Chloroaniline isomers

Aromatic phenols and alcohols were also found to act as good displacers on cyclodextrin-silica columns (67,69). Since the retention studies discussed above indicate that p-nitrophenol is more retained (Fig. 2) than the chloroaniline isomers (Fig. 3), and 4-t-butyl cyclohexanol is more retained than the Ibuprofen enantiomers (Fig. 4), p-nitrophenol and 4-t-butylcyclohexanol were selected as possible displacers for the separations discussed below. 

Thirteen chloroanilines (two chloroaniline isomers, five chloromethylaniline isomers, five dichloroaniline isomers, and 5-chloro-2-hydroxyaniline) and aniline were extracted from river and drinking water samples [933]. They were baseline resolved on a Cig column (A = 245 nm or electrochemical detection at +0.95 V vs. Ag/AgCI) using a complex 60-min 26/74- 40/60 acetonitrile/water (SpmM acetate bufTo- at pH 4.9) gradient. Excellent resolution and peak shapes were obtained. Detection limits were rqwrted as 15-25ng/L (S/N = 5) with UV detection and 3-5 ng/L for electrochemical detection. A table of analyte and values was presented. 

Uses. (9-Nitrochlorobenzene is used in the synthesis of azo dye intermediates such as o-chloroaniline (Fast YeUow G Base), i9-nitroani1ine (Fast Orange GR Base), o-anisidine (Fast Red BB Base), o-phenetidine, and (9-aminophenol (see Azo dyes). It also is used in corrosion inhibitors, pigments, and agriculture chemicals. -Nitrochlorobenzene is used principally in the production of intermediates for azo and sulfur dyes. Other uses include pharmaceuticals (qv), photochemicals, mbber chemicals (qv), and insecticides (see Insectcontroltechnology). Typical intermediates manufactured from the para isomer are -lutioaruline (Fast Red GC Base), anisidine, -aminophenol, -nitrophenol, -phenylenediamine, 2-chloro-/)-anisidine (Fast Red R Base), 2,4-dinitrochlorobenzene, and l,2-dichloro-4-nitrobenzene. 

Dichloroaniline impurities aniline, chloroaniline, dichloro-aniline isomers, trichloroaniline isomers, tetrachloroaniline. tet-rachloroazobenzene, and pentachloroazobenzene... 

The reactions of anilines (R =4-MeO and 3-C1) and diethyl acetylmalonate in nitrobenzene at 230-235°C for 1-2 hr gave 2,4-dihydroxy-3-acetyl-quinolines (667, R = 6-MeO and 7-C1). In the case of 3-chloroaniline, a mixture of the isomeric 5- and 7-chloroquinolines was obtained (46JA324). The 7-chloroquinoline was the major isomer. 

The reductive amination of hexane-2,5-dione and heptane-2,6-dione with ammonia and primary amines RNH2 (R = PhCH2, Ph2CH, PhMeCH, Ph, 4-MeOC6H4, 2-ClC6H4 and 2,6-Me2CgH3) under the influence of sodium cyanoborohydride or sodium triacetoxyboro-hydride has been studied. The reactions yield respectively pyrrolidines and piperidines as mixtures of cis- and fraws-isomers no cyclic products were obtained when 2-chloroaniline of 2,6-dimethylaniline were employed (equation 57)168. 

It of interest to note that the isobutyl group may also be replaced by a heterocyclic ring. The route to this compound, pirprofen (51-6), starts with the direct methylation of unesterihed 4-nitrophenylacetic acid (51-1). The observed selectivity for monoalkylation in this case may reside in the structure of the dianion, whose most stable form is presumably that depicted in (51-2). Catalytic reduction of the product (51-3) gives the corresponding aniline this is then converted to its acetanilide (51-4) with acetic anhydride. Treatment with chlorine followed by hydrolysis gives the chloroaniline (51-5). Double alkylation of this last intermediate with 1,4-dichloro-but-2-ene (depicted as the cis isomer for aesthetic reasons) forms the dihydropyrrole ring. There is thus obtained the NSAID pirprofen (51-6) [52]. 

Chloroaniline, CgHgClN. Its three isomers of the formula Cl.C.H, NH0 are described in Ref 1. There is also an isomer, CgHg. NHC1, called N-Chloroaniline or Phenylchloramine... 

