Preparation of ethers of (poly) glycerol

The present invention relates to a process for preparing a compound of formula (I) comprising the steps of: (a) preparing a compound of formula (II) by reduction in the vapor phase in the presence of hydrogen and a catalyst comprising ruthenium and tin, of a compound of formula (IV) (b) reacting in a liquid medium, in the presence of a catalyst, hydrogen and optionally an acid, of the compound of formula (II) and a compound of formula (III)