28 No. 2
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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
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.
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