There is provided a process for the preparation of 4-hydroxy-6-methyl-2-pyrone which comprises reacting dehydroacetic acid (DHAA) with aqueous H2SO4 containing 90-99% by weight of H2SO4 at a temperature from 60°C to 140°C and under a pressure of 10 millimetres of mercury gauge to 388 centimetres of mercury gauge, wherein (A) the H2SO4 plus H20: DHAA weight ratio is from 0.8 to 3:1 and (B) the DHAA is initially reacted with from 91 to 99% H2S04 followed by one or more staged H20 additions during the reaction whereby the total weight of H20 added and initially present in the H2S04 charged is 10% or less of the weight of H2SO4 (100% basis) initially charged, said staged H20 addition(s) being optional when 93-96% H2SO4 is initially charged.
本发明提供了一种制备
4-羟基-6-甲基-2-吡喃酮的工艺,该工艺包括在 60℃至 140℃的温度和 10 毫米
汞柱至 388 厘米
汞柱的压力下,使
脱氢乙酸(
DHAA)与含 H2SO4 重量比为 90-99%的 H2SO4
水溶液反应,其中 (A) H2SO4 加 H20:
DHAA 重量比为 0.8至3:1,以及(B)
DHAA最初与91%至99%的H2S04反应,然后在反应过程中分阶段加入一次或多次H20,其中加入的和最初存在于H2S04中的H20总重量为最初加入的H2SO4(100%基)重量的10%或更少,当最初加入93-96%的H2SO4时,所述分阶段加入H20是可选的。