Monday, January 23, 2012

Naming Common Functional Groups

For IUPAC naming, there are two ways that you may name an alcohol:
  1. Using the -ol ending. For example, if you have a propane that has a hydroxide attached to the middle, then you name it as propan-2-ol:
  2. Using the n-hydroxy- prefix, where n specifies the location of the hydroxyl  group. For example, for the same molecule mentioned above, you would name it as 2-hydroxypropane
Common Naming: methyl alcohol, ethyl alcohol, and propyl alcohol

Carboxylic Acids:
IUPAC: Whenever you see a carboxylic acid, it must be included as part of the main chain, and the carbon that has the double-bond-O must be numbered as 1. 

Then, what you do is that you name the rest of the molecule normally, and then add -oic acid to the end of the name. For example, the following would be named as methanoic acid:

Common Naming: formic acid, acetic acid, and proprionic acid.

IUPAC: The exact same process as that of carboxylic acid, except that you add -al to the ending instead of -oic acid. For example, an aldehyde that only has one carbon would be named as methanal.

Common Naming: formaldehyde, acetaldehyde, proprionaldehyde, butyraldehyde

IUPAC: Similar to method #1 of alcohol. But instead of the -ol ending, you use -one. For example, a ketone located at the 3rd carbon of a pentane will be named as: pentan-3-one

IUPAC: Find the largest chain that the amine is attached to, and that will be the main chain. Next, simply add n-amino as a prefix, where n specifies the location of the amine. Also, any extra alkyl group that's attached to the amine will have a location of N. For example, if there's a methyl attached to the amine in 2-aminopropane, then you would name the whole molecule as N-methyl-2-aminopropane.

Common name: Treat the amine as the main part of the molecule. Any alkyl groups attached to it will be considered as side groups. For example, the following molecule will be named as s-butylamine

IUPAC: The longer carbon chain will be the main chain, and the shorter one will be the prefix. Then, combine the prefix and the main chain with an oxy in between. For example, the molecule below is named as "methoxypropane":

Common naming: Each carbon chain is now considered as a side group, and the oxygen is like the centre atom. So name the alkyl groups, and add " ether" to the end of the name. For example, the molecule above would be named as "ethylpropyl ether". 

IUPAC: Amide is made from the condensation reaction between an amine and a carboxylic acid. So to name a amide:
  1. Name the carbon chain of the amine as if it is a side group. So for example, N-butyl, N-methyl, etc.
  2. Name the carboxylic acid that is reacted, and replace the -oic acid by -amide
  3. Combine the two parts, and add a space between them.
So using the above rule, the following molecule will be named as N-methyl ethanamide:

IUPAC: It's quite similar to the naming of amides. You take the name of the carboxylic acid, and replace the ending by -oate. The alcohol group becomes the alkyl side group, and just name it accordingly. So for the molecule below, you would name it as ethyl butanoate: