|Like Jekyll and Hyde, changing a functional group changes |
a molecule's behavior. Image from Library of Congress.
Change up the functional group, and you change the molecule's behavior. Like Jekyl and Hyde. Ethanol is something to drink on a Friday night, ethanal is found in the coffee you drink for the hangover the next morning (in an ironic twist, it's also produced as your body metabolized the ethanol.)
The first part of a chemical name tells the size of the carbon framework, the ending tells you about its function — or lack thereof. Names that end in -yl or -ane mean a hydrocarbon chain without any fancy functionality. Propane, a popular fuel, is a three carbon hydrocarbon chain. Methyl mercaptan (added to odorless natural gas to make it smell, and make leaks quickly noticeable), has a one carbon long "chain" in it. Change -yl to -ol and you have made an alcohol, a chain with an -OH group on it (Ethanol is CH3CH2OH, sometimes written EtOH, a 2 carbon chain with an OH group on it.)
Knowing the functional groups means knowing something about the kinds of things a molecule can do. Esters smell floral, carboxylic acids can remove a layer of skin, and are found in many lotions.
So to decode:
-ol means an alcohol (functional group = -OH) but not necessarily the kind of alcohol you drink
-al means an aldehyde (-COH); these often smell sweetish
-oxy means an ether (an oxygen sandwiched between two carbon chains)
-oic acid or -ic acid means a carboxylic acid (pronounced "car-box-sill-ick") salicylic acid, often found in face washes
-oate means an ester (a COO group sandwich between two chains); ethyl nonanoate smells like grape, the functional group is between a 2 carbon chain (ethyl) and nine carbon chain (nona)
-one means a ketone, a CO group sandwiched in between two chains
Check out Andy Brunning's of Compound Interest's great graphic on functional groups and their names and Practically Science's map of molecules in food and their smells.