Vol. 28 No. 2
March-April 2006

What Is Butadiene?
by Karl-Heinz Hellwich

What is butadiene? You might think that’s a question too simple to ask. But, are you sure? Whatever you guess, your answer will surely be better than the exam response of a student who defined butadiene as “a conjugated double bond.” Of course, butadiene is not a double bond. But, what is it then? We can approach this question on two different levels. Butadiene is a word, that is, a name for a thing. In knowledge theory there is much discussion as to whether a thing and the name for the thing can be equated. A name is arbitrary and typically emphasizes a particular aspect of the described thing. However, the thing named by the word remains the same, and many of its other properties remain uncertain, even if another designation is selected. (Another possible word to describe what we call butadiene would be tetradiene, which emphasizes the same property.) The fact that a name never describes all the properties of a thing can cause confusion.

Let’s assume that with the designation butadiene we are concerned with the substance. It is therefore clear now that it is a chemical compound. The question of whether it is a single molecule, or the macroscopic substance consisting of many molecules that is gaseous at room temperature and is used in the laboratory or in a chemical plant, is only mentioned and neglected here, but it shows that the aspect under which butadiene is considered is important.

Like the above-mentioned student, most readers will probably think of buta-1,3-diene with its two conjugated double bonds, which is the starting material for Buna® and several copolymers on multi-ton scales or used in Diels–Alder reactions. Recently, when reading a publication, I doubted this was really the starting material of the described products. The authors had failed to mention that they worked with buta-1,2 diene—also a gaseous compound at room temperature, but a much less commonly used material. Only a note at the end of the publication made it reasonable to suppose that the authors wrote about allenes and reactions at cumulated double bonds.

It is apparent that the situation noted at the beginning of this article—that is, that a thing can have different designations in different languages—must be reversed for chemical nomenclature. Here it must be ensured that the information relayed is accurate, such that the recipient of the information—a listener or a reader—understands what the author wants to convey. In the case of butadiene, an author must therefore specify whether he means buta-1,2-diene or buta-1,3-diene.

Authors of publications must realize the importance of being precise in their writing—just as they would be in the laboratory—to ensure that information is readily understood by readers and interpreted in the intended way. In an everyday laboratory setting with a closed team, abbreviations and contractions may be used that are inappropriate in a larger setting because they are inaccessible, especially if the contractions originate in chemical nomenclature or are derived from the international nonproprietary names for drugs.

Dr. Karl-Heinz Hellwich <[email protected]>, from Offenbach, Germany, is a member of the IUPAC Chemical Nomenclature and Structure Representation Division (VIII). He is also involved in an IUPAC project dealing with terminology and nomenclature of macromolecules with cyclic structures.