Draw a structure for a compound that meets each of the followi...

Question

Draw a structure for a compound that meets each of the following descriptions:

A cyclic alpha-hydroxyketone, C₅H₈O₂

Accepted Answer

Hi, everyone. Welcome back. Our next question says which structure meets the following specifications? A cyclic alpha hydroxy ketone with a formula of C six H 1002. We have four different structures labeled one through four. And our answer choices A through D are A one, B, two, C three and D four. So let's look at our structures in more detail. Recall that they, what specification they need to meet, they need to be cyclic. And all four of these have a cyclops ring. So all of them are cyclic. So we put a little check mark there. They need to be ketones. We recall that ketones have a Carbone group. So c they will monitor to an O with our groups attached on either side of that carbon carbon. In this case, all of our structures have a ketone group on the cyclops ring. So it's a carbonel group where the two R groups are the ring itself. So they all have this ring and therefore all are ketones. They all have an O group somewhere on the structure. So they all have that hydroxy group. The one thing we need to follow up on is what is an alpha hydroxy ketone? When we look at a ketone, we have that carbonel group and we have the R groups on either side, which will both start with a carbon and then continue on to the rest of the R groups. I'm drawing sort of a line down with little squiggle. We'll put R in parentheses and R prime in parentheses. So it's not the R group itself because we're focusing on the fact that there will be a carbon adjacent to the carbon carbon on either side and that will be the alpha carbon. So it's the carbon adjacent to the carbon carbon. So in the case of the ketone, there's an alpha carbon on either side. So alpha hydroxy means the hydroxy group must be on one of the alpha carpets. So let's look at structure one, we have a cyclone ring, it has its ketone on it. And then there are two alpha carbons. So the two adjacent carbons, one has a methyl group and one has an oh group. So this is indeed an alpha hydroxy ketone. So it will be our answer. So long as its formula is C six H 1002. So we see that we have six carbons. It's a five carbon ring with a methyl group. So it is C six. The next easiest one to look at is oxygen. It says ox two oxygens. And indeed, we have one in our carbonel group and one in our hydroxy group. So 02 is correct. And then finally, hydrogen, we should have 10 of them. Well, this one's a little trickier. We'll start by numbering the carbon starting with the ketone. So carbon one, carbon two being the one with the oh group and then just go around our ring. Now, let's count up the hydrogens present. I'll use hash marks here to keep track of how many I have and make sure that adds up to 10. So starting with carbon one carbon carbon, it has no hydrogens since it has the two ring carbons and a double bond to oxygen. Carbon two has the hydroxy group. So with the ring in one substituent, it has one hydrogen. So we'll put one hash mark. In addition, our hydroxy group has a hydrogen. So that will be two hash marks carbon three is in the ring, no substituents. So it has two hydrogens add two. Hash marks carbon four is the same, no substituents within the ring. So two hydrogens, carbon five has a methyl group. So it will have just one hydrogen, but the methyl group itself has three hydrogens to ch three. So 12, three more hydrogens, then we're all the way around and indeed we have 10 hydrogens. So it fulfills all our specifications. So choice A will be our answer to be thorough. Let's take a quick look at our other answer choices just to see why they're incorrect. So B number two, number two has a cyclops ring with that ketone, it has a hydroxy group two carbons away. So there's no alpha hydroxy group. In this case, in addition, there's no methane substituent. So it has only five carbon atoms. So Choice B definitely not our answer. Number three has that cycling ring. It does have a methyl group. It's got six carbons has that carbonel group, but the hydroxy group is two carbons away. So no alpha hydroxy group there. So that's why number three choice C is incorrect. And finally, number four or choice D Cyclin ring ketone group. And then on the there is a substituent on the alpha carbon but it's not the hydroxy group itself. It's ach true. Oh So the oh is there but not on the alpha carbon. So it's no alpha hydroxy group. So choice D also incorrect. So once again, the structure that fits our specifications, it's a cyclic alpha hydroxy ketone with a formula C six H 1002 is choice a structure. Number one. See you in the next video.

Draw a structure for a compound that meets each of the following descriptions:

A cyclic alpha-hydroxyketone, C₅H₈O₂

Key Concepts

Cyclic Compounds

Alpha-Hydroxyketones

Molecular Formula Interpretation

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