Properties Alcohol is a general term denoting a family of organic chemicals with common properties. Members of this family include ethanol, methanol, isopropanol and others.
Physical Properties Most of the common alcohols are colourless liquids at room temperature. The hydroxyl group generally makes the alcohol molecule polar and soluble in water, while the non-polar hydrocarbon chain tends to make alcohols insoluble.
Hydrogen Bonding & Solubility Hydrogen bonding raises the boiling point of alcohols. This is due to the combined strength of so many hydrogen bonds forming between oxygen atoms of one alcohol molecule and the hydroxy H atoms of another. The longer the carbon chain in an alcohol is, the lower the solubility in polar solvents and the higher the solubility in nonpolar solvents.
4/18/2015 Practice Arrange according to increasing boiling point. (start with lowest boiling point) 1. CH4, CH3OH, CH3CH3 Arrange according to increasing solubility (start with lowest solubility) 2. CH4, CH3CH2Cl, CH3CH2OH
4/18/2015 The small alcohols are completely soluble in water. However, solubility falls as the length of the hydrocarbon chain in the alcohol increases. Solubility
4/18/2015 The -OH end of the alcohol molecules can form new hydrogen bonds with water molecules, but the hydrocarbon “tail” doesn‘t form hydrogen bonds. So quite a lot of the original hydrogen bonds being broken are replaced by London force. Solubility
4/18/2015 Chemical Properties Deprotonation Alcohols can behave as weak acids, undergoing deprotonation. 2 R-OH + 2 NaH → 2 R-O-Na+ + H2 ↑ 2 R-OH + 2Na → 2R-O − Na+ e.g. 2 CH3CH2-OH + 2 Na → 2 CH3-CH2-O − Na+ back
4/18/2015 All alcohols are poisonous. Ethanol is no exception. While infrequent consumption of ethanol in small quantities may be harmless or even beneficial, larger does result in a state known as drunkenness, and even can cause severe health problems, such as liver and brain damage. Toxicity