Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Immobilized rhodium catalysts for the hydroaminomethylation of alkenes
Thesis (MSc)--Stellenbosch University, 2022.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | en_ZA |
| Published: |
Stellenbosch : Stellenbosch University
2022
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613954520383488 |
|---|---|
| access_status_str | Open Access |
| author | Wassenaar, Veronique |
| author2 | Mapolie, Selwyn Frank |
| author_browse | Mapolie, Selwyn Frank Wassenaar, Veronique |
| author_facet | Mapolie, Selwyn Frank Wassenaar, Veronique |
| author_sort | Wassenaar, Veronique |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2022. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/126341 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:44:21.236Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2022 |
| publishDateRange | 2022 |
| publishDateSort | 2022 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/126341 Immobilized rhodium catalysts for the hydroaminomethylation of alkenes Wassenaar, Veronique Mapolie, Selwyn Frank Malgas-Enus, Rehana Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science. Rhodium catalysts Mesoporous materials Hydroformylation Alkenes UCTD Thesis (MSc)--Stellenbosch University, 2022. ENGLISH ABSTRACT: Mesoporous silica nanoparticles (MSNs) offer a convenient route for catalyst heterogenization, thus allowing for the recoverability and reuse of noble metal catalysts. In this thesis, a series of model, physically immobilized, and chemically immobilized rhodium(I) iminopyridyl and pyridyl-triazole catalyst precursors was prepared and evaluated in the hydroaminomethylation (HAM) of 1-octene with piperidine. The ligands 4-[(2-pyridinylmethylene)amino]phenol ((L1) and N-(2-pyridinylmethylene)-1-propanamine (L2) were prepared by Schiff-base condensation of pyridine-2-carboxaldehyde with appropriate amine precursors in yields of around 80%. While the third ligand, 2-(1-octyl-1H-1,2,3-triazol-4-yl)pyridine (L3) was prepared using a selective azide-alkyne Huisgen-cycloaddition reaction with a moderate yield (60%). The model complexes were prepared using literature procedures employing the cyclooctadiene rhodium chloride dimer, [Rh(COD)Cl]2 as metal precursor. Synthesis of these complexes involves the cleavage of chloro-bridging ligands with the bidentate N-donating ligands, yielding complex intermediates (C1-Cl, C2-Cl, C3-Cl) with the formula [Rh(COD)(N^N)]Cl, (N^N= L1, L2, and L3). These complex intermediates subsequently undergo anion exchange reactions to form the final model complexes (C1, C2, C3) of formula [Rh(COD)(N^N)]BPh4, (N^N= L1, L2, L3). The prepared model ligands and complexes were characterized by FT-IR and 1H-NMR spectroscopy, while complexes were further characterized by thermal (TGA) and elemental (CHNS) analysis. The preparation of siloxane functionalized analogues of L1 was next attempted using two distinct siloxane alkyl tethers with limited success. In both cases, the resulting ligands were difficult to purify undergoing rapid degradation under ambient conditions. A siloxane-functionalized analogue of L2 was successfully prepared via Schiff-base condensation of 2-pyridine carboxaldehyde and 3- aminopropyltriethoxysilane, producing the ligand N-(2-pyridinylmethylene)-3- (triethoxysilyl)-1-propanamine (SL2) with an 81% yield. Enabling the preparation of the siloxane functionalized complex, [Rh(COD)(SL2)]BPh4 (SC2), both ligand and complex were fully characterized by FT-IR and 1H-NMR spectroscopy. MSNs with high surface areas (704 m²/g) and large wrinkle-like pores were