In 1993, the International Union of Pure and Applied Chemistry (IUPAC) issued its final nomenclature for organic compounds. Nomenclature (Nomenclature), as the name suggests, is the method of naming compounds. If we want to give each organic compound a name, we obviously cannot write all possible organic compounds and their names into a table. So we need to write a few very concise rules to help us quickly name even a compound that has never been seen before.
Naming structure The naming structure of organic compounds can be basically split into prefix (Prefix) and suffix (Suffix). The prefix generally indicates how many carbon atoms are in the compound. The suffix represents which functional groups (Functional Group) are contained in the compound. In other words, the suffix represents which organic compound this organic compound belongs to, such as alkanes (Alkane), alkenes (Alkene), alcohols (Alcohol) and so on. There is nothing to say about the prefix. It is purely a one-to-one table: 1 Carbon: Meth- 2 Carbons: Eth- 3 Carbons: Prop- 4 Carbons: But- 5 Carbons: Pent- 6 Carbons: Hex- 7 Carbons: Hept- 8 Carbons: Oct- 9 Carbons: Non- 10 Carbons: Dec- 11 Carbons: Undec- 12 Carbons: Dodec- … In IGCSE chemistry, we rarely see names above 7 Carbons. So everything from Meth- to Hex- must be memorized. No way, just memorize it by rote. The prefixes are only associated with carbon atoms, so you don’t need to count hydrogen atoms. You see several carbon atoms, and its prefix is the corresponding prefix. Let’s take an example.
The chemical formula of this compound is CH4, what is its prefix? Let’s count the carbon atoms, there’s only one, so by our correspondence, it’s Meth-.
The chemical formula of this compound is C4H10. What is its prefix? We counted four carbon atoms, so by our correspondence, it’s But-.
The third carbon atom from the left to the right has a corner. But that’s okay, it doesn’t stop us from counting carbon atoms. The chemical formula of this compound is C5H12, and because it has five carbon atoms, it is prefixed with Pent-.Now that the prefixes are finished, let’s talk about suffixes. If there are only Carbon-Carbon single bond and Carbon-Hydrogen single bond in a compound, then it belongs to alkane (Alkane). Let’s take a look at the name Alkane. It can be split into Alk- prefix and -ane suffix. The Alk- prefix represents a comprehensive compound category. It does not specify the length, but it is just a placeholder. So of course, -ane is the common suffix of this kind of compound.
We still see our three previous examples. Take a closer look, in each compound, each atom is connected with a single bond (a horizontal line), so we can say that all three of them belong to Alkane, and their suffixes are all -ane. So we have a prefix, and we have a suffix, and we can name it. The first compound has the prefix Meth- and the suffix -ane, so the full name is Methane. The second compound has the prefix But- and the suffix -ane, so the full name is Butane. The third compound has a prefix of Pent- and a suffix of -ane, so its full name is Pentane. simple right?