Methoxide

Methoxides are organic salts and the simplest alkoxides. Sodium methoxide and potassium methoxide have widespread use, though other metal-cation variants such as lithium methoxide, rubidium methoxide, caesium methoxide, and francium methoxide exist as well.

Methoxide ion

The methoxide ion has the formula of CH₃O⁻ and is the conjugate base of methanol. It is a strong organic base, even stronger than the inorganic hydroxide ion. As such, methoxide solutions must be kept free of water; otherwise, the methoxide will remove a proton from a water molecule, yielding methanol and hydroxide.

Sodium methoxide

Sodium methoxide, also called sodium methylate and sodium methanolate, is a white powder when pure. It is used as an initiator of an anionic addition polymerization with ethylene oxide, forming a polyether with high molecular weight. Both sodium methoxide and its counterpart prepared with potassium are frequently used as catalysts for commercial-scale production of biodiesel. In this process, vegetable oils or animal fats, which chemically are fatty acid triglycerides, are transesterified with methanol to give fatty acid methyl esters (FAMEs).