Abstract: Alkylphenol disulfonates of improved color are provided by neutralizing alkylphenol disulfonic acid with aqueous solutions of alkali metal hydroxides having a base content of at least 30% by weight.

Abstract: In a process for separating maleic anhydride or phthalic anhydride from a gaseous mixture by absorption into an organic absorbent flowing downwardly and countercurrently to the gaseous mixture in an absorption column having at least 4 stages, the improvement is made which comprises removing heat from a zone of the absorption column above the gaseous mixture feed point and below the top 2 stages of the column in a sufficient amount so that more than half of the temperature gradient for the absorbent liquid in the column is across at least 2 stages above the gaseous mixture feed point and below the top 2 stages of the column. Preferably said heat is removed from the absorber column by withdrawing a stream of absorbent from the lower part of the column, cooling the stream and then recycling the resulting cooled absorbent to the column.