Amines fractionation

After standing about three hours, the diphenylamine hydrochloride is filtered and washed with benzene (Note 10). The benzene is distilled from the filtrate (Note n) and the residual triphenylamine is transferred to a 500-cc. modified Claisen flask (Org. Syn. 1, 40) and distilled under reduced pressure. The first fraction consists of some benzene, then the temperature rises rapidly and a few cubic centimeters of deeply colored distillate comes over just before the amine fraction, which is collected at i95-205°/io-i2 mm. The distillate is a yellow liquid which soon solidifies to a light yellow solid. The side arm of the distilling flask should be of rather large bore (about 10 mm.) to prevent clogging by the amine which solidifies. The crude product weighs 220-235 g. and melts at 120-124°. 

Owing to the formation of neutral side products, the reaction mixture is extracted with excess 4 N hydrochloric acid, and the mixture of amines is liberated from the acid solution by neutralization with sodium hydroxide. The amine fraction is taken up in ether and dried over anhydrous sodium sulfate or solid sodium hydroxide. After removal of the ether, the 2,3-dimethylbenzyl-dimethylamine distils at 101—102°/15 mm., 107-109°/19 mm., no 1.5100-1.5102. The yield is 60-70%. 

The chemical resolution process of Scheme 6 was developed into an economically favorable one by the ready recycle of both the FPA resolving agent and the combined (mostly S) amine fractions. FPA, which was prepared by methyl formate reaction with L-phenylalanine, was shown to be stable (no racemization and no hydrolysis) when the resolution and work-up processes were conducted within the pH range of 2-12 at temperatures below 25°C (higher temperatures were not studied). FPA meeting specification was isolated in yields of ca. 95% by simple acidification of its aqueous salt solutions and filtration. 

Eudragit RL and RS are not soluble at any pH because the quaternary amine fraction is very small when compared to that of methyl methacrylate. Since the functional group is quaternary amine, the polymer swells in water, regardless of pH. As a result, water and drug molecules permeate in... 

Figure 16. Primary vs. tertiary amine, fractional changes for varying stoichiometries (O) 1.0 1.0, epoxy amine 1.0 2.0, epoxy amine 1.0 3.0, epoxy amine...

For workup the reaction mixture is cooled to 0 C, 50 mL of CH3OH are added, and the mixture is refluxed for 2 h. The solvent is evaporated, and the viscous residue treated with 15 mL of 20 % aq HCI at 0 "C and shaken with 30 mL of El20. The ethereal layer is washed with 15 mL of water and discarded. The combined aqueous phases are rendered alkaline at 0 °C by addition of 15 mL of aq KOH. The amine fraction which separates on the surface is extracted with 50 and then 30 mL of Et20. The combined ethereal extracts arc dried with anhyd MgSO,. After evaporation of the solvent the product is distilled in vacuo using a microdistillation apparatus. The enantiomeric composition is determined by GLC analysis (fused silica Chirasil-t.-Val column). 

The sources of amines included Geigy, Dow, Union Carbide, Jefferson Chemical, Ames Laboratories, and Matheson Coleman and Bell. Tertiary amines were generally obtained by N-permethylation of the corresponding technical-grade amine fraction using common techniques (16). 

Treatment of 3,4-dihydro-6,7-dimethoxyisoquinoline hydrochloride with an excess of ethyl vinyl ketone gave the epimers (30) and (31) in variable proportions, depending on the pH of the reaction medium.0-Methylpeyoxylic acid (32 R = H) and 0-methylpeyoruvic acid (32 R = Me) have been prepared and identified as constituents of the amine fraction of peyote. Acylation of 3,4-dimethoxyphenylpyruvic acid with anhydrides in the presence of perchloric acid yielded 2-benzopyrylium perchlorates (33), which were transformed into the corresponding isoquinolines (34) with ammonium acetate in glacial acetic acid. ... 

To be able to select a crystallization temperature in the single liquid phase region at a given amine fraction, the liquid-liquid equilibrium lines of the amine-water-NaClsat systems were determined. To establish to what extent an antisolvent reduces the sodium chloride solubility and to calculate the maximum obtainable magma densities during crystallization, sodium chloride solubilities in the amine-water mixtures were measured. Finally continuous crystallization experiments were carried out and the feasibility of an antisolvent recovery by a temperature increase was investigated. 

A separation similar to the above can be based upon the reaction of the amines with phthalic anhydride, cf. page 62. A more common procedure consists in the treatment of the amine fraction with acetic anhydride, the separation of the tertiary amines by moans of dilute acid and separation of the acetyl derivatives of the remaining members by crj stallization. 

Figure 8 Positive ion eiectrospray spectrum of tetramethylammonium ions produced by quaternization of trimethylamine (TMA) excreted by a patient with trimethylaminuria. When the amine fraction is quatemized with pHsJmethyl iodide, endogenous TMA is measured at mlz77, while the [ N]TMA internal standard is measured at mlz7S. The ion signal at miz74 is unlabelled tetramethylammonium produced endogenously, which would interfere with the analysis if unlabelled methyl iodide were used for quaternization.

