醋酸丁酯能与乙醇共沸吗
乙醇-水共沸物,共沸点78.13℃
正丁醇—水共沸物,共沸点93℃
乙酸正丁酯-水共沸物,共沸点90.7℃
乙酸乙酯83%-乙醇9%-水8%三元共沸物,顶温为70℃。
乙酸正丁酯—正丁醇共沸物, 共沸点117.6℃
乙酸正丁酯—正丁醇—水共沸物, 共沸点90.7℃
乙酸乙酯-乙醇共沸物, 共沸点72℃
丁醇和乙醇共沸物没有查到。
乙酸乙酯,乙酸中羟基被乙氧基取代而生成的化合物,分子式CH3COOC2H5。无色易挥发的液体;有水果香味;熔点-83.6℃,沸点77.06℃,相对密度0.9003(20/4℃);微溶于水,易溶于有机溶剂。乙酸乙酯与水和乙醇皆能生成二元共沸混合物:与水生成的共沸混合物的沸点为70.4℃;与乙醇形成的共沸混合物的沸点为71.8℃;与水和乙醇还可以形成三元共沸混合物,其沸点为70.2℃。
共沸物,又称恒沸物,是指两组分或多组分的液体混合物,在恒定压力下沸腾时,其组分与沸点均保持不变。这实际是表明,此时沸腾产生的蒸汽与液体本身有着完全相同的组成。共沸物是不可能通过常规的蒸馏或分馏手段加以分离的。并非所有的二元液体混合物都可形成共沸物。
丙酮和乙酸乙酯在常温下互溶,精馏时又形成共沸物,共沸组成含丙酮 81.14% ( 质量百分率)。
下面是维基百科全书的有关段落:
有时共沸点在分离共沸物时很有用。一个例子是醋酸和水。它们不形成共沸物,尽管单用蒸馏法从醋酸和水的混合物中分离醋酸(沸点118.1C)很困难。非常不经济。
但是乙酸乙酯和水可以组成共沸物,共沸点70.4°C。加入乙酸乙酯作为共沸剂,就可以将这种乙酸乙酯和水的共沸物蒸去,而留下几乎是纯净的冰醋酸。
英文(见参考文献):
Sometimes azeotropes are useful in separating zeotropic mixtures. An example is acetic acid and water, which do not form an azeotrope. Despite this it is very difficult to separate pure acetic acid (boiling point: 118.1°C) from a solution of acetic acid and water by distillation alone. As progressive distillations produce solutions with less and less water, each further distillation becomes less effective at removing the remaining water. Distilling the solution to dry acetic acid is therefore economically impractical. But ethyl acetate forms an azeotrope with water that boils at 70.4°C. By adding ethyl acetate as an entrainer, it is possible to distill away the azeotrope and leave nearly pure acetic acid as the residue.
参考文献:http://en.wikipedia.org/wiki/Azeotrope