Abstract: Disclosed is a process for forming a compound by mixing at least two components, which comprises the steps of:circulating a specific component along a circulation route; andmixing the specific component with a second component different from the specific component by flowing the second component different from the specific component in the middle of the circulation route under specific mixing conditions to form a compound during circulation,wherein the mixing conditions are controlled so that the mixing conditions are changed accompanied with increase in a formation amount of the compound.