Cellulose - Derivatives

Derivatives

The hydroxyl groups (-OH) of cellulose can be partially or fully reacted with various reagents to afford derivatives with useful properties like mainly cellulose esters and cellulose ethers (-OR). In principle, though not always in current industrial practice, cellulosic polymers are renewable resources.

Ester derivatives include:

Cellulose ester Reagent Example Reagent Group R
Organic esters Organic acids Cellulose acetate Acetic acid and acetic anhydride H or -(C=O)CH3
Cellulose triacetate Acetic acid and acetic anhydride -(C=O)CH3
Cellulose propionate Propanoic acid H or -(C=O)CH2CH3
Cellulose acetate propionate Acetic acid and propanoic acid H or -(C=O)CH3 or -(C=O)CH2CH3
Cellulose acetate butyrate Acetic acid and butyric acid H or -(C=O)CH3 or -(C=O)CH2CH2CH3
Inorganic esters Inorganic acids Nitrocellulose (cellulose nitrate) Nitric acid or another powerful nitrating agent H or -NO2
Cellulose sulfate Sulfuric acid or another powerful sulfuring agent H or -SO3H

The cellulose acetate and cellulose triacetate are film- and fiber-forming materials that find a variety of uses. The nitrocellulose was initially used as an explosive and was an early film forming material. With camphor, nitrocellulose gives celluloid.

Ether derivatives include:

Cellulose ethers Reagent Example Reagent Group R = H or Water solubility Application E number
Alkyl Halogenoalkanes Methylcellulose Chloromethane -CH3 Cold water soluble E461
Ethylcellulose Chloroethane -CH2CH3 Water insoluble A commercial thermoplastic used in coatings, inks, binders, and controlled-release drug tablets E462
Ethyl methyl cellulose Chloromethane and chloroethane -CH3 or -CH2CH3 E465
Hydroxyalkyl Epoxides Hydroxyethyl cellulose Ethylene oxide -CH2CH2OH Cold/hot water soluble Gelling and thickening agent
Hydroxypropyl cellulose (HPC) Propylene oxide -CH2CH(OH)CH3 Cold water soluble E463
Hydroxyethyl methyl cellulose Chloromethane and ethylene oxide -CH3 or -CH2CH2OH Cold water soluble Production of cellulose films
Hydroxypropyl methyl cellulose (HPMC) Chloromethane and propylene oxide -CH3 or -CH2CH(OH)CH3 Cold water soluble Viscosity modifier, gelling, foaming and binding agent E464
Ethyl hydroxyethyl cellulose Chloroethane and ethylene oxide -CH2CH3 or—CH2CH2OH E467
Carboxyalkyl Halogenated carboxylic acids Carboxymethyl cellulose (CMC) Chloroacetic acid -CH2COOH Cold/Hot water soluble Often used as its sodium salt, sodium carboxymethyl cellulose (NaCMC) E466

The sodium carboxymethyl cellulose can be cross-linked to give the croscarmellose sodium (E468) for use as a disintegrant in pharmaceutical formulations.

Read more about this topic:  Cellulose