Benzenes, chloronitro

Our knowledge of the mechanism of the reaction in this medium comes from an investigation of the nitration of nitrobenzene, /)-chloronitro-benzene and i-nitroanthraquinone. These compounds underwent reaction according to the following rate law ... 

Like the chloronitrobenzenes, a chloroquinoline reacts faster with sodium p-tolylsulfide when the chloro group is para to the aza-group than when it is orthoy the factor involved being about 10. However, a strikingly different behavior is noted in the much lower BS-/ BO- ratio which is 2.5 for 4-chloroquinoline ( para isomer) and 0.24 for 2-chloroquinoline ( ortho isomer). For p-chloronitro-benzene this ratio is 38, and for 2,4-dinitrochlorobenzene it is 1950. Thus far there is no case in which the reaction of a chloronitrobenzene derivative with sodium methoxide is faster than that with sodium phenylsulfide. 

Relative reactivity wiU vary with the temperature chosen for comparison unless the temperature coefficients are identical. For example, the rate ratio of ethoxy-dechlorination of 4-chloro- vs. 2-chloro-pyridine is 2.9 at the experimental temperature (120°) but is 40 at the reference temperature (20°) used for comparing the calculated values. The ratio of the rate of reaction of 2-chloro-pyridine with ethoxide ion to that of its reaction with 2-chloronitro-benzene is 35 at 90° and 90 at 20°. The activation energy determines the temperature coefficient which is the slope of the line relating the reaction rate and teniperature. Comparisons of reactivity will of course vary with temperature if the activation energies are different and the lines are not parallel. The increase in the reaction rate with temperature will be greater the higher the activation energy. 

Heijman CG, C Holliger, M A Glaus, RP Schwarzenbach, J Zeyer (1993) Abiotic reduction of 4-chloronitro-benzene to 4-chloroaniline in a dissimilatory iron-reducing enrichment culture. Appl Environ Microbiol 59 4350-4353. 

Since mtro-groups in the o- and p-positions increase the mobility of halogens directly attached to the aromatic ring (p. 106), nitrophenols can also be obtained from chloronitrobenzenes. Thus p-chloronitro-benzene can be decomposed by alkalis in the autoclave, and 2 4-dinitrophenol, an important intermediate product for the manufacture of sulphur dyes, is produced from the corresponding chlorobenzene by an even milder treatment. 

Synonyms AI3-15387 BRN 508691 CCRIS 142 l-Chloro-4-nitrobenzene 4-Chloronitro-benzene 4-Chloro-l-nitrobenzene p-Chloro-l-nitrobenzene EINECS 202-809-6 4-Nitrochlor-obenzene p-Nitrochlorobenzene 4-Nitrophenyl chloride p-Nitrophenyl chloride NSC 9792 PCNB PNCB UN 1578. 

Niimi, A.J., Lee, H.B., and Kissoon, G.P. Octanol/water partition coefficients and bioconcentration factors of chloronitro-benzenes in rainbow trout Salmogairdneri), Environ. Toxicol. Chem., 8(9) 817-823, 1989. 

Figure 14.11 Reduction of NACs in ferrogenic aquifer solid columns. Concentrations of 4-chloronitro-benzene (4-C1-NB, ) and of its transformation product 4-chloro-aniline (4-Cl-An, o) vary with position (and time) in the column. Also indicated is the excellent mass balance (a). Adapted from Heijman et al. (1995).

Phosphorus pentaselenide, 24 grams, is boiled with 23 grams of powdered selenium in an aqueous alcohol solution of sodium hydroxide for two to three hours. To the resulting solution 39 grams of p-chloronitro-benzene in hot alcohol are added and boiling continued for a further two hours. The precipitate which forms is washed with water and extracted with boiling ethyl acetate. The selenide melts at 170° to 171° C.7... 

