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Ngày đăng: 14/04/2018, 14:59

ORGANIC CHEMISTRY Dr Nam T S Phan Faculty of Chemical Engineering HCMC University of Technology Office: room 211, B2 Building Phone: 8647256 ext 5681 Email: Chapter 11: C=O ALDEHYDES-KETONES C=C SP2 carbon NOMENCLATURE OF ALDEHYDES Common names: carboxylic acid Ỉ “aldehyde” is substituted for “ic acid” IUPAC names: hydrocarbon + al Lower priority than ester Ỉ “oxo” group NOMENCLATURE OF KETONES Derived names: alkyls + ketone IUPAC names: hydrocarbon + one PREPARATION OF ALDEHYDES & KETONES Aldehydes & ketones from alkenes In the presence of an oxidizing agent, the products will be ketones / carboxylic acids Aldehydes & ketones from alkynes Markovnikov’s rule Anti-Markovnikov Aldehydes & ketones from alcohols 10 Reactions with sulfur nucleophiles 28 Reduction reactions – with hydride ion 29 • NaBH4 can reduce aldehyde, ketones, acyl chlorides, but NOT alkenes & alkynes • LiAlH4 is a stronger reducing agent than NaBH4, but NOT safe to use for aldehydes & ketones 30 Reduction reactions to hydrocarbons NOTE: 31 Oxidation reactions Aldehydes are generally easier to oxidize than primary alcohols 32 Tollens reagent Too weak to oxidize an alcohol or any other functional groups Should be used when oxidizing aldehydes containing double bond 33 REACTIONS OF ALDEHYDES & KETONES II – REATIONS AT α-C 34 Aldol additions 35 Reaction mechanism: Nucleophilic additions Aldol additions occur more slowly with ketones 36 Aldol condensations = Additions + dehydrations Easier to dehyrate than other alcohols because the double bond is conjugated with the carbonyl group 37 Aldol condensations sometimes occur under the aldol addition conditions without additional heating NOT isolated 38 Mixed / crossed Aldol additions addition products NOT useful 39 Very strong base 40 Halogenations at α-C Only hydrogen is replaced in acidic solution 41 The haloform reactions Only for methyl ketones 42
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