Lignin, a component of the cell walls of plants and the second most abundant biopolymer has long been regarded as disturbing substance in pulp production by paper industry. This view has changed in recent decades. Thus, lignin is increasingly regarded as an alternative to crude oil. Tuned and modified lignins have suitable properties to use them as building blocks for various applications as well as for the production of basic chemicals. By modifying lignin, its reactivity and uniformity can be increased. In addition, properties of the lignin can be changed and influenced by selective modification. By a solvent-free modification with dihydroxybenzene, aliphatic OH groups of the lignin side chain can be removed and covalent C-C bonds to the aromatics can be formed. At the same time, aryl-alkyl ether cleavage occurs, which reduces the molecular weight of lignin by about one third. In addition, ongoing reactions result in the reduction in the molecular weight distribution. All this leads to a more uniform and reactive lignin which is interesting as a precursor for various applications. This work provides a deeper understanding of ongoing reactions with dihydroxybenzenes and the structure of modified lignins.