Abstract: A flow reactor providing a high degree of selectivity in the reaction of a feedstock to produce one or more end product compounds, which includes: side walls defining an elongated reactor unit having a length dimension along which the feedstock is reacted under varying conditions of energy and chemical flux effective to produce the one or more end product compounds; a plurality of devices for supplying energy or chemical flux through the side walls and positioned to distribute the energy and chemical flux along the length of the reactor unit so as to optimize a property of the one or more end product compounds; devices for measuring a property of the end product compounds; and an adaptive feedback control system to determine, establish and maintain the optimum energy and chemical flux distribution along the length of the reactor based on the end product property measurement.