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KTH

1. Qiu, Shuai. Trifluoromethoxylation of Allylic Alcohols via 1,2-Aryl Migration Promoted by Visible Light-Mediated Photoredox Catalysis.

Degree: Biotechnology and Health (CBH), 2020, KTH

Visible light photoredox catalysis has proven to be a powerful tool for promoting transformations in organic synthesis. Hence this project was carried out to develop tools for predicting reactivity patterns of visible light- promoted redox reactions. Fluorination is of immense importance in organic chemistry, and so is trifluoromethoxylation. The fluorination reaction has been studied for a long time and has been accomplished in milder ways, while the generation of a trifluoromethoxy-radical at room temperature and atmospheric pressure remains a challenge. The design of the reaction in this project is to overcome the instability and take control of the catalytic event under visible- light photocatalytic conditions. The trifluoromethoxylation reaction proceeded at room temperature with the reaction time of 60 min using acetonitrile as the solvent and blue LED (10 W) as the external light source. No yield of the desired product was obtained for any of the substrates. More surprisingly, in all entries, 3,3-diphenylprop-2-en-1-ol was attained as a side product. The same side product was also detected in the entry with ambient light, concluding that the reaction was completed without any external light source. Thus, no photoredox catalysis took place.

Fotoredoxkatalys via ljus inom det synliga spektrat har visat sig vara ett kraftfullt verktyg för att gynna reaktioner inom organisk syntes. Detta projekt genomfördes med syfte att utveckla verktyg avsedda för att förutspå reaktivitetsmönster vid fotoredoxkatalys med synligt ljus. Fluorinering och trifluorometoxylering är viktiga verktyg inom organisk syntes. Fluorineringsreaktionen har studerats länge och har kunnat genomföras under milda reaktionsbetingelser, medan generering av trifluorometoxyradikal vid rumstemperatur och atomsfärstryck fortfarande är en utmaning. Reaktionen i det här projektet är designad för att kringgå instabilitetsproblemet och ta kontroll över katalysmomentet, under fotokatalysförhållanden i synligt ljus. Reaktionen utfördes i rumstemperatur med en reaktionstid på 60 minuter, med acetonitril som lösningsmedel och blå LED (10 W) som extern ljuskälla. Inget av substraten reagerade till den önskade produkten. Mer överraskande var att 3,3-difenylprop-2-en-1-ol erhölls som sidoprodukt vid alla reaktionsstillfällen. Samma sidoprodukt upptäcktes även vid reaktion genomförd i dagsljus, vilket indikerar att reaktionen skedde utan någon extern ljuskälla. Således skedde ingen fotoredoxkatalys.

Subjects/Keywords: Photoredox Catalysis; Fluorination; Trifluoromethoxylation; tvisible light; allylic alcohols; fotoredoxkatalys; trifluorometoxylering; synligt ljus; allyliska alkoholer; Chemical Engineering; Kemiteknik

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Qiu, S. (2020). Trifluoromethoxylation of Allylic Alcohols via 1,2-Aryl Migration Promoted by Visible Light-Mediated Photoredox Catalysis. (Thesis). KTH. Retrieved from http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278836

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Qiu, Shuai. “Trifluoromethoxylation of Allylic Alcohols via 1,2-Aryl Migration Promoted by Visible Light-Mediated Photoredox Catalysis.” 2020. Thesis, KTH. Accessed November 29, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278836.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Qiu, Shuai. “Trifluoromethoxylation of Allylic Alcohols via 1,2-Aryl Migration Promoted by Visible Light-Mediated Photoredox Catalysis.” 2020. Web. 29 Nov 2020.

Vancouver:

Qiu S. Trifluoromethoxylation of Allylic Alcohols via 1,2-Aryl Migration Promoted by Visible Light-Mediated Photoredox Catalysis. [Internet] [Thesis]. KTH; 2020. [cited 2020 Nov 29]. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278836.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Qiu S. Trifluoromethoxylation of Allylic Alcohols via 1,2-Aryl Migration Promoted by Visible Light-Mediated Photoredox Catalysis. [Thesis]. KTH; 2020. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278836

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

2. Ganesan, Aravind. Development of a modern catalytic system for the production of C3+ aliphatic alcohols by the Fischer-Tropsch method.

