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Physical & Chemical properties

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2,4 -dinitrophenol is a solid organic substance, with yellow colour and sweetish odour. It can be manufacture as platelets, leaflets or crystals

(The Merk Index, 1989).

It has a density of 1.683 g/cm^3 , a vapour pressure of 1.49 x 10 ^-5 mmHg at 18°C (Mabey WR, Smith JH, Podoll RT, et al., 1981), and it is soluble in water (5600 mg/L at 18°C and 2790 at 20°C from Schwarzernbach, RP., et al, 1988).

It shows solubility on different types of solvent (g/100 g solvent): 15.55 in ethyl acetate; 35.90 in acetone, 5.39 in chloroform; 20.05 in pyridine; 0.423 in carbon tetrachloride; 6.36 in toluene; it is soluble in alcohol and benzene (The Merk Index, 1989).

Its melting point is defined in the range of 112 -114°C and the boiling point cannot be defined because it sublimes when carefully heated

(The Merk Index, 1989).

2,4 -dinitrophenol is a combustible solid, though it may require some effort to ignite (Association of American Railroads; Bureau of Explosives. Emergency Handling of Hazardous Materials in Surface Transportation. Association of American Railroads, Pueblo, CO. 2005, p. 354).

In the wake of these data, for flammability and explosiveness endpoints 2,4 -dinitrophenol shows a different behaviour depending on his water content. In fact, it can be exist in paste containing > 15% of water and in dried form or with a water content < 15%.

Here below the explanation of the two behaviour:

DRIED FORM

Literature reports that the dried form of 2,4 -dinitrophenol in powder or granular form is explosive mixed with air. It may also explosively decompose on shock, friction, or concussion (International Program on Chemical Safety, 1996). Furthermore it forms explosive salts with alkalis and ammonia (Lewis, R.J. , 2004).

Thus, according to ADR European Agreement concerning the International Carriage of Dangerous Goods by Road, dried or with less than 15% water form, 2,4 -dinitrophenol by mass is classified with UN number 0076, class 1, classification code 1.1D.

WATER PAST FORM

The water paste, with a water content > 15% is considered not explosive, but as a solid desensitised explosive. For this reason this wetted form permits to suppress its explosive properties. The "market form" is usually wetted.

Hence, wetted 2,4 - dinitrophenol, with not less than 15% water by mass is classified with UN number 1320, class 4.1 classification code DT (solid desensitised explosive) according to ADR European Agreement concerning the International Carriage of Dangerous Goods by Road).

2,4 -dinitrophenol has a dissociation constant of 4.09 (temperature not specified) and appear to be stable in acid solution (Pearce PJ, Simkins RJJ., 1968).

Its octanol-water partition coefficient Log Kow is 1.54, that suggest that 2,4 -dinitrophenol has a low ability to bioaccumulation in aquatic organisms.