Stupid question

[GRAD]

I had a question on achiever ochem that wanted me to name a cyclohexane with three substituents. I know i should name the structure based on lowest numbering, but in that case, i could have gone one of two ways.... and i got it wrong. i dunno its embarrassing to get nmenclature wrong. How do you name cyclohexanes if the substituents are equally positioned?

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[Dr. juju]

I had a question on achiever ochem that wanted me to name a cyclohexane with three substituents. I know i should name the structure based on lowest numbering, but in that case, i could have gone one of two ways.... and i got it wrong. i dunno its embarrassing to get nmenclature wrong. How do you name cyclohexanes if the substituents are equally positioned?

is that the one with two methyls and a meta ethyl?
you always have to go by the numbering that gives you lowest possible for all substituents. I think it would be some thing like 3 ethyl-1,1 dimethylcyclohexane.
ps. no it's not embarassin I get them wrong here and there too. I have to keep reminding myself to pay more attention to all answer choices and do not rush through the test
good luck

 

[GRAD]

http://photos.e46fanatics.com/data/500/tupac.JPG

The answer is A, i thought i would number it from the propyl cause then the ethyl would be 2, which would be better????

 

[GRAD]

 

[GRAD]

my question is why isnt it c??

 

[lifeisgood]

my question is why isnt it c??

I got this one wrong too. I'mm pretty sure it's because for C you have 2 4's and for A you have 2 1's....I think a good rule of thumb (since alkyl substituents have the same priority) would be to add the numbers together. 3+1+1+4=9 and 2+4+4+1=11...Not sure if that is the correct thinking and you would always have to account for the presence of high priority fxnl groups like carboxylic acids, etc....

 

[naivegrl124]

Remember that when naming rings, you want to 1. Get the lowest possible set of numbers for the substituents 2. The place where it is most substituted will be numbered 1 and proceeding from there you try to get the lowest set of number for the other substitutents. So thats why the answer is A, hope that helps!

 

[GRAD]

so bc its dimethyl thats why its 1?

 

[allstardentist]

Remember that when naming rings, you want to 1. Get the lowest possible set of numbers for the substituents 2. The place where it is most substituted will be numbered 1 and proceeding from there you try to get the lowest set of number for the other substitutents. So thats why the answer is A, hope that helps!

Right on the money

 

[GRAD]

thanks!