Ochem Destroyer #186

[Dencology]

Advertisement - Members don't see this ad

Hey guys, what is the answer to #186 Destroyer in Ochem?

It said that Carboxylic acid has the higher priority but does it mean that when it comes to #ing it, it will take precedent over Cl?

i have D as the answer.

 

[osimsDDS]

yea this problem is really really weird, it says to assume that COOH group has the highest priority but then it gives Cl and even the other alkyl group first and second!!! wtf is going on...this question drove me crazy

 

[PooyaH]

I think by that it just means that if you want to name the compound, COOH has the highest priority, so this way you'd know where C1 is so you can locate C2, C3, and C4 carbons!

 

[klutzy1987]

LOL.

When it says the highest priority it means when you are counting the carbons (i.e. carbon 1,2,3) It is not telling you to rank that as the highest substituent. The question can be worded better but that is what its saying. After you understand that it really is a good question.

 

[osimsDDS]

haha yea but in the answer choices the designate COOH as #3 haha, COOH should be #2 after Cl

 

[DRHOYA]

Hey guys, what is the answer to #186 Destroyer in Ochem?

It said that Carboxylic acid has the higher priority but does it mean that when it comes to #ing it, it will take precedent over Cl?

i have D as the answer.

Read carefully the wording of the question. When it says "assuming COOH group has highest priority", it is referring to the actual numbering of the chain itself..........not that is has highest priority when assigning configuration at C2. At C2, the Cl gets the #1 priority, followed by the R-group (b/c that C is in turn bonded to another Cl).....and the COOH is #3. Based on that...the H is up, so keep the confiugation at R. Hope that helps. Tricky wording.

 

[osimsDDS]

hahah thats confusing as hell...i tried to figure this problem out for like a month hahah

 

[Dencology]

so what is the answer?

 

[klutzy1987]

The answer in the destroyer is correct. Once you understand the qestion the answer makes perfect sense.

 

[shoombol tallah]

haha yea but in the answer choices the designate COOH as #3 haha, COOH should be #2 after Cl

thats what i thought too. Can some show me how the R group has a higher priority than the carboxlyic acid? when i add them up i get 3 O's and 1 H for the COOH group equaling 49 . and for the R group i get 1 Cl, 1 C, and 1 H equaling 48.5. So my reasoning was that the COOH group had a higher priority than the R group. Any help would be greatly appreciated 🙂

 

[klutzy1987]

haha yea but in the answer choices the designate COOH as #3 haha, COOH should be #2 after Cl

Because the R group has a c and the next substituent after the C is a Br while on the carboxy acid the next substituent after the C is an oxygen. The Bromine will always take precedence over the Oxygen regardless of ow many oxygen bonds there are.

 

[klutzy1987]

thats what i thought too. Can some show me how the R group has a higher priority than the carboxlyic acid? when i add them up i get 3 O's and 1 H for the COOH group equaling 49 . and for the R group i get 1 Cl, 1 C, and 1 H equaling 48.5. So my reasoning was that the COOH group had a higher priority than the R group. Any help would be greatly appreciated 🙂

I do not know what you are doing with that number stuff but it has no bearing how much the entire thing weighs. The first substituent is all that matters. In this case you are comparing a Br to an O and Br weighs more therefore it has priority. How many O are irrelevant

 

[shoombol tallah]

I do not know what you are doing with that number stuff but it has no bearing how much the entire thing weighs. The first substituent is all that matters. In this case you are comparing a Br to an O and Br weighs more therefore it has priority. How many O are irrelevant

oh ok so first point of difference instead of total atomic mass 🙂 cool thanks 👍

 

[Andrew324]

Yeah Br wins over Cl by the way. I got the middle one wrong because I was thinking the opposite. Br has a larger mass so it beats Cl in priority