Discovery of catalysts for amidation and transesterification reactions using fluorescence-based high-throughput screening methods
- Abstract
- Catalyst development for organic reactions often requires selecting highly active catalysts from numerous candidates, but traditional evaluation of catalyst activity is time-consuming and labor-intensive. To overcome these vulnerabilities, high-throughput screening (HTS) methods using colorimetric or fluorometric responses have been developed, which enable rapid sample processing using relatively inexpensive equipment compared to conventional analytical techniques such as chromatography, mass spectrometry, and nuclear magnetic resonance. In this study, we developed fluorescence-based HTS methods utilizing fluorescent probes to enable rapid catalyst evaluation for organic reactions. Using the developed HTS methods, the most efficient catalysts for amidation and transesterification reactions were identified, and the applicability of these selected catalysts were subsequently verified.
Direct amidation of carboxylic acids with amines holds significant importance; therefore, catalytic processes involving boronic acids have undergone extensive investigation. However, studies focused on the amidation of aromatic carboxylic acids remain limited. Various boronic acid catalysts were evaluated for amidation using a new fluorescence-based HTS method that utilized the fluorescence turn-on characteristics of an anthracene-based probe in response to the amidation reaction. Our findings reveal that 2- hydroxyphenylboronic acid, previously deemed inefficient for aliphatic acids, effectively catalyzes the amidation of aromatic acids. The catalysts identified through this method consistently achieved high yields, reaching up to 98% across a broad spectrum of substrates.
The development of heterogeneous metal oxide catalysts for transesterification reactions is crucial owing to their seamless reusability and environmental friendliness. In recent years, numerous studies have been conducted on rare-earth oxides, such as lanthanide metal oxides. Various metal oxides were screened for transesterification using another new fluorescence-based HTS method that employed ratiometric fluorescence change of a pyrene excimer probe. Praseodymium (IV) oxide yielded the highest catalytic activity among the prepared metal oxides. Various substrates were successfully transesterified, and biodiesel was also produced in a high yield (90%) from soybean oil through transesterification using the catalyst. The selected catalyst required minimal amounts for the transesterification of various organic substrates (0.7 mol%) and soybean oil (0.8 wt%).
- Issued Date
- 2025
- Type
- Thesis
- Alternative Author(s)
- Jeong Yup Ryoo
- Department
- 대학원 화학과
- Advisor
- Han, Min Su
- Table Of Contents
- Abstract i
Contents iii
List of Tables vii
List of Figures viii
I. Introduction to fluorescence-based high-throughput screening 1
1.1. High-throughput screening in catalyst development 1
1.2. Optical response-based high-throughput screening methods – Colorimetric 1
1.3. Optical response-based high-throughput screening methods – Fluorometric 5
1.4. Principles of fluorescence 9
1.5. Fluorescence modulation 10
1.6. Advantages of fluorescence-based analysis over colorimetric or absorbance-based
analysis 13
1.7. Research Overview 13
II. Discovery of boronic acid catalyst for direct amidation of aromatic carboxylic acids
using fluorescence-based high-throughput screening 14
2.1. Introduction 14
2.1.1. Diverse strategies to synthesis amides 14
2.1.2. Catalytic strategies to synthesis amides 16
2.1.3. Catalytic direct amidation reactions 18
2.1.4. Research overview 21
2.2. Results and discussion 22
2.2.1. Development of an HTS method for amidation with an anthracene-based
fluorescent probe 22
2.2.2. HTS of boronic acid derivative catalysts 26
2.2.3. Optimization of reaction conditions 29
2.2.4. Substrate scope 31
2.2.5. Putative mechanism for direct aromatic amidation with catalyst C7 33
2.3. Conclusions 34
2.4. Experimental 35
2.4.1. Materials and instruments 35
2.4.2. Synthesis and characterization of fluorescent probe and amidation product 35
2.4.3. Procedure for fluorescence-based HTS of amidation 37
2.4.4. General procedure for amidation of aromatic carboxylic acids with amines 37
2.4.5. Characterization of amide products 38
III. Discovery of lanthanide metal oxide catalyst for transesterification reaction using
fluorescence-based high-throughput screening and application to biodiesel production 43
3.1. Introduction 43
3.1.1. Various catalytic strategies for transesterification 43
3.1.2. Metal oxide catalysts for transesterification 46
3.1.3. Biodiesel production by transesterification 47
3.1.4. Rare-earth oxide catalyst for transesterification 48
3.1.5. Research overview 49
3.2. Results and discussion 50
3.2.1. Development of HTS method for transesterification with pyrene excimer
fluorescent probe 50
3.2.2. HTS of transition or lanthanide metal oxide catalysts 54
3.2.3. Optimization of reaction conditions 58
3.2.4. Substrate scope 60
3.2.5. Application to biodiesel production 63
3.3. Conclusions 65
3.4. Experimental 66
3.4.1. Materials and instruments 66
3.4.2. General procedure for preparation of transition or lanthanide metal oxides 66
3.4.3. Synthesis of pyrene excimer probe, bis(4-(1-pyrenyl)butyl) maleate (BPBM) 66
3.4.4. General procedure for fluorescence-based HTS of transesterification 67
3.4.5. General procedure for transesterification of aryl esters with alcohols 68
3.4.6. Transesterification of glyceryl trioctanoate 68
3.4.7. Production of biodiesel by transesterification of soybean oil 68
3.4.8. Characterization of ester products 69
References 72
Appendix S 1
List of spectral copies of 1H, 13C, 19F NMR S 1
Spectral copies of 1H, 13C, 19F NMR S 5
Curriculum Vitae
- Degree
- Doctor
- Appears in Collections:
- Department of Chemistry > 4. Theses(Ph.D)
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