N 21.34%, Nitro-N 14.22%, One isomer, 2,4,6-Trinitro-3-chloroaniline,3-cbloropicryU amide, or 3-chloropicramide, Cl.CgH(N02)3.-NH2, is dsscribed in the literature as brn-violet ndls(from ale), mp 185 86° it was first prepd by Borsche Feske(Ref 2) and then by De Monchy(Ref 3), Its expl props were not detd... 

Several reactive chloro compounds have been used to attempt to effect the controlled monochlorination of aromatic amines. One such reagent is N-chlorosuccinimide, with which the chlorination of aniline, for example, can be largely restricted to monosubstitution, although a mixture of isomers (orthopara, 1.9 1) is obtained.24 One approach to the achievement of specific ortho chlorination is illustrated by the synthesis of o-chlorobenzanilide (Expt 6.61), readily hydrolysable to o-chloroaniline. The anilide is formed, by a type of Swi mechanism indicated below, when AT-phenylhydroxylamine is benzoylated and the product is treated with thionyl chloride.25 The reaction has been successfully applied to several substituted JV-phenylhydroxylamines, prepared by the controlled reduction of the corresponding substituted nitro compounds (cf. Expt 6.87). 

Alkaline formaldehyde is also useful in removing the amino group of ortho- and pam-chloroanilines 50-55% yields of chlorobenzene are obtained. With 2,5-dichloroaniline, however, the yield falls to 10%. The formaldehyde procedure cannot be applied to nitroamines inasmuch as reduction of the nitro group occurs. Only a 20% yield of nitrobenzene is obtained from o-nitroaniline, and with the meta and para isomers the yield drops to 10%.4... 

Concentration of the Organic Solvent in the Eluent. As in other reversed-phase systems, the solute retention curves (log k vs. % organic modifier) on cyclodextrin-silicas are quasi-linear, at least over a limited concentration range. Such curves are shown in Figs. 2-4 for the positional isomers of nitrophenol (Fig. 2) and chloroaniline (Fig.3), and the enantiomers of Ibuprofen (Fig.4). Similar retention curves were observed and published for other positional iscmers (67), cis/trans isomers (68) and enantiomers (69). ... 

Adsorption isotherms of p-nitrophenol and the most retained isomers of chloroanilines. Conditions 15 cm x 4.6 mm ID column packed with beta-cyclodextrin-silica solvent 10 % v/v methanol water temperature 30 C. 

Displacement chromatogram of a chloroaniline mixture containing 44.7 umol of the meta isomer, 29.8 umol of the ortho isomer and 16.4 umol of the para isgmer. Conditions 50 cm x 4.6 mm ID beta-cyclodextrin-silica column, carrier solvent 10 % v/v methanol water displacer 13 mM p-nitrophenol dissolved in the carrier solvent displacer flow-rate 0.2 mL/min column temperature 30 C. 

The isomeric o-, m- andp-chloroaniline, which under El give identical spectra, have been characterized by means of resonance-enhanced multiphoton ionization (REMPI) combined with a linear TOF mass spectrometer151. The method is based on the difference the three isomers display in the shapes of their metastable parent ion decays. 

OH, O and Nj radicals were reported to react with chloro-and hydroxy-derivatives of aniline at diffusion-controlled rates with k> dm mol s and the rates are nearly identical for all isomers of chloroaniline. The OH radical reaction involves both addition and direct H abstraction and the extent of the two reactions is determined by the position of the substituent. The initially formed OH adduct then undergoes dehydration to give the anilino radical. The attack of the OH radical at the carbon bonded to Cl is a minor pathway (not more than 15%) as was confirmed by the detection of Cl ions. 

As sample values of viscosity, compare the data in Table 5-XI. Notice the substituted anilines. Here, even though an tn/ramolecular H bond may form in the ortho isomer, the second amino hydrogen gives intermolecular association, and ortho- and/>ara-chloroaniline have similar viscosities. Both values are larger than that shown for the nonassociated o-chlorotoluene. Dihydroxybenzenes and derivatives provide similar data (721) as do nitroanilines, zdthough these compounds are further complicated by intermolecular H bonding. They show mixed association. ... 

