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Current position: Home>> News Center >> the technical development of the recrystallization of raw materials
the technical development of the recrystallization of raw materials
Veröffentlicht:2015-08-13

it is known that in the organic synthesis of recrystallization is a very simple, but also very important, which is simple and convenient, but really not easy to deformation, especially solvent, as well as in the phenomenon of it, and so have the treatment of very deep knowledge, in an article on the deformation we want to help!
the principle of
the solubility in solvents and solid mixture is closely related to the temperature. in general, the temperature is increased, the solubility erhöht.wenn the dissolution of the solid in the hot solvent is saturated due to the solubility when cooling the saturated solution and in the crystals. the purification of substances with different solubility solvent and impurities, the cleaning of materials market the solution separately. impurities and leave all or most remains in the solution (if the solubility in a solvent with minimal, saturated solution by filtration removes for cleaning).
from
assume that a solid mixture of 9.5 g of extract (0.5 g / b composition, by recrystallization in a solvent at room temperature in a and b, the solubility of the sa and sb), there are, in general, the following three conditions:
(1) impurities easily soluble at room temperature (sb) sa). the sb = 2.5 g / 100 ml at room temperature, sa = 0.5 g / 100 ml when a cook here the solubility of 9.5 g / 100 ml, 100 ml of solvent is used, the mixture in the cooks the auflösung.wenn the filtrate at room temperature cooled (without taking account of the operation of the deposition a9g losses) and b remained in the mother liquor, a loss is very small, i.e., 94% were recovered. if a solubility of these cooks 47.5 g / 100 ml 20 ml of solvent can be used if the mixture cook completely dissolved, then can be separated a9.4 g, b is in the mother cleaning materials for the 99%.
it is obvious that, if the solubility of impurities in the cold and low solubility in cold product dissolved or solvent with temperature properties, both for the recovery.
(2) the impurities are difficult to resolve (sb chang), completely can be resolved - a, b filter.
(3) the solubility are equal (sa = sb). in room temperature, the 2.5 g / 100 ml, albeit with 100 ml of solvent, pure a7 grams. but if impurities by recrystallization, product separation is difficult. the content of a and b, recrystallization for separation of the products.
overall, it is from the above discussion, in any case, a lot more content, impurities are all negative (pollution, too much impact on the crystallization speed, which prevents from).allgemeine recrystallization only suitable for cleaning impurities on 5% below the solid organic mixture.


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