Continuous transesterification method

A continuous process for preparing esters, comprising the steps of providing a substantially microwave-transparent reaction tube, wherein the substantially microwave-transparent reaction tube has a longitudinal axis and wherein the longitudinal axis is parallel in direction to propagation of microwaves from a monomode microwave applicator,

• continuously feeding and mixing at least one polyol ester of the formula (I)
• (R1—COO)mR2 (I),
• in which
• R1 is hydrogen or an optionally substituted hydrocarbyl radical having 1 to 50 carbon atoms,
• R2 is an optionally substituted hydrocarbyl radical having 2 to 10 carbon atoms and
• m is a number of from 2 to 10 and is less than or equal to the number of carbon atoms in R2
• with at least one monohydric alcohol of the formula (II)
• R3—OH (II)
• in which
• R3 is an optionally substituted hydrocarbyl radical having 1 to 30 carbon atoms, to form a reaction mixture, continuously reacting the reaction mixture under microwave irradiation in the substantially microwave-transparent reaction tube to give at least one ester of the formula (III)
• R1—COO—R3tm (III)
• in which
• R1 and R3 are each as defined above.