A very recent set of calorimetric measurements on the isomeric o-, m- and p-chloro-anilines has been reported100. Although the gas-phase values for the o- and m-isomers are indistinguishable, they are both more stable than the p-isomcr. In the liquid phase, the m-isomer is somewhat more stable than the o-isomer. From equation 2, and the archival values for the enthalpies of formation of liquid and gaseous chlorobenzene of 11.0 1.3 and 52.0 1.3 kJmol-1, the predicted enthalpy of formation for any liquid chloroaniline is —7 kJmol-1, while that for any gaseous chloroaniline is 57 kJmol-1. The predictions are in accord with the experimental results. Earlier measurements are discrepant 101,102. 

Ion pair RP-HPLC with DA-UVD offers a good alternative for determination of mixtures of PAA which are difficult to resolve by usual RP-HPLC procedures. After optimization as for the pH and anionic component of the isocratic mobile phase, it was opted for phosphate buffer at pH 2.5, containing 5 mM of sodium 1-hexanesulfonate and MeOH in 65 35 volumetric proportion. The method was applied to detection of banned azo dyes, after reduction to PAA, of which the banned ones are denoted by (entries in Table 1 carrying note e). In a study involving 2-, 3- and 4- chloroaniline (lh), 2- (lb) and 4-toluidine (Id), 3-, 4- (2g) and 5-chloro-2-toluidine, 3-, 4- and 5- nitro-2-toluidine (2h), 2,3-, 2,4- (2e) and 2,6-diaminotoluene (2f), 1- (8a) and 2- naphthylamine (9a) under identical conditions, the isomers were well separated from each other, except for 2- and 4-toluidine which had distinct but close retention times with no baseline separation211. 

The photochemistry of the constitutional isomers of 91a is relatively simple. The maximal absorption of 3-chloroaniline (109) in aqueous solution is located at 286 nm. The main photoproduct of 109 in aqueous solution is 3-aminophenol209. The transformation is almost quantitative, independent of the presence of oxygen, but secondary photoproducts such as resorcinol could be detected upon prolonged irradiation. These observations suggest that the reaction is initiated by a heterolytic C—Cl bond cleavage, followed by hydrolysis. 

The reaction between [Mo(0)Cl2(Tp )] and 4-bromoaniline in refluxing toluene gave geometric isomers of [Mo(0)Cl(Tp )]( i-0)[Mo(Cl)(=NCgH4Br)Tp ], both structurally characterized, whereas a similar reaction between [Mo(0)Cl2(Tp )] and 4-chloroaniline yielded only one product, [MoTp (0)Cl]( x-0)[MoTp -(C1)(=NC6H4C1)].71... 

Aromatic bases such as the toluidines, xylidines, chloroanilines, 1-naphthyl-amine, benzidine, and tertiary amines can be simply converted into their sulfonic acids by heating ( baking ) with ammonium hydrogen sulfate. This method has the advantage over normal sulfonation by sulfuric acid that exactly theoretical amounts can be used so that no higher sulfonation product is obtained. Further, isomers are rarely obtained, since the sulfo group almost always enters exclusively at the /rara-position or, if that is occupied, at the or/Ao-position, and never at the meta-position. 

MBOCA is a man-made chemical and has not been found in nature (lARC 1974). It is produced commercially by reacting formaldehyde with 0-chloraniline (HSDB 1991 lARC 1974). Pure MBOCA is a colorless crystalline solid (Smith and Woodward 1983). The technical grade of MBOCA that is available in the United States comes mainly from Japan in the form of tan/yellow fused prills or pastilles. The diamine purity is 99.8%, typically with 0.2% free o-chloroaniline (monomer). Isomers are produced as side reactions such as trimers and tetrameres-diamines with three-and four-ring structures joined by methylene groups. Isomers constitute up to 8-10% of MBOCA. The dimer makes up to 90-92% of the MBOCA produced today for coatings and cast polyurethanes. There is no commercial use for pure dimer MBOCA other than for laboratory work. 

By this process, the o-isomer is converted to o-ansidine (ANS), and m-nitrochlorobenzene gives m-chloroaniline (MCA). The mixture of ANS and MCA thus obtained can be separated by dissociation-extraction. 

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