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 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 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of partially oxidizing a hydrocarbon, let’s look at the combustion reaction of CH 3 OH (methanol), in which 1 H has been replaced by an –OH group. 2CH 3 OH + 3O 2 2CO 2 + 4H 2 O Heat released is 640 kJ/mol of methanol (1.5 moles of O 2 required to with 1 mole of CH 3 OH!)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 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 Reduction of hydrocarbons vs. their oxidation OH CH 3 OH Partially Oxidized
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 +