Thin-layer chromatography acids using

Baker Chemical Co. Molinate sulfoxide was prepared by reacting [ring- Cjmolinate with equimolar m-chloroperbenzoic acid in chloroform (10). The product was puriTied by preparative thin-layer chromatography (TLC) using acetone hexane (1 1) as the developing solvent. The final radiopurity was 98%,... 

Form T2,2, 5/,2"-terthiophene (349 pmol) and 3,3 -di-n-butyl-4,4 -dimethyl-2,2 -dipyrrylmethane (349 pmol) were dissolved in 35 ml CH2C12 at ambient temperature and then treated with 26.9 jjlL of trifluoroacetic acid. At the first sign of baseline material by thin-layer chromatography (TLC) using silica gel and CH2CI2, the reaction was quenched by adding 52.2 p,L of DBU and p-chloranil (873 pmol) and the solution stirred for 4 hours at ambient temperature. The mixture was then treated with 36p,L of triethylamine and stirred for 1 hour. Excess triethylamine (5.190 mmol) was then added and mixture stirred for 15 minutes. The reaction mixture was then precipitated in methanol and 76.9 mg product isolated as a brownish-purple solid. 

Thin layer chromatography is used for the analysis of free amino acids from sanguine plasma in different progression states in maladies diabetes, renal syndrome, and hepatic cirrhosis.Elution was performed on cellulose plates and the densitometry was achieved with a photodensitometer (Shimadzu CS-9000) at 575 nm. In the case of hepatic cirrhosis, a better resolution was obtained. A mixture of w-butanol-acetone-acetic acid-water (35 35 7 23 vol/vol/vol/vol) was used as the mobile phase. 

Figure 1.1 Separation of complex standard lipid mixtures on a 20 cm x 20 cm high-performance thin-layer chromatography plate using four developments. The first development was up to a distance of 5 cm above the origin in the solvent system ethyl acetate/1-propanol/chloroform/ methanol/0.025% KCl, 25 25 25 10 9 vol./vol. The second development was up to 8 cm above the origin in the solvent system toluene/ether/ethanol/acetic acid, 60 40 1 0.23 vol./vol. The third development was to the full length (9 cm) in the solvent system hexane/diethyl ether, 94 6 vol./ vol., followed by the last development to full length in hexane. The plates were freed of solvent between developments by blowing with hot air. Reproduced with permission from Yao, J. K. and Rastetter, G. M., Microanalysis of complex tissue lipids by high-performance thin-layer chromatography, Analytical Biochemistry, 150, 111-16.

Si02 HNO3 is prepared by treatment of silica gel with nitric acid. In the experiment, phenol is nitrated to produce a mixture of products. Thin-layer chromatography is used to analyze the mixture, and the ortho and para nitrated phenols are separated by column chromatography using a silica gel column. If unreacted phenol is detected in the TLC analysis, an extraction technique is used to separate it from the para isomer. This separation technique is based on the fact that a nitrated phenol is more acidic than phenol itself. 

Amino acids differ characteristically from one another depending mainly on the character of the amino group. Aliphatic amino acids are essentially different from those amino acids whose amino group is bound to an aromatic nucleus. Aromatic amino acids usually do not present a problem of identification, and methods described for the identification of amino compounds can well be used in this case too (p. 326). Characteristic representatives of aliphatic amino acids are a-amino acids obtained on hydrolysis of proteins. a-Amino acids are nonvolatile, water-soluble compounds, melting usually above 200 °C and over a pretty wide interval. Therefore, the melting point of an amino acid cannot be considered as a suitable identification constant, and it must always be compared with an authentic sample, or the influence of the rate of heating on its value must be checked. This property is ascribed to the dipolar character of the molecule, NH3 — CHR—COO". It is important to stress that paper or thin-layer chromatography is used for the reliable identification of amino acids. 

Techniques for thin-layer chromatography jnay use similar solvent systems with either microcrystalline cellulose or silica gel being favoured. Additional solvent systems, for example benzene/methanol/acetic acid or pyridine/ethyl acetate/acetic acid/water are particularly useful for silica gel chromatography. Detailed descriptions of the technique have appeared elsewhere (Bobbit, 1963 Randerath, 1968 Stahl, 1969 Smith and Seakins, 1976), the latter containing a particularly good up-to-date account of the apparatus, materials and techniques used. The use of the technique is particularly facilitated by the availability of ready-prepared plates. 

