What is the longest chemical formula




The purpose of the IUPAC nomenclature is to be able to clearly assign chemical compounds to their structure by means of their names. Not all nomenclature rules are listed here, only a selection so that students in chemistry class can name the simpler organic substances.


Hydrocarbon nomenclaturee



Step 1 In the case of hydrocarbons, the longest carbon chain named after the corresponding alkane.

1
2
3
4
5
6
7
8
9
10
methaneEthane
propane
butane
Pentane
Hexane
Heptane
Octane
Nonane
Decane

Example:



Longest chain: 3 carbon atoms, so there is a propane.


The number of attached atoms or groups of atoms is named by a prefix after the Greek alphabet. The first ten prefixes are listed here:

1
2
3
4
5
6
7
8
9
10
Mono *)
Tuesday
Tri
Tetra
Penta
Hexa
Hepta
Octa
Nona
Deca

*) Mono can be used with am attached atom or one attached atom group can be omitted, Chloromethane is therefore mostly not referred to as monochloromethane.

Example:



2 Methyl groups are attached to the longest chain, so the name is dimethylpropane.



2nd step The longest carbon chain is dated shorter, unbranched chain end numbered and named. If the number of carbon atoms is the same, multiple bonds have priority.

Example:



The numbering is from right to left, because the right shorter, unbranched chain end is. The longest chain consists of 6 carbon atoms: it is therefore a -hexane.



3. step Attached alkyl groups are named and sorted alphabetically.

Alkyl groups of aliphatic, saturated hydrocarbons

1
2
3
4
5
6
7
8
9
10
Methyl-Ethyl
Propyl
Butyl
Pentyl
Hexyl
Heptyl
Octyl
Nonyl
Decyl


Alkyl groups of unsaturated, cyclic and aromatic hydrocarbons

Propenyl (attached group with three carbon atoms and one double bond)
Ethynyl (attached group with two carbon atoms and one triple bond)
Cyclohexyl (pendant cyclic ring bond, C.6H11)
Phenyl (attached aromatic ring bond, C.6H5)


Example:


 
The molecule contains one ethyl group (marked in red) and three methyl groups (marked in blue).



4. step The number of identical alkyl groups is determined and their position in the numbered carbon chain is in alphabetable sequence specified.

Exiel:


 
The single ethyl group is attached to third Carbon atom. Hang from the three methyl groups
two on the second and one on the fourth Carbon atom.

The full name is 3-ethyl-2,2,4-trimethylhexane.



Nomenclature of organic substance groups with functional groups

If there is no hydrocarbon, it is named after functional group with the appropriate ending. This applies here Priority rule: The designation is always based on the functional group with the highest priority. The priorities are listed in the table in descending order. The carbon atom on the priority functional group is number 1. If a molecule contains a carboxy group COOH, then it is definitely a carboxylic acid with the ending -acid, even if there are other functional groups in the molecule. These are then given the appropriate prefix. The carboxy group of alkanoic acids has the highest priority. Only radicals and cations have a higher priority. The list of priorities is not exhaustive:


structure
Substance group
Ending
prefixExamples
R-COOHCarboxylic acid-acidCarboxy
Ethanoic acid
R-CO-Haldehyde-alOxo-
Ethanal
R.1-CO-R2Ketone-onOxo-Propanone
RAWalcohol-oilHydroxy
Ethanol
R-NH2Amine-aminAmino
Methylamine
R.1-O-R2Ether-etherR.2yloxy-
Diethyl ether


Example:



It is a carboxylic acid and not an alcohol because the COOH group the higher priority than has the OH group. The carbon chain consists of three carbon atoms and is derived from propane. The hydroxy group sits on the second carbon atom. The name is 2-hydroxypropanoic acid. This is also known under the name of lactic acid.



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