The carboxymethylcellulose It is a compound derived from cellulose, a polymer of glucose. It also receives the names of cellulose or carmellose gum. May be in the form of sodium salt.
Carboxymethylcellulose is hygroscopic and soluble in water, unlike cellulose, which is insoluble in water. It has some substituted -CH groupstwoOH of glucose molecules that form cellulose by -CH groupstwoOCHtwoCOOH. This substitution gives ionic properties to its structure..
But what is cellulose? It is a biopolymer made up exclusively of β-glucose molecules, linked by β-1,4-o-glucosidic bonds. Cellulose has the formula (C6H10OR5)n with a minimum value of 2000 for n. The polymer can have a linear or fibrous structure, being the main constituent of the plant cell wall.
Its compact structure is impenetrable by water and therefore insoluble in it. Despite being made up of glucose, cellulose cannot be used by animals, since they lack the cellulase enzyme to break the β1,4-glucosidic bonds.
The carboxymethyl group attached to cellulose gives carboxymethylcellulose a negatively charged surface. These charges allow its use in the ion exchange chromatography technique, functioning as a cation exchanger that is used in the purification of proteins..
Due to its hydrophilic property, carboxymethylcellulose is used in the treatment of dry eyes. Likewise, due to this property, it has been used in the manufacture of diapers and sanitary products of this type. These applications serve as an example of the enormous list of uses and / or applications that this compound has.
Article index
RnOCHtwo-COOH
White powder. Sodium carboxymethyl cellulose: white or milky fibrous particles.
Odorless and tasteless.
It is soluble (20 mg / mL).
It is insoluble in methanol, ethanol, diethyl ether, acetone, chloroform and also in benzene.
274ºC.
0.7 - 0.9 g / cm3.
It is similar to that of acetic acid and its dissociation constant is 5 x 10-5.
The upper image shows the structure of a carboxymethylcellulose monomer unit. Note that the H of the hydroxyl groups are substituted by the CH groupstwoCOOH; Except for the OH group at C-3. That is, according to the image, the polymer is not completely substituted.
CH groupstwoCOOH can be deprotonated and surrounded by electrostatic attraction of Na cations+: CHtwoCOO-Na+. It is thanks to them that carboxymethylcellulose is very soluble in water, as it is capable of forming hydrogen bonds with it (CHtwoCOOH-OHtwo). This is the main cause of its marked hydrophilic and hygroscopic character..
Also, these groups are much more voluminous than hydroxyls, so that the physicochemical properties of the polymer change with respect to the original cellulose. Its large size prevents the formation of internal hydrogen bonds, that is, between the monomeric chains, leaving the rings totally exposed to interactions with water..
Therefore, the greater the degree of substitution of OH by CHtwoCOOH, the higher the hydrophilic character of the resulting cellulose. Microscopically this difference may not be very obvious; but on macroscopic scales, it would be equal to being able to dissolve a block of wood in a container of water if such substitutions occurred on the spot..
To obtain carboxymethylcellulose, from cellulose fibers, the Druvacell procedure is followed:
A) The cellulose fibers are treated with isopropanol and alkalis in order to produce their swelling and the ionization of the hydroxyl groups.
B) The cellulose fibers from the previous treatment are further alkalized by treatment with NaOH, according to the following reaction:
RceOH + NaOH => RceOH ∙ NaOH
C) Cellulose fibers bound to NaOH then react with sodium chloroacetate to produce sodium carboxymethylcellulose:
RceOH ∙ NaOH + ClCHtwoCOO-Na => RceOCHtwoCOO-Na+ + NaCl + HtwoOR
The union of the COO group- cellulose to give rise to carboxymethiclulose makes it soluble in water and more reactive.
Carboxymethylcellulose has numerous uses and applications due to its hydrophilicity and its ability to combine with numerous compounds. Among its uses are the following.
-It is used as a thickener and stabilizer in food. In addition, it is used as a dietary fiber and emulsifier. It is used in the shake of ice creams, creams and creams, as well as an aid in the formation of gels in gelatin and puddings..
-It is used as a suspending agent in fruit juices and as a protective colloid in mayonnaise. It is also used to cover the surface of fruits.
-Because carboxymethylcellulose is not metabolized by the body, it can be used by people on a low-calorie diet.
-Carboxymethylcellulose solutions form gels used in heart, thoracic and corneal surgeries.
-In chest operations, the lungs are stapled and covered with a carboxymethylcellulose solution. This in order to avoid leaks of the air contained in the alveoli and the entry of fluids into the lungs..
-In the field of orthopedics, carboxymethylcellulose is used in the lubrication of the joints, especially in the wrists, knees and hips. The polymer solution is injected into the joints to prevent erosion, inflammation, and possible cartilage destruction.
-It is used in the treatment of dry and irritated eyes. It is also used as a protective agent to prevent damage to the eyeball, such as can occur in the placement of contact lenses.
-Carboxymethylcellulose is also used in the treatment of constipation, favoring the formation of stool with the appropriate consistency. It is used as a laxative.
-A combination of carboxymethylcellulose-heparin has been used for the prevention of adhesion during surgeries.
-It acts as a stabilizing and hydrophilic agent in most cement preparations and construction materials. Improves the dispersion of sand in the cement, also increases the adhesive action of the cement.
-It is also used as part of the adhesives for upholstery papers.
The branch of industry that perhaps has the highest consumption of carboxymethylcellulose is in the production of soaps and detergents. It acts as an inhibiting agent that prevents fats, removed from the surface of fabrics by detergents, from reattaching them.
-It is used in the elaboration of adhesives for the paper, since it does not stain it, it does not give off odor and it is removable. This makes it ideal for use in repairing books or other materials..
-It has also been tested in mixtures with starch and phenol formaldehyde for the elaboration of glues that allow the union of wood sheets.
It is used to avoid the precipitation of the tartaric salts present in the wine.
-Coating waxed papers and boards with carboxymethylcellulose preparations reduces the consumption of waxes. It also reduces the consumption of printing ink, resulting in higher gloss surfaces. In addition, the surface of the paper has greater smoothness and greater resistance to grease.
-Carboxymethylcellulose improves the bond between the paper fibers, improving their coloration. It is also used as an auxiliary dispersant in the extrusion of cellulose pulp fibers, avoiding their flocculation..
Carboxymethylcellulose acts as a dispersing agent for pesticides. In addition, it is used as a glue to bond the insecticide to the surface of plant leaves. On some occasions, it is used as an aid in the degradation of some highly polluting fertilizers.
It is used as a thickener, stabilizer and film former in creams, lotions, shampoos and hair care products. In addition, it is used in the preparation of gels for use in dental cleaning..
It is used in the production of oil-based paints and varnishes, acting as a thickening and dispersing agent for pigments in fluids..
Used to increase the viscosity of latex.
It is used to join porcelain pieces, since carboxymethylcellulose solutions originate few ashes when firing.
-It is used in its raw form to avoid deformation of the fabrics. Carboxymethylcellulose, in combination with starch, is used in laundries. It is also used in the finishing of fabrics. During their manufacture, the fabrics are impregnated with carboxymethylcellulose and then treated with acid and heat.
-It is used in the printing of fabrics, collaborating as a thickening agent for textile paints and varnishes.
-Carboxymethylcellulose is used in the coating of drug tablets. The polymer is insoluble in acidic stomach conditions, but soluble in the small intestine, where therapeutic agents are absorbed.
-It is also used as a gel-former, drug carriers in the form of ointments. In addition, it is used as a stabilizing agent in suspensions and emulsions. It is used as a bioadhesive in tablets that bind to body mucus.
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