Alcohol is an organic compound that is characterized by the existing one or more groups of hydroxyl, that is –OH, that is connected to the carbon atom in the alkyl group. It is also considered to be derived from the water where the alkyl group replaces one of the hydrogen atoms. This is typically represented by ‘r’ in the organic system. They are commonly present in our surrounding and is used in the form of perfumes, sweeteners etc. They are mostly colourless and are soluble in water, depending on their molecular weight. The boiling points are higher as compared to alkanes as the molecules attract each other more strongly than in case of propane molecules. Hydrogen molecules can make bonds with both water molecules and other alcohol molecules. Let’s have a look at the types of alcohol in the next section.
What are the different types of alcohol?
There are three different kinds of alcohols. They are differentiated on the basis of the group of hydroxyl and its position of attachment. The three kinds of alcohols are primary, secondary and tertiary.
What is a primary alcohol?
The carbon atoms of the OH group are connected to just one alkyl group. Methanol is an example of primary alcohol.
What is a secondary alcohol?
The carbon atom of the OH group is connected to two alkyl groups on either of the sides.
What is a tertiary alcohol?
The carbon atom of the OH group is connected to three alkyl groups on either of the sides. The physical structure determines the properties.
Some important properties of alcohol
- They have an odour that can be termed as biting in the passage of the nasal area. Ethanol, however, is on the sweeter side.
- Alcohols can be used as protic solvents mainly because of their hydrogen bonds
- There are 2 opposite solubility tendencies, the presence of OH helps promote solubility while the presence of carbon prevents that.
- They have high boiling points as compared to ether or hydrocarbon due to the bonding of hydrogen.
- They can show both, acidic or basic properties and hence are very similar to water in this regard.
- Alcohols can be dehydrated to form alkenes or can be oxidized to form aldehydes, carboxylic acid or even ketones.
- The hydrogen bond, boiling point, and acidity all decrease as we move from primary to tertiary.
What are simple alcohols?
They are referred to by the common names derived by using the word ‘alcohol’ after the appropriate alkyl group’s name. For example, a chain made up of a single carbon and an OH group attached to it will commonly be known as methyl alcohol while a chain consisting of double carbons and an OH group attached to it will commonly be known as ethyl alcohol.
What are higher alcohols?
The alcohol variant that contains about 4 – 10 carbon atoms are known as higher alcohols. They are oily and are known to have a fruity smell. Some also have more than 12 carbon atoms and hence are known to be solid at room temperature.
Some common alcohols and their formula
- Methanol or methyl alcohol – C H3 OH
- Ethanol or Ethyl alcohol – C H3 C H2 OH
- 1 Propanol – C H3 C H2 C H2 OH
- 2 Propanol – (CH3)2 C H OH
- 1 Butanol – C H3 (CH2)3 OH
- 2 Butanol – (CH3) C H (OH) C H2 C H3
- 2 Methyl 1 Propanol – (CH3)2 C H C H2 OH
- 1 Pentanol – C H3 (CH2)4 OH
- Cyclopentanol – cyclo – C5 H9 OH
- Cyclohexanol – cyclo – C6 H11 OH
Alcohol and their toxicity
There are certain alcohol kinds that can cause serious harm to human. Ethanol has a direct impact on the DNA and can cause severe repercussions. This is due to its metabolites namely acetaldehyde and acetic acid.
Tertiary alcohols do not metabolize into forming aldehydes and hence do not cause any harm through its mechanisms.
There are some secondary and tertiary alcohols that are not as harmful as ethanol as the liver does not decompose it into anything harmful.
Some other alcohols like methanol, are more dangerous and harmful as compared to ethanol as they take a longer time to metabolize and their by-product is something more toxic. Methanol, for example, can lead to loss of sight or even death.
What are the various applications of alcohol?
- They are used as beverages but only when the ethanol content ranges between 3-40 percent in volume.
- They are also used as an agent to anti-freezing when mixed with ethylene glycol and water.
- Ethanol is used as an antiseptic
- Some variants are also used as fuels, like methanol.
- They are also used in labs as preservatives.
- Methanol is known as wood alcohol and is made by making a mixture of carbon monoxide and hydrogen. They are used widely as industrial solvents and can prove to be fatal in case of over ingestion.
- Ethanol is also called grain alcohol and is suitable for consumption and can be used as motor fuel, depending on the source of extraction.
- Isopropyl alcohol is used as an industrial solvent and also as rubbing alcohol that can be applied to the skin.
- Ethylene glycol is used for automotive anti-freezing and in hydraulic fluids, inks, and paints. It is also used in making waxes, resins, and polyester.
- Glycerol is a sweet substance and is used in making explosives and gelatin blasting. It is also used as a vasodilator and a moisturizing agent.
Some processes and reactions that alcohol can go through
- Dehydration: they can react with ROH to give ethers and water through this process.
- Esterification: a process called Fischer esterification is used to get an ester from an alcohol and carboxylic acid reaction.
- Oxidation: oxidizing primary alcohols can form aldehydes.
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