Borate, impregnation with

However, the hydrogenation catalysts can be promoted also by compounds which are ineffective for the iron ammonia catalysts, e.g., by silica and silicates, silicofluorides, borates, and phosphates. An interesting type of hydrogenation catalysts was found in the form of zeolites which by ion exchange were impregnated with heavy metal salts. 

The hepatopancreas of H. schlegelii was found to contain an unusual cerebroside, a mannosylceramide, isolated from the monohexosylceramide fraction by t.l.c. on borate-impregnated silica gel.265 Its structure was shown to be /3-D-mannosylceramide, whose major sphingosine base is 4-sphingenine, and the fatty acids constitute a mixture of normal (77% of the total acids) and a-hydroxy acids, with hexadecanoic acid preponderant (43.7% of the total acids).265... 

Sfiica impregnated with saturated and unsaturated hydrocarbons (squalene, paraffin oil), silicone and plant oils, complexing agents (silver ions, boric add and borates, unsaturated and aromatic compounds), tigands (EDTA, digitonin), and transition metal salts silanized silica gel impregnated with anionic and cationic surfactants Cross-linked, polymeric dextran gels (Sephadex)... 

A variety of methods have been described for the separation of molecular species of sphingomyelin and glycosphingolipids. Silica gel TLC systems impregnated with sodium arsenite, sodium borate or silver nitrate have been used for different purposes. Most information is available on ceramide separations... 

Ktj era [55] has separated several diols on alumina layers. He used layers impregnated with 3% ammonium borate solution in order to separate the 1,2-diols from other glycols. Silver nitrate solution was used for visuahsation. TLC-separation of stereoisomeric diols also has been achieved by Fischer and Koch [30] on layers of fibrous alumina. 

An additional challenge of biomedical applications of TLC relate to the separations of cyclic nucleotides from noncyclic phosphates. Potter and Yamazaki (48) employed alumina TLC and ammonium acetate pH with ammonium hydroxide to effect these separations. Hynie (49) separated 3 S cGMP using borate impregnated silica in butanol-methanol-ethyl acetate-ammonium hydroxide. Tomasz (SO) separated cyclic pyr/purines on cation exchange, pretreated with HCI, as opposed to the popular anion (PEI) systems. The run with 0.05 M oxalic acid is appealing. 

Figure 8.12. Schematic separation of ceramides by TLC on layers of silica gel G, impregnated with 2 % sodium arsenite (plate A) and 2 % sodium borate (plate B), using a solvent system of chloroform-methanol (95 5, v/v) for development [467], Abbreviations na, normal fatty acid ha, hydroxy fatty acid db, dihydroxy base tb, trihydroxy base sat, saturated.

Chromatographic separation was carried out on silica gel plates and cellulose plates impregnated with sodium borate (B). The experiments revealed that borate complexes of AA and DHAA could be separated from each other. TLC was also attempted using direct (D), reverse-phase (RP), and reverse-phase sodium borate (RP-B) TLC plates with and without metaphosphoric acid (MPA). A good separation of the three AA isomers and DHAA isomers was achieved on D and RP cellulose plates. Using an RP-silica-MPA plate, the three A A isomers as well as the three DHAA isomers were fairly separated from their own group members. The separation of six stereoisomers, three AA, and three DHAA was achieved using D-cellulose-MPA plate. 

Silica gel was coated on inert flexible poly(ethyleneterephthalate) to 100 pm thickness. Polyacrylic was used as a binder in these plates. Cellulose plates were coated to a 160 pm thickness without binder on inert flexible ester base. Impregnation with B was accomplished by uniformly spraying a 3% B solution on silica gel or cellulose plates. The plates were air-dried and then heated to 100°C for 20 min. For RP-TLC the dried silica gel, cellulose, or borate plates were uniformly impregnated with silicone oil by allowing a 5% solution... 

Sato et al. [195] have studied the surface borate structures and the acidic properties of alumina-boria (3-20 wt.%) catalysts prepared by impregnation method using B(MAS)-NMR measurements and TPD of pyridine, as well as their catalytic properties for 1-butene isomerization. The number of Brpnsted acid sites was found to increase with increasing boria content, and the catalytic activity was explained by the strong Brpnsted acid sites generated by BO4 species on the surface of alumina. 

With both the borate- and phosphate-impregnated rayon, the mesoporosity appears to be developed independently of the inherent microporosity and not as the result of... 

The use of silica gel TLC plates (impregnated or not with arsenite) allows the separation of ceramide species into different groups of relative structural homology. This is based on the position and numbers of hydroxyl groups on the ceramide molecules. However, TLC allows a possible further fractionation of ceramide species according to the unsaturation of sphingoid bases or fatty acids. This is made possible by the impregnation of the silica gel plates with borate and silver nitrate. 

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