Preparative microdroplet synthesis of carboxylic acids from aerobic oxidation of aldehydes

Abstract

Preparative synthesis of carboxylic acids from the aerobic oxidation of aldehydes in microdroplets with moderate to excellent yields.

A microdroplet-accelerated Biginelli reaction: mechanisms and separation of isomers using IMS-MS

“…55 This acceleration presumably arises as the microdroplet evaporates, a process that leads to high concentrations of reagents in conned spaces. Additional factors such as change in pH, 27,28 droplet size, 28,29 reagent concentration, 28,34,46 solvent system, 17,30 and droplet temperature, 30,31 may also inuence these reactions.…”

“…Recently, the groups of Cooks, [17][18][19][20][21][22][23][24][25][26] Zare, [27][28][29][30][31][32][33][34][35][36][37][38][39] and others [40][41][42][43][44][45][46] have reported the acceleration of reactions in microdroplet environments during the process of electrospraying reagents into a mass spectrometer. 32 Intrigued by the possibility of faster rates for multicomponent reactions, we explored the use of microdroplets as a means of enabling a rapid Biginelli reaction (Scheme 2).…”

Reaction of chloroauric acid with histidine in microdroplets yields a catalytic Au–(His)2complex

“…Some factors, like size, with or without high voltage, solvent, and lasting reaction time of the microdroplet will have a direct effect on the high yields. 40 Recently, there have some technology explored for increasing the yield of the product and scaling-up the microdroplet reaction. 21,38,[40][41][42] Heated ultrasonic nebulization (HUN) has been used successfully for this purpose in our group.…”

“…40 Recently, there have some technology explored for increasing the yield of the product and scaling-up the microdroplet reaction. 21,38,[40][41][42] Heated ultrasonic nebulization (HUN) has been used successfully for this purpose in our group. 43 We report here the use of ultrasonic nebulization to make a scaled-up preparation the catalytic Au-(His) 2 complex.…”

Scale-up of microdroplet reactions by heated ultrasonic nebulization

“…† As the temperature was increased from 30 C to 50 C, the average droplet size decreased from 6.9 mm to 5.4 mm, which is closer to the microdroplet size (2-3 mm) in ESI. Previous reports 39,55,56 have indicated that the droplet size has a large effect on the reaction rate in microdroplets; thus we speculate that the increased reaction rate in HUN at higher temperature is caused by the smaller droplet size. The following three reactions were also conducted at 50 C. The reaction in the nebulization cell is accelerated by the continuously atomized microdroplets from the reactant solution.…”