Chemistry > General Organic Chemistry > 4.0 Nomenclature of hydrocarbons
General Organic Chemistry
1.0 Introduction
2.0 Classification of organic compounds
3.0 Homologous series
4.0 Nomenclature of hydrocarbons
4.1 The alkanes $(C_nH_{2n+2})$
4.2 The alkenes $(C_nH_{2n})$
4.3 The alkynes $(C_nH_{2n-2})$
4.4 Combined alkenes and alkynes
4.5 Cyclic hydrocarbons
5.0 Nomenclature of compounds containing halogens and nitro groups
6.0 Nomenclature of compounds with functional groups named as suffixes
6.1 Ethers and thioethers
6.2 Alcohols & thiols
6.3 Acids, salts of acids and acid anhydrides
6.4 Esters
6.5 Acid halides
6.6 Amides
6.7 Nitriles
6.8 Aldehydes
6.9 Ketones
6.10 Amines and ammonium salts
7.0 Nomenclature of aromatic compounds
7.1 Halogen and nitro-substituted aromatics
7.2 Carboxylic acids and derivatives
7.3 Phenols and thiophenols
7.4 Aldehydes & Ketones
7.5 Sulfonic acids and sulfonic acid derivatives
7.6 Aromatic amines
7.7 Diazonium ions $\left( {ArN_2^ + } \right)$
8.0 Radicofunctional naming
9.0 Organic reactions
9.1 Substitution or displacement reactions
9.2 Addition reaction
9.3 Elimination reaction
9.4 Rearrangement reactions
10.0 Electrophiles
11.0 Nucleophiles
12.0 Breaking and forming of bonds
13.0 Reaction intermediates
13.1 Carbocations
13.2 Carbanions
13.3 Carbon radical
13.4 Carbenes
13.5 Nitrenes
13.6 Arenium ions
13.7 Benzynes
14.0 Electron displacement effects
15.0 Inductive effects
16.0 Hyperconjugation
17.0 Resonance
18.0 Mesomeric effect
19.0 Electromeric effect
20.0 Inductomeric effect
21.0 Steric inhibition of resonance
22.0 Ortho effect
4.1 The alkanes $(C_nH_{2n+2})$
4.2 The alkenes $(C_nH_{2n})$
4.3 The alkynes $(C_nH_{2n-2})$
4.4 Combined alkenes and alkynes
4.5 Cyclic hydrocarbons
6.2 Alcohols & thiols
6.3 Acids, salts of acids and acid anhydrides
6.4 Esters
6.5 Acid halides
6.6 Amides
6.7 Nitriles
6.8 Aldehydes
6.9 Ketones
6.10 Amines and ammonium salts
7.2 Carboxylic acids and derivatives
7.3 Phenols and thiophenols
7.4 Aldehydes & Ketones
7.5 Sulfonic acids and sulfonic acid derivatives
7.6 Aromatic amines
7.7 Diazonium ions $\left( {ArN_2^ + } \right)$
9.2 Addition reaction
9.3 Elimination reaction
9.4 Rearrangement reactions
13.2 Carbanions
13.3 Carbon radical
13.4 Carbenes
13.5 Nitrenes
13.6 Arenium ions
13.7 Benzynes
A. Unbranched chains
The first twelve members are given as below,
| n | Name | Molecular formula | Constitutional formula |
| 1 | methane | $CH_4$ | $CH_4$ |
| 2 | ethane | $C_2H_6$ | $CH_3CH_3$ |
| 3 | propane | $C_3H_8$ | $CH_3CH_2CH_3$ |
| 4 | butane | $C_4H_{10}$ | $CH_3CH_2CH_2CH_3$ |
| 5 | pentane | $C_5H_{12}$ | $CH_3CH_2CH_2CH_2CH_3$ |
| 6 | hexane | $C_6H_{14}$ | $CH_3CH_2CH_2CH_2CH_2CH_3$ |
| 7 | heptane | $C_7H_{16}$ | $CH_3CH_2CH_2CH_2CH_2CH_2CH_3$ |
| 8 | octane | $C_8H_{18}$ | $CH_3CH_2CH_2CH_2CH_2CH_2CH_2CH_3$ |
| 9 | nonane | $C_9H_{20}$ | $CH_3CH_2CH_2CH_2CH_2CH_2CH_2CH_2CH_3$ |
| 10 | decane | $C_{10}H_{22}$ | $CH_3CH_2CH_2CH_2CH_2CH_2CH_2CH_2CH_2CH_3$ |
| 11 | undecane | $C_{11}H_{24}$ | $CH_3CH_2CH_2CH_2CH_2CH_2CH_2CH_2CH_2CH_2CH_3$ |
| 12 | dodecane | $C_{12}H_{26}$ | $CH_3CH_2CH_2CH_2CH_2CH_2CH_2CH_2CH_2CH_2CH_2CH_3$ |
The group derived from one of these alkanes by removal of a terminal (end) hydrogen is called an alkyl group. The group name is found by removing "ane" from the alkane name and adding "yl".
Example:
Butane: $CH_3-CH_2-CH_2-CH_3$
Butyl: $CH_3-CH_2-CH_2-CH_2-$
Note: The free valence must be on the terminal carbon.
B. Branched chains
The following steps are taken in naming an alkane with a branched chain.
(a). Find the longest continuous carbon chain and select the appropriate alkane name. (Do not include the side chains in the carbon count).
(b). Name all of the side chains (carbon chains attached to the longest chain) and list them in alphabetical order. Ignore multiplicative prefixes such as "di-" (2), "tri-" (3), "tetra-$ (4) etc. Also ignore "sec-" and "tert-" but not "iso".
(c). Number the longest chain so that substituents have the lowest possible numbers and insert location numbers before each of the side chain names.
Note: The name of the following groups are as below,
Question: Write the I.P.U.A.C. name of the following compounds.
Solution:
(a)
The I.P.U.A.C. name is 3-methylpentane.
(b)
The I.P.U.A.C. name is 2,4,6-trimethylheptane.
Wrong I.P.U.A.C. name is: 3,4,6-trimethylheptane.
(c)
The I.P.U.A.C. name is but-2-ene.
(d)
The I.P.U.A.C. name is 4-isopropyl-2,2-dimethylheptane.
Wrong I.P.U.A.C. name is: 2-isopropyl-4,4-dimethylheptane.
(e)
The I.P.U.A.C. name is 4,4-dimethyl-2-pentene.
(f)
The I.P.U.A.C. name is propene.
(g)
The I.P.U.A.C. name is buta-1,3-diene.
(h)
The I.P.U.A.C. name is Hex-1-en-5-yne.
Wrong I.P.U.A.C. name is: Hex-5-en-1-yne.
(i)
The I.P.U.A.C. name is 4-ethyl-5-methyloctane.
Wrong I.P.U.A.C. name is: 5-ethyl-4-methyloctane
