Aniline separation from acetanilide

Dilute hydrochloric or sulphuric acid finds application in the extraction of basic substances from mixtures or in the removal of basic impurities. The dilute acid converts the base e.g., ammonia, amines, etc.) into a water-soluble salt e.g., ammonium chloride, amine hydrochloride). Thus traces of aniline may be separated from impure acetanilide by shaking with dilute hydrochloric acid the aniline is converted into the soluble salt (aniline hydrochloride) whilst the acetanilide remains unaffected. 

Pure samples are best prepd by the methylation of acetanilide or benzanilide to the N-methyl compds followed by acid hyd. It has been prepd commercially by the action of methyl ale on aniline in an autoclave under press and by the action of methyl amine on halobenzenes. For a summary of prepns see Refs 6 9. It may be separated from aniline and dime thy laniline by treatment of the mixt with benzenesulfonyl chloride. Dimethylamline fails to react and is extd out with dil acid. Aniline forms benzenesulfonanilide which is acidic and is removed by washing with dil base, leaving the N-methylbenzenesulfonanilide. Purified N-methylaniline is obtd by acid hyd (Ref 8). N-Methylaniline is used as an additive to raise the octane no of motor fuels (Ref 6), as a dyestuff intermediate (Ref 3), in the prepn of Tetryl (see below), and in the prepn of Methylcentralite (Encycl, Vol 2, C137-R)... 

The basicity of amines and the solubility in water of amine salts can be used to separate water-insoluble amines from water-insoluble, nonbasic compounds. Shown in Figure 23.2 is a flowchart for the separation of aniline from acetanilide, a neutral compound. 

Fig. 10. Exchange reactions. A. Between AcCoA and H-CoA. The reaction mixture contained 0.01 ml of H-CoA solution (0.027 /imole), 0.07 ml of 4 X 10 M AcCoA (2.8 nioles) prepared in water, 0.10 ml of DEAE-cellulose enzyme fraction (30 lig protein) from a rapid inactivator human and 0.8M potassium borate buffer, pH 8.0 in a total volume of 0.27 ml at 27 °. Aliquots of 0.02 ml were removed and immediately mixed with 0.05 ml of 3 X 10" M DTNB dissolved in 0.05 M sodium acetate buffer, pH 5.0 (0.15 Mmoles) at 4° to stop the reactioa Aliquots of 0.01 ml were then removed from this mixture, and the Ac- H-CoA was separated from the H-CoA on DEAE-cellulose ion-exchange paper. The Ac- H-CoA area was cut out, placed in a counting vial, eluted with 0.02 ml of 0.6 N HCl and counted. Complete reaction mixture (o) mixture without AcCoA ( ) mixture with enzyme previously inactivated b y heating at 55° for 15 min (A). B. Between H-aniline and acetanilide. The reaction mixture contained 0.005 ml of H-aniline dissolved in water (115 mC/mmole, 0.0019 /tmole), 0.20 ml of 3 X lO M acetanilide dissolved in 0.1 M sodium pyrophosphate buffer, pH 8.0 (6.0 Mmoles), 0.10 ml of DEAE-cellulose enzyme fraction from a rapid inactivator human (30 Mg protein) and 0.10 M sodium pyrophosphate buffer, pH 8.0, in a total volume of 0.305 ml at 27°. Aliquots of 0.01 ml were removed, placed on CM-cellulose strips, and treated with 0.005 ml of acetone-absolute ethanol (1 1) to stop the reaction. The H-acetanilide was separated from the H-aniline by eluting the strips with glycine buffer at pH 2.8. The H-acetanilide area was cut out, placed in a count-...

In a 500-cc. round-bottomed, three-necked flask fitted with a reflux condenser, dropping funnel, and a mercury-sealed stirrer (Note 1) is placed a solution of 46 g. (0.5 mole) of dry aniline in 125 cc. of pure dry benzene. Stirring is started, and a solution of 42 g. (0.5 mole) of ketene dimer (p. 64) in 75 cc. of pure dry benzene is added dropwise over a period of half an hour. The reaction mixture is then heated under reflux on the steam bath for one hbur. After the major portion of the benzene has been removed by distillation from the steam bath, the remainder is removed under reduced pressure. The residue is dissolved in 500 cc. of hot 50 per cent aqueous alcohol from which the aceto-acetanilide separates on cooling. The mixture is cooled to 0° before filtration. A second crop of crystals can be obtained by adding 250 cc. of water to the mother liquor and cooling again (Note 2). The total yield of product, m.p. 82-83.5°, is 65 g. (74 per cent of the theoretical amount). Further purification by recrystallization from 300 cc. of 50 per cent alcohol yields 55 g. of a product which melts at 84-85°. 

Experiment Add 1 c.c. of aniline to 1 c.c. of acetic anhydride, heat to incipient ebullition, and then, after cooling, add twice the volume of water. The crystals of acetanilide separate out easily if the walls of the vessel be rubbed with a glass rod these are filtered off, and may be recrystallised from a little hot water. 

MOFs can also be used as the stationary phase for both NP- and RP-HPLC. Fu et alP explored MIL-lOO(Fe) as a novel stationary phase for both NP and RP HPLC. Two groups of analytes (benzene, toluene, ethylbenzene, naphthalene, and 1-chloronaphthalene aniline, acetanilide, 2-nitroaniline, and 1-naphthylamine) were used to test the performance of MIL-lOO(Fe) in RP mode, whereas chloroaniline and toluidine isomers were employed to evaluate its performance in NP mode. Baseline separation of all the tested analytes was achieved on MIL-100(Fe)-packed colunm with good precision. The hydrophobic property stemmed from the aromatic ring walls of the pores in MIL-100(Fe) frameworks dominates the selective separation of neutral analytes and basic anilines in RP mode, whereas the interactions between the nitrogen atoms in the analyte and the Fe active sites in MIL-1 OO(Fe) govern the separation of chloroaniline and toluidine isomers in NP mode. The mesoporous cages, accessible windows, excellent chemical and solvent stability, metal active sites, and aromatic pore walls... 

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