Gels, chromonics

Aloe is a medicinal plant that has been used since ancient times by cultures in many countries and continents for many of the same applications. Africa is blessed with a wide variety of Aloe spp. each used by the indigenous cultures. Fleshy leaves are the source of two of the main products, gel and latex, with both products showing distinct differences in their chemical composition. Chemical composition of gel consists mainly of water with carbohydrate polymers and a range of other organic and inorganic components. In contrast, the chemical composition of the latex includes many phenolic compounds such as anthraquinones and chromones. The objective of this paper is to review the the botany, chemistiy and pharmacological properties of Aloes from Africa. 

Both flavanones and 2 -hydroxychalcones are oxidised to flavones in the absence of solvent by In salts supported on silica gel <05TL253> and the former also by Mn(OAc)3 <05SC2723>. Various 3-(perhaloacyl)chromones, which exist as a mixture with their covalent hydrates, have been obtained from 2-hydroxy-2-(perhaloalkyl)chroman-4-ones on heating with the formylating agent, diethoxymethyl acetate <05SL1164>. 

The addition of NaCl to the DSCG/ water phase diagram has been described by Yu and Saupe [45]. The general effect is to move the phase boundaries upwards and to the left, i.e., a sample that would otherwise have been in the N phase will tend towards the M or M + I. In the dye industry, the final products are usually salted out and therefore tend to contain large quantities of salt. This reduces the solubility of the dye and can turn a respectable mesophase into a curdled gel. As might be expected, if the chromonic species is anionic like DSCG, the cation... 

The isoflavones were more easily sulfonated than the corresponding flavones and, as with chromones, the 5-hydroxyflavones were more reactive towards sulfonation than the 7-hydroxy analogues. A solution of chlorosulfonic acid in chloroform (4 1) is used as a spray reagent in TLC for detection of coumarins and flavanoids in silica gel G plates. ... 

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