12 - METHODS FOR THE SYNTHESIS OF ALCOHOLS (to date) OH I -...

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Unformatted text preview: METHODS FOR THE SYNTHESIS OF ALCOHOLS (to date) OH I - OH 1. BH3 OH H+/H2O OH 2. NaOH/H2O2 1. OsO4 2. H2O2 OH OH 1. mCPBA OH 2. H+/H2O SYN O Aldehydes OH H R ANTI H R O Na OH Ketones R R R R O epoxides OH R R OH ELECTROPHILIC AND NUCLEOPHIC CARBON Methylmagnesium bromide d- H3 C d+ Mg Br Methyl lithium Methyl chloride d- d+ d+ H3 C Li H3C d- Cl TYPICAL ELECTROPHILES Methyl chloride d+ H3C d- Cl acetone O dd+ Alcohols, carbonyl compounds and carboxylic acids: REDUCTION Reduction: Addition of H2 (or H-), loss of O or O2 ; loss of X2 H H R C R H C OH H Prim ary alcohol H O NaBH4 RC or H Rane y Ni/ H2 Aldehyde O LiAlH4 R C OH Carboxylic ac id mus t convert OH to leaving group H H R C H R C OH R' Secondary alcohol R' mus t convert OH to leaving group R C R' H R or Rane y Ni/ H2 R C R' Ke tone H Li H A l H R" R" O NaBH4 C OH R' Terti ary alcohol H Li thi um al umi nium hydri de Na H HB H H Sodi um bor ohydri de Comparison of Reducing Agents • LiAlH4 is stronger. • LiAlH4 reduces more stable compounds which are resistant to reduction. => Alcohols, carbonyl compounds and carboxylic acids: OXIDATION Oxidation: loss of H2 , addition of O or O2, addition of X2 (halogens) H H R C H R H H C R OH H R C OH R H2 SO4 C OH Carboxylic ac id O R C H2 SO4 R' Secondary alcohol R' C Aldehyde Na2Cr2O7 / O Na2Cr2O7 / H H Prim ary alcohol H R C O PCC X R' Ke tone PCC R" R" R C R' H R C OH R' Terti ary alcohol X NH CrO3Cl- ...
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This note was uploaded on 11/27/2011 for the course CHEMICAL E 20.410j taught by Professor Rogerd.kamm during the Spring '03 term at MIT.

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