German method

The process of nitrating cellulose described below was used in the German factories at Kriimmel [19] and Aschau [20] during World War II. 

The nitration plant was identical in principle with that described above, with mechanical stirring. In the German method cellulose in the form of crepe paper prepared from 70% birch and 30% spruce was nitrated. Cellulose, tom to pieces in rollers, was dried to reduce its moisture content from 6-7 to 1.2%. Towards the end of the war the drying stage was omitted at Kriimmel, and cellulose containing 6-7% of moisture was nitrated, since the time saved and the economy in steam achieved then was reckoned sufficient compensation for the need to make use of more concentrated acids. 

The mixed acid was warmed to the required temperature (30°C at Kriimmel and 18°C at Aschau) by means of temperature stabilizers. These were cylindrical tanks provided with a coil to heat or to cool the content, and a mechanical stirrer. 

The data collected in Table 98 show the composition of the mixed acid used in the German plants. The cellulose to acid ratio was 1 45. 

The nitration process consisted in immersing cellulose in the mixed acid. At Kriimmel a charge of 25 kg was immersed for 30 min, while at Aschau 21 kg of cellulose were immersed for 40 min. Towards the end of nitration the temperature was around 25°C. The nitrators were provided with stirrers able to revolve at a speed of 00 r.p.m. This rate was maintained during the addition of cellulose to the nitrators, after which the rate of rotation was slowed down to 1(X) r.p.m. After the nitra- 

The nitrating mixture is prepared from fresh concentrated nitric acid, 55% regenerated nitric acid (from the denitration of spent acid), and 96% sulphuric acid recovered by distillation. The mixture of acids is fed into the nitrator from a metering tank through a vacuum started siphon. Toluene is conveyed to the nitrator from another metering tank by means of compressed nitrogen. Air is considered as too dangerous to use, because the explosibility of mixtures of toluene vapour with air. 

Plant for mononitration consists of two cast iron pre-nitrators, each having a capacity of 0.5 m3 and a main cast iron nitrator of 15 m3 capacity. Toluene and acid are run into the pre-nitrators, a toluene to acid ratio of 1 2.5 being maintained. The mixture is transferred to the main nitrator through an overflow in the quantity necessary to fill the nitrator (10-12 m3). A temperature of 34-40°C is maintained in both nitrators by means of a cooling coil. 

The aim of dividing the operation into two stages is to achieve the most effective thermal control, since the conversion of toluene to mononitrotoluene is the most exothermic of all the stages of the reaction, as already mentioned in the section dealing with the theory of nitration. The operation is effected in 5-6 hr. 5000 kg of MNT is obtained from each charge of the nitrator. 

When nitration has been completed the reaction mixture is transferred by compressed air to a cast iron separator with a capacity of 15 m3, where it is allowed to remain at rest for 6 hr to separate into two liquid phases. Then the spent acid is conveyed to a special cast iron tank, where it stays for a few days to recover the temainder of the MNT, which is collected from the surface and added to the toluene to be mononitrated. The spent acid, having a composition  

Live steam is passed through the mixture of MNT and alkali. The unnitrated toluene Mid benzene (the latter is a common impurity of toluene) are thus expelled. The steam is introduced until MNT begins to distil, after all the hydrocarbons or other volatile impurities have been expelled. The condensate, containing toluene and MNT, is either recycled for nitration to liquid nitro compounds, e.g. for mining explosives, or is used as a solvent for varnishes. 

---

Methods submitted by industry are partly used for implementation in national collections of analytical methods (e.g., in the German Method Collection of 35 LMBG). This activity often involves a modification of the analytical procedure and extended validation. Some examples for this approach are discussed by Lutz Alder in this Handbook. 

The elements of the multi-residue method should be used as needed. There is no requirement, for example, to test the full version of the German method DEG 19 without any deviation. This full method combines GPC and silica gel cleanup. A poor recovery of compounds from the silica gel is not a reason to reject the multiresidue approach, provided that the chromatograms of GPC eluates are free from interference. 

The German method of prepn was described by Brandoer and Goepp (Refill)... 

HI) German Method is essentially the same as the plant procedures described in Ref... 

The consumption of fuel for producing ono ton of tin is reckoned in the Cornish smelting works at a little more than a ton and a half, sometimes thirty-five hundredweight, and tin loss of tin in the process amounts to about fivo per cent - German Method.—In the tin-smelting establishments of Altenberg, et cetera, instead of the reverberatory, a... 

Kasc s Method, also known as German Method). 

W.H.Rogers "The Sensitivity of Explosives to Bullet Impact , OSRD 5745(1945)(The rept deals with "ordinary cast HE s, with ordinary pressed HE s, with some sluminized expls and with some liquid expls. A German method of testing is briefly described on p 11) 9)Anon, "Ordnance Proof Manual , OPM 7-24, Aberdeen PG, Md(1945), p 5 10)Ohart(1946), 31 ll)Anon,... 

I960) (Cold forging known as "Swaging process") 14W.deVore, Ordn 48, 316-24 (1963) (A German method of cold extrusion as improved and expanded by the Kelsey Hayes Co, Romulus, Mich, so that artillery shells of large caliber can be mass produced quickly and economically)... 

SBET, simple bioaccessibility extraction test PBET, physiologically based extraction test DIN, E DIN 19738 German method RIVM, in vitro digestion model, National Institute of Public Health and the Environment,... 

In a German method, applied at the Kriimmel factory, the crude acid TNT, after it has been washed free from nitrosylsulphuric acid, is washed several times with water at a temperature of 90°C in brick washing vats lined with sheet lead, or in stainless steel tanks. The deacidification is finally followed by neutralization with an NaHC03 solution of concentration about 1%. The product obtained in this stage has a freezing point of 78.8-78.3°C. 

The Anglo-German process is a combination of the English and German methods. After calcination the ore is smelted in a shaft furnace, and the matte is concentrated in a reverberatory furnace. The subsequent smelting to coarse-metal can be effected in either type of furnace. 

Another Frendi method is described in Ref 3a A German method for detn of exudation is described in Ref 7... 

German Method. The manufacture of bromoacetone in Germany 1 was carried out by treating an aqueous solution of sodium or potassium chlorate with acetone and then adding in small quantities the proper quantity of bromine. 

---