The synthesis of a series of ten 1,1,1-trichloro[fluoro]-3-alken-2-ones [CX3C(O)C(R-2)=C(R-1)OR, where X=Cl and F; R-1/R-2/R=H/H/Et, Me/H/Me, H/Me/Et, H/-(CH2)(2)- and H/-(CH2)(3)-] from the acylation reactions of enol ethers with trichloroacetyl chloride or trifluoroacetic anhydride in the presence of equimolar amounts of pyridine and 10% mol-equiv. of imidazolium based ionic liquid [BMIM]-BF4 or [BMIM]-PF6 is reported. The reaction time, the ionic liquid recyclation and yields were investigated and this method showed advantages over the methods described in the literature. (c) 2006 Elsevier B.V. All rights reserved.