It is prepared by the direct chlorination of toluene in the presence of PClj. It is purified by fractionation from the unchanged toluene and the higher chlorinated products. It is used for benzylating amines and for preparing benzyl alcohol. 

If pure 3-bromo-4-aminotoluene is required, the crude base may be purified either by steam distillation or, more satisfactorily, by distillation under reduced pressure. The oil is dried with 5 g. of sodium hydroxide pellets, and distilled under reduced pressure from a Claisen fiask with a fractionating side arm a little p-tolui-dine may be present in the low boiling point fraction, and the pure substance is collected at 92-94°/3 inin. or at 120-122°/30 mm. The purified amine solidifies on cooling and melts at 17-18°. 

They are actually using crystallization to purify the amine from any non-amine contaminants. They later freebased the crystals and fractional distilled to get pure amphetamine with a yield of 50%. 

Bio-Rex 70 2.4 0.70 Weakly acidic cation exchanger with car-boxylate groups on a macroreticular acrylic matrix for separation and fractionation of proteins, peptides, enzymes, and amines, particularly high molecular weight solutes. Does not denature proteins as do styrene-based resins. 

Isolates from Indian tobacco Q obelia inflata L.), as a cmde mixture of bases, have been recognized as expectorants. The same (or similar) fractions were also used both in the treatment of asthma and as emetics. The principal alkaloid in T. inflata is lobeline (49), an optically active tertiary amine which, unusual among alkaloids, is reported to readily undergo mutarotation, a process normally associated with sugars. Interestingly, it appears that the aryl-bearing side chains in (49) are derived from phenylalanine (25, R = H) (40). 

The fine mica fraction is deslimed over 0.875—0.147-mm (80—100-mesh) Trommel screens or hydrocylcones, or is separated with hydrosi2ers. The deslimed pulp (<0.589 mm (—28 mesh)) of mica, feldspar, and quart2 is then fed to a froth flotation circuit where these materials are separated from each other either by floating in an acid circuit with rosin amine and sulfuric acid (2.5—4.0 pH), or an alkaline circuit (7.5—9.0 pH) with tall oil amine, goulac, rosin amine acetate, and caustic soda (see Eig. 2). 

Reductive alkylations and aminations requite pressure-rated reaction vessels and hiUy contained and blanketed support equipment. Nitrile hydrogenations are similar in thein requirements. Arylamine hydrogenations have historically required very high pressure vessel materials of constmction. A nominal breakpoint of 8 MPa (- 1200 psi) requites yet heavier wall constmction and correspondingly more expensive hydrogen pressurization. Heat transfer must be adequate, for the heat of reaction in arylamine ring reduction is - 50 kJ/mol (12 kcal/mol) (59). Solvents employed to maintain catalyst activity and improve heat-transfer efficiency reduce effective hydrogen partial pressures and requite fractionation from product and recycle to prove cost-effective. 

Isomer separation beyond physical fractional crystallization has been accompHshed by derivatization using methyl formate to make /V-formyl derivatives and acetic anhydride to prepare the corresponding acetamides (1). Alkaline hydrolysis regenerates the analytically pure amine configurational isomers. 

The polyamide copolymer of dodecanoic acid with methylenedi(cyclohexylamine) (MDCHA, PACM) was sold as continuous filament yam fiber under the tradename QIANA. As late as 1981, over 145,000 t was produced using high percentages, typically 80%, of trans, trans MDCHA isomer. The low melting raffinate coproduct left after t,t isomer separation by fractional crystallisation was phosgenated to produce a Hquid aUphatic diisocyanate marketed by Du Pont as Hylene W. Upon terrnination of their QIANA commitment, Du Pont sold the urethane intermediate product rights to Mobay, who now markets the 20% trans, trans—50% cis, trans—30% cis, cis diisocyanate isomer mixture as Desmodur W. In addition to its use in polyamides and as an isocyanate precursor, methylenedi (cyclohexyl amine) is used directiy as an epoxy curative. The Hquid diamine mixture identified historically as PACM-20 is marketed as AMICURE PACM by Anchor Chemical for performance epoxies. 

Carbonyl sulfide occurs as a by-product ia the manufacture of carbon disulfide and is an impurity ia some natural gases, ia many manufactured fuel gases and refinery gases, and ia combustion products of sulfur-containing fuels (25). It tends to be concentrated ia the propane fraction ia gas fractionation an amine sweetening process is needed to remove it. 

Although pH determines the ratio of hypohalous acid to hypohaUte ion, the fraction of the total available halogen present as HOX is dependent on of the halamine as well as the concentration of excess amine. In the case of chloroisocyanurates, which are the most widely used /V-ch1oramine disinfectants in swimming pools and spas, the extent of hydrolysis at 1 ppm av CI2 (as monochloroisocyanurate) is - 34% but only - 1% when 25 ppm cyanuric acid is added (4). Nevertheless, effective disinfection can stiU occur with chloroisocyanurates if a sufficient FAC is maintained, eg, 1—3 ppm. The observed reduction in disinfection rate because of cyanuric acid (6) has been shown to be direcdy related to the concentration of HOCl formed by hydrolysis of chloroisocyanurates (10). 

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