prepared via the surfactant-templating method and characterized by FT-IR spectroscopy, TGA, BET, SEM, and HR-TEM. The average pore and particle diameters of the MSNs were measured to be 12.9 nm (BET) and 29 nm (HR-TEM), respectively, with moderate size distributions (±4 nm). The model complexes were successfully incorporated onto the support material by physical immobilization using wet-impregnation to https://scholar.sun.ac.za iv produce C1-MSN, C2-MSN, and C3-MSN and chemical immobilization to yield SC2-MSN. All immobilized complexes were characterized by FT-IR spectroscopy, SEM-EDS, and TGA, while C1-MSN was further characterized by BET to confirm incorporation of the complex into particle mesopores. The rhodium content of the metal-decorated MSNs was determined by ICP-AES and found to range between 2.79% and 14.65%. The model pre-catalysts (C1, C2, C3) were applied in the HAM of 1-octene and piperidine with catalyst loadings of 0.1 mol% at 75 ˚C and 30 bar syngas for 1 hour. Under these moderate conditions, C1 showed amine selectivities 50% higher than those of C2 and C3. The physically immobilized pre-catalysts were also evaluated and displayed similar activities and amine selectivities, although a greater concentration of reaction intermediates was seen for the physically immobilized complexes C2- and C3-MSN. The covalently immobilized complex, SC2-MSN was also evaluated in the transformation, showing high conversions (93%) and amine selectivities (67%) similar to its physically immobilized analogue C2-MSN. During preliminary recycling studies, the physically immobilized complex C1-MSN showed a slight reduction in activity while moderate amine selectivity was maintained, despite a 10-fold reduction in rhodium content measured by ICP-AES. Finally, the covalently immobilized complex SC2-MSN, showed significant recycling potential as no metal leaching was detected following initial catalytic evaluation. AFRIKAANS OPSOMMING: Mesoporiese silika-deeltjies (MSNs) bied 'n gerieflike roete vir katalisator heterogenisering wat die herwinbaarheid en hergebruik van edelmetaalkatalisators toelaat. In hierdie tesis is was 'n reeks model, fisies geïmmobiliseerde, en chemies geïmmobiliseerde rodium(I) iminopiridiel en piridiel-triasool katalisator voorlopers berei en geëvalueer in die hidroaminometilering (HAM) van 1-okteen met piperidien. Die ligande 4-[(2-piridinielmetileen)amino]fenol (L1) en N-(2-piridinielmetileen)-1-propaanamien (L2) is berei deur Schiff-basis kondensasie van piridien-2-karboksaldehied met toepaslike amienvoorlopers in opbrengste van ongeveer 80%. Die derde ligand, 2-(1-oktiel-1H-1,2,3-triasool-4-iel)piridien (L3) is met behulp van 'n selektiewe asied-alkyn Huisgen-sikloaddisiereaksie in 'n matige opbrengs (60%) berei. Die modelkomplekse is berei deur gebruik te maak van literatuurprosedures met die siklooktadieen rhodiumchloried dimeer, [Rh(COD)Cl]2. Bereiding van hierdie komplekse behels die splitsing van chloor-bruggende ligande met die bidentaat N-donerende ligande, wat die intermediêre komplekse (C1-Cl, C2-Cl, C3-Cl) met die formule [Rh(COD)(N^N)]Cl, (N^N= L1, L2, L3) lewer. Hierdie kompleks intermediêre ondergaan daarna anioonuitruilingsreaksies om die finale modelkomplekse (C1, C2, C3) met formule [Rh(COD)(N^N)]BPh4, (N^N= L1, L2, L3) te vorm. Die bereide model ligande en komplekse is deur FT-IR spektroskopie en 1H-KMR spektroskopie gekarakteriseer, komplekse is verder deur termiese (TGA) en elementêre (CHNS) analise gekarakteriseer. Die bereiding van siloksaan-gefunksionaliseerde analoë van L1 is vervolgens met beperkte sukses gepoog deur van twee afsonderlike siliel-alkiel-kettings gebruik te maak. In beide gevalle was die gevolglike ligande moeilik om te suiwer en het vinnige afbraak onder atmosferiese toestande ondergaan. 