Abstract: Process for the chemical mechanical polishing of a layer of isolating material based on silicon or a silicon derivative, in which abrasion of the layer of isolating material is carried out by rubbing said layer using a fabric which brings into play an abrasive containing an acid aqueous solution of colloidal silica containing individualized colloidal silica particles, not linked together by siloxane bonds, and water as the suspension medium and new abrasives based on such suspensions.

Abstract: A process for the preparation of the enol lactone of 2-oxocyclohexylidene acetic acid wherein(i) glyoxylic acid is allowed to react with cyclohexanone in the presence of a halogen acid in order to obtain a crude reaction product B1, then(ii) said crude reaction product B1 is allowed to react, after solubilisation in an organic solvent, in the presence of a strong acid soluble in said organic solvent or of strongly acid resins, in order to obtain the enol lactone of 2-oxocyclohexylidene acetic acid which is isolated if desired,and application to the preparation of 2-coumaranone.