| abstract |
A sulfuric acid ester containing a plurality of carbonyl groups or a salt thereof, and a surfactant. The sulfuric acid ester is a compound represented by the following formula:n nR 1 —C(═O)—R 2 —C(═O)—R 3 —OSO 3 Xn wherein R 1 , R 2 and R 3 are as defined herein; X is H, a metal atom, NR 4 4 , imidazolium optionally containing a substituent, pyridinium optionally containing a substituent, or phosphonium optionally containing a substituent, where R 4 s are each H or an organic group and are the same as or different from each other; and any two of R 1 , R 2 , and R 3 optionally bind to each other to form a ring. |