TNCB

THOD Terre Haute Ordnance Depot TNC1B or TNCB tr i nitr och lor ob enz ene... 

Commercial DNCB, yel crysts, mp ca 5 0°, consists mostly of 2,4-DNCB with a small amt of 2,6-DNCB. This product is considered more toxic than NB. It causes dermatitus systemic poisoning(Ref 12). DNCB is an expl si more powerful than DNB and comparable in sensitivity to TNT(Ref 4). The expl props of DNCB its mixts with PA, TNT or AN were studied by Burlot Tavernier(Ref 7). It has been reported that phosgene is produced on low order deton of DNCB(Ref 6). DNCB is used as an intermediate in one method for the manuf of tetryl. It may also be further nitrated to 2, 4,6 -Trinitro-l-chlorobenzene(abbreviated TNCB) and also known as Picryl Chloride(See below) Refs l)Beil 5, 262-64, (137-39) [196-97] 2)G.Koerner A. Contardi, AttiAccadLincei-Rend 23, 4 64-71(1914) SS 10, 77(1915) 2a) Ullmann 2(1928), 277-78 3)J. Mason, JCS... 

It is an acid, which can be prepd by nitration with mixed acid of DNCB or of chlorobenzene its lab prepn includes heating of PA with phosphorus pentachloride or other methods(Refs 1, 4, 5, 8, 10 13). TNCB is readily hydrolyzed to form PA and, similarly to PA, it attacks metals to form expl salts, some of which are very sensitive(Ref 8). Its chloride salt, called Chloropicryl Chloride, was prepd without danger of expln(Ref 10). Some of its additive compds are also expl. It is very toxic causing dermatitis(Ref 5 11)... 

TNCB is an expl si more powerful than TNT and comparable ro it in sensitivity. 

A weighed sample of TNCB is dissolved in methanol and refluxed for two hours with a measured vol of 0.1N NaOH soln (two equivalents of NaOH, plus a slight excess). The following reactions take place ... 

Assuming that the normality of HC1 soln is exactly the same as that of the NaOH soln, and if the vol of NaOH soln(added before refluxing) is V, then vol(V4), required for converting TNCB to PA, can be ealed from the equation. 

If TNCB is free of PA, then the vol (v3) would be equal to (v 4), but as tech grade TNCB usually contains some PA( formed as result of hydrolysis), v3 would be larger than v4... 

Assume that (v3+v4 ) for the sample is equal to V, while for compd consisting of pure TNCB it is V3, and for pure DNCB V2< If V1 is larger than V2 and smaller than V3, then the percentage (x) of DNCB in sample can be ealed from the equation ... 

Chloropicryl Chloride See Chloride Salt of TNCB(or Picryl Chloride) under Chlorobenzene and Derivatives... 

Then the soln contg Na picrate,NaCL and an excess of NaOH is titrated potentiometrically with 0. IN HC1 until the 1st potentiometric break in the curve is observed. Burette reading would indicate the vol(v f), required to neutralize the excess NaOH. Titration is continued until the 2nd break in the curve is observed. This burette reading(Vg), minus(V() indicates the vol(v3), required to convert Na picrate back to PA Assuming that the normality of HC1 soln is exactly the same as that of the NaOH soln, and if the vol of NaOH soln(added before refluxing) is V, then vol(V4), required for converting TNCB to PA, can be calcd from the equation. v4 =V-v2... 

Prepn of TNCB chloride in good yield by passing COCl into a soln of the pyridine salt of styphnic acid in acetone) ll)Sax(1957), 948 1223 12)PATR 2510 (195 8), pp Ger 48 204 13)Ullmann 12 (I960), 800... 

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