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Catalyst immobilization techniques for continuous flow synthesis

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dc.contributor.advisor Klavs F. Jensen. en_US Nagy, Kevin David en_US
dc.contributor.other Massachusetts Institute of Technology. Dept. of Chemical Engineering. en_US 2012-04-26T18:50:26Z 2012-04-26T18:50:26Z 2011 en_US 2012 en_US
dc.description Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, February 2012. en_US
dc.description Cataloged from PDF version of thesis. en_US
dc.description Includes bibliographical references (p. 181-199). en_US
dc.description.abstract Catalytic processes are ubiquitous in both research and industrial settings. As continuous flow processes continue to gain traction in research labs and fine and pharmaceutical chemical processes, new opportunities exist for implementing previously difficult catalytic transformations. The major goal of this thesis is to expand and evaluate techniques for immobilized catalyst systems relevant to continuous flow. Fundamental studies in characterizing mixing, dispersion, and residence time distributions in small scale continuous flow systems are also presented. Given the numerous benefits associated with studying chemical processes at small length scales, microfluidic devices are the tool of choice for most studies in this thesis. Thermomorphic solvents offer the potential for homogeneous catalytic processes with biphasic catalyst recovery and recycle. A major limitation of these processes is the number of synthetically useful thermomorphic solvent combinations demonstrated in literature. A screening program using the modified UNIFAC (Dortmund) activity coefficient model to evaluate phase splitting behavior has been developed to predict thermomorphic behavior. Calculation of 861 binary solvent combinations results in 43 potential thermomorphic and 44 biphasic solvent combinations. Extension of the program to ternary solvents resulted in a new class of ternary solvents that display thermomorphic behavior with tunable critical solution temperatures. Evaluation of thermomorphic processes as a general method is presented. Traditional catalyst immobilization techniques rely on covalent grafting and are well suited to continuous flow processing due to the strong interactions of the catalyst to the support. Fluorous physisorption, which relies on interactions between a fluorous support and a fluorous-tagged catalyst, is characterized and presented as an immobilization technique for flow chemistry. The use of a fluorous-tagged Co(III)-salen catalyst to effect the ring opening of epoxyhexane with water is presented. Application of the platform to the ring closing metathesis of N,Ndiallyltosylamide using a fluorous-tagged Hoveyda-Grubbs metathesis catalyst results in significantly accelerated loss of activity over time compared to the salen catalyst. Use of continuous flow selective adsorption reactors to enhance catalytic processes is presented. Continuous feeds of a homogeneous catalyst into a sorbent where the catalyst displays an affinity for the sorbent results in accumulation of the catalyst in the packed bed. The net effect is an enhancement in turnover frequency and turnover number relative to homogeneous flow. Application of this platform to a Lewis acid catalyzed Diels-Alder reaction results in an order of magnitude improvement in turnover frequency compared to batch and homogeneous flow. en_US
dc.description.statementofresponsibility by Kevin David Nagy. en_US
dc.format.extent 230 p. en_US
dc.language.iso eng en_US
dc.publisher Massachusetts Institute of Technology en_US
dc.rights M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. en_US
dc.rights.uri en_US
dc.subject Chemical Engineering. en_US
dc.title Catalyst immobilization techniques for continuous flow synthesis en_US
dc.type Thesis en_US Ph.D. en_US
dc.contributor.department Massachusetts Institute of Technology. Dept. of Chemical Engineering. en_US
dc.identifier.oclc 784106724 en_US

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