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Questions tagged [isomers]

Compounds that have identical molecular formula but different chemical structure.

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Confused with CIP Rules

I really tried very hard to understand what the highlighted text means, but I didn't find anything. I also tried very hard myself, but I cannot understand what the author is trying to say. And one ...
Peter swift's user avatar
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2 answers
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What exactly does 'isomerism' mean?

Today, I was confronted with this question - Is 2-methylpenten-3-one an isomer of 5-hexen-1-ol? Some people say yes; while some say otherwise. I'll put forward the logic on both sides. The side of ...
ChemGeek007's user avatar
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Does 1-chloro-4-(chloromethylidene)cyclohexane show geometrical isomerism?

Would this compound show geometrical isomerism, or GI for short? There certainly wouldn't be any restricted rotation for any atoms in the ring, as for the chiral carbon having chlorine and hydrogen (...
Mr Gubbo's user avatar
5 votes
1 answer
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Optical activity in tritiated cyclobutane

How would we determine the optical activity in a compound as such: The biggest difficulty I'm having is determining the R-S configuration as that will determine whether the pair are enantiomers or ...
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Geometrical isomerism in 1-(chloromethylidene)-3,5-dimethylcyclohexane

Will this compound exhibit geometrical isomerism? This question was asked in JEE (Mains) 2020, which is an entrance exam held in India annually. The official answer given for this question was "...
Haider's user avatar
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How exactly are mirror images of molecules rotated to determine enantiomeric pair?

I know there are many similar questions to this but none could clear my confusion over how exactly the mirrored molecules is rotated i.e on which axis it is rotated to superpose with the original ...
ADITYA DAS's user avatar
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Are these stereoisomers considered geometrical isomers?

I came across this compound in the Black Book of Organic Chemistry by Ashish Mishra. The question asked whether this compound could show geometrical isomers. Now, I know the compound has the ...
Man's user avatar
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Which of these molecules have stereoisomers?

Problem: Which of these molecules have stereoisomers? Solution: (The molecules with a red X beside them are the ones with stereoisomers.) Question: What is the method used to identify which molecules ...
Nora's user avatar
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What is the number of different compounds formed from the monochlorination of cis-1,2-dimethyl cyclopentane?

I encountered this question in the Black Book of Organic Chemistry by Ashish Mishra while preparing for a college entrance exam. According to the answer key the answer is 12. I have only managed to ...
Man's user avatar
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Why does polar solvents favor Ketonization and non-polar solvents favor Enolization? [duplicate]

I was just studying isomerism, when I came across this statement for keto-enol tautomerism: A polar solvent favors ketonization, while a non-polar solvent favors enolization. And I just can't get my ...
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Isomers of Pentaaminechlorocobalt(III) chloride

What kind of isomers does $\ce{[Co(NH3)5Cl]Cl2}$ exhibit? I can rule out geometrical and optical due to there being $\ce{5 NH3}$ ligands which central metal atom cannot have different positions of $\...
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Why is the 'cis-1,3-dimethylcyclobutane' conformation of both methyl groups at the bottom more unstable than both at the top?

I'm having trouble understanding why both methyl groups on top of the ring is a more stable conformation than both at the bottom of the ring. I found a reasoning that says the steric strain between ...
JERry's user avatar
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Are conformational isomers diasteromers?

I am currently struggling on seeing where exactly conformational isomers fit within stereochemistry & how (and whether) they are a subset of diasteromers. I've seen potentially conflicting ...
Mosrod's user avatar
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Is neo-octane possible and if yes, what is its structure? [closed]

I know iso-octane is an exception and is 2,2,4-Trimethylpentane which intuitively contains both iso and Neo groups. But then what is the structure of neo-octane or even is it possible?
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To what extent should a question such as: "how many enantiomers are there?" take geometric isomerism into account?

Pretty simple question here. How many enantiomers are there for the structure $\ce{CH3CH=CHCH(CH3)CH2CH3}$? On the one hand, there is just one chiral centre so one would suggest $2$. On the other ...
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Converting Quartz data from one (P3221) space group to another (P3121)

For my studies, I’ve done a lot of work on coal fly ash QXRD QPA on TOPAS which has been a fun and interesting challenge. Apart from theory reviewing, a lot of my learning so far has come from a prior ...
Hendrix13's user avatar
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Counting total number of stereoisomers of 1,2-dibromo-3,4-dimethylcyclobutane [closed]

I came across this question in one of my tests. The answer assumes the major product (the anti markovnikov one) being formed. That is, I wish to determine number of stereoisomers of 1,2-dibromo-3,4-...
Rishi Shekher's user avatar
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1 answer
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Separating alkane/alkene isomers on the GC but the isomers have the same retention time

I'm trying to differentiate between n-octane, 3-octene, and 4-octene from a mixed sample using gas chromatography, but n-octane and 3-octene seem to have the same signal and 4-octene is shouldering ...
Lia Kim's user avatar
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How many E/Z isomers are possible for vitamin A?

