YES-27-Y-04: Kinetics and Photochemistry of New “Green” Solvent Breakdown in Air

Kinetics and Photochemistry of New “Green” Solvent Breakdown in Air

Dr. Terry J. Dillon (York) and Prof. Paul Seakins (Leeds)

 

Background

Solvents make up the bulk of waste from the chemical industry, yet to date, little attention is paid to the environmental impact of these volatile organic compounds (VOC) once released to the atmosphere. Traditional solvents such as toluene and tetrahydrofuran are unsustainably sourced from petroleum, toxic {1}, and are known to breakdown in air to yield large quantities of harmful pollutant gases such as ozone and formaldehyde. With environmental impact and sustainability at the forefront of York research efforts, we have developed novel, sustainable, less-hazardous ‘green’ solvents to replace traditional compounds {2-3}. However, the gas-phase photochemistry of these new compounds is unknown {4-6}. Most green solvents are oxygenated VOC (examples ketones, esters, ethers), a class of compounds with highly unpredictable chemical behaviour in air. 

 

Figure 1 – in previous work, the reaction between OH and the new solvent pinacolone (PCO, t-C4H9C(O)CH3) exhibited Arrhenius-like kinetics (left panel), in contrast to state of the science Structure Activity Relationship prediction. Rapid photolysis of pinacolone (right) resulted in this solvent having a worse air quality impact than the traditional solvents it could replace (from Mapelli et al. {5})

In previous projects we determined that certain new solvents (see Figure 1) were associated with poor air quality outcomes; their reactivity in air was both larger than predicted and larger than the traditional solvents they may replace {5}. In this project you will conduct lab-based experiments to discover and assess the impacts of new green solvents on air quality. Results will inform new solvent design so that benign chemical features can be incorporated into future solvent development. 

Objectives:

Determine gas-phase oxidation rates for both photolysis and reactions with free-radicals; reveal mechanisms for new solvent breakdown in air; assess air quality impacts via metrics such as atmospheric lifetime, photochemical ozone creation potential; inform and improve new solvent design.

Experimental Approach

This project will use various photochemical techniques available in the York and Leeds laboratories (Figure 2). These include Pulsed Laser Photolysis – Laser Induced Fluorescence for temperature dependent kinetic studies of solvent + radical reactions; UV-vis. spectroscopy for solvent spectra; a fast-flow reactor coupled to UV-LEDs for photolysis quantum yields; the HIRAC chamber for product studies {7}.

Figure 2 –the photochemistry laboratories in both universities are equipped with a wide range of capabilities for this project, including a variety of pulsed laser apparatus, the photolysis reactor in York (left) and the HIRAC chamber in Leeds (right).

Bespoke training and support will be provided by supervisors and the research teams in York and Leeds. 

www.york.ac.uk/chemistry/research/wacl/

www.york.ac.uk/chemistry/research/photochemistry-spectroscopy/

eps.leeds.ac.uk/chemistry-research-groups/doc/atmospheric-planetary-chemistry

Whilst no prior experience of any particular technique is necessary, the successful applicants will demonstrate an aptitude for quantitative chemical analyses and a strong interest in photochemistry and atmospheric science.

Literature:

{1} Prat, D. et al. (2016), CHEM21 selection guide of classical- and less classical-solvents. Green Chem., 18, 288, 10.1039/c5gc01008j

{2} Byrne, F. et al. (2017). 2,2,5,5-Tetramethyltetrahydrofuran (TMTHF): a non-polar, non-peroxide forming ether replacement for hazardous hydrocarbon solvents, Green Chem., 19, 3671, 10.1039/c7gc01392b 

{3} www.york.ac.uk/chemistry/research/green/research/altsolvents/

{4} Mapelli, C.M. et al. (2022). Atmospheric breakdown chemistry of the new “green” solvent 2,2,5,5-tetramethyloxolane via gas-phase reactions with OH and Cl radicals. Atmos. Chem. Phys. (22), 14589, 10.5194/acp-22-14589-2022

{5} Mapelli, C.M. et al. (2023). Atmospheric breakdown chemistry of the new “green” solvent 2,2,5,5-tetramethyloxolane via gas-phase reactions with OH and Cl radicals. Atmos. Chem. Phys. (22), 14589, 10.5194/acp-23-7767-2023

{6} Metcalf, J.D.M. et al. (2025). Atmospheric breakdown kinetics and air quality impact of potential “green” solvents, the oxymethylene ethers OME3 and OME4. Atmos. Chem. Phys. (25), 9169, 10.5194/acp-25-9169-2025

{7} hirac.leeds.ac.uk/about-hirac/