2010 Dat Destroyer #229

[crackedbytheDAT]

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Hi all,

I am going through the Dat Destroyer 2010 #229 and am having a little difficulty. It asks for the configuration of C-2 C-3 and C-4. I am having trouble with assigning priority groups at C-3. I know that the Cl will be 1, but how do you determine priority between the C-2 side or the C-4 side? C2 has an H, CL and carboxylic acid attached. And C4 has an H, bromine and alcohol attached, in case that helps.

Thanks.

 

[crackedbytheDAT]

anybody? please answer even if its a stupid question. im just not getting it for some reason.

 

[LuckyTangerines]

I have the 2011 Destroyer but I think I know which problem you're referring to. This problem is fairly tricky if you do it too quickly. I admit I got this problem on my first try. The key here in assigning priority is to find the first major point of difference. I'll try my best to explain but hopefully you'll be able to understand.

On C-2, the first priority is obviously the Cl since it has the highest atomic number and the lowest priority is the H. Now you have to compare between the carboxylic acid carbon and the C-3 Carbon.

For the carboxylic acid, the carbon has the following attached to it, in order or priority: O, O, O (For the double bond between C and O, pretend they're single bonds each to an O)

For the C-3 carbon, the carbon has the following directly attached to it, in order or priority: Cl, C, H. Now compare the between these two Carbons with the information we have and we find that the first major difference is between O in the carboxylic acid and Cl on C-3. Since Cl has a higher atomic number than O, the C-3 carbon has priority over the the carboxylic acid so we get the R configuration.

Now if you do the same thing for assigning priority on C-4 you should get the S configuration.

Hope this helps!

 

[crackedbytheDAT]

I have the 2011 Destroyer but I think I know which problem you're referring to. This problem is fairly tricky if you do it too quickly. I admit I got this problem on my first try. The key here in assigning priority is to find the first major point of difference. I'll try my best to explain but hopefully you'll be able to understand.

On C-2, the first priority is obviously the Cl since it has the highest atomic number and the lowest priority is the H. Now you have to compare between the carboxylic acid carbon and the C-3 Carbon.

For the carboxylic acid, the carbon has the following attached to it, in order or priority: O, O, O (For the double bond between C and O, pretend they're single bonds each to an O)

For the C-3 carbon, the carbon has the following directly attached to it, in order or priority: Cl, C, H. Now compare the between these two Carbons with the information we have and we find that the first major difference is between O in the carboxylic acid and Cl on C-3. Since Cl has a higher atomic number than O, the C-3 carbon has priority over the the carboxylic acid so we get the R configuration.

Now if you do the same thing for assigning priority on C-4 you should get the S configuration.

Hope this helps!

Thanks for your help but I'm pretty sure it is a different question in 2010. 2011 might have a similar question that was changed up a bit. I appreciate the response tho.