Solvent effect is the effect of solvents on reaction rate, equilibrium and even reaction mechanism, most of the organic reactions in solvents, the properties of solvents are not only to the reaction rate but also to the equilibrium of reaction. Solvents can be divided into polar solvents and non-polar solvents, and polar solvents can be classified as proton solvents and non-proton dipole solvents. The effect of solvent on the reaction velocity constant depends on the relative stability of the solvent molecule and the corresponding solvent transition state. In organic reactions, the free radical reaction of alkanes is generally not affected by the solvent effect.