'n Siloksaan-gefunksionaliseerde analoog van L2 is suksesvol berei deur middel van Schiff-basis kondensasie van 2- piridienkarboksaldehied en 3-aminopropieltrietoksiesilaan, waarin SL2 in 'n 81% opbrengs geproduseer is. SL2 het die bereiding van die siloksaan-gefunksionaliseerde kompleks SC2 moontlik gemaak. Beide ligand en kompleks was volledig gekarakteriseer deur FT-IR en 1H-KMR spektroskopie. MSN’s met hoë oppervlakareas (704 m²/g) en groot plooiagtige porieë is berei deur middel van die surfaktant-templaat metode en gekaraktiseer deur FT-IR spektroskopie, TGA, BET, SEM en HR-TEM. Die gemiddelde porie- en partikeldiameters van die MSNs is gemeet as onderskeidelik 12.9 nm (BET) en 29 nm (HR-TEM) met matige grootte verspreidings (± 4 nm). Die modelkomplekse is suksesvol op die draermateriaal geïnkorporeer deur fisiese immobilisasie deur gebruik te maak van nat-impregnering om C1-MSN, C2-MSN https://scholar.sun.ac.za vi en C3-MSN te lewer. Chemiese immobilisasie het ook SC2-MSN gelewer. Alle geïmmobiliseerde komplekse is gekaraktiseerd deur FT-IR spektroskopie, SEM-EDS en TGA, terwyl C1-MSN verder deur BET gekaraktiseerd is om inkorporering van die kompleks in partikel mesopore te bevestig. Die rodium inhoud van elke geïmmobiliseerde kompleks is toe deur IKP-AES bepaal as tussen 2.79% en 14.56%. Die model voor-katalisators (C1, C2, C3) is aangewend in die HAM van 1-okteen en piperidien met katalisatorlading van 0.1 mol% onder matige toestande. Na katalise het C1 amienselektiwiteite rondom 80% vertoon, wat byna 50% hoër was as dié wat vir C2 en C3 waargeneem is. Die geënkapsuleerde voor-katalisators is ook geëvalueer en het soortgelyke aktiwiteite en amienselektiwiteite getoon. 'n Groter konsentrasie van reaksie-tussenprodukte is ook egter opgemerk vir C2- en C3-MSN. SC2-MSN is ook in die transformasie geëvalueer, en het hoë omsettings (93%) en amienselektiwiteite (67%) soortgelyk aan sy geënkapselde analoog C2-MSN getoon. Tydens voorlopige herwinningstudies het C1-MSN 'n effense vermindering in aktiwiteit getoon, terwyl matige amienselektiwiteit gehandhaaf is, ten spyte van 'n 10-voudige vermindering in rodium inhoud gemeet deur IKP-AES. Laastens het SC2-MSN beduidende herwinningspotensiaal getoon, aangesien geen metaalloging na aanvanklike katalitiese evaluasie bespeur is nie. Masters 2022-11-18T11:03:19Z 2023-01-23T06:53:04Z 2022-11-18T11:03:19Z 2022-12 Thesis http://hdl.handle.net/10019.1/126341 en_ZA Stellenbosch University xxii, 126 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Rhodium catalysts Mesoporous materials Hydroformylation Alkenes UCTD Wassenaar, Veronique Immobilized rhodium catalysts for the hydroaminomethylation of alkenes |
| title | Immobilized rhodium catalysts for the hydroaminomethylation of alkenes |
| title_full | Immobilized rhodium catalysts for the hydroaminomethylation of alkenes |
| title_fullStr | Immobilized rhodium catalysts for the hydroaminomethylation of alkenes |
| title_full_unstemmed | Immobilized rhodium catalysts for the hydroaminomethylation of alkenes |
| title_short | Immobilized rhodium catalysts for the hydroaminomethylation of alkenes |
| title_sort | immobilized rhodium catalysts for the hydroaminomethylation of alkenes |
| topic | Rhodium catalysts Mesoporous materials Hydroformylation Alkenes UCTD |
| url | http://hdl.handle.net/10019.1/126341 |
| work_keys_str_mv | AT wassenaarveronique immobilizedrhodiumcatalystsforthehydroaminomethylationofalkenes |