*2.1. Materials*

The aryldiazonium 2-, 3-, and 4-methylbenzenediazonium (2MBD, 3MBD, and 4MBD, respectively) were prepared as tetrafluorborate salts under nonaqueous conditions, as described elsewhere [42,43]. The reagents used in their preparation were from Sigma-Aldrich (Taufkirchen, Germany). They were stored in the dark at low temperatures ( *T* < 5 ◦C) to minimize their decomposition and were recrystallized periodically. All chemicals were of the maximum purity available and were used without further purification. methyl phenyl ethers, ArOMe, cresols, ArOH, chlorotoluenes, ArCl, and toluene were from Sigma-Aldrich (Germany). The coupling agent, sodium 2-Naphthol-6-sulfonate ((2N6S), was from Pfaltz & Bauer (USA). The salts NaCl, LiCl, and LiClO4 were from Sigma-Aldrich (Germany) and other materials employed were from Panreac (Barcelona, Spain). All solutions were prepared by using deionized water (resistivity > 18 M Ω·cm).

Hereafter, solution compositions are given by their percent of MeOH (by volume). Molar concentrations were calculated by ignoring the small excess volume of mixed solvents [44].
