for remove undesirable ions.
I dont know the percent of ethanol and water or if they mixed together or not?
Dear Shirin,
We wash the end product during chemical synthesis, to eliminate or wash out the impurities. The impurities mean undesired reactants or by-products, which are left unreacted or made as side products, while we synthesize something. If an author say, wash with water and ethanol that means you first wash the end product with water, and then with ethanol.
There are two possibilities:
Washing with water is performed to get rid of those species, which are soluble in water, and can wash out with water.
Washing with ethanol might be preferred to purify the compound/end-product/crystals from some organic species.
Anyone who performs such washing, should be careful to check whether the synthesized compound is highly soluble in water, and does it carry impurities? which are ionic in nature as well as organic molecules. In such a case, you can use the solvent mixture of ethanol and water. The ratio or percentage of mixed solvent system, depends upon the solubility of the synthesized compound, and expected impurities considering their ionic or organic nature. The ratio of ethanol should be higher than water, if the compound is greatly soluble in water, and if washing with water carries your end product significantly, for example. So it depends upon the nature of compound, its solubility, impurities and their solubility.
Hope this might be helpful!
Rozina
Dr. Nasresfahani,
There are no limitations as to the quantities of water and ethanol to be used for washing. There are no limitations as to the percentages of water or ethanol in water and ethanol mixtures to be used for washing either. The goal is to wash all the undesired cations or anions out of the system you are dealing with.
Good luck
Maohong Fan
Dear Shirin,
We wash the end product during chemical synthesis, to eliminate or wash out the impurities. The impurities mean undesired reactants or by-products, which are left unreacted or made as side products, while we synthesize something. If an author say, wash with water and ethanol that means you first wash the end product with water, and then with ethanol.
There are two possibilities:
Washing with water is performed to get rid of those species, which are soluble in water, and can wash out with water.
Washing with ethanol might be preferred to purify the compound/end-product/crystals from some organic species.
Anyone who performs such washing, should be careful to check whether the synthesized compound is highly soluble in water, and does it carry impurities? which are ionic in nature as well as organic molecules. In such a case, you can use the solvent mixture of ethanol and water. The ratio or percentage of mixed solvent system, depends upon the solubility of the synthesized compound, and expected impurities considering their ionic or organic nature. The ratio of ethanol should be higher than water, if the compound is greatly soluble in water, and if washing with water carries your end product significantly, for example. So it depends upon the nature of compound, its solubility, impurities and their solubility.
Hope this might be helpful!
Rozina
The answer from Rozina is absolutely right. The situation is that the impurities are water soluble and it is removed by washing with water and then the adhering water is an impurity for the product. So it is washed with alcohol. The alcohol gets dried just by keeping the product open for some time after alcohol washing. Cases where you want to check whether moisture is completely removed or not, further tests can be conducted on the washings collected ( even anhydrous CuSO4 can be used for crude testing)
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