH but too unstable to isolate
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| acetals or ketals formed when... | second molar equivalent of ROH is added to the equilibrium of hemiacetal/hemiketal and R'OH in the presence of an acid to protonate OH group to produce good LG
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| blocking groups | acetals and ketals - they are unreactive toward bases so aldehydes/ketones temporarily changed to acetal/ketal to prevent it from reacting with a base - often create ring with HOCH2CH2OH (five membered ring)
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| what happens when aldehydes/ketones dissolved in aqueous solution? | they will establish equilbrium with their hydrate - geminal diol (two OH groups attached to previously carbonyl Carbon with its two substituents)
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| aldol condensation | when aldehyde or ketone reacts with another aldehyde or ketone, catalyzed by acid or base
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| base catalyzed aldol condensation | 1. base abstracts alpha-H
2. enolate ion attacks carbonyl C
3. resulting alkoxide ion removes H+ from water and regenerates catalyst and leaves aldol product
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| acid catalyzed aldol condensation | 1. acid catalyzed tautomerization to an enol
2. carbonyl O is protonated (making carbonyl highly electrophillic)
3. enol can attack electrophile
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| with heat and a base, an aldol will ____ because ____ | become and enal bc the aldol is unstable and the enal is stabilized by its conjugated double bonds
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| when do halogens add to ketones at the alpha carbon? | presence of base or acid
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| in the presence of a base, halogenation of ketones at the alpha carbon results in.. | halogenated carbonyl, halogen ion, and water - it is also difficult to prevent halogenation at more than one alpha position
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| in the presence of the acid, halogenation of ketones at the alpha carbon results in... | halogenated carbonyl, halogen ion, and regenerated H+ acid
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| haloform rxn | base + methyl ketone results in alpha carbon completely halogenated -> where base then attacks carbonyl and triple halogenated alpha carbon becomes a leaving group when C=O regenerated -> result in carboxylate ion and haloform
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| haloform definition | HCX3
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| Wittig rxn | converts ketone to alkene using phosphorous ylide
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| ylide | neutral molecule that combines with negativly charged carbanion for use in the Wittig rxn - Phosphorous bound to 3 benzyl rings and a negatively charged carbon
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| steps in Wittig rxn | negatively charged carbanion attacks carbonyl C of ketone/aldehyde forming betaine (nucleophillic addition) that quickly breaks down to an alkene with the R group on the ylide
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| a carbonyl cmpd with a dbl bond between alpha and beta C can is called _____ | alpha beta unsaturated carbonyl
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| characteristics of the C-C dbl bond in alpha beta unsaturated carbonyl | 1. beta carbon less susceptible to nucleophillic attack due to e' withdrawing capability of carbonyl
2. provides resonance when carbocation formed when all e' are at the O of the carbonyl bond
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| formic acid | O
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H-C-OH
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| acetic acid | O
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CH3-C-OH
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| benzoic acid | O
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benzene-C-OH
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| carboxylic acids like to be have as ____ in ____ rxns | acids or substrates in nucleophillic substitution reactions
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| acidity of carboxylic acids... | they are very strong for organic acids bc when dissociated, their conjugate base is stabilized by resonance
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| what types of group on the alpha carbon will increase the acidity of a carboxylic acid? | e' withdrawing groups bc they help further stabilize conjugate base
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| physical properties of carboxylic acids | high bp due to H bond dimers, if saturated and more than 8 carbons - solids, unsaturated impede crystal lattice structure and lower BP
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| when can carboxylic acids mix with water? | <4 C's: soluble
5-10 C's: increasingly less soluble
>10 C's: insobluble
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| carboxylic acids solubility in nonpolar solvents | yes, soluble bc dimer form allows carboxylic acid to solvate w/o disrupting hydrogen bonds of the dimer
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| decarboxylation | process in where carboxylic acid loses CO2, rxn is usually exothermic but has high activation energy
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| how is the activation energy of decarboxylation lowered? | when the beta carbon is a carbonyl bc either the anion intermediate is sstabilized by resonance or the acid forms stable cyclic intermediate
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| what is needed to form acyl chlorides? | carboxylic acids and inorganic acid chlorides (SOCl2, PCl3, and PCl5)
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| acyl chlorides act as what kind of acids? | bronsted-lowry - they donate alpha hydrogen like aldehydes but the e' withdrawing Cl stabilizes conjugate base more than the H of an aldehyde
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| acyl chlorides are the most or least reactive of the carboxylic acid derivatives, and why? | most reactive bc of the stability of the Cl- leaving group
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| what happens when any carboxylic acid derivative is in the presence of water? | it will hydrolyze to give the corresponding carboxylic acid, and can occur under acidic or basic conditions
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| acid chloride + alcohol = | ester
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| acid chloride + amine = | amide
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| acid chloride + RCOOH = | anhydride
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| alcohols + carboxylic acids = | esters (via nucleophilic substitution), catalyzed by strong acid
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| esterification | alcohols + carboxylic acids = esters
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| transesterification | esters + alcohol = carboxylic acid
way to trade alkoxy groups on an ester
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| acetoacetic ester synthesis | production of ketone from acetoacetic ester due to strongly acidic properties
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| steps in acetoacetic ester synthesis | 1. base is added to remove alpha H's
