Dramatic increase in the rate of the Mukaiyama aldol reaction by ‘fluorous nano flow’ system in the lowest concentration of a fluorous catalyst

Miniaturized continuous flow reaction vessels: influence on chemical reactions

“…A wide variety of materials such as glass, quartz, silicon, polymers, and metals can be used to fabricate microreactors. 39,40 For synthetic applications glass is the most popular choice 5,16,[41][42][43] due to the availability of the fabrication equipment as acquired from MEMS and m-TAS technologies, to its transparency, its chemical inertness as well as its compatibility with a wide range of solvents, and its suitability with electrokinetic fluidic pumping. 6,44 A possible limitation encountered when using glass to fabricate microfluidic devices for organic reactions is the reactivity of the silanol groups on its surface.…”

“…Recently, Mikami et al 41 have reported a significantly increased reactivity of the Mukaiyama aldol reaction of benzaldehyde with trimethylsilyl enol ether carried in a microreactor controlled by a nano feeder (Scheme 7). A solution of both reagents in toluene was injected in one inlet, while a solution of a fluorous catalyst, viz., Sc[N(SO 2 C 8 F 17 ) 2 ] 3 , in perfuoromethylcyclohexane was injected in a separate inlet.…”

“…74 Scheme 7 Mukaiama aldol reaction in a ''fluorous nano flow'' system. 41 cases quantitative conversions have been obtained using the microreactor as compared to 52-76% for the lab-scale approach.…”

“…Reactions are conducted for a time long enough to collect a volume of product sufficient to be analyzed. The samples are then analyzed by HPLC, 9,14,109,110 GC-MS, 15,[113][114][115] GC, 19,41,100,117 or LC-MS. 16,74,72,111 However, to be effectively used for screening and process development, analysis of on-chip reactions has to be done in real time. Any delay time due to interfacing makes it more difficult to interpret the exact influence of the parameter settings on the reaction outcome.…”

Evaluation of the Heterogeneously Catalyzed Strecker Reaction Conducted Under Continuous Flow

“…The use of a homogeneous catalyst within a continuous system would, however, mean that even if reaction selectivity could be obtained, via sequential addition of reagents, the reaction products would still require purification in order to remove, and potentially recycle, the catalytic material. [18] To circumvent this problem, many authors have reported the use of solid-supported catalysts, [19] which has been shown to increase the ease with which reaction products can be isolated from the activating agent; by enlarge, however, the transfer of a reaction from homogeneous catalysis to a heterogeneous environment leads to a profound increase in reaction time. Additional optimization can therefore be required in order to obtain acceptable yields on the desired time scale; a process that is usually achieved by the use of heat and/or excess catalytic material.…”