Ionic liquids (ILs) are often hailed as the green saviours of organic chemistry.
Ionic liquids (ILs) are often hailed as the green saviours of organic chemistry. In the past few years they have entered the realms of industry and many hope that they will become widely employed by the chemical and pharmaceutical industries. However, swathes of data still need to be collected before the compounds can be considered as viable solvent alternatives by pharmaceutical companies such as GlaxoSmithKline (GSK). This is the message that Alan Curzons, from GSK’s corporate environment, health and safety department gave when he spoke at the RSC’s Ionic Liquids conference in London.
Because ILs have no measurable vapour pressure they are non-volatile, a feature which enhances their green reputation. However, Curzons called for IL proponents to stop claiming that ILs are green simply because they do not release volatile organic compounds. ’This is only a relatively small component,’ he said.
Curzons called for more data on ILs before they can be used routinely by the pharmaceutical industry. Before seriously considering ILs, a company such as GSK would need information on their safety and environmental impact, and a life cycle assessment is an ’absolute must’, he said. Added to the cost of getting the compounds past regulatory hurdles, such assessments would be expensive exercises.
What is more, Curzons would want to see a common solvent used across a number of drug manufacturing process steps. ’If we can’t get a product out of an ionic liquid without using solvents, then we haven’t made a significant benefit,’ he said. He also doesn’t want to be dazzled by the huge number of ILs available without a simple and rapid way to screen them. What Curzons would like to see is a limited number of ILs with broad applications.
He told Chemistry World that ’the evaluation of ILs in GSK processes is still limited. This is not likely to change until some of the key questions raised by my presentation and others are answered. Until an application is discovered that provides a significant business benefit/s, I don’t think we will see ILs being used on a manufacturing scale in GSK. At the present rate of progress, unless there are significant changes in the state of the art, I think it is unlikely that we will see widespread use of ILs within the next ten years’.
Ken Seddon, a director of the Queen’s University Ionic Liquids Laboratories (Quill), told delegates how there has been a dramatic increase in the number of papers published on ionic liquids recently. However, many of these had a ’seen it all before’ feel, he warned, with a large number of papers being published on the Heck reaction alone. ’We don’t need these,’ he said. ’One or two detailed papers would do.’