In flow syntheses, chemical productions take place in a closed system where it is possible to regulate temperature and pressure, thereby improving the reaction conditions in a safe environment. The photo shows Assistant Professor Anders Thyboe Lindhardt in his laboratory.
Imagine a small machine about the size of a suitcase. You put some carefully selected chemical ingredients in one end and a little later the finished medicine comes out the other end as pills. This is just one of the prospects for a new chemical technology that handles all reactions and purifications in a closed system.
The field of organic chemistry is constantly renewing itself and industry requires new synthetic methods for constructing increasingly complex molecules. We are on the threshold of a new chapter in the world history of chemistry, where we can possibly say farewell to conical flasks, fume hoods and batch processes, and bid an entirely new method of chemical reactions welcome to the laboratory and to industry in the ton scale.
Industrial paradigm shift on the way
The method is called flow chemistry which is a new approach for manufacturing large quantities of chemicals and – as the name implies – in a continuous reaction sequence. The principle is simple. You feed the necessary precursors or chemical ‘building blocks’ into a machine that uses pumps, tubes and small reactors to carry out a chain of reactions in a closed system where you can very accurately regulate pressure and temperature with no limitations regarding safety.
Flow chemistry is a developing scientific field, and something of an international research race is in full swing. This is because the technology is promising and heralds an industrial shift in which virtually all chemical processes can be taken out of the laboratory, made cleaner and more efficient, and be carried out on a far greater scale than anyone dared dream of just a few years ago.
“Everything we know about good chemistry and good chemical batch processes can be turned upside down by flow chemistry. The technology provides some completely new reaction conditions and thus makes it possible to take some decisive innovation steps towards new products with new properties in areas such as the pharmaceutical or material industries,” says Assistant Professor Anders Thyboe Lindhardt.
No toxic fumes or danger of explosion
Safety is another obvious advantage of flow chemistry processes. There is no danger of toxic fumes, dangerous gases or explosion. In contrast to traditional organic synthesis that chemists carry out in round-bottomed flasks in fume hoods with exhaust fans, flow chemistry takes place in a small machine with no human contact.
The advantages of flow chemistry – in addition to increased safety – include the possibility to work with more rapid exchange of heat and cold and at a higher pressure, thus enabling reaction conditions that have not previously been possible. In other words, researchers can safely and accurately take all the good aspects of the traditional chemistry laboratory and use them in a production context.
“Flow chemistry is really a shortcut from basic research to application. Only a few years ago, we were pottering around with good chemistry and good chemical processes in flasks in the fume hoods, but we had no chance of scaling up the production of compounds in large amounts,” says Assistant Professor Lindhardt.
“Today it’s possible to upgrade the reactivity of the chemical ingredients and thereby increase the amount of the substance you want to produce. But this requires a special flow chemistry machine – and we have one at Aarhus University,” he adds.
Chemical chain in a closed system
It does not look anything like a high-technology wonder, but looks can be deceiving. It is built from scratch with advanced equipment for every tiny part of the chemical chain and with a clear engineering focus on creating the best possible reaction conditions for the substances being put in the system.
According to Assistant Professor Lindhardt, one of the main architects of the machine, it works as intended. It converts the chemist’s technical batch procedure into a continuous process and works, in principle, as a small chemistry factory. It can mix, cool and heat precisely in one and the same process, and thereby reduce the reaction time significantly.
To start with, the researchers are investigating how flow synthesis could improve on already known batch processes. They will subsequently develop chemical processes that can only be carried out in a flow machine, and thereby produce new chemical entities or everyday commodities in a better and more energy efficient way.