The nitration of the 2-anilino-4-phenylselenazole (103) is much more complicated. Even careful nitration using the nitrate-sulfuric acid method leads to the formation of a mixture of variously nitrated compounds in an almost violent reaction. By the use of column chromatography as well as thin-layer chromatography a separation could be made, and the compounds could be partly identified by an independent synthesis. Scheme 33 shows a general view of the substances prepared. Ring fission was not obser ed under mild conditions. 

To determine the phosphoHpid and fatty acid compositions chromatographic methods (28) like gas chromatography (gc), thin-layer chromatography (tic), and high performance Hquid chromatography (hlpc) are used. Newer methods for quantitative deterrnination of different phosphoHpid classes include P-nmr (29). 

Finally, the techniques of nmr, infrared spectroscopy, and thin-layer chromatography also can be used to assay maleic anhydride (172). The individual anhydrides may be analyzed by gas chromatography (173,174). The isomeric acids can be determined by polarography (175), thermal analysis (176), paper and thin-layer chromatographies (177), and nonaqueous titrations with an alkaU (178). Maleic and fumaric acids may be separated by both gel filtration (179) and ion-exchange techniques (180). 

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). 

Thin-Layer Chromatography (tic). Tic (126) is used widely for quahtative analysis and micro-quantity separation of amino acid mixtures. The amino acids detected are developed by ninhydrin coloring, except for proline and hydroxyproline. Isatia has been recommended for specific coloring of pToline (127). 

Chemical stabiUty studies are monitored by siUca gel thin-layer chromatography (dc) or by high performance Hquid chromatography (hplc) using a reverse-phase C g coated column (24). Hplc peaks or dc spots are visualized by thek uv absorption at 245 nm the tic spots can also be detected by ceric sulfate or phosphomolybdic acid staining. 

Thin-Layer Chromatography TLC) The function of TLC in organic synthesis is primarily one of allowing the experimenter to follow the progress of the reaction without actually interrupting the reaction. Since successful TLC can be carried out on a minute scale, only a very small fraction of the reaction mixture need be withdrawn and subjected to analysis. The following example of the TLC analysis of the chromic acid oxidation of borneol, described by Davis (3), is a useful model. 

Thin layer chromatography of (-)-DAG on Silica Gel G using the solvent system, benzene methanol acetone acetic acid (70 20 5 5), shows one spot with Rf 0.7. 

Olefins, sultones, alkanes, and alkenesulfonates may be separated by liquid chromatography on silica gel using hexane, trichloromethane-hexane, ethanol-dime thy lcarbonate, and ethanol-ammonium hydroxide as the eluents. Pueschel and Prescher [110] achieved the separation of alkene-1,4-sultone and alkene-1,3-sultone from each other and from other sulfonic acid esters in AOS by thin-layer chromatography on silica gel G with 4 1 diethylcarbonate-ligroine as the... 

Amino Acids, Thin-layer chromatography has found wide application in the clinical chemistry laboratory. An application that is practicable in the Laboratory of Neonatology is the screening of serum and urine for the amino acidopathies. In order to do this we use a micro ultrafiltering apparatus which has been designed in our laboratory (37). This is seen in Figure 29. 

The alcoholysis and transamination of various aminophosphines have been studied as functions of the basicity of the attacking nucleophile and the substituents on phosphorus. As might be expected the reaction is facilitated by electron-withdrawing groups on phosphorus. The hydrolysis of tris(dimethylamino)phosphine (90) to phosphorous acid has been investigated using thin-layer chromatography and the amides (91) and (92) have been identified as intermediates. 

Chromatographic characterisation of hydrolysis products Hydrolysis products from sodium polypectate were analysed by thin-layer chromatography on silica gel G-60, using ethyl acetate / acetic acid / formic acid / water (9 3 1 4, by volume) as the mobile phase system. Sugars were detected with 0,2% orcinol in sulphuric add-methanol (10 90ml) [14]. 

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