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A class of chemical compounds is defined by the presence of one or more hydroxyl (OH) groups linked to the carbon atom of an alkyl group; alcohol (hydrocarbon chain). When compared to water (H2O), alcohols can be thought of as organic derivatives in which one of the hydrogen atoms has been replaced by an alkyl group, which is commonly denoted by the letter R in organic structures. For example, in ethanol (or ethyl alcohol), the alkyl group is represented by the ethyl group, which is represented by the symbol CH2CH3.
Depending on how closely the carbon of the alkyl group is bound to the hydroxyl group, alcohols can be divided into three categories: primary, secondary, and tertiary. At room temperature, the vast majority of alcohols are colorless liquids or solids. Alcohols with a low molecular weight are highly soluble in water; as the molecular weight of the alcohol increases, it becomes less soluble in water, and the boiling temperatures, vapor pressures, densities, and viscosities of the alcohol increase as a consequence.
Nomenclature of Alcohols
Alcohols are the first example of how the parent alkane was used as the beginning point for the nomenclature of all families of compounds, as was the case with all other families of compounds. As part of the functional grouping process, the prefix -ane is changed to indicate the presence of a functional group. The -OH group in alcohol is identified by determining the longest straight carbon chain that contains it. Anol is substituted for the -ane suffix, and the position of the -OH group on the chain is determined by a numerical value assigned to it.
Alkanols are the generic name for alcohol according to the International Union of Pure and Applied Chemistry, and they are represented in reactions by the general formula R-OH. The existence of other substituents in alcohol is indicated by their names and numerical places, with the hydroxyl group always occupying the lowest possible position in the number of substituents present.
IUPAC Nomenclature for Alcohols
It is recommended that the following approach be used when assigning IUPAC substitutive names to alcohol.
Choose the longest continuous chain to which the hydroxyl group is directly bonded that is also the longest continuous chain. Drop the final -e from the name of the alkane that corresponds to the chain and replace it with the suffix -ol to distinguish it from the others.
Number the carbon atoms in the longest continuous carbon chain in such a way that the carbon atom containing the hydroxyl group has the lowest number. This number can be used as a locant to indicate the position of the hydroxyl group in the molecule.
Prefixes are used to indicate the position of another substituent as a prefix, and the locants are the numbers that correspond to their places along the carbon chain.
Types of Nomenclature in Alcohol
There are three different systems for naming alcoholic beverages.
- Common or trivial system
- Carbinol system
- IUPAC system
Formula | Parent Hydrocarbon | Common name | Carbinol name | IUPAC name |
CH3-OH | Methane | Methyl alcohol | Carbinol | Methanol |
CH3-CH2-OH | Ethane | Ethyl alcohol | Methyl carbinol | Ethanol |
CH3-CH(OH)-CH3 | Propane | Isopropyl alcohol | Dimethyl carbinol | 2-Propanol |
(CH3)3-C-OH | 2-Methyl propane | Tert-butyl alcohol | Trimethyl carbinol | 2-Methyl-2-propanol |
Ethanol is referred to by several names, including ethyl alcohol, grain alcohol, and the spirit of wine. This system of naming for alcohol was developed by Harmann Kolbe, a German chemist who lived in the nineteenth century and who used the term “carbinol” to refer to methanol in his descriptions of the substance. The International Union of Pure and Applied Chemistry (IUPAC) adopted the current approved systematic nomenclature for alcohol in Paris in 1957, and it is still in use today.
Classification of Alcohols
Alcohols have a variety of qualities that are influenced by the number of carbon atoms that are linked to the specific carbon atom that is attached to the OH group. On the basis of this classification, alcoholic beverages can be divided into three categories.
It is possible to make primary alcohols by attaching one carbon atom (in red) to another carbon atom. Its usual formula is RCH2OH. It is classified as a primary alcohol.
A secondary (2°) alcohol is alcohol in which the carbon atom (in red) containing the OH group is attached to two additional carbon atoms (as opposed to one carbon atom alone). R2CHOH is the typical formula for this secondary alcohol.
It is possible to have three different carbon atoms bonded to each other and still be considered to be in the presence of a tertiary (3°) alcohol. R3COH is the generic formula for this compound.
Conclusion
Alcohols are named according to the International Union of Pure and Applied Chemistry (IUPAC) system by altering the ending of the parent alkane name to -ol. Alcohols are classed based on the number of carbon atoms that are bonded to the carbon atom that is attached to the OH group in their structure. Alcohols are among the most frequent organic molecules found in the environment. In addition to being employed as sweeteners and scent ingredients, they are also valuable intermediates in the synthesis of other compounds, and they are among the most widely produced organic chemicals in the industrial sector.
