Ketones_aldehydes_chap18

Ketones_aldehydes_chap18 - Ketones and Aldehydes 1. Chain...

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1 Ketones and Aldehydes 1. Chain elongation through addition of a ketone, use 1,3-dithanes S S H H pKa = 32 slightly acidic e' withdrawing S + base, n-butyllithium C 4 H 9 -Li S S H : - S S H - R-X Br + S S H H+, HgCl 2 H 2 O H O aldehyde, 4c Cl 1) n-BuLi 2) R'-X S S H+, HgCl 2 H 2 O O ketone Ex. Make O Solution-
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2 S S H H 1) n-BuLi H+, HgCl 2 H 2 O 2) Cl S S H 1) n-BuLi 2) Cl S S 2. Synthesis of Ketones from carboxylic acids- R OH O LiOH Base R O- O R'-Li R C O-Li+ O-Li+ R' H 3 O+ R C OH OH R' -H 2 O R R' O can use 2 equiv. if cheap Ex. Make the following compound starting with a carboxylic acid. O LiOH OH O LiCH 2 CH 3 H 3 O+ 3. Synthesis of ketones from nitriles
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R R' O H 3 O+ R C N R'-MgX Grignard C N R R' MgX C N R R' H H 3 O+ C N R R' H H + H 2 O C N R R' H H + O H H C N R R' H H + O H H C R R' + O H NH 3 Limitations of Grignard, no acidic protons and no competing nucleophilc alkenes. i.e. C=N, C=O, use aprotic sovent
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Ketones_aldehydes_chap18 - Ketones and Aldehydes 1. Chain...

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