This thesis is based on the syntheses of para-substitued benzyl chlorides from para-substitued benzyl alcohols. The following compounds have been synthesized: 4-phenylbenzyl chloride and 4- phenoxybenzyl chloride using hydrochloric acid, and 4-methylbenzyl chloride, 4-methoxybenzyl chloride, 4-methyltiobenzyl chloride and 4-tert-butylbenzyl chloride using thionyl chloride. The above mentioned compounds were purified after the synthesis and their identity and purity were confirmed by nuclear magnetic resonance. Conductometric measurements were used to determine solvolysis rate constants at 60 °C in 80 % aqueous ethanol previously synthesised para-substituted benzyl chlorides in order to show Hammett-Brown correlation. For this purpose, logarithms of solvolysis rate constants were correlated with σ+ values in order to determine the nucleophilic substitution mechanism through which the solvolysis of these substrates proceeded. A correlation of log k versus σ+ values yielded two lines which represented two reaction mechanisms, SN1 and SN2 mechanism. Solvolysis reactions of 4-methoxybenzyl chloride, 4-methyltiobenzyl chloride and 4-phenoxybenzyl chloride proceed through SN1 mechanism, while 4-tert-butylbenzyl chloride and 4-phenylbenzyl chloride react with solvent through SN2 mechanism. Due to the fact that a point for 4-methylbenzyl chloride is situated at the intersection of the two lines, for this compound will be conducted an additional investigation in order to determine the exact reaction mechanism, however, it can be assumed that its solvolysis proceeds through the SN2 mechanism. In addition, quantum-mechanical calculations were carried out. Using the IEFPCM-wB97XD/6-311+G(3df, 3pd) level of theory, geometries of 4-methylbenzyl chloride and 4-phenylbenzyl chloride, as well as those of the corresponding SN2 transition structures were optimized. A frequency calculations were further performed on the optimized geometries using standard conditions in order to estimate free energies of substrates and transition structures. Free energies of activation for the SN2 reactions of the substrates with water were calculated, as well as first-order rate constants. The results reveal that relative theoretical and experimental reactivities of the substrates are consistent.