Chromatography 1458 amines

Table 4 lists the specifications set by Du Pont, the largest U.S. producer of DMF (4). Water in DMF is deterrnined either by Kad Fischer titration or by gas chromatography. The chromatographic method is more rehable at lower levels of water (<500 ppm) (4). DMF purity is deterrnined by gc. For specialized laboratory appHcations, conductivity measurements have been used as an indication of purity (27). DMF in water can be measured by refractive index, hydrolysis to DMA followed by titration of the Hberated amine, or, most conveniendy, by infrared analysis. A band at 1087 cm is used for the ir analysis. 

Hydantoin itself can be detected ia small concentrations ia the presence of other NH-containing compounds by paper chromatography followed by detection with a mercury acetate—diphenylcarba2one spray reagent. A variety of analytical reactions has been developed for 5,5-disubstituted hydantoias, due to their medicinal iaterest. These reactions are best exemplified by reference to the assays used for 5,5-diphenylhydantoiQ (73—78), most of which are based on their cycHc ureide stmcture. Identity tests iaclude the foUowiag (/) the Zwikker reaction, consisting of the formation of a colored complex on treatment with cobalt(II) salts ia the presence of an amine (2) formation of colored copper complexes and (3) precipitation on addition of silver(I) species, due to formation of iasoluble salts at N. ... 

Analytical methods iaclude thin-layer chromatography (69), gas chromatography (70), and specific methods for determining amine oxides ia detergeats (71) and foods (72). Nuclear magnetic resonance (73—75) and mass spectrometry (76) have also been used. A frequentiy used procedure for iadustrial amine oxides (77) iavolves titratioa with hydrochloric acid before and after conversion of the amine to the quaternary ammonium salt by reaction with methyl iodide. A simple, rapid quaHty control procedure has been developed for the deterrniaation of amine oxide and unreacted tertiary amine (78). 

Contaminant by-products depend upon process routes to the product, so maximum impurity specifications may vary, eg, for CHA produced by aniline hydrogenation versus that made by cyclohexanol amination. Capillary column chromatography has improved resolution and quantitation of contaminants beyond the more fliUy described packed column methods (61) used historically to define specification standards. Wet chemical titrimetry for water by Kad Eisher or amine number by acid titration have changed Httle except for thein automation. Colorimetric methods remain based on APHA standards. 

Instmmental methods of analysis provide information about the specific composition and purity of the amines. QuaUtative information about the identity of the product (functional groups present) and quantitative analysis (amount of various components such as nitrile, amide, acid, and deterruination of unsaturation) can be obtained by infrared analysis. Gas chromatography (gc), with a Hquid phase of either Apiezon grease or Carbowax, and high performance Hquid chromatography (hplc), using siHca columns and solvent systems such as isooctane, methyl tert-huty ether, tetrahydrofuran, and methanol, are used for quantitative analysis of fatty amine mixtures. Nuclear magnetic resonance spectroscopy (nmr), both proton ( H) and carbon-13 ( C), which can be used for quaHtative and quantitative analysis, is an important method used to analyze fatty amines (8,81). 

The characterizations of MDA and PMDA are similar to those normally used for aromatic amines. In the manufacture of PMDA, the MDA isomer distribution and the formation of side products is deterrnined primarily by gas chromatography (48,49). The amine content is deterrnined by acid titration... 

Air Monitoring. The atmosphere in work areas is monitored for worker safety. Volatile amines and related compounds can be detected at low concentrations in the air by a number of methods. Suitable methods include chemical, chromatographic, and spectroscopic techniques. For example, the NIOSH Manual of Analytical Methods has methods based on gas chromatography which are suitable for common aromatic and aHphatic amines as well as ethanolamines (67). Aromatic amines which diazotize readily can also be detected photometrically using a treated paper which changes color (68). Other methods based on infrared spectroscopy (69) and mass spectroscopy (70) have also been reported. 

The assay of ethyleneamines is usually done by gas chromatography. Compared to packed columns, in which severe tailing is often encountered due to the high polarity of the ethyleneamines, capillary columns provide better component separation and quantification. Typically, amines can be analyzed using fused siUca capillary columns with dimethyl silicones, substituted dimethyl silicones or PEG Compound 20 M as the stationary phase (150). 

