SN1 reaction

An SN1 reaction is a nucleophilic substitution whose rate-determining step is unimolecular ionization of the substrate, usually producing a carbocation before nucleophile attack.

Carbocation: A positively charged carbon species with three bonds and an electron-deficient valence shell. Substrate ionization usually creates this intermediate before the nucleophile forms a new bond.
Nucleophile: An electron-pair donor that forms a bond to an electron-poor atom. It attacks the carbocation after the rate-determining ionization step.
SN2 reaction: A nucleophilic substitution in which bond formation and leaving-group departure occur in one concerted step. Unlike SN1, SN2 rate depends on both substrate and nucleophile concentrations.
Tert-butyl chloride solvolysis: The reaction of tert-butyl chloride with a solvent, commonly used to study unimolecular substitution kinetics. Its tertiary carbocation formation makes it a classic example of SN1 solvolysis.
SN1 reaction rate law: The kinetic relationship showing that an SN1 reaction rate depends on substrate concentration, not nucleophile concentration. The unimolecular rate-determining ionization gives the reaction its defining first-order rate law.
Nucleophilic substitution: A reaction in which a nucleophile replaces a leaving group at an electrophilic center. SN1 is one mechanistic pathway within this broader reaction class.
E1 reaction: A unimolecular elimination reaction that forms an alkene through a carbocation intermediate. E1 shares the ionization step with SN1 but forms an alkene rather than a substitution product.
Lucas test: A qualitative test that distinguishes classes of alcohols by their reaction with hydrogen chloride and zinc chloride. Its differing turbidity times reflect how readily alcohol-derived substrates form carbocations.
Leaving group: An atom or group that departs with the bonding electron pair during a chemical reaction. Its departure in the slow ionization step determines whether the carbocation can form readily.
Solvent effects: Changes in reaction behavior caused by the physical and chemical properties of a solvent. Polar protic solvents stabilize separated ions and can favor substrate ionization.

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