In chemistry, a derivative is defined as a compound that’s produced from a similar compound through chemical processes. It can also be derived from a compound through decomposition and the removal of certain functional groups.
While derivatives are sometimes required for analytical purposes, it’s important to avoid using too many. That’s because chemical derivatives require additional reagents and generate more unwanted byproducts, which can have a negative impact on the environment.
In fact, reducing the use of derivatives, especially in large-scale chemical manufacturing, is one of the 12 principles of green chemistry. Read on to find out more about what derivatives are and how they’re used, as well as some common examples.
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What is a derivative in chemistry?
A derivative is a chemical compound that’s structurally derived from a parent compound through one or several steps. This might involve the use of reagents, catalysts, enzymes, and reactants.
There are various ways to achieve chemical derivation, one of which is through the partial substitution of a functional group while retaining one structural feature for every step. Commonly used in organic chemistry, the chemical derivation process allows compounds to be modified to serve a specific purpose.
Chemical derivatives may be simple or complex. They can also be undesired transitory chemicals or desired final products.
How are derivatives used in chemistry?
Derivatives have several applications in chemistry, although they’re mainly used for analytical purposes and to produce desired end products. The end products themselves are technically derivatives of original compounds.
Analysis in organic chemistry
Before spectroscopic analysis became a common laboratory tool, chemical derivatives were used in analytical chemistry. Conducting melting point analysis on crystalline derivatives, for instance, can help chemists to identify many types of unknown organic compounds.
Take 2,4-dinitrophenylhydrazone – a derivative based on aldehydes or ketones – as an example. Aldehydes and ketones are primarily distinguished by the position of the carbonyl group. In an aldehyde, the carbonyl group is attached to a carbon at the end of the carbon chain, whereas in a ketone it’s attached to a carbon within the chain. Once the melting point has been established, you can use a table of melting points as a reference to determine the original organic chemical.
Producing desired end products
Many derivatives are transitory byproducts that are created through the derivatisation process. In synthesising important organic compounds such as medicines, blocking or protecting groups are used to temporarily block the chemical reaction of functional groups that are meant to be preserved.
This is common in the modification of molecules with multiple functional groups. Only a target functional group is exposed to chemical reactions. The most reactive but non-targeted functional group typically requires protection from other reactants.
A protecting group masks a functional group to prevent it from reacting. Consider the example below. A diol is converted into an aldehyde through the use of an oxidising agent. However, one of the hydroxyl groups is protected by introducing a protecting group. The protecting group is then removed after the oxidation process.
Examples of derivatives in chemistry
Organic chemical derivatives are used to make various products including medicines such as semi-synthetic antibiotics, as well as many types of industrial and household items. For example, naphthalene (a derivative of benzene) is often used as an insect repellent.
Some examples of chemical derivatives are summarised below.
- Carboxylic acid derivativesOne broad category of chemical derivatives is those derived from carboxylic acids. A carboxylic acid has a carbon that’s attached to a hydroxyl group and double-bonded to an oxygen. The R group varies, thus determining the type of compound. Some common types of compounds in this category include:
- Esters – the hydrogen of the hydroxyl group is replaced by another R group. An example of this is ethyl acetate, which is used in glue, nail varnish remover and in the decaffeination process of coffee and tea.
- Acyl halides – in this type of compound, the hydroxyl group is replaced by a halogen. Benzoyl bromide is one example of an acyl halide. It’s often used in tear gas and microemulsions.
- Amides – the hydroxyl group is replaced by an amino group. An example of this is n-methylacetamide, which is a metabolite.
- Benzene derivativesAnother broad class of derivatives are those derived from benzene. Some of these can also be derived from other groups of chemicals, including carboxylic acids.Benzene is an aromatic, cyclic hydrocarbon that has six carbons and six hydrogens. The bonds between the carbons alternate from a single bond to a double bond. A benzene ring minus one hydrogen is called a phenyl group.Here are some examples of benzene derivatives:
- Chlorobenzene – one of the halogenated benzenes, chlorobenzene contains one chlorine atom per molecule. It’s commonly used in the production of herbicides and rubber./li>
- Toluene – this is a substituted aromatic hydrocarbon that has a methyl group attached to a phenyl group, replacing a hydrogen from the original benzene molecule. It’s often found in paint solvent and can also be used as an octane booster in gasoline.
- Benzaldehyde – the simplest aromatic aldehyde with a formyl substituent, benzaldehyde is often used as an artificial almond flavouring for food products. Some cosmetics and personal care products also contain this compound.
Avoiding chemical derivatives
It’s important to avoid using unnecessary derivatives in chemistry because they require additional reagents and generate extra waste. And of course, this isn’t good for the environment. One way to reduce intermediate derivatives and protect groups is to use enzymes.
Many intended organic compounds can be synthesised from original compounds by simply introducing enzymes. This can help to minimise, if not eliminate, the need for additional reagents and reduce intermediate products. One excellent example of this simplified process is the manufacture of semi-synthetic antibiotics like ampicillin and amoxicillin.