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Intermediate

Quick Reference
Also Known AsReactive intermediate, transient intermediate, mechanistic intermediate

What is Intermediate?

A species formed during a reaction mechanism that is consumed in a subsequent step and does not appear in the overall balanced equation. Intermediates have finite lifetimes and exist in energy wells between transition states. They can sometimes be isolated or detected spectroscopically.

Properties & Characteristics

A reaction intermediate is a transient species formed in one elementary step of a reaction mechanism and consumed in a subsequent step; it does not appear in the overall balanced equation. Intermediates have finite (though often very short) lifetimes. Common types: carbocations, carbanions, free radicals, carbenes, nitrenes, benzyne, enols, and organometallic species. They are detected by spectroscopic (EPR, flash photolysis) or trapping methods.

Uses & Applications

Understanding reaction intermediates is central to: mechanistic organic chemistry (predicting products and stereochemistry), kinetic analysis (steady-state approximation for short-lived intermediates), catalyst design (stabilising or destabilising key intermediates to control reaction rates), and drug metabolism studies (cytochrome P450 produces reactive intermediates from prodrugs).

Safety Information

Many reactive intermediates are highly toxic, mutagenic, or explosive: carbocations alkylate DNA, free radicals cause oxidative stress, nitrene intermediates from azides and organic nitrogen explosives can detonate. Understanding intermediates helps predict unexpected hazardous by-products in chemical reactions.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Intermediate
Synonyms Reactive intermediate, transient intermediate, mechanistic intermediate

Frequently Asked Questions

A species formed during a reaction mechanism that is consumed in a subsequent step and does not appear in the overall balanced equation. Intermediates have finite lifetimes and exist in energy wells between transition states. They can sometimes be isolated or detected spectroscopically.

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