Which of the following names are correct? Correct those that a...

Question

Which of the following names are correct? Correct those that are not correct.

e. 4,4-dimethyl-2-pentyne

f. 2,5-dimethyl-3-hexyne

Accepted Answer

Well, everyone on this video, we have defined the correct names and correct those that are missed names. So starting off with the first one here, we have 45 dime opt two I M. So first is to identify the parent chain, we see we have O C team as a prefix, meaning we have eight carbons on our parent chain. So we start off number one by doing so. So 1234, 567 and eight, I'll go ahead and number these in as well. So it can make it easier for us later on. We're adding all these substituent and so on. So we have completed the O C part of it. Now we see here, we also have two Y N E. So Y N E is the ending of our triple bonds. For example, if you remember for alkenes, we have an ending of A&E, but this time we have an al kine. So that's why we have the ending of Y N E. And to be more exact, we have at the second carbon, that's where our triple bond is starting. So I'll go ahead and add that triple bond in here. All right, let's maybe make this a little bit cleaner again. We have a triple bond starting at the second carbon going on to the third carbon. All right. So we have completed our parent chain here. Let's now go ahead and add in our substituent. So we see here in the name, we have 45 dimethyl. So we have a total of two metal groups in our structure. One at the fourth position. So we're going to go ahead and add the C H three there and at the fifth Position as well. So we see we do have two metal groups and at the 4th and 5th position. Now, what we need to do is add in all the necessary protons to fulfill all the carbon's octets starting off with carbon number one, we have H three C carbon two and three have their octets for four and five. We just need more and more hydrogen there. Then for six and seven, we do need two more hygienes to fulfill its Octa. So let's draw that in. And then for the 8th carbon is another terminal carbon. So that's CH three. All right. So let's go ahead and actually name this without looking at the given name. So first of course, as we know, we have to identify the longest structure that contains this triple bond. So that's definitely going to be a parent chain of eight carbons. And because we have a triple bond of an octane, we have an oc time. So Y N E, right? And now we can go ahead and consider and add in this triple bond. So once we consider the triple bond and it's at the second carbon, that's opt to iron. Now, once we add this triple bond, we just need to worry about substituent. So once we add a substituent, again, we have a methyl group of four and five. So we have a di methyl group and then adding in our parent chain, that's O C T oct two I Y N E ending. So this name is exactly the same as the one provided in the question text. So we can say that for number one molecule A is going to be correct. It has the correct naming. So go ahead and highlight that as my final answer for part one and moving on to part two, the name is five methyl hept two iron. So we see here that we have a prefix of H E P T meaning that we have seven carbons in our parent chain. So go ahead and draw that first. So we have and seven. I'll go ahead and actually number in those carbons as well. 456 and seven. All right, perfect. So again, we started off with the Hept prefix. Now continue on to the ending. We have two Y N E or two I. That means that at the second carbon, we also have a triple bond. So I can go ahead and draw that triple bond in all right. Now, moving on to our substituent, we see we have a five metal in the beginning of our name. So we have one metal group at the fifth carbon position. So go ahead and add that in last step. Of course, is just to add in all the necessary hydrogen atoms to fulfill these octets. So we have ach three group at the terminal end carbons, four needs two hydrogens as well as carbon six. Now, for carbon five, we just need one more proton. And then again, a carbon seven is a terminal carbon. So we just need three more protons. So if we use the same methods as the one we use for part A, we can go ahead and find a name here. So we see here that the parent chain again is seven cartons and we do have a triple bond. So instead of a hept, this is in hep, I would now consider our triple bond at the second position. We have a PT two. I. Now I am in again, these substituent that we get that we have a metal group on the fifth position. So we have five dash metal adding in our parent change of name. So he P two I, as we can see that this name then is going to be the exact same as the one in the question text. So this means for part two, this molecule B, it's also going to have its correct name. I'm gonna go ahead and highlight that as my final answer. So both of these given names provided, it is going to be the correct names for the structure.

Which of the following names are correct? Correct those that are not correct.
e. 4,4-dimethyl-2-pentyne
f. 2,5-dimethyl-3-hexyne

Key Concepts

IUPAC Nomenclature

Alkyne Structure

Substituent Naming and Positioning

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