How do chemists find a procedure to produce a given substance?

Question

How do they find out exactly what reactions they can use to produce some substance they want to produce? Is there some reaction database that helps them find a way to make the target substance out of available chemicals?

For example, let's say they want to produce ethanol. There are multiple ways to do this: they could use the fact that yeast can transform sugars into ethanol and carbon dioxyde and use distillation to produce concentrated ethanol, or use ethylene hydration to get the same thing.

The question is: how could they find those ways? How do they know what will be produced by a given reaction, or inversely, what reaction will yield a given substance? Some reactions are well known and were just observed and studied, but what about the obscure ones?

Thanks.

Answer 1

Chemists use many sources of information to do this.

Part of being trained as a chemists is learning, in general terms, what kinds of reactions are known and what their best uses are. That training can go 5-10 years beyond a bachelors degree and is very intensive.

Beyond what you can keep in your head, one of the most important information sources is the "primary literature", consisting of:

• Patents
• Journal publications

As an example, see this patent about ethanol manufacture.

Alternatively, see this very recent journal publication dealing a new catalytic reaction.

Having all of this information out there is a start, but it's a vast collection spread out over many publishers and 100 years or more. To find what you need, it's essential to have a good indexing system. This allows you to search large databases of reactions and molecules for references that exactly match, or which are close to what you need.

This last part - being able to reason by analogy - is critical to being able to get the most out of the primary literature. Maybe I don't find an exact match for the exact reaction I want to do. But I find something pretty close. Here's where my training and reasoning ability come in to either decide to adapt what I've found or keep looking for something better.

An example of one of these search systems is Chemical Abstracts Service, but there are others.

As a professional chemist, you're expected to keep up with all of the main journals in your field so you stay up to date. You do this by reading articles, talking to people, giving talks, and going to conferences.

There's another category of information consisting of 'reviews'. These are articles that summarize a large area of chemistry - for example, recent large-scale methods for the production of ethanol.

The discovery/invention of new reactions is a very active area of current chemical research.