1. 1 12.2 Properties of Alcohols, Ethers, and Thiols Chapter 12 Organic Compounds with Oxygen and Sulfur Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

2. 2 Boiling Points of Alcohols Alcohols contain polar OH groups. form hydrogen bonds with other alcohol molecules. have higher boiling points than alkanes and ethers of similar mass. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

3. 3 Boiling Points of Ethers Ethers do not have a polar group. have an O atom, but there is no H attached. cannot form hydrogen bonds between ether molecules. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

4. 4 Solubility of Alcohols and Ethers in Water Alcohols and ethers are more soluble in water than alkanes because the oxygen atom can hydrogen bond with water. with 1-4 C atoms are soluble, but not with 5 or more C atoms.

5. 5 Comparing Solubility and Boiling Points Molar Boiling Soluble Compound Mass Point (°C) in Water? Alkane CH 3 ─CH 2 ─CH 3 44-42 No Ether CH 3 ─O─CH 3 46-23 Yes Alcohol CH 3 ─CH 2 ─OH 4678 Yes

6. 6 Reactivity of Alkanes vs. Alcohols Hydrocarbon + O 2  carbon dioxide + water + heat energy  Ex. CH 4 + 2O 2  CO 2 + 2H 2 O  Heat released is 802 kJ/mol of methane Effect of partially oxidizing a hydrocarbon, let’s look at the combustion reaction of CH 3 OH (methanol), in which 1 H has been replaced by an –OH group. 2CH 3 OH + 3O 2  2CO 2 + 4H 2 O Heat released is 640 kJ/mol of methanol (1.5 moles of O 2 required to with 1 mole of CH 3 OH!) 

7. 7 These reactions illustrates two important principles. 1 st, the more reduced a molecule, the more energy is released during oxidation on a molar basis. Methane is fully reduced and gives off more energy during combustion than methanol. 2 nd, the number of oxygen molecules required to react with a fuel molecule can give an estimate of how much energy is available. More highly reduced molecules require more oxygen during combustion and produces more energy.

8. 8 Reduction of hydrocarbons vs. their oxidation OH CH 3 OH Partially Oxidized

9. 9 Solubility of Phenol Phenol is soluble in water. has a hydroxyl group that ionizes slightly (weak acid). is corrosive and irritating to skin. + H 2 O + H 3 O +