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Reactive intermediate
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<p>In <a href="/facts/Chemistry/SrNqkGVm">chemistry</a>, a reactive intermediate or an intermediate is a short-lived, high-energy, highly reactive <a href="/facts/Molecule/N9ljSfFq">molecule</a>. When generated in a <a href="/facts/Chemical_reaction/GpqWlKrz">chemical reaction</a>, it will quickly convert into a more stable molecule. Only in exceptional cases can these compounds be isolated and stored, e.g. low temperatures, <a href="/facts/Matrix_isolation/fvouuLHy">matrix isolation</a>. When their existence is indicated, reactive intermediates can help explain how a chemical reaction takes place. </p><p>Most chemical reactions take more than one <a href="/facts/Elementary_step/TIsVN2hN">elementary step</a> to complete, and a reactive intermediate is a high-energy, hence unstable, product that exists only in one of the intermediate steps. The series of steps together make a <a href="/facts/Reaction_mechanism/9lanyVuy">reaction mechanism</a>. A reactive intermediate differs from a reactant or product or a simple <a href="/facts/Reaction_intermediate/BjD9HAHt">reaction intermediate</a> only in that it cannot usually be isolated but is sometimes observable only through fast <a href="/facts/Spectroscopic/mj71FuNK">spectroscopic</a> methods. It is stable in the sense that an <a href="/facts/Elementary_reaction/EHoFw8rl">elementary reaction</a> forms the reactive intermediate and the elementary reaction in the next step is needed to destroy it. </p><p>When a reactive intermediate is not observable, its existence must be <a href="/facts/Inferred/RBbe95bP">inferred</a> through experimentation. This usually involves changing reaction conditions such as temperature or concentration and applying the techniques of <a href="/facts/Chemical_kinetics/D8vyX4aE">chemical kinetics</a>, <a href="/facts/Chemical_thermodynamics/dIQMQsd0">chemical thermodynamics</a>, or <a href="/facts/Spectroscopy/mj71FuNK">spectroscopy</a>. Reactive intermediates based on carbon are <a href="/facts/Radical_(chemistry)/qFymuVoT">radicals</a>, <a href="/facts/Carbene/3WxNSStY">carbenes</a>, <a href="/facts/Carbocation/vIggUxTh">carbocations</a>, <a href="/facts/Carbanion/AyYH2udQ">carbanions</a>, <a href="/facts/Aryne/hpwc0VwK">arynes</a>, and <a href="/facts/Carbyne/rxFKkHCM">carbynes</a>. </p>