Oxidation States of Carbon • Addition of H (or “H-”) Reduction 2 • Loss of O2 or O carboxylic aldehyde alcohol alkane acid (or ketone) • Loss of H 2 Oxidation • Addition of O2 or O + Neither oxidation nor reduction: Addition or loss of H , H2O, or HX Oxidation and Reduction in Biology • Addition of H (or “H-”) Reduction 2 • Loss of O2 or O + h, in plants carbon dioxide e.g., glucose 4 C-O bonds per C 1 C-O bond per C 0 C-H bond per C 1 C-H bond per C + O2, in animals • Loss of H 2 Oxidation • Addition of O2 or O + Neither oxidation nor reduction: Addition or loss of H , H2O, or HX Biological Oxidation Gone Wrong component of glue alcohol 2 NAD+ dehydrogenase 2 NADH gamma-hydroxybutyrate (GHB, an intoxicant/ date rape drug) Dr. Kevin Carpenter, biochemical geneticist (specialist in pediatric metabolic disorders), Children’s Hospital at Westmead (Sydney), Australia. Behind him: The Agilent GC/MS New York Times, Nov. 8, 2007 “Sleuthing for Danger in Toy Beads” used to analyze the Aqua Dots. Alcohol Oxidation: Strong Oxidizers 2- Chromate (Cr2O7 ) is a strong oxidizing agent; it oxidizes primary alcohols all the way to carboxylic acids, and secondary alcohols to ketones. Na2Cr2O7 unavoidably H2SO4 aldehyde carboxylic acid primary alcohol Na2Cr2O7 Cannot be oxidized further. H2SO4 ketone secondary alcohol Alcohol Oxidation: Mild Oxidizers Swern oxidation is a mild oxidation process; it oxidizes primary alcohols just to aldehydes (and not all the way to carboxylic acids). It also oxidizes secondary alcohols to ketones. 1. DMSO , -60 °C oxalyl chloride aldehyde primary alcohol 2. Et3N Smith describes PCC as Swern another mild oxidizing agent that achieves the same goal. oxidation The reagents and waste ketone products from Swern oxidation secondary alcohol are much less toxic; no one uses PCC any more. Alkene Ozonolysis Splits C=C double bonds, converts alkene carbons into carbonyls (C=O). 1. O3 + 2. (CH3)2S Mild Permanganate Oxidation of Alkynes - At pH = 7, permanganate (MnO4 ) converts alkynes to C=O groups, but keeps the C-C bond intact. KMnO4 H2O internal alkyne pH = 7 KMnO4 H2O terminal alkyne pH = 7 Strong Permanganate Oxidation of Alkynes - Under harsher conditions, MnO4 cleaves the C≡C bond to yield carboxylic acids. 1. KMnO4 KOH, + 2. H3O internal alkyne 1. KMnO4 KOH, + 2. H3O terminal alkyne O3, H2O (ozonolysis) also cleaves C-C bond, w/ same products..