A method for preparing 1,3-dioxane compounds of the formula (I): ##STR1## wherein R.sup.1 and R.sup.2, independently of one another, represent hydrogen or a hydrocarbon radical; and X.sup.1 and X.sup.2, independently of one another, represent an electronegative groups, which method entails reacting a bis(hydroxymethyl) compound of the formula (II): ##STR2## in which X.sup.1 and X.sup.2 each, independently of one another, are as defined above, with an orthocarboxylic acid ester of the formula R.sup.4 --C(OR.sup.5).sub.3 (III), in which R.sup.4 represents hydrogen or a hydrocarbon radical and R.sup.5 represents a hydrocarbon radical, and with an aldehyde or ketone of the formula R.sup.1 --CO--R.sup.2 (IV), in which R and R each, independently of one another, are as defined above.