2000 Progress Report: Aqueous Polyglycol Solutions as Environmentally Benign Solvents in Chemical Processing

EPA Grant Number: R828133
Title: Aqueous Polyglycol Solutions as Environmentally Benign Solvents in Chemical Processing
Investigators: Kirwan, Donald J. , Gainer, John L.
Institution: University of Virginia
EPA Project Officer: Hahn, Intaek
Project Period: June 1, 2000 through May 31, 2003 (Extended to May 31, 2004)
Project Period Covered by this Report: June 1, 2000 through May 31, 2001
Project Amount: $335,000
RFA: Technology for a Sustainable Environment (1999) RFA Text |  Recipients Lists
Research Category: Sustainability , Pollution Prevention/Sustainable Development


The objective of the research project is to explore aqueous solutions of polyethylene glycol and polypropylene glycol as environmentally benign alternatives to industrial solvents in chemical processing. Particular emphasis is on the replacement of reaction solvents and precipitation agents in pharmaceutical and fine chemical processes.

Progress Summary:

In this first year of the project, significant advances have been made in the exploration of nonvolatile, nontoxic, aqueous PEG and PPG solutions as reaction solvents for reaction classes commonly employed in pharmaceutical syntheses. Reactant and product solubilities and reaction kinetics have been measured at room temperature for the following model organic reactions: Diels-Alder (two reactions), SN1, and SN2; the values were compared with those for the traditional, volatile organic solvents normally used. In general, at greater than 70 percent PEG/PPG, these solvents exhibited significant solubility for the organic reactants studied. For the SN1 reaction, the rate constants were 1 to 3 orders-of-magnitude larger than in traditional solvents; for the Diels-Alder reactions, the rate constants were higher than those in traditional solvents, indicating significant potential as replacement solvents for these reaction classes. For the SN2 reactions, the rate constants were found to be 1 to 2 orders-of-magnitude lower in the polyglycol systems. However, depending upon the balance of environmental and economic concerns, solvent replacement still may be justified.

Future Activities:

The next area of investigation for the substitution of reaction solvents will be a study of the temperature dependence of solubilities and kinetics in these alternative solvents. The polyglycol solvents are nonvolatile as compared with traditional solvents that contribute significantly to VOC emissions. Therefore, it is likely that reactions can be operated at higher temperatures without any adverse environmental consequences and thereby have improved reaction productivity. A second area of investigation will be the influence of the solvents on reaction selectivity using a model Diels-Alder reaction. This is an area of extreme importance to economic solvent substitution and must be fundamentally investigated. Finally, modeling of reaction kinetics in these solvents will be undertaken to permit generalization of the results beyond the particular model reactions studied.

We also will initiate further experimental studies and modeling of the solubility capabilities of these solvents. This will have particular relevance to precipitation and crystallization of pharmaceuticals and fine chemicals by anti-solvent addition. Studies of crystal nucleation and growth in these solvents also will be initiated.

Journal Articles on this Report : 4 Displayed | Download in RIS Format

Other project views: All 7 publications 5 publications in selected types All 4 journal articles
Type Citation Project Document Sources
Journal Article Leininger NF, Clontz R, Gainer JL, Kirwan DJ. Polyethylene glycol-water and polypropylene glycol-water solutionsas benign reaction solvents. Chemical Engineering Communications 2003;190(4):431-444. R828133 (2000)
  • Abstract: Taylor & Francis-Abstract
  • Journal Article Leininger NF, Gainer JL, Kirwan DJ. Effect of aqueous PEG or PPG solvents on reaction selectivity and Gibbs energies. AIChE Journal 2004;50(2):511-517. R828133 (2000)
  • Full-text from PubMed
  • Abstract from PubMed
  • Full-text: Wiley-Full Text HTML
  • Abstract: Wiley-Abstract
  • Journal Article Wang X, Ponder CS, Kirwan DJ. Low Molecular Weight Poly(ethylene glycol) as an Environmentally Benign Solvent for Pharmaceutical Crystallization and Precipitation. Crystal Growth & Design 2004;5(1):85-92. R828133 (2000)
  • Abstract: ACS-Abstract
  • Journal Article Wang X, Gillian JM, Kirwan DJ. Quasi-Emulsion Precipitation of Pharmaceuticals. 1. Conditions for Formation and Crystal Nucleation and Growth Behavior. Crystal Growth & Design 2006;6(10):2214-2227. R828133 (2000)
  • Abstract: ACS-Abstract
  • Supplemental Keywords:

    chemicals, toxics, VOC, intermediates, pollution prevention, green chemistry, clean solvents, clean technologies, waste minimization, environmentally conscious chemical manufacturing, engineering, alternatives, organics, chemistry, solubility., RFA, Scientific Discipline, Sustainable Industry/Business, Environmental Chemistry, Sustainable Environment, Technology for Sustainable Environment, Economics and Business, cleaner production, waste minimization, environmentally conscious manufacturing, environmentally benign solvents, green process systems, alternative solvents, solvent substitute, chemical processing, aqueous discharge streams, aqueous polyglycol solutions, pollution prevention, Volatile Organic Compounds (VOCs), green chemistry, pharmaceutical industry, aqueous solvents

    Progress and Final Reports:

    Original Abstract
  • 2001
  • 2002
  • Final