| 摘要 |
<p>Pure methylterephthalic acid and/or 4-methylisophthalic acid is obtained from the crude solid product obtained by oxidising pseudocumene with molecular O2 in the presence of a Co catalyst by (a) treating the crude product with acetic acid, optionally contg. up to 40% wt. water, at 80-220 degrees C, in order to dissolve the acids but not the coloured impurities, (b) separating the undissolved solids while maintaing the liquid at 80-200 degrees C and (c) recovering the solid acids from the soln. Pref. the quantity of acetic acid or aqs. acetic acid is 2-40 times the weight of the acids. The acids are used in the prepn. of polyesters, alkyd resins and plasticisers. The acids are purified economically, and Co and trimellitic acid can be recovered from the separated impurities.</p> |
