Free Radicals

Introduction

Chemical species known as free radicals have a singly occupied orbital. They are very reactive while being neutral. With a few notable exceptions, these "dangling" connections render free radicals very chemically reactive toward other substances or even against themselves; their molecules spontaneously dimerize/polymerize if they make contact. Only at trace amounts in an inert medium or a vacuum are most of radicals relatively stable. There are several techniques to produce free radicals, including synthesis using incredibly dilute or rarefied reagents, reactions at extremely low temperatures, or dissociation of bigger molecules.

What are Free Radicals?

An atom/ ion/molecule with unpaired valence electrons or an open electron shell is referred to as a radical (more specifically, a free radical) in chemistry but is also sometimes referred to as having 1 or even more "dangling" covalent bonds.

With a few notable exceptions, these "dangling" connections render free radicals very chemically reactive to other substances or even against themselves; their molecules frequently spontaneously dimerize/polymerize if they interact. Only at small levels in an inert medium or a vacuum are most of radicals relatively stable.

The hydroxyl radical (𝐻𝑂 ∗ ), which is 1 hydrogen short of a water molecule & hence has 1 link "dangling" from the 𝑂, is a well-known instance of a free radical. Two further examples include the superoxide anion ( ∗𝑂2), which is oxygen with an extra electron, and the carbene molecule, which has 2 dangling bonds.

Ethyl Free Radical

Examples

• Superoxide anion radical.

• Hypochlorite

• Peroxynitrite radical.

• Hydrogen peroxide.

Types of Free Radicals

Stable free radicals

Moses Gomberg identified triphenylmethyl as the first essentially stable free radical in 1900. Given that it has three rather than four substituents, the core carbon in this molecule is trivalent, and a dot is used to symbolize its unshared electron. Only particular organic solvents can keep triphenylmethyl free radicals stable; when air, water, or strong acids are present, they are quickly destroyed by irreversible reactions.

Unstable free radicals

Simple free radicals like methyl (∗ 𝐶𝐻3), are also present and essential as temporary intermediates in several chemical processes. These are very reactive and transient methyl radicals. Along with reacting with lead and other metals, they also quickly and spontaneously vanished, mostly dimerizing into ethane, $\mathrm{CH_{3}\:-\:CH_{3}}$. In the wake of this discovery, methods for creating reactive free radicals in the gas phase have been substantially expanded.

What Causes Free Radicals?

Free radicals can occasionally be produced by metabolic processes that the body appears to expect. Because these metabolic processes are fundamental and necessary to the body, eliminating them would be both impossible and harmful to the organism.

Free radicals can enter the body from outside sources as well, including X-rays, smoking, and other things.

The presence of free radicals in living things' bodies leads to fast pairings of other elements and the formation of lengthy reaction chains. These radicals react with every molecule extremely quickly, and in living things—especially humans—these processes are known as "oxidation reactions."

Properties of Free Radicals

• In general, free radicals have no electrical charge.

• They have an odd (unpaired) electron in their structure.

• They are quite unstable

• They are transient.

• Because they contain odd electrons, they are extremely reactive species.

• They frequently establish covalent bonds with the odd electrons by pairing up with them.

• They often develop in the presence of peroxides, ultraviolet or visible light, or both.

What are Free Radicals in Food?

The function of free radicals in biological oxidations has received more attention during the past 10 years. Both food scientists and physiologists have grown more interested in the topic. Food preservation requires the presence of free radical scavengers in the form of both naturally occurring and added antioxidants.

Since free radicals are thought to play a role in the development of several diseases, including ischaemic heart disease, it is advised that antioxidant vitamin consumption be increased, especially for diets greater in polyunsaturated fats. More people are consuming convenience & snack items that absorb a lot of frying oil.

The level of harm to lipid breakdown products is likely to have risen because poly- unsaturated fatty acids are highly susceptible to oxidation by free radicals throughout food storage & frying. Loss of vital nutrients and the emergence of off flavours can occur in meals when polyunsaturated fatty acids, vitamin A & beta-carotene are oxidized non- enzymatically and by the enzyme lipoxygenase.

Conclusion

It can be concluded that any molecular species that have an unpaired electron in an atomic orbital and is capable of independent existence is referred to as a free radical. Most radicals exhibit some similar characteristics when an unpaired electron is present. Many radicals are extremely reactive and inherently unstable. They can act as oxidants or reductants by either giving or receiving an electron from another molecule. The hydroxyl radical, hydrogen peroxide, superoxide radical, oxygen singlet, nitric oxide radical, hypochlorite & peroxynitrite radicals are the oxygen-containing free radicals that are most significant in many disease situations. These are very reactive substances that can harm biologically important components including DNA, carbohydrates, proteins & lipids in cell membranes and the nucleus. Important macromolecules are attacked by free radicals, which damage cells and disrupt homeostasis. Free radicals may attack every type of molecule in the body. Lipids & proteins are the main targets among them.

FAQs

1. What causes the body's free radicals to die?

To stop free radicals from doing damage, antioxidants interact with them and neutralize them. Another name for antioxidants is "free radical scavengers." Some of the antioxidants that the body utilizes to combat free radicals are produced by it. Endogenous antioxidants are the name given to these compounds.

2. Are free radicals beneficial?

Free radicals play a vital function" because they help the heart pump more blood under stress. On the other hand, ongoing stress can cause heart failure, and elevated amounts of free radicals may contribute to this issue.

3. Free radicals are extremely reactive, why?

Radicals are extremely reactive and require a lot of energy to form. "More reactive" when referring to radical reactivity often denotes a move toward a more exothermic abstraction of the hydrogen atoms. As a result, the stability of the carbon-centred radical is less likely to affect the reaction.

4. Do free radicals exist in oxygen?

In the organism, oxygen disintegrates into solitary electron-free atoms. These atoms, sometimes referred to as free radicals, scour the body for additional electrons to form a pair since electrons like to exist in pairs. Damage to DNA, proteins, and cells results from this.

5. What influences the radical's stability?

The radical's energy level is referred to as its stability. The radical is unstable when its internal energy is high. It will try to lessen its energy level. The radical is stable if its internal energy level is low.