Propietats químiques de la carboximetil cel·lulosa

Cellulose derivatives with carboxymethyl substituents are prepared by treating cellulose with sodium hydroxide to form alkali cellulose, and then reacting with monochloroacetic acid. The glucose unit that constitutes cellulose has three replaceable hydroxyl groups, so products with different degrees of substitution can be obtained. 1mmol of carboxymethyl is introduced into the solution of water and dilute acid per 1g of dry weight, but it can swell and be used for ion exchange chromatography. Carboxymethyl pKa is about 4 in pure water and about 3.5 in 0.5mol/L NaCl. It is a weak acidic cation exchanger and is usually used for the separation of neutral and basic proteins when pH>4. Més del 40 per cent dels grups hidroxil substituïts per carboximetil es poden dissoldre en aigua per formar una solució col·loïdal estable d'alta viscositat.