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. O d -. . Alcohols. organic analog of water. Hydrogen bond donor. O-H d +. Hydrogen bond acceptor. - 42 o C. propane. boiling point. ethanol. + 78 o C. O. d +. d -. CH 2 CH 2 CH 3 CH 2 CH 2 CH 2 CH 2 H 2 C. d -. d +. O. O. O. H. H. H 3 C. H 3 C. H 3 C. H. H.
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.. Od- .. Alcohols organic analog of water Hydrogen bond donor O-Hd+ Hydrogen bond acceptor - 42oC propane boiling point ethanol + 78oC
O d+ d- CH2CH2CH3 CH2 CH2CH2CH2H2C d- d+ O O O H H H3C H3C H3C H H H Alcohols Solubility in H2O (g/100 mL) formula boiling point C2H5OH 78 miscible C4H9OH 117 7.9 miscible CH3OH 65 C6H13OH 158 0.5 C8H17OH 194 insoluble d+ d-
Alcohols - Nomenclature 1. Longest continuous chain with - OH 2. Root name + “-ol” 3. Position of - OH given smallest number 4. Ring of cyclic alcohols numbered from - OH 5. Compounds with more than one - OH called “diols” or “triols”
Alcohols heptan ol 6 4 2 4-ethyl- 3- 7 1 5 3 2 4 5 3 1 6-methyl- 2,4- octane diol 6 7 8 phenol
classes of alcohols 1o alcohol 3 2 1 4 1- butanol 2o alcohol 2- propanol 3o alcohol 2-methyl- 2- propanol
Alcohols Classify and name: 1o 2o 3o 1-methyl cyclohexanol 1o 2-phenyl- 1-propanol
H H H H H H H H C C C C C C C C H H H H H H OH OH H H H H H O : H H Alcohols - reactions dehydration reverse of hydration of alkenes + H2O a) electrophile b) nucleophile step 1 H+ : : H+
H H H H O H : : H H H H H H : C C C C C C H H H H H H H O step 2 + step 3 + H+ regenerate catalyst
hydration - dehydration H+ +H2O [alcohol] Q = K = 5 [alkene] [H2O] G = -RT ln K/Q
H C CH3 H H3C H C C C C H H H CH3 H 4 1 2 3 2-butanol 4 3 1 3 1 2 2 4 trans- 2-butene 1-butene major minor major product = most substituted
H What are dehydration products of 1-methylcyclohexanol? OH a)major product b) minor product CH3 H major product
Oxidation of alcohols Primary alcohols: 1+ 2- 2- 1+ 2- 3+ 1- 1+ 1+ 1+ 1+ 2- carboxylic acid aldehyde 1o alcohol [O] = oxidizing agent Cr2O72- dichromate Cr3+ permanganate MnO4- 1. binding O 2. removing H oxidation = lossof e- densityfrom C
Oxidation of alcohols Secondary alcohols: no reaction 2o alcohol ketone
Oxidation of alcohols Tertiary alcohols: no reaction