1,3-Dinitrobenzene

Description

1,3-Dinitrobenzene (1,3-DNB) is an impurity present in the manufacture of 2,4,6-trinitrotoluene. Workers in munitions plants are at risk of exposure. While it does not bioaccumulate, it persists in the environments (air, water, and soil) with slow rates of degradation. Metabolism in animals (rabbits) results in reduction of the nitro functionalities to amine functionalities to produce 2,4-diaminophenol, m-nitroaniline, m-phenylenediamine, and 2-amino-4-nitrophenol. Human exposure is generally dermal contact or inhalation of vapor.

Chemical properties

orange to yellow crystalline powder. Freely soluble in benzene, chloroform, ethyl acetate, soluble in alcohol, slightly soluble in water. Can evaporate with water vapour.

The Uses of 1,3-Dinitrobenzene

1,3-Dinitrobenzene (1,3-DNB) is an impurity present in the manufacture of 2,4,6-trinitrotoluene. Dinitrobenzene (as a mixture of 1,2-dinitro- 1,3-dinitro- and 1,4-dinitro-isomers) is used in the manufacture of dyes and explosives, and in organic syntheses.

Definition

ChEBI: 1,3-dinitrobenzene is a dinitrobenzene that is benzene disubstituted at positions 1 and 3 with nitro groups. It has a role as a neurotoxin.

Preparation

1,3-Dinitrobenzene is accessible by nitration of nitrobenzene. The reaction proceeds under acid catalysis using sulfuric acid. The directing effect of the nitro group of nitrobenzene leads to 93% of the product resulting from nitration at the meta-position. The ortho- and para-products occur in only 6% and 1%, respectively.

Synthesis Reference(s)

The Journal of Organic Chemistry, 38, p. 4243, 1973 DOI: 10.1021/jo00964a007
Synthesis, p. 1085, 1992 DOI: 10.1055/s-1992-26309

General Description

1,3-Dinitrobenzene is a yellow solid with a slight odor. Sinks in water. (USCG, 1999)

Air & Water Reactions

Slowly mixes with water.

Reactivity Profile

All three isomers have similar properties and may react vigorously with oxidizing materials. Their reaction with nitric acid (nitration) will lead to a mixture of trinitrobenzenes possessing high-explosive properties [Urbanski, 1967, vol. 3, p. 290]. If heat and reaction conditions of the nitration are not controlled, detonation comparable to TNT may occur [Anon., J. R. Inst. Chem., 1960, 84, p. 451]. Mixture of 1,3-dinitrobenzene with tetranitromethane was found highly explosive [Urbanski, 1964, vol. 1, 592]. 1,2-dinitrobenzene is a severe explosion hazard when shocked or exposed to heat or flame. When heated to decomposition all dinitrobenzens emit toxic fumes of nitrogen oxides [Sax, 9th ed., 1996, p. 1374].

Health Hazard

Inhalation or ingestion causes loss of color, nausea, headache, dizziness, drowsiness, and collapse. Eyes are irritated by liquid. Stains skin yellow; if contact is prolonged, can be absorbed into blood and cause same symptoms as for inhalation.

Fire Hazard

Behavior in Fire: May explode

Safety Profile

Suspected carcinogen. Human poison by ingestion. Experimental poison by ingestion, intraperitoneal, and intravenous routes. Human systemic effects by skin contact: cyanosis and motor activity changes. Experimental reproductive effects. An eye irritant. Mutation data reported. Mixture with nitric acid is a high explosive. Mixture with tetranitromethane is a hgh explosive very sensitive to sparks. When heated to decomposition it emits toxic fumes of NOx. See also 0and pDINITROBENZENE.

Environmental Fate

Biological. Under anaerobic and aerobic conditions using a sewage inoculum, 1,3- dinitrobenzene degraded to nitroaniline (Hallas and Alexander, 1983). In activated sludge inoculum, following a 20-d adaptation period, no degradation was observed (Pitter, 1976).
Photolytic. Low et al. (1991) reported that the nitro-containing compounds (e.g., 2,4- dinitrophenol) undergo degradation by UV light in the presence of titanium dioxide yielding ammonium, carbonate, and nitrate ions. By analogy, 1,3-dinitrobenzene should degrade forming identical ions.
Chemical/Physical. Releases toxic nitrogen oxides when heated to decomposition (Sax and Lewis, 1987). 1,3-Dinitrobenzene will not hydrolyze in water (Kollig, 1993).

Solubility in organics

Soluble in acetone, ether, pyrimidine (Weast, 1986), alcohol (27 g/L), pyridine (3,940 g/kg at 20–25 °C) (Dehn, 1917); freely soluble in benzene, chloroform, ethyl acetate (Windholz et al., 1983), and toluene.

Purification Methods

Crystallise 1,3-dinitrobenzene from alkaline EtOH solution (20g in 750mL 95% EtOH at 40o, plus 100mL of 2M NaOH) by cooling and adding 2.5L of H2O. The precipitate, after filtering off, is washed with H2O, sucked dry, and crystallised from 120mL, then 80mL of absolute EtOH [Callow et al. Biochem J 32 1312 1938]. Alternatively crystallise it from MeOH, CCl4 or EtOAc. It can be sublimed in a vacuum. [Tanner J Org Chem 52 2142 1987, Beilstein 5 IV 739.]

Toxicity evaluation

Cultured astrocytes and brain capillary endothelial cells were exposed to 1 mM concentrations for 1 day in an in vitro blood–brain barrier (BBB) model, resulting in cell death.