Knecht compound

Kneaders Kneading Kneading mixers Knecht compound Knecht method Knife mills Knight and Allen Knives Knize Ten Knockdown Knockdown resistance... 

Nitrating cellulose with pure HNO is the simplest method of obtaining CN. In practice, nitration does not occur with acid concentrations below 75%. At acid concentrations <75%, an unstable compound (so called Knecht compound) is formed which has been described as a molecular complex or an oxonium salt of the nitric acid (72). HNO concentrations of 75—85% yield CN with 5—8% N, which dissolve in excess acid. CN with % N of 8—10% are formed at acid concentrations of 85—89%. Above 89%, a heterogeneous nitration occurs without apparent swelling of the cellulose fibers. CN with 13.3% N can be obtained with 100% HNO. Addition of inorganic salts to 100% HNO can raise the % N to 13.9. 

Knecht Compound. Knecht (Refs 1 2) treated cellulose with 65% nitric acid (d 1.14 g/cc) and obtained an addition product. After removing the acid retained mechanically he established that the addition compd contained-nitric acid corresponding to 7.7% N. This is approximately equivalent to one N02 group for... 

According to the expts of Andress (Ref 5) the composition of the Knecht compound after being kept under reduced press for some time should be denoted by the formula 2C6H 0Os.HNO3. He demonstrated that the compound produces a characteristic X-ray fiber diagram... 

Trogus (Ref 6) collected data concerning the concn of nitric acid to produce the Knecht compound, and concluded that it is formed when a mixt of almost equivalent quantities of the hydrates HN03.H20 and HN03.3H20 act on cellulose... 

The product of absorption of nitric add vapours by cellulose is according to Wilson not a Knecht compound, since it did not give the characteristic X-ray diagram although its chemical composition is approximately that of the Knecht compound. 

Fig. 116. Diagram by Trogus [5] /—Formation of the addition (Knecht) compounds, //—Nitrationjof cellulose (in % N), ///—Freezing temperatureof HNO3-H2O solutions, IV— Partial vapour pressure of HNO3 in aqueous nitric acid. Hatched area — strong swelling of cellulose fibre. Cross hatched area — solution of cellulose fibre...

Tire structure of Knecht compound has been examined by T. CTbanski ar Zyszczyhski [541. On the basis of infra red spectra they came to a conclusii that the cellulose moiety of the Knecht Compound is partly oxidized and shov the presence of a carbonyl group similar to that of oxycellulose (Vol. II, p. 321... 

Fig. 116. Diagram by Trogus [S] /—Formation of the addition (Knecht) compounds,...

---