Extraction acidic extractants

A.cidic Extractants. Acidic extractants, HE, react with REE according to a cation-exchange reaction ... 

Our own work in Cardiff has largely been concerned with chemotaxonomic studies of Erythrim alkaloids using GC-MS as the primary analytical technique for screening a wide range of Erythrina species. (Games et al. 1974, Barakat et al. 1977, Abdullah et al. 1979, Jackson and Chawla 1982, Jackson et al. 1982). The alkaloids occur in all parts of the plants and earlier studies in other laboratories have been carried out with roots, bark, leaves and seeds as well as whole plants. Most of our studies have been carried out with seeds, and to a lesser extent leaves. The alkaloid content has varied from 0.5—1% but is sometimes much less than 0.1%. Initial studies were usually carried out with 5—10 g samples of seeds which were extracted for alkaloids with methanol, and separated into free alkaloids or alkaloid glycoside fractions hot acidic hydrolysis of the latter then afforded a liberated alkaloid fraction. In our more recent work an initial extraction of the seeds has also been carried out with hexane to remove lipid material prior to the methanol extraction acid extraction of the hexane extract then afforded a hexane fraction with a similar pattern of alkaloids to the free alkaloids. In this way a somewhat higher recovery of alkaloids was obtained from the samples in preparative scale isolations, than by methanol extraction alone. 

M.p. 190-192 C. The enolic form of 3-oxo-L-gulofuranolactone. It can be prepared by synthesis from glucose, or extracted from plant sources such as rose hips, blackcurrants or citrus fruits. Easily oxidized. It is essential for the formation of collagen and intercellular material, bone and teeth, and for the healing of wounds. It is used in the treatment of scurvy. Man is one of the few mammals unable to manufacture ascorbic acid in his liver. Used as a photographic developing agent in alkaline solution. 

C8H10N4O2. An alkaloid occurring in tea, coffee and guarana, from which it may be prepared by extraction, It is also manufactured by the methylation of theobromine and by the condensation of cyanoacetic acid with urea. Crystallizes with H2O or anhydrous from organic solvents. M.p. (anhydrous) 235"C, sublimes at 176 C. Odourless, and with a very bitter taste. Caffeine acts as a stimulant and diuretic, and is a constituent of cola drinks, tea and coffee. 

Trichloroethanoic acid, CCI3COOH. A crystalline solid which rapidly absorbs water vapour m.p. 58°C, b.p. 196-5" C. Manufactured by the action of chlorine on ethanoic acid at 160°C in the presence of red phosphorus, sulphur or iodine. It is decomposed into chloroform and carbon dioxide by boiling water. It is a much stronger acid than either the mono- or the dichloro-acids and has been used to extract alkaloids and ascorbic acid from plant and animal tissues. It is a precipitant for proteins and may be used to test for the presence of albumin in urine. The sodium salt is used as a selective weedkiller. 

Dow process The process for the extraction of magnesium from sea-water by precipitation of Mg(OH)2 by Ca(OH)2 followed by solution of the hydroxide in hydrochloric acid. 

For chemical processes, some examples are the elimination of aromatics by sulfonation, the elimination of olefins by bromine addition on the double bond (bromine number), the elimination of conjugated diolefins as in the case of the maleic anhydride value (MAV), and the extraction of bases or acids by contact with aqueous acidic or basic solutions. 

A first operation on the crude, desalting (washing by water and caustic), extracts salts (NaCl, KCl and the MgCb that is cdn eft4rdJt6 NaCl by the caustic), reduces acid corrosion as well as it minimizes fouling and deposits. /... 

Carbon disulphide is an excellent solvent for fats, oils, rubber, sulphur, bromine and iodine, and is used industrially as a solvent for extraction. It is also used in the production of viscose silk, when added to wood cellulose impregnated with sodium hydroxide solution, a viscous solution of cellulose xanthate is formed, and this can be extruded through a fine nozzle into acid, which decomposes the xanthate to give a glossy thread of cellulose. 

This reaction is also used on a large scale, to obtain iodine from seaweed. The ash from burnt seaweed ( kelp ) is extracted with water, concentrated, and the salts other than iodides (sulphates and chlorides) crystallise out. The more soluble iodides remain and the liquor is mixed with sulphuric acid and manganese dioxide added the evolved iodine distils off and is condensed. 

Chlorine is also used in the manufacture of hydrochloric acid, the extraction of titanium, and the removing of tin from old tinplate ( de-tinning ). 

Addition of an oxidising agent to a solution of an iodide (for example concentrated sulphuric acid, hydrogen peroxide, potassium dichromate) yields iodine the iodine can be recognised by extracting the solution with carbon tetrachloride which gives a purple solution of iodine. 

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