DAT Destroyer Organic Chem #63 - Constitutional Isomers question

Mrhyde

Becoming Dr. Jekyll
Apr 13, 2015
170
44
Status
Pre-Dental
DAT Destroyer Organic Chem #63 - Constitutional Isomers question


So I know that the formula for getting the number of stereo centers is 2^n with n being the number of chiral carbons.

I know for number 63, that it is 2^2 = 4 - 1 = 3 since its meso.

BUT I am confused as to how to get the correct number of constitutional isomers ?

Is there a math method that we have in which we can use the answer for the number of stereo isomers in order to derive the number of constitutional isomers ? or is there some type of formula to get the number of constitutional isomers or any tricks ?

Thank you for any help !
 

orgoman22

DAT DESTROYER
Lifetime Donor
Sponsor
Vendor
10+ Year Member
Mar 12, 2005
4,185
3,038
New York City
www.orgoman.com
Status
Non-Student
DAT Destroyer Organic Chem #63 - Constitutional Isomers question


So I know that the formula for getting the number of stereo centers is 2^n with n being the number of chiral carbons.

I know for number 63, that it is 2^2 = 4 - 1 = 3 since its meso.

BUT I am confused as to how to get the correct number of constitutional isomers ?

Is there a math method that we have in which we can use the answer for the number of stereo isomers in order to derive the number of constitutional isomers ? or is there some type of formula to get the number of constitutional isomers or any tricks ?

Thank you for any help !


No. There is no way to tell the exact number of constitutional isomers. Did you know that computer programs have been developed to only ESTIMATE the number !!!!! For example, a compound like C30H44O4N would have billions !!! For the DAT, you might be asked a simple one such as C4H10O. Try it.,,,,,and you will find there are 7 ! For a multiple choice exam it is unlikely you would go over 7 constitutional isomers !!!!

Hope this helps

Dr. Romano
 
  • Like
Reactions: Mrhyde

orgoman22

DAT DESTROYER
Lifetime Donor
Sponsor
Vendor
10+ Year Member
Mar 12, 2005
4,185
3,038
New York City
www.orgoman.com
Status
Non-Student
DAT Destroyer Organic Chem #63 - Constitutional Isomers question


So I know that the formula for getting the number of stereo centers is 2^n with n being the number of chiral carbons.

I know for number 63, that it is 2^2 = 4 - 1 = 3 since its meso.

BUT I am confused as to how to get the correct number of constitutional isomers ?

Is there a math method that we have in which we can use the answer for the number of stereo isomers in order to derive the number of constitutional isomers ? or is there some type of formula to get the number of constitutional isomers or any tricks ?

Thank you for any help !
Hope you like the answers, you don't hit like so I don't know. If need more help just ask.

Dr. Romano
 
  • Like
Reactions: Mrhyde
OP
Mrhyde

Mrhyde

Becoming Dr. Jekyll
Apr 13, 2015
170
44
Status
Pre-Dental
Hope you like the answers, you don't hit like so I don't know. If need more help just ask.

Dr. Romano
Haha I always try to hit the 'like' button , perhaps i may have forgotten on some questions. I really appreciate the help on everything!

So the best way is to just draw out the structures and count them to get the number of constitutionals ?
 

orgoman22

DAT DESTROYER
Lifetime Donor
Sponsor
Vendor
10+ Year Member
Mar 12, 2005
4,185
3,038
New York City
www.orgoman.com
Status
Non-Student
Haha I always try to hit the 'like' button , perhaps i may have forgotten on some questions. I really appreciate the help on everything!

So the best way is to just draw out the structures and count them to get the number of constitutionals ?
Yes but also try to look for different functional groups. For example, if you are able to draw some alcohols there certainly will be ethers. If you can draw some aldehydes there will usually be some ketones.

Hope this helps

Dr. Romano
 
Aug 21, 2016
4
1
Status
Pre-Dental
Yes but also try to look for different functional groups. For example, if you are able to draw some alcohols there certainly will be ethers. If you can draw some aldehydes there will usually be some ketones.

Hope this helps

Dr. Romano
One question sir, for #63 can't we also draw an ethyl group coming off this cyclopentane? It would make 1 additional const isomer.
 

orgoman22

DAT DESTROYER
Lifetime Donor
Sponsor
Vendor
10+ Year Member
Mar 12, 2005
4,185
3,038
New York City
www.orgoman.com
Status
Non-Student
One question sir, for #63 can't we also draw an ethyl group coming off this cyclopentane? It would make 1 additional const isomer.
You have an old addition of our book. It has been corrected. The problem states that all isomers contain a cyclopentane ring and methyl groups. I have written many new questions in the 2017 book that are not in the 2016 book.

Hope this helps.

Dr. Romano
 
  • Like
Reactions: greyworm