TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The reaction temperature, measured by an infrared temperature sensor on the surface of the reaction vessel, remains at: 180-200 degrees C for dichloroalkanes and bis(chloroalkyl)ethers; 130-170 degrees C for dibromoalkanes and bis(bromoalkyl)ethers; and 90-110 degrees C for diiodoalkanes and bis(iodoalkyl)ethers. In the method, in case of an inhomogeneous reaction mixture, the desired product (0.1-5 mol.%) is added to the reaction mixture for homogenization that homogenizes and precludes its uncontrollable overheating. In the close vessel mode, a discontinuous or continuous-flow microwave reactor is used, and in the case of the use of a continuous-flow reactor, the reaction mixture being fed is heated above the boiling point of the alkylhalogenide (that is created), which returns from the microwave reactor along with the partially reacted reaction mixture, and the alkylhalogenide created in this way is continuously separated by distillation to reduce the risk of its reaction with the phosphite present. The high reactivity of diiodoalkanes or bis(iodoalkyl)ethers is limited by reducing the maximum used microwave power of the reactor from 5-50% of the maximum power depending on the construction details of the specific reactor to prevent the local overheating of the reaction mixture at low temperatures, at which diiodoalkanes or bis(iodoalkyl)ethers react. Preferred Components: In the method: an iodine, bromine or chlorine derivative is used as the dihaloalkane or bis(haloalkyl)ether; and triethyl phosphite or triisopropyl phosphite is used as the trialkyl phosphite. EXAMPLE - Triethyl phosphite (2.8 ml) and 1,2-dichloroethane (4.5 ml) were placed in a microwave (MW) test tube (with a volume of 10 ml), and the entire reaction mixture was securated (5x) and while mixing it was MW-heated in a type I reactor to 190 degrees C for 120 minutes. This procedure was repeated another nine times. All ten of the reaction mixtures acquired in this way were then jointly evaporated in a rotary vacuum evaporator at 65 degrees C, under 2 mbar pressure, to obtain an unrefined reaction mixture composed of diethyl 2-chloroethylphosphonate and diethyl ethylphosphonate. Then the unrefined reaction mixture was vacuum distillated at 74-75 degrees C under a pressure of 0.08 mbar, to give diethyl 2-chloroethylphosphonate (yield 62%).