4- Chloroaniline, concentration

Purnell CJ, Warwick CJ. 1980. Application of electrochemical detection to the measurement of 4,4 -methylenebis(2-chloroaniline) and 2-chloroaniline concentrations in air by high-performance liquid chromatography. Analyst 105(1254) 861-867. 

Chlorodiphenyl. Diazotise 32 g. of o-chloroaniline (Section IV,34) in the presence of 40 ml. of concentrated hydrochloric acid and 22 -5 ml. of water in the usual manner (compare Section IV,61) with concentrated sodium nitrite solution. Transfer the cold, filtered diazonium solution to a 1 5 htre bolt-head flask surrounded by ice water, introduce 500 ml. of cold benzene, stir vigorously, and add a solution of 80 g. of sodium acetate trihydrate in 200 ml. of water dropwise, maintaining the temperature at 5-10°. Continue the stirring for 48 hours after the first 3 hours, allow the reaction to proceed at room temperature. Separate the benzene layer, wash it with water, and remove the benzene by distillation at atmospheric pressure distil the residue under reduced pressure and collect the 2-chlorodiphenyl at 150-155°/10 mm. The yield is 18 g. Recrystalliae from aqueous ethanol m.p. 34°. 

Aj Preparation of 3-Chloromethyl-6-Chloro-7-Sulfamyl-3,4-Dihydro-Benzothiadizine-1,1-Dioxide—Jo 8 ml of 40-50% chloroacetaldehyde aqueous solution and 7 ml of dimethyl-formamide are added 10 grams of 2,4-disulfamvl-5-chloroaniline. The mixture is heated on a steam bath for 2 hours after which it Is concentrated at reduced pressure. The residue Is triturated with water. The solid material is recrystallized from methanol-ether after-treatment with activated carbon to give 7.2 grams of product, MP 229°-230°C. 

Mix together 4.4 grams of ammonium chloride, 18 ml of methanol, 9 ml of water and 3.0 grams of 2-sulfamyl-4-chloro-nitrobenzene. Heat the mixture to reflux. Add portionwise 4.4 grams of iron filings during a period of about VA hours. Cool the mixture and filter. Concentrate the filtrate to a residue. Triturate the residue with 15 ml of water and filter the solid. Recrystallize the solid from aqueous methanol to yield substantially pure 2-sul-famyl-4-chloroaniline. 

Fig. 3.72. (a) Standard HPLC chromatogram. (1) Benzidine, (2) o-toluidine, (3) 4-chloroaniline, (4) 3,3-dimethoxybenzidine, (5) 3,3-dimethylbenzidine, (6) 4-aminobiphenyl (7) 3,3-dichloroben-zidine. Detection wavelength 280 nm amino concentration approximately 50 pg/ml. HPLC conditions are described in the text, (b) Chromatogram of a genuine leather sample treated with the MAE procedure. Reprinted with permission from C. S. Eskilsson et al. [140]. 

In a 250-ml. round-bottomed flask fitted with mechanical stirrer, reflux condenser, and thermometer are placed 38.3 g. (0.30 mole) of -chloroaniline (Note 1), 41 ml. (0.6 mole) of concentrated aqueous ammonia (sp. gr. 0.9), and 21 ml. (0.3S mole) of carbon disulfide. The mixture is stirred vigorously, and when it is heated to 30° the reaction starts. The tempierature is maintained at 30-35° by external cooling (Note 2). The reaction mixture turns into a deep-red turbid solution within a few minutes, and then suddenly a heavy yellow precipitate of ammonium /(-chlorophenyldithiocarbamate separates. To the mixture 15 ml. of water is added, and stirring is continued for 1 hour. The mixture is filtered with suction, and the residue is washed with... 

Concentrations, in pg/L, of diflubenzuron declined from 20.3 at 1 h to 2.4 at 4 days 4-chlorophenylurea increased slightly from 5.6 to 7.2 during this interval 4-chloroaniline increased from 0.7 at 1 h to 2.6 at 4 days... 

The reaction of methyl 10, l l -dihydropyrrolo[ l, Z-b [ l, 2,5]bcnzothiadiazcpinc-l l -acetate 5,5-dioxide 73 or the corresponding ethyl ester 74 with potassium hydroxide in EtOH at 25 °C gave the acid 75 (Scheme 14), which upon treatment with trifluoroacetic anhydride in tetrahydrofuran (THF) underwent intramolecular cyclization to afford 76. The 1,2,5-thiadiazepines 73 and 74 were then heated with an excess of concentrated ammonium hydroxide to give the carboxamide 77. The acid 75 upon reaction with 4-chlorophenol, 4-chlorobenzyl alcohol, or 4-chloroaniline in the presence of iV-(3-dimethylaminopropyl)-iV -ethylcarbodiimide hydrochloride (EDCI) and 4-dimethylaminopyridine (DMAP) afforded the respective esters and amide 78-80 <1996FES425>. 

Small Quantities. To 9 mg of 4,4 -methyleneA/s-(2-chloroaniline), add 10 mL of 0.1 M hydrochloric acid (prepared by slowly adding 1 mL of concentrated acid to 119 mL of cold water). Mix to dissolve. Add 5 mL of 0.2 M potassium permanganate solution (0.3 g of solid potassium permanganate dissolved in 10 mL of water) and 5 mL of 2.0 M sulfuric acid (prepared by cautiously adding 1 mL of concentrated acid to 8 mL of cold water). Mix and let stand overnight (at least 10 hours). Decolorize if necessary with sodium metabisulfite or ascorbic acid. Neutralize by careful addition of 5 M sodium hydroxide solution (20 g of NaOH dissolved in 100 mL of cold water). Wash the remaining solution into the drain.6... 

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). ... 

Many trial-and-error experiments can be avoided during the development of a displacement chromatographic separation, when the isotherm of at least the most strongly adsorbed sample component is known. Therefore, as the next step, the adsorption isotherms of the most retained iscmers of chloroaniline and Ibuprofen, the examples discussed above, were determined as shown in Figs. 8 and 9. It can be seen by cxnparing the isotherms of the solute and prospective displacer pairs that indeed p-nitrophenol can be used as a displacer for the separation of the chloroaniline iscmers. The situation is more complicated with Ibuprofen and 4-t-butylcyclchexanol because their isotherms cross each other at 1.5 irM. This indicates that successful separations can be expected only below this concentration level. Other examples of crossing isotherms were also reported (69). 

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