- Carboxymethyl cellulose
Carboxymethyl cellulose, or CMC, is a
cellulose derivative with carboxymethyl groups (-CH2-COOH) bound to some of thehydroxyl groups of the glucopyranosemonomer s that make up the cellulose backbone.Preparation
It is synthesized by the
alkali -catalyzed reaction of cellulose withchloroacetic acid . The polar (organicacid )carboxyl group s render the cellulosesoluble and chemically reactive.The functional properties of CMC depend on the degree of substitution of the cellulose structure (i.e., how many of the hydroxyl groups have taken part in the substitution reaction), as well as the chain length of the cellulose backbone structure.
Uses
CMC is used in
food science as aviscosity modifier orthickener , and to stabilizeemulsion s, for instance inice cream . It hasE number E466. It is also a constituent of many non-food products, such asK-Y Jelly ,toothpaste ,laxative s, diet pills,water -basedpaint s,detergent s, and variouspaper products. They have highviscosity , are not toxic, and are generally non-allergenic. CMC is used as alubricant in non-volatileeye drop s (artificialtear s). Sometimes it ismethylcellulose (MC) which is used, but its non-polarmethyl groups (-CH3) do not add any solubility or chemical reactivity to the base cellulose.ee also
*
Hydroxypropyl cellulose
*Methylcellulose External links
* [http://www.lsbu.ac.uk/water/hycmc.html CMC chemical structure and properties]
* [http://aic.stanford.edu/sg/bpg/annual/v01/bp01-04.html MC and CMC: commercial preparations and various uses, including paper conservation; bibliography]
* [http://www.healthopedia.com/drugs/quick/carboxymethylcellulose CMC use in eye drops]
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