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10 Cards in this Set
- Front
- Back
Primary amines, RNH2, add to aldehydes and ketones to yield ?
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imines, R2C=NR
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Secondary amines, R2NH, add similarly to yield....
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enamines, R2N-CR=CR2
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Imines are important intermediates in?
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many metabolic pathways
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Imine formation and enamine formation appear different because
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one leads to a product with a C=N double bond and the other leads to a product with a C=C double bond
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Both Imine and Enamine are typical examples of nucleophilic addition rxns in which .....
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water is eliminated from the initially formed tetrahedral intermediate and a new C=Nu double bond is formed
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Imines are formed in a process that begins with a ________ ____________nucleophilic addition of the primary amine to the carbonyl group, followed by transfer of a proton from nitrogen to oxygen to yield ?
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- reversible, acid-catalyzed
- a neutral amino alcohol, or carbinolamine |
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Protonation of the carbinolamine oxygen in Imines formation by an acid catalyst then converts the -OH into ________ and E1-like loss of water produces _________ _______. Loss of a proton from nitrogen gives ?
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- a better leaving group (-OH2+),
- an iminium ion - the final product and regenerate the acid catalyst |
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Imine formation is _______ at both high pH and low pH but reaches a maximum rate at?
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- slow
- at a weakly acidic pH around 4 to 5 |
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Rxn of an aldehyde or ketone with a secondary amine, R2NH, rather than a primary amine yields?
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an enamine
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The process of making an enamine is identical to imine formation ______ ______ _____, but at this point there is noproton on nitrogen that can be lost to form a neutral imine product. The difference is that??
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- up to the iminium ion stage
- a proton is lost from the neighboring carbon (the alpha carbon) yielding an enamine |