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The hydroxyl radical, Lewis structure shown, contains one unpaired electron. Lewis dot structure of a Hydroxide ion compared to a hydroxyl radical. In chemistry, a radical, also known as a free radical, is an atom, molecule, or ion that has at least one unpaired valence electron.
When a plant recognizes an attacking pathogen, one of the first induced reactions is to rapidly produce superoxide (O − 2) or hydrogen peroxide (H 2 O 2) to strengthen the cell wall. This prevents the spread of the pathogen to other parts of the plant, essentially forming a net around the pathogen to restrict movement and reproduction.
The hydroxyl radical has a very short in vivo half-life of approximately 10 −9 seconds and a high reactivity. [5] This makes it a very dangerous compound to the organism. [6] [7] Unlike superoxide, which can be detoxified by superoxide dismutase, the hydroxyl radical cannot be eliminated by an enzymatic reaction.
Most experimentally observed reactions are built up from many elementary reactions that occur in parallel or sequentially. The actual sequence of the individual elementary reactions is known as reaction mechanism. An elementary reaction involves a few molecules, usually one or two, because of the low probability for several molecules to meet at ...
Both the negatively charged anion HO −, called hydroxide, and the neutral radical HO·, known as the hydroxyl radical, consist of an unbonded hydroxy group. According to IUPAC definitions, the term hydroxyl refers to the hydroxyl radical (·OH) only, while the functional group −OH is called a hydroxy group. [1]
Free radical reactions are redox reactions that occur as part of homeostasis and killing microorganisms. In these reactions, an electron detaches from a molecule and then re-attaches almost instantly. Free radicals are part of redox molecules and can become harmful to the human body if they do not reattach to the redox molecule or an antioxidant.
Here, the new radical is generated on the polymer chain, which can further undergo a similar type of reaction to generate more styrene molecules. This process is known as the radical mediated depolymerization of polystyrene. Radical elimination reactions are found in enzyme-catalyzed pathways.
These reactions can happen due to the free radicals having an unpaired electron in their valence shell, making them highly reactive. [1] Radical additions are known for a variety of unsaturated substrates, both olefinic or aromatic and with or without heteroatoms. Free-radical reactions depend on one or more relatively weak bonds in a