2. alkyl halide alkylates the resulting enolate ion
3. alkylacetoacetic ester is decarboxylated in presence of acid and heat resulting in ketone
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| amides are formed when... | amine + carboxylic acids or one of its derivities
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| order of reactivity of carboxylic acid (most to least) | acyl chloride > acid anhydride > carboxylic acid > ester > amide
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| important facts about nitrogen containing cmpds | 1. they may act as Lewis base donating their lone pair of e's
2. they may act as a nucleophile where lone pair of e's attacks positive charge
3. N can take on 4th bond and become positively charged
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| what decreases amine basicity | e' withdrawing substituents, steric hindrence, aromaticity
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| what increases amine basicity | e' donating substituents
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| amine basicity from highest to lowest when functional groups are e' donating? | 2 > 1 > ammonia
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| physical properties of ammonia and amines | hydrogen bond capability of ammonia to 2 amines raise bp and increases solubility in water
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| what is special about chiral amines? | at RT, the lone pair of e's moves rapidly and inverts configuration rapidly so molecule spends equal amt of time in each enantiomer
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| aldehydes/ketones + amines = | imines/enamines + water (requires acid catalyst)
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| steps in condensation rxn with ketones | 1. lone pair on amine attacks ketone or aldehyde in nucleophilic addition
2. OH grp is protonated by acid catalyst to make a good leaving group
3. unstable intermediate will produce enamine or imine
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| enamine formed when... | secondary amine gives up its alpha hydrogen in condensation rxn with ketones where alkene with amine grp (enamine) forms
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| imine formed when... | hydrogen lost from primary amine to make a C=N when water leaves unstable intermediate in condesnation rxn with ketones
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| imine products of condensation rxns can.. | exist as a tautomer with its corresponding enamine
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| Wolff-Kishner rxn | reduces ketone/aldehyde by removing oxygen and replaces it with 2 hydrogens - used for when molecule can't survive hot acid to reduce to alkane
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| steps in wolff-kishner reduction | 1. lone pair of hydrazine N attacks ketone (Nu: addition)
2. acid protonates OH grp to make good LG
3. C=N formed to release water forming hydrazone and acid
4. hot strong acid added to deprotonate N of C=N to produce alkane, water, and N2 gas
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| amines can be alkylated with ___ in a _______ rxn | alkylated with alkyl halides in a nuclephilic substitution rxn
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| amino groups are good or poor leaving groups? | poor - they need to be converted to quarternary ammonium salt by repeated alkylations to be a good leaving group
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| what is the rxn mechanism to eliminate a quarternary ammonium salt? | E2 mechanism with strong base
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| Hoffman elimination | heating quarternary ammonium hydroxide and results in alkene
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| Hoffman product | least stable alkene in the Hoffman elimination
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| Saytzeff product | most stable alkene in the Hoffman elimination
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| nitrous acid + strong acid = | HO-N=O + H+ --> [:N+=O:: <-> :N+-O:+] + H2O
(product is nitrosonium ion)
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| primary amines + nitrous acid = | diazonium salt
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| diazoniam group | two Nitrogens triple bonded to each other as a functional group
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| diazotization of an amine rxn steps | 1. nitrous acid protonated by strong acid
2. resulting nitrosonium ion reacts with primary amine
3. resulting N-nitrosonium (unstable) deprotonates to N-nitrosoamine and tautomerizes to diazenol
4. diazenol in acid dehydrates to diazonium ion
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| diazenol | R-N=N-O-H (tautomer of RHN-N=O)
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| diazotization of an amine requires... | aromatic primary amines
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| the diazonium grp can be replaced to the following.. | OH group, halide, H, or -N=N-Ar
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| secondary amines + nitrosonium ion = | N-nitrosoamine (amine N's lone pair still attacks positive charge on the nitrosonium ion and then water abstracts proton to form N-nitrosoamine)
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| amide | caboxylic derivative containing nitrogen
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| amides behave as... | weak acid or weak base
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| amides are hydrolyzed by... | strong acids or strong bases
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| amides with a hydrogen attached are able to... | hydrogen bond with each other
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| beta lactams | cyclic amides, highly reactive due to large ring strain
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| Hoffman degradation | primary amides react with stronly basic solns of Cl or Br to form primary amines with CO2 as the byproduct
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| steps in Hoffman degradation | base abstracts H from 1-amide>(-)N attacks X2 >base abstracts H from resulting N-haloamide>rearrangment moves R grp to N (Br as LG)
>OH- attacks C in isocyonate while lone pair abstracts H from H2O>resulting carbamic acid decarboxylated>>primary amine
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| isocyonate | R-N=C=O, rearrangement that occurs in product of deprotnated product of N-haloamide and base (intermediate in Hoffman degradation rxn)
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| carbamic acid | R-NH-COOH, formed when isocyanate reacts with water
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| advantage of Hoffman degradation over other methods of producing amines? | other rxns rely on SN2 reaction which prevents production of amines on a tertiary carbon -- Hoffman degradation can produce amines w/ primary, secondary, or tertiary alkyl position
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| phosphoric acid | O
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OH-P-OH
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OH
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| when heated, phosphoric acid forms... | phosphoric anhydrides
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| phosphoric anhydrides + alcohols = | esters
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