Alcohol formation can be suppressed by consistently working under inert atmosphere (argon) and by using dry materials and chemicals. During the experiments evidence arose that during sample collection and especially during sample processing, the alcohol is formed. Since the benzyl alcohol formation is a consecutive reaction of benzylmagnesium bromide and does not occur or compete with the actual Grignard synthesis, the fraction of detected benzyl alcohol was stoichiometrically considered as benzylmagnesium bromide for the selectivity evaluation.