Carbohydrates with nitric acid

Crystallizes from water in large colourless prisms containing 2H2O. It is poisonous, causing paralysis of the nervous system m.p. 101 C (hydrate), 189°C (anhydrous), sublimes 157°C. It occurs as the free acid in beet leaves, and as potassium hydrogen oxalate in wood sorrel and rhubarb. Commercially, oxalic acid is made from sodium methanoate. This is obtained from anhydrous NaOH with CO at 150-200°C and 7-10 atm. At lower pressure sodium oxalate formed from the sodium salt the acid is readily liberated by sulphuric acid. Oxalic acid is also obtained as a by-product in the manufacture of citric acid and by the oxidation of carbohydrates with nitric acid in presence of V2O5. 

Derivation Oxidation of lactose or similar carbohydrates with nitric acid. 

CAUTION It is generally known that trinitrotoluene is a high explosive and that the treatment of glycerol, cellulose, and other carbohydrates with nitric acid/sulfuric acid leads to other explosives. The nitration of many other compounds may form products (or intermediates) which may be explosives, and precautions against detonations must be taken. Alkali salts of nitromethane or nitro-methane derivatives are sensitive to impact when dry [1]. In fact, the addition of bases or acids to nitromethane is said to render the compound susceptible to detonation according to a recent publication [2]. An explosion during the nitrolysis of an acetyl compound may... 

The reaction of aldoses with nitric acid leads to the formation of aldaric acids by oxidation of both the aldehyde and the terminal primary alcohol function to carboxylic acid groups Aldaric acids are also known as saccharic acids and are named by substi tutmg aric acid for the ose ending of the corresponding carbohydrate... 

Oxidation of Carbohydrates. Oxahc acid is prepared by the oxidation of carbohydrates (7—9), such as glucose, sucrose, starch, dextrin, molasses, etc, with nitric acid (qv). The choice of the carbohydrate raw material depends on availabihty, economics, and process operating characteristics. Among the various raw materials considered, com starch (or starch in general) and sugar are the most commonly available. Eor example, tapioka starch is the Brazihan raw material, and sugar is used in India. 

Aldaric acid (Section 25.19) Carbohydrate in which carboxylic acid functions are present at both ends of the chain. Aldaric acids are typically prepared by oxidation of aldoses with nitric acid. 

Like all carbohydrates, cellulose possesses the clearly marked prominent properties of an alcohol owing to the presence of hydroxyl (alcoholic) groups. The presence of those groups explains the ability of cellulose to form esters with nitric acid and with acetic acid which have attained great practical importance, and also with sulphuric, phosphoric and different organic adds, as well as the formation of cellulose ethers. 

Panzer obtained a gel-like carbohydrate substance from defatted bacilli (human strain) by successive extraction with water, hydrochloric acid, sodium carbonate, sodium nitrate, hot water and potassium hydroxide. The resulting liquors each yielded a gum-like substance which was sulfur-, nitrogen- and phosphorus-free. Oxidation of this derivative with nitric acid gave oxalic acid but no mucic acid. Panzer concluded that the substance was probably a pectin but not a galactan. It is now known that drastic oxidation of this nature would give oxalic acid from any sugar derivative. It is possible that by using controlled oxidation, mucic acid could be obtained from this carbohydrate. 

Traditionally, oxalic acid has been extracted from natural products by treating them with an alkaline solution, followed by crystallization of the acid. Sodium hydroxide is the alkaline material most commonly used for this procedure. Today, a number of methods are available for the commercial preparation of oxalic acid. In one procedure, carbon monoxide gas is bubbled through a concentrated solution of sodium hydroxide to produce oxalic acid. Alternatively, sodium formate (COONa) is heated in the presence of sodium hydroxide or sodium carbonate to obtain the acid. Another popular method of preparing oxalic acid involves the oxidation of sucrose (common table sugar) or more complex carbohydrates using nitric acid as a catalyst. The reaction results in the formation of oxalic acid and water as the primary products. 

Nitric acid oxidation of coal, with or without oxygen, leads to the formation of complex mixtures of the benzenoid or aromatic type of organic acida Nitric acid oxidation of carbohydrates yfelds oxalic acid. Nitric acid of 50-76 per cent concentration at temperatures of 20-40 C oxidizes tetra-hydrofuran to good yields of succinic acid. Oxidation with nitric acid of a secondary aliphatic alcohol or an aliphatic ketone results in fistion of the aliphatic chain at the point of attachment of the functional group accom-... 

Esters of cellulose with interesting properties such as bioactivity and thermal and dissolution behavior can be obtained by esterification of cellulose with nitric acid in the presence of sulfuric acid, phosphoric acid, or acetic acid. Commercially important cellulose esters are cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate. Cellulose esters of aliphatic, aromatic, bulky, and functionalized carboxylic acids can be synthesized through the activation of free acids in situ with tosyl chloride, iV,iV -carbonyldiimidazole, and iminium chloride under homogeneous acylation with DMA/LiCl or DMSO/TBAF. A wide range of cellulose esters that vary in their DS, various substituent distributions, and several desirable properties can be obtained through these reactions. Recently, a number of enzymes that degrade cellulose esters have been reported. Some of them are acetyl esterases, carbohydrate esterase (CE) family 1, and esterases of the CE 5 [169-172] family. 

But in a reaction that has not hitherto been encountered, that is, with nitric acid, the carbohydrates yield dicarboxylic acids called aldaric acids, compounds in which both termini have been oxidized So, D-glucose yields glucaric add (Equation 11.4). 

Certain aliphatic compounds are oxidised by concentrated nitric acid, the carbon atoms being split off in pairs, with the formation of oxalic acid. This disruptive oxidation is shown by many carbohydrates, e.g., cane sugar, where the chains of secondary alcohol groups, -CH(OH)-CH(OH)-CH(OH)CH(OH)-, present in the molecule break down particularly readily to give oxalic acid. 

Nitric acid is formed during these reactions and in some cases the addition of sodium fluoride as a base can be advantageous. This is the case with higher carbohydrates like cellulose and... 

Esterification with mixed acids is often suitable for the preparation of carbohydrate nitrates, but sometimes a less vigorous method is required. For this purpose, a solution of anhydrous nitric acid in chloroform was introduced by Koenigs and Knorr and found suitable for preparing... 

---