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Chemistry MCQ question please help
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ngwengsamowo
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Structural isomerism and stereoisomerism should be considered when answering this question.
If a molecule contains two non-identical chiral carbon atoms, four optical isomers exist. How many isomers are there with
● molecular formula C7H14O and
● a five-membered ring and
● a tertiary alcohol group? A)4 B)5 C)9 D)13
Answer is C)9, WHY?
If a molecule contains two non-identical chiral carbon atoms, four optical isomers exist. How many isomers are there with
● molecular formula C7H14O and
● a five-membered ring and
● a tertiary alcohol group? A)4 B)5 C)9 D)13
Answer is C)9, WHY?
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ngwengsamowo
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_JB_
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This is the first isomer I found. (How many chiral centres are there?)
![Name: Isomer 1.png
Views: 722
Size: 23.8 KB]()
This is the second isomer I found. (How many chiral centres are there?) Ofc, there is one more that I will let you find yourself
This is the second isomer I found. (How many chiral centres are there?) Ofc, there is one more that I will let you find yourself
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ngwengsamowo
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(Original post by _JB_)
This is the first isomer I found. (How many chiral centres are there?)
![Name: Isomer 1.png
Views: 722
Size: 23.8 KB]()
This is the second isomer I found. (How many chiral centres are there?) Ofc, there is one more that I will let you find yourself
This is the first isomer I found. (How many chiral centres are there?)
This is the second isomer I found. (How many chiral centres are there?) Ofc, there is one more that I will let you find yourself
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_JB_
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_JB_
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ngwengsamowo
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ROadmanKys
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Dat1Guy
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_JB_
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#10
(Original post by ROadmanKys)
isnt this structure incorrect? the 2nd carbon has 5 bonds.
isnt this structure incorrect? the 2nd carbon has 5 bonds.
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_JB_
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ngwengsamowo
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Grizzelex
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#13
From the ER: "The structure should start with a cyclopentyl
ring with an OH group and a methyl group on carbon atom 1. There is one carbon atom left to add.
Cambridge International Advanced Subsidiary and Advanced Level
9701 Chemistry June 2017
Principal Examiner Report for Teachers
© 2017
•
If this carbon atom goes on carbon atom 2 of the ring as a methyl group we have a molecule with two
chiral centres and therefore four isomers.
•
If this carbon atom goes on carbon atom 3 of the ring as a methyl group we have a molecule with two
chiral centres and therefore four more
isomers, making eight so far.
•
If this carbon atom goes on the methyl group already
attached to carbon atom 1 this becomes an ethyl
group. This molecule is not chiral, giving one more isomer, making nine. "
ring with an OH group and a methyl group on carbon atom 1. There is one carbon atom left to add.
Cambridge International Advanced Subsidiary and Advanced Level
9701 Chemistry June 2017
Principal Examiner Report for Teachers
© 2017
•
If this carbon atom goes on carbon atom 2 of the ring as a methyl group we have a molecule with two
chiral centres and therefore four isomers.
•
If this carbon atom goes on carbon atom 3 of the ring as a methyl group we have a molecule with two
chiral centres and therefore four more
isomers, making eight so far.
•
If this carbon atom goes on the methyl group already
attached to carbon atom 1 this becomes an ethyl
group. This molecule is not chiral, giving one more isomer, making nine. "
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ZJLee2000
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elwin_raj
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#15
The cyclic structure will be symmetrical. Thus it is not optically active. So no chiral carbon.
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hussnain ali
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#16
all these three isomers u have mentioned are also structural isomers of each other the question also accounted for structural isomers now this number comes to 12 and answer is wrong u r only accounting for stereo isomers
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