Degree: Energy Technology, 2019, KTH

This thesis deals with converting a mixture of H2 and CO, also referred to as syngas or producer gas, to higher or mixed alcohols and other fuels through a process called Fischer Tropsch Synthesis (FTS). It is a beneficial pathway that minimizes the dependence on oil and similar fossil fuels which contribute to rapid climate change by releasing harmful greenhouse gases. The syngas used in FTS, is generally obtained through gasification of biomass to make the entire process renewable and to make the resulting fuel carbon neutral. The products are pure due to prior cleaning of syngas mixture to remove oxides of nitrogen, sulphur and other particulate matter, before the process, thereby drastically reducing the net exhaust gas emissions. The major objective of this project is to design a novel catalyst system and subject it to a series of experimentation for testing its selectivity towards alcohols. This is because the present catalytic systems are either very expensive to assemble or confer to a low yield. Two cobalt (Co) based catalysts, one without a promoter and the other which is promoted by zirconium (Zr), are prepared. The activity and selectivity of Co catalysts are finally compared with the existing Swedish Biofuels AB’s Iron (Fe) based catalyst promoted by copper (Cu) and chromium (Cr) along with characterization of the optimum reaction parameters like temperature, pressure, GHSV and syngas ratio for FTS. Aqueous incipient impregnation approach was adopted wherein the Co active metal and Zr promoter (only in second catalyst) are introduced step-wise on a ϒ-alumina support to synthesize the catalyst after which it is heat treated through drying, calcination and reduction to obtain the active Co metal catalyst. A high temperature FTS, was employed for the yield of alcohols and other gasoline derivatives according to literature. Finally, the liquid and gaseous products are analyzed through GC or GC/MS analysis techniques. The unpromoted Co catalyst’s activity is regarded as a failure due to satisfactory results. There were a few problems associated with the catalyst alone like poor mechanical stability that could be attributed to the use of an incorrect binder. Other problems included methanation due to haphazard temperature variations and inefficient catalyst reduction. For the promoted Co catalyst, the yield of alcohols and hydrocarbons was significantly higher than the unpromoted Co catalyst. A temperature of 300 °C, a GHSV of 360 h-1 , a pressure of 10 bar and a H2:CO ratio of 1.3:1 were the optimal background conditions for FTS. Higher temperature caused methanation and reduced the chain growth probability factor, α, that resulted in the formation of lower hydrocarbons only. Any increase in gas ratio and GHSV, also increased the rate of methane formation and caused diffusion limitations. For a one-stage setup with the reversal of exhaust gases, the conversion rates of CO and H2 were quite promising. This success can be attributed to a higher calcination temperature that increased the degree of…

Subjects/Keywords: syngas; Cobalt; Fischer-Tropsch; alcohols; hydrocarbons; syngas; kobolt; Fischer-Tropsch; alkoholer; kolväten; Energy Systems; Energisystem

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Ganesan, A. (2019). Development of a modern catalytic system for the production of C3+ aliphatic alcohols by the Fischer-Tropsch method. (Thesis). KTH. Retrieved from http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259958

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Ganesan, Aravind. “Development of a modern catalytic system for the production of C3+ aliphatic alcohols by the Fischer-Tropsch method.” 2019. Thesis, KTH. Accessed November 29, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259958.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Ganesan, Aravind. “Development of a modern catalytic system for the production of C3+ aliphatic alcohols by the Fischer-Tropsch method.” 2019. Web. 29 Nov 2020.

Vancouver:

Ganesan A. Development of a modern catalytic system for the production of C3+ aliphatic alcohols by the Fischer-Tropsch method. [Internet] [Thesis]. KTH; 2019. [cited 2020 Nov 29]. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259958.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Ganesan A. Development of a modern catalytic system for the production of C3+ aliphatic alcohols by the Fischer-Tropsch method. [Thesis]. KTH; 2019. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259958

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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