Sodium carboxymethylcellulose (CMC), a carboxymethylated derivative of cellulose, also known as cellulose gum, is an anionic fiber Chemicalbook cellulose ether, and is the most important ionic cellulose gum. It is usually an anionic polymer compound obtained by reacting natural cellulose with caustic alkali and monochloroacetic acid. The molecular weight of the compound varies from several thousand to one million.