Draw the condensed structural formula for each of the following:
b. trans-2-pentene

Question

Draw the condensed structural formula for each of the following:

b. trans-2-pentene

Accepted Answer

Hi, everybody. Let's look at our next problem, provide the correct condensed structural formula of trans three hept. So let's think about what this would look like. We have a Hept. So we have a seven carbon chain is our longest chain. It's labeled three heptane. So the double bond must be between carbon three. So C three double bonded to C four and then it's in a trans arrangement. So since there's no substituents, it's just our chain, the two parts of the chain must be on opposite sides of the double bond. So we have four answer choices for a possible structural formula. So let's walk through how we would arrange this and match it up with our structures. So each of our possibilities does have AC C double bond and we know this must be carbon three and carbon four. So let's look at choice. A, we'll focus starting on the double bond first. So if we label the two carbons in the double bond, carbon three and carbon four, we see that we have two hydrogens on opposite sides of this double bond attached to carbon three and four. And then two carbon chains on either side. So let's see if they correspond to our expected HEP. So starting with carbon three and going backwards into the attached chain, I have two carbons. So it would be corresponding carbon two and carbon one. So that would be fine on the other side of the double bond. So we have carbon four, finishing the double bond and then I see a three carbon branch and that would correspond to carbons 56 and seven. So it looks like choice. A here is correct. We've got a seven carbon chain you expect from HEPT the double bond from carbon three to carbon four. And it's in a trans arrangement with the two chains on opposite sides of the double bond and the two hydrogens on opposite sides. Choice A is correct. Let's take a close look at our other answer. Choices to understand why they're not. So in choice B I have my two carbons with their double bonds, but I have my two carbon chains on the seam side, both on the top of the double bond and my two hydrogens on the bottom. So this is a sis arrangement. So choice B is incorrect. Then in choice C I have my carbon carbon double bond, but my two hydrogens are both on the same carbon. And then my two chains, carbon chain, hydrocarbon chains, two alkyl chains are on the other carbon. So this is incorrect recall that a CS arrangement means the two similar substituents being on the same side of but attached to two different carbons. Then we look at choice D got our carbon carbon double bond. And it is also in the cy arrangement with hydrogens on the same side of the double bond, we also have the wrong number of carbons. We have, we label three and four and go back from three, we have there's carbon two carbon one and there's an extra carbon on the end. So even if we didn't see that it was a sis arrangement, we've got an extra carbon. So choice D is not correct. So again, for the correct condensed structural formula of trans three hept, we have choice A where it's our cc double bond on the left side going up from it, we have an ethyl group going down from it to hydrogen, on the right side, going up from it to hydrogen. So opposite side going down from it, we have a three carbon group finishing the rest of the chain. See you in the next video.

Draw the condensed structural formula for each of the following:
b. trans-2-pentene

Verified video answer for a similar problem:

Key Concepts

Condensed Structural Formula

Trans Isomerism

Pentene Structure