Chloro-2,6-dinitrobenzene

Checked by Arthur C. Cope, David J. Marshall, and Ronald M. Pike. 

The temperature of diazotization is critical. Lower yields are obtained if the temperature rises above 40°. 

l-Chloro-2,6-dinitrobenzene is a skin irritant, and contact with it should be avoided. 

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Good yields of fluoro-substituted aromatics have been obtained when 1 -chloro-2,4-dinitrobenzene (10) and 1-chloro-2,6-dinitrobenzene (13) are first treated with pyridine or methyl-substituted pyridines to form intermediate salts 11 and 14 and then reacted with potassium fluoride in dimethylformamide or nitrobenzene to give the fluorides 12 and 15."°... 

The filtered product is then thoroughly washed with water and crystallized from a benz or acet soln. For details see Ref 82, pp 59—61 An alternate, two-stage method of producing Tetryl is used in Germany. In the first stage dinitrome thy laniline is prepd by reacting chloro-dinitrobenzene with methylamine in the presence of Na hydroxide. In the second stage the... 

VII. Preparation. There are two industrial methods of manufg PA 1) nitration of Phenol 2) nitration of dinitrophenol prepd by hydrolysis of chloro dinitrobenzene... 

It can be obtained by reacting sodium hydrogen ethylene glyoxide and chloro-dinitrobenzene followed by nitration, or chlorotrinitrobenzene, as reported by Faiboume and Toms [88] ... 

The nitration of chlorobenzene was first mentioned in 1862 by Riche [6], Later the reaction was studied by Sokolov [7] and Holleman and de Bruyn [8], Junglleisch [9] was the first to describe the method of preparation of chlorodinitrobenzene from o- or p- chloronitrobenzene. Laubenheimer [10] investigated the products of the nitration of m- chloronitrobenzene, and Ostromyslenskii [11] determined the structure of the products obtained by Jungfleisch, i.e. of 1,2,4- and 1,2,6-chloro-dinitrobenzenes. Finally in 1894 the Griesheim factory reported [12] on a method of preparing chlorotrinitrobenzene by direct nitration of chlorobenzene. 

According to Desvergnes [18] said Frankland and F. FL Gamer [24], chloro-dinitrobenzene can be nitrated with a mixture containing less nitric acid and more sulphuric acid. The resultant product is of higher purity said the yield is also higher. 

The hydrolysis process is effected in a wrought iron reactor of 4 m3 capacity, equipped with a cooling jacket, a heating coil and a stirrer. The reactor is charged with water heated to 70°C then a 42% solution of NaOH is run in from a measuring tank in such a quantity as to obtain 2130 1. of a 7% NaOH solution (5% in excess of the calculated quantity). Then 360 kg of molten chloro-dinitrobenzene at a temperature of 70-75°C is added over a period of 10 min. The temperature rises to 100°C. When the vigorous stage of the reaction has subsided the mixture is heated to 100-110°C for 1 hr. 

Alcoholysis of l-chloro-2,4-dinitrobenzene to 2,4-dinitroanisole. To 800 kg of methyl alcohol in the reactor 196 kg of sodium hydroxide and 600 kg of chloro-dinitrobenzene are added in 10 equal portions. The reagents are added alternately. During this operation, which requires 7 hr, a temperature at 40-45°C is maintained. Then the temperature is raised to 50°C by heating the reactor jacket and kept there for 30 min, before cooling the whole mixture to 35°C (which takes 3 hr). The crystals of the product together with the mother liquor are then transferred to a vacuum filter for separation. The product obtained is washed four times with water, centrifuged and finally transferred to the nitration plant. 

Nowadays 2,4-dinitroaniline is prepared on a large scale by treating chloro-dinitrobenzene with ammonia. The method was first reported by Engelhardt and Lachinov [9] in 1870. Heating 2,4-dinitrophenol with an excess of urea at 208°C... 

DOT CLASSIFICATION 6.1 Label Poison SAFETY PROFILE A poison by ingestion. Mutation data reported. Potentially explosive. When heated to decomposition it emits very toxic fumes of CT and NOx. See also other chloro-dinitrobenzenes. 

The iodine atom in iodobenzene (unlike that in the corresponding aliphatic compounds) is very resistant to the action of alkalis, potassium cyanide, silver nitrite, etc. This firm attachment of the iodine atom to the benzene ring is typical of aromatic halides generally, although in suitably substituted nitio-compounds, such as chloro-2,4-dinitrobenzene, the halogen atom does possess an increased reactivity (p. 262). 

Dinitrophenylhydrazine is a very important reagent for the identification of aldehydes and ketones (pp. 342, 346). It is readily prepared from chloro-2,4-dinitrobenzene (I). In the latter compound the chlorine is very reactive in... 

Another example of the analogy between pyrazole and chlorine is provided by the alkaline cleavage of l-(2,4-dinitrophenyl)pyrazoles. As occurs with l-chloro-2,4-dinitrobenzene, the phenyl substituent bond is broken with concomitant formation of 2,4-dinitrophenol and chlorine or pyrazole anions, respectively (66AHC(6)347). Heterocyclization of iV-arylpyrazoles involving a nitrene has already been discussed (Section 4.04.2.1.8(i)). Another example, related to the Pschorr reaction, is the photochemical cyclization of (515) to (516) (80CJC1880). An unusual transfer of chlorine to the side-chain of a pyrazole derivative was observed when the amine (517 X = H, Y = NH2) was diazotized in hydrochloric acid and subsequently treated with copper powder (72TL3637). The product (517 X = Cl, Y = H) was isolated. 

Polymer-supported tetraphenylphosphonium bromide is a recyclable catalyst for halogen-exchange reactions. The reaction of 1 equivalent of chloro-2,4-dinitrobenzene with 1 5 equivalents of spray-dned potassium fluoride and 0.1 equivalent of this catalyst in acetonitnle at 80 C for 12 h gives 2,4-dinitro-fluorobenzene m 98% yield An 11% yield is obtained without the catalyst [3 /]. 

Benzofuroxan and 5-methylbenzofuroxan are oxidized by trifluoro-peracetic acid to o-dinitrobenzene and 3,4-dinitrotoluene, respectively. 4-Nitro- and 4,6-dinitrobenzofuroxan are unaffected by this reagent, whereas the 5-chloro and 5-methoxy compounds are destroyed.Milder reagents (performic, peracetic acids) do not oxidize benzofuroxans. ... 

Heterocyclic bases which readily form quaternary salts with the more usual reagents will also react with suitably activated aryl and heterocyclyl halogen compounds, the classic case being the salt formed from pyridine and l-chloro-2,4-dinitrobenzene. Reactions of this type have been studied by Chapman et Salt formation between... 

Beagent 1 Spray solution 1 Dissolve 2 g l-chloro-2,4-dinitrobenzene in 100 ml ethanol. 

Nicotinic acid and related compounds react with l-chloro-2,4-dinitrobenzene in the manner of the cyanogen bromide reaction to yield derivative I, which possibly also decarboxylates at elevated temperature. In alkaline medium this derivative first adds an hydroxyl ion and then undergoes ring opening to yield the colored derivative II. 

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