If E/Z is a type of stereoisomerism, then you should be able to use the formula $2^n,$ where $n$ is the number of stereogenic centres. How is it that there are 16 possible E/Z isomers according to the ...
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Assigning configuration of chiral plane - selecting of the pilot atom

I am little confused about when it comes to assigning configuration of planarly chiral cyclophanes - and I think it comes down to selection of pilot atom. All sources I have came across say that the ...
Fractal's user avatar
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Why are these structural formulas not isomers of C5H12? [closed]

A Biology textbook question stated that there are three isomers of C5H12, the structural formula of the first two isomers pentane and 2-methylbutane were pictured, the reader was then asked to draw ...
Simon's user avatar
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How does phenol show tautomerism?

I read that atleast one alpha carbon has to be sp3 wrt the functional group (and has to have atleast 1 alpha Hydrogen atom) for it to show tautomerism. I am able to see that in the keto isomers of ...
Zeit Shpaga's user avatar
2 votes
1 answer
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Difficulty in E-Z nomenclature and counting number of geometrical isomers

I have found above four molecules as the geometrical isomers just by drawing them and checking if they are superimposable. I'm not sure that these are the only ones. I have tried using E and Z but ...
Rishi Shekher's user avatar
-1 votes
1 answer
516 views

What kind of isomers are ethyl butanoate and propyl propanoate?

Are ethyl butanoate (1) and propyl propanoate (2) metamers or functional group isomers? My book claims they are metamers, but here one group is $\ce{-CO-OR}$ and another is $\ce{-CO-OR'}$ where $\ce{R}...
a_i_r's user avatar
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4 votes
1 answer
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Why does 2,3 dichlorobutane have 2, and not 3, stereoisomers

I understand how and that the R,S and R,R stereoisomers are different. But I don’t see why the R,R and S,S compounds are stereoisomers and not meso compounds with each other. Online it says that ...
Kirandk's user avatar
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2 answers
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Is eta hexachloro cyclohexane optically active compound?

Quoting from Wikipedia, Hexachlorocyclohexane (HCH), $\ce{C6H6Cl6}$, is any of several polyhalogenated organic compounds consisting of a six-carbon ring with one chlorine and one hydrogen attached to ...
Infinite's user avatar
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2 votes
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Reactivity of 1-bromo-4-tert-butylcyclohexane isomers with methanol

(1s,4s)-1-bromo-4-tert-butylcyclohexane (1) and (1r,4r)-1-bromo-4-tert-butylcyclohexane (2) are heated (E2) with $\ce{NaOCH3}/\ce{CH3OH}.$ Which isomer will react faster? What will change when $\ce{...
Stormin nn's user avatar
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Why does 1-ethylidene-2,3-dimethylcyclopropane exhibit cis-trans isomerism?

I think the carbons 2 and 3 have different configuration according to the CIP rules which makes the groups different: Am I correct? Is there any official criteria regarding these cases ?
Ali's user avatar
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How does the size of a molecule subject to photo-isomerization affect it's isometric configuration?

When azobenzene is photo-excited to a higher energy configuration, the electron orbital take new energy levels and position's, changing the over all configuration of the molecule. Now, if various ...
C-Consciousness's user avatar
1 vote
1 answer
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Number of stereoisomers of 1,3,5-trimethylcyclohexane

When I searched the stereoisomers of 1,3,5-trimethylcyclohexane, I got four structures given below. I don't get how structures 1 and 2, 3, and 4 are not the same. Could anyone explain?
L lawliet's user avatar
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3 votes
2 answers
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How can I find all possible isomers of a given molecule?

I attend a course on combinatorics (mathematics) which contains many examples related to chemistry. Unfortunately, I don't have enough chemistry knowledge to feel comfortable with the examples. For ...
Matt N.'s user avatar
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0 answers
58 views

Do ketdione molecules have diol tautomers?

In my chemistry textbook there's a keto-enol tautomerism example: But will it also be in equilibrium with pent-1,3-dien-2,4-diol in a reaction like this or will it just be a functional isomer?
Frisk17's user avatar
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1 answer
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Why this structure is diastereomers instead of enantiomers

In this diagram optical isomers has divided in to 2 categories, one is diastereomers and enantiomers. Is the example for diastereomers correct? For me its looks like enantiomers
Zayden's user avatar
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2 answers
802 views

Why doesn't 2,3-pentadiene show geometrical/cis-trans isomerism?

