A composition, which is suitable for the production of stilbene compounds, can be separated from tall oil. It contains esters of pinosylvin or pinosylvin derivatives and it is concentrated in relation to these. Preferably, the composition contains esters of pinosylvin monomethyl ethers, the acid part of which is formed of an inorganic acid or an organic acid, in particular an organic acid, which is present in the crude tall oil or which is generated from this oil during the process of refining it. Typically, such acids are fatty and resin acids and lower alkane acids. With the invention, it is possible to generate, at an industrial scale, product fractions, and the pinosylvin compounds which are separated from the fractions can be used as such or they can be further modified by means of different chemical methods.