isopropoxide

Isopropoxide, also known as propan-2-olate, is the alkoxide derived from isopropanol. In practical terms it refers to the isopropoxide anion (RO−) where R is the isopropyl group (CH3)2CH−. The term is common for the salts and esters of this alkoxide, with sodium isopropoxide (NaOPr) and potassium isopropoxide (KOPr) among the typical examples.

Isopropoxide is a strong, but somewhat hindered, base and a reactive nucleophile in organic synthesis. As an alkoxide, it readily deprotonates acidic compounds and participates in nucleophilic substitution reactions such as the Williamson ether synthesis, where it reacts with alkyl halides to form isopropyl ethers. It also reacts with carbonyl compounds to form enolates under suitable conditions and can act as a catalyst or reagent in various condensation reactions. In its salt forms, it is soluble in many organic solvents and is widely used as a general base and nucleophile.

Preparation and handling of isopropoxide typically involve deprotonation of isopropanol with a strong base, such as sodium hydride or sodium metal, under strictly anhydrous conditions to give sodium isopropoxide, for example: NaH + (CH3)2CHOH → NaOPr + H2. It can also be prepared by metathesis from the corresponding metal alkoxide salts. Isopropoxide reacts readily with water and carbon dioxide, converting to isopropanol and metal hydroxide, or forming alkyl carbonates upon CO2 exposure. Due to its caustic and reactive nature, it is stored under inert atmosphere and anhydrous conditions.

See also alkoxide, sodium methoxide, and tert-butoxide.