To produce the subject compound useful e.g. as a dyeability improving agent for fiber in high purity by separating and recovering by-produced alkyl alcohol, refluxing to a reactive distillation column and including a polymerization inhibitor in the refluxing liquid, thereby enabling stable distillation in high efficiency.

A compound of formula III is produced by reacting a compound (A) of formula I (R1 is H or methyl; R2 is a 1-4C alkyl) with a compound of formula II (R4 is a 1-8C alkyl; R3 is H or R4; R5 is a 1-4C alkylene) using a reactive distillation column (X). In the above process, the byproduced alkyl alcohol (B) is continuously discharged from the distillation column X together with the compound A, the distilled alcohol B is separated and recovered, at least a part of the alcohol B is refluxed to the distillation column X and the reactive distillation is carried out in a state containing an amine-based polymerization inhibitor (C) in the refluxing liquid. Preferably, the reactive distillation is carried out by charging the alcohol B to the refluxing line of the distillation column X or the top of a cooling apparatus in an amount corresponding to 10-200 ppm based on the column top distillate of the distillation column X.