Introduction to Carboxylic Acids

Hydrides as Reducing AgentsLithium aluminum hydride (LiAlH 4 ) is a strong reducing agent. It will reduceany C=O containing functional group to an alcohol.2. H 3 O +(or just H 2 O)1. LiAlH 4primary alcoholcarboxylic acidand then anotherequivalent adds,unavoidably.Oneequivalent ofH - adds,Reduced by LiAlH 4 :aldehydeketonecarboxylicacidesteracyl halideamideHydrides as Reducing AgentsSodium borohydride (NaBH 4 ) is a mild reducing agent. It is only capable ofreducing aldehydes and ketones to alcohols.NaBH 4EtOHaldehydeprimary alcoholNaBH 4EtOHReduced by NaBH 4 :ketonesecondary alcoholaldehydeketone

Biological Cofactors as Redox AgentsCofactor: A small-molecule “helper” that is required by an enzyme to catalyze areaction. Many vitamins are cofactors.NADH reduces byacting as an H - donorenzymeNADH(derived from niacin,vitamin B 3 )NAD + oxidizes byacting as an H - acceptorNAD +Hindered Reducing Agents Stop At Aldehyde(Chapter 21)OAlHH AlOROR'ester“DIBAL-H”R HaldehydeOROHcarboxylic acidLiHOAlOOOO(Chapter 21)RClacyl halideLiAlH(OtBu) 3R Haldehyde