3PropertiesAlcohol is a general term denoting a family of organic chemicals with common properties. Members of this family include ethanol, methanol, isopropanol and others.
4Physical PropertiesMost 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.
5Hydrogen 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 alcoholis, the lower the solubilityin polar solvents andthe higher the solubility innonpolar solvents.
6PracticeArrange according to increasing boiling point. (start with lowest boiling point)1. CH4, CH3OH, CH3CH3Arrange according to increasing solubility (start with lowest solubility)2. CH4, CH3CH2Cl, CH3CH2OH4/11/2017
8SolubilityThe small alcohols are completely soluble in water. However, solubility falls as the length of the hydrocarbon chain in the alcohol increases.4/11/2017
9SolubilityThe -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.4/11/2017
10Chemical 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+back4/11/2017
11ToxicityAll 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.4/11/2017