甲醇除水。。？ 试剂纯化手册上的方法methanol [67-56-1] m 32.0, b 64.5°, d15 0.79609, d25 1.32663, n15 1.33057, n25 1.32663,pk25 15.5. almost all methanol is now obtained synthetically. likely impurities are water, acetone,formaldehyde, ethanol, methyl formate and traces of dimethyl ether, methylal, methyl acetate, acetaldehyde,carbon dioxide and ammonia. most of the water (down to about 0.01%) can be removed by fractional distn.drying with cao is unnecessary and wasteful. anhydrous methanol can be obtained from "absolute" materialby passage through linde type 4a molecular sieves, or by drying with cah2, casc 4, or with just a little moresodium than required to react with the water present; in all cases the methanol is then distd. two treatmentswith sodium reduces the water content to about 5 x 10~5%. [friedman, gill and doty j am chem soc 834050 1961.] lund and bjerrum [chem ber 64 210 7937] warmed clean dry magnesium turnings (5g) andiodine (0.5g) with 50-75ml of "absolute" methanol in a flask until the iodine disappeared and all themagnesium was converted to methoxide. up to il of methanol was added and, after refluxing for 2-3h, it wasdistd off, excluding moisture from the system. redistn from tribromobenzoic acid removes basic impurities andtraces of magnesium oxides, and leaves conductivity-quality material. the method of hartley and raikes [/chem soc 127 524 7925] gives a slightly better product. this consists of an initial fractional distn, followedby distn from aluminium methoxide, and then ammonia and other volatile impurities are removed by refluxingfor 6h with freshly dehydrated cuso4 (2g/l) while dry air is passed through: the methanol is finally distd.(the aluminium methoxide is prepared by warming with aluminium amalgam (3g/l) until all the aluminiumhas reacted. the amalgam is obtained by wanning pieces of sheet aluminium with a soln of hgcl2 in drymethanol). this treatment also removes aldehydes， 查看更多
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