The synthesis of a series of fourteen 4-alkoxy-1,1,1-trihalo-3-alken-2-ones (2,3) [CX3COC(R-2)=C(R-1)OMe, where X = Cl, F; R-1/R-2 = Me/H, Bu/H, i-Bu/H, Ph/H, Thien-2-yl/H, -(CH2)(4)-, -CH(CH2)(4)CH(CH2)(2)-] from the acylation reactions of acetals (1) with trichloroacetyl chloride or trifluoroacetic anhydride in the presence of equimolar amounts of pyridine and imidazolium based ionic liquid ([BMIM][BF4] or [BMIM][PF6]) is reported. The reaction time, yields and IL recyclation are also investigated and this method showed advantages over the methods described in the literature.