Chemical Properties
yellow crystals with an almond odour
Uses
1-Chloro-2,4-dinitrobenzene is used as a reagent for the detection and determination of pyridine compounds. It has been used as alkylating agent to evaluate the depletion of intracellular erythrocyte glutathione (GSH). It is an irreversible inhibitor of human thioredoxin reductase.
Uses
1-Chloro-2,4-dinitrobenzene is a benzene derivative and is used in biochemical research as a substrate for glutathione S-transferase.
Definition
ChEBI: 2,4-Dinitrochlorobenzene is a C-nitro compound that is chlorobenzene carrying a nitro substituent at each of the 2- and 4-positions. It has a role as an epitope, an allergen and a sensitiser. It is a C-nitro compound and a member of monochlorobenzenes.
Production Methods
Although chlorobenzene can be dinitrated directly, this results in unnecessary isomer problems. 4-Chloronitrobenzene is usually nitrated with mixed acid (35/65) at 60 ℃ to give the pure dinitro isomer. However, 2- chloronitrobenzene can be nitrated to produce 2,4-Dinitrochlorobenzene, together with ca. 10 wt % of the isomeric 2- chloro- 1,3-dinitrobenzene. This may be separated for disposal, but the mixed isomers are preferably used directly if tolerated by the end product (e.g., sulfur dyes).
General Description
Pale yellow needles, almond odor.
Reactivity Profile
Self-reactive, [Halpern, Chem. and Eng. News, 29:2666(1951)]. The mixture of 2,4-Dinitrochlorobenzene with hydrazine hydrate caused a violent reaction.
Hazard
Toxic by ingestion, inhalation, and skin
absorption. Combustible. Upper explosive limit
22%. A skin irritant.
Health Hazard
TOXIC; inhalation, ingestion or skin contact with material may cause severe injury or death. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.
Fire Hazard
Combustible material: may burn but does not ignite readily. When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion hazards. Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated. Runoff may pollute waterways. Substance may be transported in a molten form.
Contact allergens
This substance is one of the strongest primary skin irritants known, and a universal contact allergen. Occupational dermatitis has been reported, but current use is decreasing or performed with completely closed systems. DNCB is sometimes used for topical treatment of alopecia areata, severe warts, and cutaneous metastasis of malignant melanoma
Safety Profile
Poison by skin contact
and intraperitoneal routes. Moderately toxic
by ingestion. A severe human skin and eye
irritant. Acts as a primary irritant as well as a
sensitizer of skin. An allergen. Mutation data
reported. Combustible when exposed to
heat or flame. A moderate explosion hazard
when exposed to flame, sparks, heated to
1 50°, or when shocked in a sealed container.
Explosive reaction with ammonia at
17O℃/40 bar. To fight fire, use CO2, dry
chemical. Reacts violently with hydrazine
sulfate or hydrazine hydrate. See also
NITRO COMPOUNDS of AROMATIC
HYDROCARBONS.
Purification Methods
Usually it is recrystallised from EtOH or MeOH. It has also been crystallised from Et2O, *C6H6, *C6H6/pet ether or isopropyl alcohol. A preliminary purification step is to pass its solution in *benzene through an alumina column. It has also been purified by zone refining. It exists in three forms: one stable and two unstable. The stable form crystallises as yellow needles from Et2O, m 51o, b 315o/760mm with some decomposition, and is soluble in EtOH. A labile form also crystallises from Et2O, m 43o, and is more soluble in organic solvents. The second labile form has m 27o. [Hoffman & Dame, J Am Chem Soc 41 1015 1919, Welsh J Am Chem Soc 63 3276 1941, J Chem Soc 2476 1957, Beilstein 5 IV 744.]
