Inorganic esters Cellulose nitrates

Cellulose is esterified with certain inorganic acids such as nitric acid, sulfuric acid, and phosphoric acid. A prerequisite is that the acids used can bring about a strong swelling thus penetrating throughout the cellulose structure. The esterification can be considered as a typical equilibrium reaction in which an alcohol and acid react to form ester and water. Of the inorganic esters cellulose nitrate is the only important commercial product. 

Cotton linters or wood pulp are nitrated using mixed acid followed by treatment with hot acidified water, pulping, neutralization, and washing. The finished product is blended for uniformity to a required nitrogen content. The controlling factors in the nitration process are the rates of diffusion of the acid into the fibers and of water out of the fibers, the composition of mixed acid, and the temperature (see Cellulose esters, inorganic esters). 

The first successhil attempt to make textile fibers from plant cellulose can be traced to George Audemars (1). In 1855 he dissolved the nitrated form of cellulose in ether and alcohol and discovered that fibers were formed as the dope was drawn into the air. These soft strong nitrocellulose fibers could be woven into fabrics but had a serious drawback they were explosive, nitrated cellulose being the basis of gun-cotton (see Cellulose esters, inorganic esters). 

The most widely used inorganic ester of cellulose is cellulose nitrate (CN), also called nitrocellulose or gun cotton. Celluloid is produced from a mixture of CN and camphor. It was first made in 1833 when cellulose-containing linen, paper, or sawdust was reacted with concentrated nitric acid. It was the first synthetic cellulose product that was recognized. Initially, CN was used as a military explosive and improvements allowed the manufacture of smokeless powder. A representation of CN is given in structure 9.7. 

Flexographic inks -cellulose nitrate m [CELLULOSE ESTERS - INORGANIC ESTERS] (Vol 5) -dispersed pigment [PIGMENT DISPERSIONS] (Vol 18) -fluorescent pigments m [LUMINESCENT MATERIALS - FLUORESCENT PIGMENTS (DAYLIGHT)] (Vol 15) -from triarylmethane dyes [T RIPHENYLMETHANE AND RELATED DYES] (Vol 24)... 

Although Lhe first cellulose plastic (cellulose nitrate plastic-based on an inorganic ester of cellulose) was developed in 1865. the first organic cellulose ester plastic was not offered commercially until 1927. In that year, cellulose acetate plastic became available as sheets, rods, and tubes. Two years later, in 1929. it was offered in the form of granules for molding. It was the first thermoplastic sufficiently stable to be melted without excessive decomposition, and it was the first thermoplastic to be injection molded. Cellulose acetate butyrate plastic became a commercial product in 1938 and cellulose propionate plastic followed in 1945. The latter material was withdrawn after a short time because of manufacturing difficulties, but it reappeared and became firmly established in 1955. 

Approximately 2% of the 5 x 1011 metric tons of cellulose generated yearly by biosynthesis throughout the world is recovered industrially and of these 108 tons, about 2% is transformed into various esters (3/4) and ethers (1/4). Historically, cellulose nitrate is the oldest (inorganic) ester synthetized, but it has found almost no applications as a biopolymer. The first organic ester and which remains widely used in the field of life sciences is cellulose acetate (1865). Ethers are more recent, since methylation was first described in 1905. 

The history of the development of polymers is intimately tied to cellulose nitrate, also referred to as nitrocellulose. This inorganic cellulose ester is obtained by reacting cellulose with a mixture of nitric acid and sulfuric acid for about 30 min. 

Inorganic esters Nitrocellulose (cellulose nitrate) Cell-OH + HNO, Cell-O-NO, -t H,0 Nitric acid or another powerful nitrating agent... 

Inorganic esters of cellulose have been known for well over 100 years and are still commercially viable products. Cellulose nitrate, commonly called... 

Because of its historical importance cellulose nitrate has traditionally dominated the content of articles devoted to inorganic esters of cellulose. While not understating the importance of cellulose nitrate, this report emphasizes the value of other inorganic esters of cellulose, including cellulose phosphate, cellulose sulfate, and cellulose sulfonates. 

Inorganic esters of cellulose include all esters where the atoms linked directly to the cellulosic oxygens are non-carbon, for examples, cellulose nitrate, cellulose sulfate, cellulose sulfonate, and cellulose phosphate. 

---