急问二氯甲烷除水方法？ 见purification of laboratory chemicals p195 dichloromethane shaken with portions of conc. h2so4 until the acid layer remained colourless,then washed with water, aqueous 5% na2co3, nahco3 or naoh, then water again. pre-dried with cacl2, and distd from caso4,cah2 or p2o5. stored away from bright light in a brown bottle with linde type 4a molecular sieves, in an atmosphere of dry n2. other purification steps include washing with aq na2s203, passage through a column of silica gel, and removal of carbonyl-containing impurities as described under chloroform. it has also been purified by treatment with basic alumina, distd, and stored over molecular sieves under nitrogen [puchot et al. j am chem soc 108 2353 1986] dichloromethane from japanese sources contained meoh as stabiliser which is not removed by distn. it can, however, be removed by standing over activated 3a molecular sieves (note that 4a sieves cause the development of pressure in bottles), passed through activated a1203 and distd [gao et al. j am chem soc 109 5771 1987] it has been fractionated through a platinum spinning band column, degassed, and distd onto degassed molecular sieves, linde 4a, heated under high vacuum at over 450 degree until the pressure readings reached the low values of10 -6 mm-1-2h [mohammad and kosower j am chem soc 93 2713 1971] rapid purification: reflux over cah 2 (5% w/v) and distil. store over 4a molecular sieve 查看更多
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