n-Amyl acetate n-amyl alcohol water → 1-Pentanol

Beteiligte Stoffe

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One of the commercially important ways to manufacture n-amyl acetate is by the catalytic esterification of n-amyl alcohol with acetic acid. n-Amyl acetate (b.p.=148.4° C.), n-amyl alcohol (b.p.=138.1° C.) and water (b.p.=100° C.) form a minimum ternary azeotrope boiling at 94.8° C. and containing 10.5 weight percent n-amyl acetate, 33.3 wt. % n-amyl alcohol and 56.2 wt. % water. n-Amyl acetate forms a binary azeotrope with water boiling at 95.2° C. containing 59 wt. % n-amyl acetate. n-Amyl alcohol also forms a binary minimum azeotrope with water which boils at 95.8° C. and contains 45.6 wt. % n-amyl alcohol. Thus in the esterification of n-amyl alcohol with acetic acid to form n-amyl acetate and water, the rectification of this mixture has two binary and a ternary azeotrope to contend with, and yields the lowest boiling constituent, namely the n-amyl acetate - n-amyl alcohol - water ternary azeotrope. It is therefore impossible to produce n-amyl acetate from n-amyl alcohol and water mixtures by rectification because the lower boiling ternary azeotrope will always come off overhead as the initial product. Any mixture of n-amyl acetate, n-amyl alcohol and water subjected to rectification at one atmosphere pressure will produce an overhead product boiling at 94.8° C. and containing 10.5 wt. % n-amyl acetate, 33.3 wt. % n-amyl alcohol and 56.2 wt. % water. Extractive distillation would be an attractive method of effecting the separation of n-amyl acetate from n-amyl alcohol if agents can be found that (1) will break the n-amyl acetate - n-amyl alcohol - water azeotrope and (2) are easy to recover from the n-amyl alcohol, that is, form no azeotrope with n-amyl alcohol and boil sufficiently above n-amyl alcohol to make the separation by rectification possible with only a few theoretical plates.

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