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1,3-butadiene is drawn in the s-cis (cisoid) conformation in the introduction. Is this the preferred conformation? Explain. Why is the s-cis conformation shown?

Answer 1

There is no reason to prefer one to the other.

Since the middle bond between #C_2-C_3# is single, it can rotate freely. Only if the #H#'s around that bond were replaced by other atoms, that either reject or attract one another, would there be a preferred (not obligate) position. If not, then everything depends on physical circumstances like temperature and pressure.

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Answer 2

Carter Allen

The s-cis (cisoid) conformation of 1,3-butadiene is not the preferred conformation because it introduces steric hindrance between the two terminal methyl groups. The s-cis conformation is shown because it represents one of the possible conformations of 1,3-butadiene, illustrating the concept of cis and trans geometric isomers.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.