01867nas a2200205 4500008004100000022001400041245010300055210006900158260011000227300001200337490000700349520105000356100002301406700002001429700002101449700001901470700003001489700002101519856012101540 2010 eng d a1463-926200aContinuous flow synthesis of functionalized silver nanoparticles using bifunctional biosurfactants0 aContinuous flow synthesis of functionalized silver nanoparticles aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcAPR a609-6150 v123 a

Silver nanoparticles were synthesized by continuous flow methods using biosurfactants, namely, oleic acid sophorolipid (OASL) and stearic acid sophorolipid (SASL). Both the sophorolipids can act as reducing and capping agents. The effect of temperature on the completion of nanoparticle formation and the particle growth dynamics (size) were studied in batch mode. While the completion of the reaction using oleic acid sophorolipid needed 20 min, only 5 min were required with the stearic acid sophorolipid as capping and reducing agent. Hence all the continuous flow experiments were carried out using the stearic acid sophorolipid. The continuous flow synthesis of silver nanoparticles was carried out in a stainless steel helical coil and also in a spiral polymeric minichannel reactor. The DLS results show that higher flow rate leads to the formation of bigger and polydisperse particles because of incomplete reactions. Higher residence time allowed the completion of reaction leading to spherical, small and monodisperse particles.

1 aKumar, D., V. Ravi1 aKasture, Manasi1 aPrabhune, Asmita1 aRamana, C., V.1 aPrasad, Bhagavatula L. V.1 aKulkarni, A., A. uhttp://library.ncl.res.in/content/continuous-flow-synthesis-functionalized-silver-nanoparticles-using-bifunctional-001655nas a2200181 4500008004100000022001400041245009200055210006900147260007100216300001400287490000700301520095700308100002101265700002201286700002201308700002201330856012101352 2013 eng d a1083-616000aContinuous flow multipoint dosing approach for selectivity engineering in sulfoxidation0 aContinuous flow multipoint dosing approach for selectivity engin a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcOCT a1293-12990 v173 a

A continuous synthesis approach with multipoint dosing of one of the reagents is demonstrated for the synthesis of sulfoxide compounds such as proton pump inhibitors. Use of multipoint dosing of the oxidizing agent helped to minimize the possibility of over-oxidation leading to sulfone. Different oxidizing agents were used, and the effect of various parameters (viz. mole ratio of sulfide to oxidizing agent, temperature, residence time, concentration of oxidizing agent, etc.) on the yield of the desired sulfoxide compound was studied. Single-point and multipoint dosing approaches of the oxidizing agent were used for the most promising set of parameters. The performance was compared in terms of conversion of sulfide and the selectivity of the desired sulfoxide. Numbering up approach was used to produce the sulfoxide in a relatively large quantity at laboratory scale with complete conversion and over 99% selectivity for the sulfoxide.

1 aKulkarni, A., A.1 aNivangune, N., T.1 aJoshi, Rohini, R.1 aJoshi, Ramesh, A. uhttp://library.ncl.res.in/content/continuous-flow-multipoint-dosing-approach-selectivity-engineering-sulfoxidation-001956nas a2200169 4500008004100000022001400041245011800055210006900173260007100242300001400313490000700327520126300334100001501597700002201612700002101634856013101655 2015 eng d a1083-616000aContinuous-flow nitration of o-xylene: effect of nitrating agent and feasibility of tubular reactors for scale-up0 aContinuousflow nitration of oxylene effect of nitrating agent an a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcSEP a1138-11470 v193 a

Continuous-flow nitration of o-xylene has been studied with different nitrating agents over a wide range of conditions for different parameters such as temperature, residence time, and concentrations. A nitrating mixture comprising sulfuric acid and fuming nitric acid was seen to yield higher selectivity for the isomer 1,2-dimethyl-3-nitrobenzene over the isomer 1,2-dimethyl-4-nitrobenzene and also a non-negligible quantity of dinitro derivatives of o-xylene. With only fuming nitric acid as the nitrating agent, the reaction was selective for 1,2-dimethyl-4-nitrobenzene over 1,2-dimethyl-3-nitrobenzene. Impurities mainly come from nitration of mononitro derivatives, and this occurs more from nitration of the 3-nitro isomer because of its higher reactivity with nitric acid. An economic analysis of the continuous-flow reactor for the production of 1,2-dimethyl-4-nitrobenzene at 100 and 500 kg/h in a jacketed tubular reactor showed that numbering-up is a more economical approach for higher production capacity. A combination of large- and small-sized tubes depending upon the relative rates of heat generation during a reaction will achieve more profit and a shorter payback period than having the entire reactor made of a single tube size.

1 aSharma, Y.1 aJoshi, Ramesh, A.1 aKulkarni, A., A. uhttp://library.ncl.res.in/content/continuous-flow-nitration-o-xylene-effect-nitrating-agent-and-feasibility-tubular-reactors-0