Lecture 39 - • In the imine is stable the two stages can...

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Reading for Wednesday Chapter 25: 25.9-25.12
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4 th Exam This Thursday! May 5 th 6-7:30 PM 120 Budig Chapters 23 Chapter 24 Chapter 25 (1-3,7)
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Exam 4 Review Session Tuesday May 3 rd 6:00 PM 1001 Malott
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Mon. 6:00-7:30 pm MAL 3092 Tues. 2:30-4:00 PM MAL 2007 PLUS Sessions THIS WEEK
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Preparation of amines (25.7A) Direct nucleophilic substitution (S N 2) Useful for making: 1º amines from NH 3 , used in large excess. Quaternary ammonium salts (use alkyl halide in excess)
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Gabriel Synthesis of 1º amines (25.7A) Phthalimide used as N source Phthalimide is deprotonated and alkylated Hydrolysis of the alkylated phthalimide gives a 1º amine
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Prep. of amines by reduction of other functional groups (25.7B) Nitro compounds 18.14C Nitriles 22.18B Amides 20.7B
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Reductive Amination of Ketones and Aldehydes (25.7C) Two stages to this process: Formation of an imine (or iminium ion) Reduction of the imine (or iminium ion) to an amine
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Reductive Amination of Aldehydes and Ketones (25.7C)
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Unformatted text preview: • In the imine is stable, the two stages can be performed in sequence • The imine is isolated, and then can be reduced using NaBH 4 • This kind of reductive amination was performed in Chem 627 this semester • Most imines are not stable. • In such cases, they are reduced “in situ” (i.e. in the same pot in which they are formed) • NaBH 3 CN is needed in these cases (weaker reducing agent than NaBH 4 ) Reductive Amination of Aldehydes and Ketones (25.7C) Why NaBH 3 CN and not NaBH 4 ? • Imine formation is an equilibrium process; almost always some ketone or aldehyde present at equilibrium • NaBH 4 reduces ketones and aldehydes; NaBH 3 CN does not Why NaBH 3 CN and not NaBH 4 ? • Reaction typically performed in CH 3 OH at pH ~ 5 • This is acidic enough to protonate imines, but not aldehydes/ketones • Protonated imines are reactive enough to be reduced by NaBH 3 CN...
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Lecture 39 - • In the imine is stable the two stages can...

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