The invention relates to a method for producing magnesium compounds by means of precipitation, wherein (1) an aqueous solution or suspension of a magnesium compound is mixed with a precipitant, selected from the group of alkali, oxin, inorganic phosphate and inorganic salt of carbonic acid, and the corresponding magnesium compound precipitates, (2) the mixture from step (1) is mixed with a flocculating agent as applicable, (3) the solid is separated from the liquid from the mixture from step (1) and step (2), as applicable, (4) the separated solid is mixed with water in the presence or in the absence of a flocculating agent, (5) the solid is separated from the liquid from the mixture from step (4) as applicable, (6) steps (4) and (5) are repeated once or repeatedly as applicable, (7) and the separated solid is dried as applicable, after the addition of further compounds as applicable, characterized in that the aqueous solution or suspension of a magnesium compound in step (1) is obtained (i) by reacting an organo-magnesium compound with aldehyde or a ketone or another electrophile and subsequent aqueous preprocessing of the reaction mixture at a pH value of 10 at maximum or (ii) from a magnesium salt having a calcium content and/or potassium content of 200 ppm each at maximum, relative to the magnesium salt used.