There are two different groups bonded to each terminal C in the C=C=C system, and there is restricted rotation about the C=C=C. So why doesn't it show cis-trans isomerism? The most common answer I get ...
user119212's user avatar
2 votes
1 answer
926 views

Why is the formation of the nitro isomer more favorable under acidic conditions

In the reaction between chloropenataamminecobalt and nitrite either the NO2 or the ONO linkage isomer is formed. This preference seems to be mainly due to the pH of the solution with acidic conditions ...
Joey Costello's user avatar
-4 votes
1 answer
117 views

Why total stereoisomers is 1 even if no geometrical isomers and optical-isomers are present [closed]

Let's for example take the complex structure type $\ce{MA_6}$, What will be the Total number of Stereo-isomers (=[Geometrical-isomers]+[optical-isomers]). My effort was that There will be no G.I and ...
Mridul Kumar's user avatar
1 vote
1 answer
126 views

How many geometrical isomers will be formed here?

Can someone help me calculate the number of geometrical isomers in this compound? According to me there should be 3 isomers here but according to my teacher, there are 4.I believe that both EZ and ZE ...
Ritvish's user avatar
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1 vote
0 answers
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Total number of Isomers of [Co(NH3)5(NO2)](NO3)2 [closed]

I encountered this question in my country's Chemistry textbook of class 12. No solutions are published, but the answer given at the back states - "There are 10 possible isomers. (Hint: There are ...
Anonymous's user avatar
7 votes
0 answers
586 views

Does solvate isomers exist for coordination compounds with ammonia solvent as ligand?

I could find many sources confirming the hydrate isomerism(with water as solvent) but I couldn't find any information about any other solvent. In all the sources "hydrate/solvate isomerism" ...
Govind's user avatar
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0 answers
343 views

Number of enol forms of acetylacetone

Here is what I tried: These are the two enolic forms that I could make. So according to me, the total number of distinct enol forms of acetylacetone is $2$. But the answer is 3, what am I missing?
Soumil Gupta's user avatar
7 votes
2 answers
376 views

What is the error in the number of aromatic isomers of C7H8O?

I am a student studying basic organic chemistry (isomerism) and was asked a question to find the number of aromatic isomers of $\ce{C7H8O}$.In fact this was a question in IITJEE exam. So I tried to ...
Ritanshu's user avatar
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5 votes
1 answer
3k views

The total number of stereoisomers of 1,2-dibromo-3,4-dichlorocyclobutane

I tried writing all the geometrical isomers for 1,2-dibromo-3,4-dichlorocyclobutane, and then saw if they were optical or not. And I am getting the answer as 10: However, the given answer is 8. I can'...
Perseus's user avatar
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0 answers
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Confusion in D/L nomenclature [duplicate]

With regard to carbohydrates, it is known that in a Fischer projection, if the $-OH$ group is on the right side of the lowest priority asymmetrical (chiral) carbon, then we name it as D and if it is ...
Soumil Gupta's user avatar
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0 answers
737 views

Chirality of conformations of butane

I have read that the conformations of butane are as follows: I came across a question about number of chiral conformations of butane. My Attempt : The total or fully eclipsed is achiral because it ...
Nil's user avatar
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4 votes
0 answers
542 views

Tautomerism between cyclohex-2-en-1-one and cyclohex-3-en-1-one

I think cyclohex-2-en-1-one and cyclohex-3-en-1-one should undergo tautomerism as shown below: I'm calling it tautomerism because of it's similarity with the tautomerism mechanism in basic medium. I ...
Box Box Box Box's user avatar
3 votes
1 answer
124 views

Confusion in R/S Nomenclature and Chirality [closed]

I have many confusions regarding optical isomerism: What is the use of the R/S nomenclature? I understand that it is used to distinguish between the different spacial arrangements that are possible ...
Soumil Gupta's user avatar
1 vote
0 answers
46 views

How do molecules with opposite rotational photoisomerization bonds behave? [closed]

If a molecules bond change upon isomerization with the respective bonds straining the molecules as they orient themselves opposite from each other, would the molecule undergo some kind of ...
C-Consciousness's user avatar
2 votes
1 answer
2k views

Why is [M(AB)2] a geometrical isomer?

Our teacher told us that for coordination number 4 and tetrahedral shape $\ce{[M(AB)2]}$ doesn't have a plane of symmetry, so it shows optical isomerism. What if we take a plane passing through the ...
Soumil Gupta's user avatar
4 votes
1 answer
293 views

What is the isomeric relation between bicyclo and spiro hydrocarbons?

Take for example octahydropentalene (bicyclo[3,3,0]octane) and spiro(3.4)octane: I would think that they are chain isomers of sort but according to nomenclature counting rules, they are both 8-carbon ...
napstablook's user avatar
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3 votes
0 answers
328 views

Isomerisation Reactions of Alkyl Halides

My organic chemistry textbook says: Haloalkanes on heating at 573K or in presence of anhydrous at low temperature undergo molecular rearrangement to form an isomeric haloalkane. I noticed a ...
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