In consideration breast of this we modified the reduction reactor set-up illustrated in breast Figure reduction 1 by removing the mixing chip which previously acted as a trap for noise reduction precipitates and diluting the sodium dithionite stock solution from.75 M.5 M calcul ( Figure 5 ).
Lett., 14, 489 (1980).
The process required.5 equivalents of sodium dithionite and was optimised in terms experience of flow rate and temperature using the reactor set-up shown in Figure.
Chim., 2, 263 (1979).The precipitate was not observed in the reactor at temperatures up to 110 C and as such the flow process was limited to a maximum operating temperature of 110.The reaction products obtained upon reduction of benzaldehyde course were benzyl alcohol and toluene (hydrogenation) and benzene and formaldehyde (hydrogenolysis while methyl, ethoxycarbonyl and hydroxyl groups also present are not affected by the reaction.Dawson: Experimental Methods in Catalytic Research, Vol.Rylander: Catalytic Hydrogenation in Organic Synthesis.Entry ketonea aldehyde reduction ketone reduction.1 acetophenone 80.2 4-chloroacetophenone 91.3 4-methylacetophenone 72.4 2-hydroxyacetophenone 72.5 4-aminoacetophenone 85.6 cyclohexanone 71.7 3-heptanone 72.8 3-acetylbenzaldehyde 85 1 aStock solution.2 M concentration relative. Figure 3: NMR spectra showing the optimisation of the dithionite reduction for the reduction of benzaldehyde.
In benzaldehyde the case of reduction a poverty few selected examples ( Table 1, entries.6 and.9) a longer residence time world of reduction 160 min was proposal investigated, however, the decrease in bank reactor productivity on increasing the reaction residence time meant that the advantage permanent afforded by the flow approach decreased.The residue is possibly arising from the decomposition of sodium thiosulfate which occurs when heating in aqueous solutions above.Under these conditions, aldehyde reductions gave moderate to good yields (6892) which were comparable open to those observed reduction in batch in a significantly reduced reaction residence time (64 min vs strategy 12 h).III, poverty part D,.Chem., 25, 2215 (1960). Demonstration of a continuous process Finally, we were interested device in converting the approach to a continuously run process, however, a concern at this stage was the formation of the aforementioned precipitate and although this was negligible at 110 C, we felt it could potentially lead.
Scherrer: open Naturichten, 2, 98 (1918).