REACTIONS OF ALCOHOLS - 17 Broadway Ave

1 REACTIONS OF ALCOHOLS . & ETHERS. 1. Combustion (Extreme Oxidation). alcohol + oxygen carbon dioxide + water 2 CH3CH2OH + 6 O2 4 CO2 + 6 H2O. 2. Elimination (Dehydration). H2SO4/100 C. alcohol alkene + water H2SO4/100 C. CH3CH2CH2OH CH3CH=CH2 + H2O. 3. Condensation H2 SO4/140 C. excess alcohol ether + water H2 SO4/140 C. 2 CH3CH2OH CH3CH2 OCH2CH3 + H2O. 4. Substitution Lucas Reagent ZnCl2. alcohol + hydrogen halide alkyl halide + water ZnCl2. CH 3CH2OH + HCl CH3CH 2Cl + H2O. This reaction with the Lucas Reagent (ZnCl2) is a qualitative test for the different types of ALCOHOLS because the rate of the reaction differs greatly for a primary, secondary and tertiary alcohol. The difference in rates is due to the solubility of the resulting alkyl halides Tertiary Alcohol turns cloudy immediately (the alkyl halide is not soluble in water and precipitates out).

2 Secondary Alcohol turns cloudy after 5 minutes Primary Alcohol takes much longer than 5 minutes to turn cloudy 5. Oxidation Uses an oxidizing agent such as potassium permanganate (KMnO4) or potassium dichromate (K2Cr2O7). This reaction can also be used as a qualitative test for the different types of ALCOHOLS because there is a distinct colour change. dichromate chromium 3+. (orange) (green). permanganate manganese (IV) oxide (purple) (brown). Tertiary Alcohol not oxidized under normal conditions CH 3. KMnO4. H 3C C OH. K2Cr2O7. NO REACTION. CH 3. tertbutyl alcohol Secondary Alcohol ketone + hydrogen ions H. O. KMnO4. H 3C C CH 3. K2Cr2O7 C + 2 H+. H3C CH 3. OH. propanone 2-propanol Primary Alcohol aldehyde + water carboxylic acid + hydrogen ions KMnO4 O H H KMnO4.

3 O H H. CH 3CH2CH 2OH. K2Cr2O7. C C C H + H 2O C C C H + 2 H+. K2 Cr2O 7 HO H H. H H H. 1-propanol propanal propanoic acid 6. Acid-Base REACTIONS Like water, ALCOHOLS can act as an acid or base, depending on what it is reacting with. When they react as an acid, the alkyl oxide ion (R-CH2O-) is formed. ethanol + sodium ethoxide ion + sodium ion + hydrogen 2 CH3CH2OH + 2 Na 2 CH3CH2O- + 2 Na+ + H2. When they react as a base, the alkyl oxonium ion (R-CH2OH2+) is formed ethanol + sulfuric acid ethyloxonium ion + bisulfate ion CH3CH2OH + H2SO4 CH3CH2OH2+ + HSO4- Preparation of ALCOHOLS 1. Hydration of an Alkene H2 SO 4 / 100 C. alkene + water alcohol H H H. H2 SO4 / 100 C. H2C CHCH3 + H2O H C C C H. H OH H.

4 2. Oxidation of an Alkene This reaction uses an oxidizing agent like KMnO4 or K2Cr2O7 to produce a diol . KMnO4. alkene + water "diol". K2Cr 2O7. KMnO4 H H H. H2C CHCH3 + H2O H C C C H. K2Cr 2O7. OH OH H. REACTIONS of Ethers 1. Ethers do not react with oxidizing or reducing agents. 2. Combustion ether + oxygen carbon dioxide + water CH3-O-CH3 + 3 O2 2 CO2 + 3 H2O. 3. Reaction with Concentrated . Binary Acids ether + 2 binary acid 2 alkyl halides + water . CH 3 OCH 2CH3 + 2 HCl H3 CCl + ClCH2CH3 + H2O. 4. Reaction with Atmospheric Oxygen This is a slow reaction in which highly unstable peroxides are formed ether + oxygen peroxide CH 3 OCH 2CH3 + O2 H3 COOCH2CH 3. HOMEWORK. Pg 44 # 7-9. Pg 48 # 12, 13 of Practice Pg 48 # 2-4, 6 of Sectio