Heat exchangers acetic anhydride production

Zirconium heat exchangers resist corrosion in the production of acetic acid and anhydride. Outlook, Teledyne Wall Chang, 4 2,1. 

Most anhydrides are prepared from carboxylic acids by exchange with the readily available acetic anhydride. Heating these and then distilling the acetic acid and excess acetic anhydride shifts the equilibrium toward the higherboiling product (Eq. 6.15) [21]. Five- and six-membered cyclic anhydrides usually form simply on heating the dicarboxylic acid to about 120°C. 

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