Various benzyl alcohols were investigated to verify the effectiveness of the honeycomb reactor. The reaction rate was compared using the standard tube reactor and the honeycomb reactor (Table ). With benzyl alcohol and benzyl alcohols bearing various substituents such as OMe, Me, Br, CF3 and COOMe at the 4-position, the reaction was uniformly accelerated using the honeycomb reactor and proceeded almost without generation of byproducts. a Conv (%) = 2a-f (area%)/(2a-f (area%) + 1a-f (area%)×F)×100. F: relative sensitivity coefficient on HPLC (factor). Relative sensitivity coefficients were summarized in Supporting Information File 1.; b Quantitative yield using an authentic sample on HPLC.; c Reaction conditions were described in entry 1 in Table .; d Reaction conditions were described in entry 6 in Table .