Amines separation

Into a 750 ml. round-bottomed flask furnished with a reflux condenser place a solution of 34 g. (18-5 ml.) of concentrated sulphuric acid in 100 ml, of water add 33 g. of di-n-butyl cyanamide and a few fragments of porous porcelain. Reflux gently for 6 hours. Cool the resulting homogeneous solution and pour in a cold solution of 52 g. of sodium hydroxide in 95 ml. of water down the side of the flask so that most of it settles at the bottom without mixing with the solution in the flask. Connect the flask with a condenser for downward distillation and shake it to mix the two layers the free amine separates. Heat the flask when the amine with some water distils continue the distillation until no amine separates from a test portion of the distillate. Estimate the weight of water in the distillate anp add about half this amount of potassium hydroxide in the form of sticks, so that it dissolves slowly. 

In order to obtain a pure product the amine is dissolved in about 700 cc. of boiling ethyl acetate under a reflux condenser. When the amine has dissolved the solution is rapidly cooled and stirred, whereupon the amine separates in almost white crystals. Further crops of crystals may be obtained on concentrating the solution and cooling. The last portions may be colored, hut one... 

The mixture may be allowed to stand for a longer period (overnight) without harm. Frequently a granular precipitate of a tin complex of the amine separates. 

Sadain, S. K. and Koropchak, J. A., Condensation nucleation light scattering detection for biogenic amines separated by ion-exchange chromatography, /. Chromatogr. A, 844, 111, 1999. 

DIBENZOCYCLOHEPTANES AND DIBENZOCYCLOHEPTENES Drugs in this structural class have effected a revolution in the treatment of severely depressed patients such that deinstitutionalization is a feasible public policy. The compounds often show other CNS activities which depend on the length of the side chain. One-carbon chains generally lead to anticonvulsant activity amines separated from the nucleus by three carbons usually donvey antidepressant activity. Selected examples possess significant anticholinergic activity. 

FIGURE 1.55 Structures of primary, secondary, tertiary, and quaternary amines separated on strata-X-CW. 

The proton-transfer behaviour of [47] differs in one important respect from that of the other proton sponges. It is found that the rates of equilibration of the protonated amine with the free amine in mixtures of the two in [ Hg]Me2SO at 30°C is fast on the nmr timescale and averaged proton signals are observed (Zirnstein and Staab, 1987). For mixtures of [33] and the free amine, separate proton signals are observed. Quantitative information about the extent to which the rates of proton transfer for [47] differ from those of the other proton sponges must await detailed kinetic studies. 

Hofmann amine separation org chem A technique to separate a mixture of primary, secondary, and tertiary amines they are heated with ethyl oxalate there is no reaction with tertiary amines, primary amines form a diamide, and the secondary amines form a monoamide when the reaction mixture is distilled, the mixture is separated into components. haf-mon am,en, sep-3,ra-sh3n ... 

It is used in IC systems when the amperometric process confers selectivity to the determination of the analytes. The operative modes employed in the amperometric techniques for detection in flow systems include those at (1) constant potential, where the current is measured in continuous mode, (2) at pulsed potential with sampling of the current at dehned periods of time (pulsed amperometry, PAD), or (3) at pulsed potential with integration of the current at defined periods of time (integrated pulsed amperometry, IPAD). Amperometric techniques are successfully employed for the determination of carbohydrates, catecholamines, phenols, cyanide, iodide, amines, etc., even if, for optimal detection, it is often required to change the mobile-phase conditions. This is the case of the detection of biogenic amines separated by cation-exchange in acidic eluent and detected by IPAD at the Au electrode after the post-column addition of a pH modiher (NaOH) [262]. 

Technology development and cost reduction of COj capture using oxy-fuel combustion and amine separation ... 

Acid-treated clays Alcylation reactions (e.g. of benzene with benzyl chloride) Dimerization reactions (e.g. of a-methylstyrene) Etherification reactions (e.g. of ferf-butanol with methanol) Condensation reactions (e.g. of cyclohexanone) Separation of close boiling aromatic amines Separation of isomers of xylene... 

Moore, F.L. Liquid-liquid extraction of uranium and plutonium from hydrochloric acid solution with tri(iso-octyl)amine Separation from thorium and fission products, Anal. Chem. 30(1958) 908-911. 

Electron transfer in acetonitrile has to occur over a distance greater than the van der Waals radii, because electron transfer happens before the rise of the CIP. First, the SSIP is formed from benzophenone and the amine, separated at least by the encounter distance of 700 pm [21], which afterwards collapses to the CIP. 

According to these results, a recommendation was made to conduct the AIX separations in pure HC1 or HF solutions to try to observe the predicted sequence, Equation 32. Accordingly, the amine separations of the group-5 elements were systematically redone by W. Paulus et al. [177]. The reversed extraction sequence Pa > Nb > Db > Ta has been established exactly as theoretically predicted. That was the first time when predictions of extraction behavior of the heaviest elements based on quantum-chemical calculations were made, and also confirmed by specially designed experiments. 

Amines have also been microencapsulated within small cellulosic or polyelectrolyte capsules. This is a method for keeping the amine separate from the epoxy resin during storage. When the user decides to initiate cure, the capsules are broken, usually in the application process, and the amine is free to react with the epoxy resin. A successful example of this type of product is an epoxy adhesive that can be preapplied to machine screw threads. When the screw is ultimately threaded into place, the shearing action causes the capsule to break. Bond strengths are generally low for this type of adhesive, but this may not be important in certain applications. 

FIGURE 5-27. Effect of column surface upon retention of organic amines ( ) separation on a fully coated C]8 column, (b) Separation on a column with 50% coating level of C18. (c) Separation on a column of silica. The mobile phase is acetonitrile/ water (60 40) with 4 mM dibasic ammonium phosphate (pH 7.8). The sample components are (1) benzocaine, (2) lidocaine, (3) etidocaine, and (4) tetracaine. (Reprinted from reference 4 with permission.)... 

Lehtonen - used molecular connectivity indices to correlate chromatographic parameters with molecular structure for n-ethylbenzamides, amines, and dansyl-amines separated by HPLC. The best regression equation for 22 isolated amines from wines is ... 

---