Aryl fluoroalkyl ethers have been prepared from the reaction, at room temperature in HMPA, of fluo-ro-substituted alkoxides with activated fluoro-,149 nitro-,149 and, at 150 °C, also chloro-arenes150,151 and some chloro-substituted pyrazines (equation 15), pyrimidines, quinolines,150,152 and pyridines.152 Disubstitution was observed in die presence of comparably activated leaving groups such as in 2,4- and 2,6-di-chloronitro- or cyano-benzenes, whereas regiospecific substitution took place at position 4 in 3,4-dichloronitro- or cyano-benzene and at position 2 in 2-fluoro-6-chlorocyanobenzene.151 Steric hindrance and the number of fluorine substituents in the alkoxide pose limits to the reactivity. Thus, tertiary alkoxides, or alkoxides containing more than four fluorine substituents, displace activated nitro and fluoro, but not chloro substituents.149,150 The secondary hexafluoro-2-propoxide anion does not react even with the more reactive nitro and fluoro derivatives.149... 

The search for electrophilic catalysis could in principle be aided by use of tertiary amines as nucleophiles, in which case an intramolecular or solvent assisted proton shift, formulated in [13] and [14], is eliminated. Thus Ayediran, Bamkole and Hirst (1974) studied salt effects on the reactions of 4-fluoro- and 4-chloronitro-benzene with trimethylamine in DMSO, which proceed according to equations (29) and (30). It had been noted (Suhr, 1967) that the... 

In a 500-cc. three-necked, round-bottomed flask fitted with a reflux condenser, mechanical stirrer, and thermometer are placed 48.5 g. (0.22 mole) of the sodium sulfinate and 60 cc. of a mixture of 75 cc. of ethylene glycol and 120 cc. of carbitol or methyl car-bitol. The mixture is stirred and heated in an oil bath until solution is complete, after which 31.5 g. (0.2 mole) of 4-chloronitro-benzene (m.p. 76-78°) is added. The mixture is heated for three and a half hours at 141-143° (thermometer in the mixture), with continued stirring, and then is allowed to cool overnight. After addition of 20 cc. of water, the pasty lumps are broken up, and the solid is filtered with suction and washed with 50-75 cc. of hot water. The solid is then transferred to a 1-1. flask and refluxed with 250 cc. of 95 per cent alcohol for fifteen minutes. After cooling, the -nitro- -acetylaminodiphenylsulfone is filtered with suction and washed on the funnel, first with 25 cc. of alcohol and then with 25 cc. of ether. After drying in the air, the tan-colored solid weighs 32-33 g. (50-52 per cent of the theoretical amount) and melts at 226-228° (Note 2). 

Electrolytic apparatus, 35, 22 Electrolytic reduction of o-chloronitro-benzene, 35, 23 Enanthaldehyde, 34, 51 Enanthaldehyde, 6-METHYL-/3-0X0-, dimethyl acetal, 32, 79... 

SYNS CHLORO-m-NITROBENZENE m-CHLORONITROBENZENE m-CHLORONITRO-BENZENE pOT) m-NITROCHLOROBENZENE m-NITROCHLOROBENZENE, soUd pOT)... 

To see why it is that a group activates the positions ortho and para to it most strongly, let us compare, for example, the carbanions formed from / -chloronitro-benzene and /w-chloronitrobenzene. Each of these is a hybrid of three structures, I 1I1 for para attack, IV-Vl for meta attack. In one of these six structures, II,... 

Nitroanilines are employed extensively in dye manufacture. Amination of o-chloronitro-benzene, at 175 °C and 40 atmospheres, affords o-nitroaniline. Partial reduction of m-dinitrobenzene gives the corresponding meta-derivative. The para-isomer 15b is used more extensively than the other nitroanilines in dye manufacture. In addition to amination of p-chloronitrobenzene, it can be made by nitration of acetanilide to yield (21), followed by hydrolysis. 

P.R. Brookes and A.G. Livingston, Biological detoxification of 3-chloronitro benzene manufacture wastewater in an extractive membrane bioreactor. Water Res., 28 (1994) 1347. 

The kinetics of chlorine displacement is strongly dependent on the position of the activating substituent 4-chloronitrobenzene reacts faster than 2-chloronitro-benzene with potassium fluoride whereas, in 2,4-dichloronitrobenzene, chlorine in the 2-position is exchanged more rapidly than chlorine in the 4-position (refs. 4-8). These observations are consistent with an addition-elimination process involving an anionic adduct (Meisenheimer s complex) which has been observed by h and 19F NMR (ref. 9) or UV spectroscopy (ref. 3) ... 

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