Determination of ethyleneamines in air can be accomplished by absorbing the amines on NITC (1-naphthyl isothiocyanate) treated XAD-2 resin, then desorbing the derivative from the treated tubes and quantifying the amount using high performance Hquid chromatography (hplc). Sensitivity is reported as 0.37 and 0.016 mg/m for EDA and DETA, respectively, pet sample (153,154). 

In recent years the solid-phase hydrosilylation reaction was successfully employed for synthesis of hydrolytically stable surface chemical compounds with Si-C bonds. Of special interest is application of this method for attachment of functional olefins, in particular of acrolein and some chiral ligands. Such matrices can be used for subsequent immobilization of a wide range of amine-containing organic reagents and in chiral chromatography. 

This ester is formed by standard procedures and is readily cleaved with Pd(Ph3P)4 in CH2CI2 to form trimethylsilyl esters that readily hydrolyze on treatment with water or alcohol or on chromatography on silica gel (73-98% yield). Amines can be protected using.the related carbamate. ... 

The diphenylmaleimide is prepared from the anhydride, 33-87 % yield, and cleaved by hydrazinolysis, 65-75% yield. It is stable to acid (HBr, AcOH, 48 h) and to mercuric cyanide. It is colored and easily located during chromatography, and has been prepared to protect steroidal amines and amino sugars. " ... 

Protamine kinase (from rainbow trout testes) [37278-10-7] [EC 2.7.1.70]. Partial purification by hydoxylapatite chromatography followed by biospecific chromatography on nucleotide coupled Sepharose 4B (the nucleotide was 8-(6-aminohexyl)amine coupled cyclic-AMP). [Jergil et al. Biochem J139 441 1974.]... 

Additional evidence that a dynamic equilibrium exists between an enamine, N-hemiacetal, and aminal has been presented by Marchese (41). It should be noted that no acid catalysts were used in the reactions of aldehydes and amines discussed thus far. The piperidino enamine of 2-ethylhexanal (0.125 mole), morpholine (0.375 mole), and p-toluene-sulfonic acid (1.25 x 10 mole) diluted with benzene to 500 ml were refluxed for 5 hr. At the end of this time the enamine mixture was analyzed by vapor-phase chromatography, which revealed that exchange of the amino residue had occurred in a ratio of eight morpholine to one piperidine. Marchese proposed a scheme [Eqs. (4), (5) and (6)] to account for these... 

L. A. Holland and J. W. Jor genson, Separ ation of nanoliter samples of biological amines by a comprehensive two-dimensional microcolumn liquid chromatography system . Anal. Chem. 67 3275-3283 (1995). 

Figure 12.12 Coupled SEC-RPLC separation of Plioflex rubber stock (a) SEC (b) RPLC ti ace of fraction 1, Wingstay 100 (Eive-peak pattern is representative of diarylphenylenedi-amine isomers) (c) RPLC ti ace of fraction 2, mixed disulfide and MBTS (2,2 -thiobis (ben-zothiazole)). Obtained under the same conditions as given for Eigure 12.11. Reprinted from Journal of Chromatography, 149, E. L. Johnson et al, Coupled column chromatography employing exclusion and a reversed phase. A potential general approach to sequential analysis , pp. 571-585, copyright 1978, with permission from Elsevier Science.

A mixture of 2.3 parts of 2-(4-methoxyphenyl)ethyl methanesulfonate, 4.9 parts of 1-[(4-fluorophenyOmethyl] -N-(4-piperidinyl)-1H-benzimidazol-2-amine dihydrobromide, 3.2 parts of sodium carbonate, 0.1 part of potassium iodide and 90 parts of N,N-dimethylformamide is stirred overnight at 70°C. The reaction mixture is poured onto water. The product is extracted with methylbenzene. The extract is washed with water,dried, filtered and evaporated. The residue is purified by column-chromatography over silica gel using a mixture of trichloro-methane and methanol (98 2 by volume) as eluent. The pure fractions are collected and the eluent is evaporated. The residue is crystallized from 2,2 -oxybispropane, yielding 2.2 parts (48%) of 1 -(4-fluorophenvlmethyl)-N-[1 - [2-(4-methoxvphenyl)ethvl] -4-piperidinyl] -1H-benzlmidazol-2-amine MP 149.1°C. 

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