Questions tagged [stereochemistry]
Applicable to questions about the spatial arrangement of atoms in a molecule and how they affect its physical or chemical properties.
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The mean of the thick C-C bond and wedge-shaped C-C bond in the Haas projection of glucopyranose
This is more of a question about the "rules" of chemistry than science：When glucose (glucopyranose) is expressed in the Haas projection, it looks like this.
https://en.wikipedia.org/wiki/...
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Number of stereoisomers of 4,4'-(4,5-dimethylcyclohex-4-ene-1,2-diyl)di(but-3-en-2-ol)
I am having trouble finding the total number of stereoisomers of 4,4'-(4,5-dimethylcyclohex-4-ene-1,2-diyl)di(but-3-en-2-ol).
I have tried dividing the problem into three parts. The left set of chiral ...
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Does steric hindrance affect the enantiomer ratio in a reaction?
Interestingly, the authors synthesized four substituted cyclophanes (7q, 7r, 7s, and 7t) that show planar chirality, and the enantiomers (Rp and Sp) are present in a 1:1 molar ratio.
It's fascinating ...
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How to determine the value of the NOE from the NOESY spectrum?
I have 1D NOESY spectra from which I need to find out the value of the NOE (%). Is it enough to simply measure the intensity of the resulting peaks or is it necessary to subtract it from the ...
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What do γ (gamma) and λ (lambda) mean in organic chemistry?
From the Wikipedia entry on Cyhalothrin:
Pyrethroids such as cyhalothrin are often preferred as an active
ingredient in agricultural insecticides because they are more
cost-effective and longer ...
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R or S configuration?
The respective configutations of a and b are...?
I tried to find the answer for a (for me is: 2S, 3S) but I'm not sure of my results, can someone help me?
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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-...
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How many stereogenic centers exist in the atropine?
I'm pretty sure that both C bonded to N are stereogenic centers. I don't know about the others, any help? Is this correct?
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Twisting stereoisomers with rings to determine R/S [closed]
I know that if the smallest atomic number group is not in the back, we can twist the molecule so that it is in the back and then determine if it is R/S (Left image). But if the chiral center is ...
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Total number of stereoisomers of truxillic acid
Total number of stereoisomers of the compound will be:
This was a question asked in our mock test. I've tried by considering pseudo-chirality on the carbon atoms. But I don't know where to start.
I ...
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Why is α-truxillic acid not meso compound? [duplicate]
I know that for a compound to be meso it should be optically inactive and should have multiple chiral centres but in case of α-truxillic acid, it is optically inactive due to centre of symmetry being ...
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Can you have a diastereomer with one chiral center? If yes, give me example [closed]
If we say yes, how? Because if the compound have 1 chiral carbon, thus if it is S and another compound is R thus is mirror imagested
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Diastereotopic methylene protons in achiral molecules
Are the protons in methylene groups of achiral molecules such as propane-1,2,3-triol or 3-hydroxypentanedioic acid diastereotopic?
Consider propane-1,2,3-triol. To me, replacing one of the protons in ...
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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 (...
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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 ...
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Can O-alkyl sulphoxides be chiral?
Consider the two molecules below.
A chemical drawing software that I won't name says that the one on the left is chiral with configuration R at sulphur, whereas the one on the right isn't.
I checked ...
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Why do we use cis/trans for 1,4-dichlorocyclohexane, but R/S nomenclature for its 1,3 isomers?
1,4-dichlorocyclohexane has two isomers, and 1,3-dichlorocyclohexane has three:
Looking at the substituted carbon, the reason for the isomers is the same: either the chlorine points up or it points ...
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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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Does the chlorination of 4-methylcyclopentene generate two enantiomers or two diastereomers?
Does the chlorination of 4-methylcyclopentene generate two enantiomers or two diastereomers?
I think it makes two enantiomers (or one pair of enantiomer) since the starting compound is achiral, but ...
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Reactivity of Grignard reagent
I had the following question at an exam:
What is the fastest reacting compound towards nucleophilic addition with Grignard reagent?
(a) Acyl chloride
(b) Aldehyde
(c) Ester
It is obvious that ester ...
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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 "...
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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 ...
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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 ...
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Enantiomers of 1,2-dichlorocyclohexane
The other day in class we were discussing the enantiomers of 1,2-dichlorocyclohexane and my teacher told us that (R,R) and (S,S) are different isomers while (R,S) and (S,R) are the same.
I understand ...
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Is there a plane of symmetry in [Ma3b2c]?
We have been taught to look for plane of symmetries in inorganic complexes. If there is a plane of symmetry then the complex is optically inactive, otherwise it is optically active. In this particular ...
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Why does this compound only have one pair of enantiomers?
I've been doing some reading about enantiomers, which are apparently chiral molecules that are non-superimposable mirror images of each other. An example I found of this in some problems that I've ...
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Is the compound optically active? [duplicate]
My work -
The compound seems to have a plane of symmetry(POS)(The plane of the compound itself seems to be the POS)
Because- all carbon atoms in the benzene ring, the - COOH, the C=C, are all SP2 ...
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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 ...
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R and S Configuration Understanding
So I have been trying to understand how to draw R and S configurations. I feel like I have understood how to draw them, but every time I do a question, I get a wrong answer.
So here is what I have ...
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What is the relationship between Ha and Hb in the given compound, trans-1,3 dichlorocyclobutane. Are they enantiotopic or homotopic?
The question is to find the TOPICITY relationship between Ha and Hb in the given compound, (trans 1,3 dichlorocyclobutane)
They seem to be in the same chemical environment, so I tried the ...
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How to depict small molecules such as D-glucose based on isomeric SMILES
The isomeric SMILES for D-glucose is C([C@@H]1[C@H]([C@@H]([C@H](C(O1)O)O)O)O)O.
The Haworth projection looks like this:
I can parse the SMILES and draw the ...
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Is there a formula to determine the total number of constitutional isomers?
Is there a trick or a formula that given a molecular formula, allows you to know exactly how many constitutional isomers can be formed with that many atoms? Or is it more of a trial-and-error ...
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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 ...
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Why is cyclooctene the smallest cycloalkene to have cis-trans isomerism?
What prevents cis and trans isomers from existing in smaller cycloalkenes, for example, cyclohexenes for more than a short period of time?
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How the tertiary carbons of cyclohexane are assigned the stereo-descriptors (r)?
We assign the stereodescriptors R and S for chiral centres - carbons and other atoms, as per the set of sequence rules (CIP rules).
The pseudochiral centres are given the descriptors (r) & (s) ...
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Determining R-S configuration with lowest priority groups in plane of paper
I was studying R-S nomenclatures and determining configurations of molecules when I came across a certain problem, which had the 4th priority group on the plan of paper (not on a dash or wedge)
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Optical rotation and chirality
I had the same question as in Molecular chirality and optical rotation
In the answer, it says that there can't be such a mirror position where the effect of one molecule be cancelled by other. But I'm ...
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Point group of trimethyl borate $\ce{B(OCH_3)3}$
What's the point group of trimethyl borate $\ce{B(OCH_3)3}$.
The answer that my teacher gave is $D_{3h}$ but I'm struggling to see the n perpendicular $C_2$ axes and the horizontal plane of reflection....
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Is trans-1,2-dimethylcyclopropane optically active or not?
According to my book it is optically active, but no valid reason is given. But what I found is there exists an alternating axis of symmetry, and so my conclusion is the compound would be inactive or ...
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If the substituents are distinguishable, is it possible to prioritize them using the CIP rules?
In the R/S stereochemical nomenclature,
when we try to determine the priority of substituents around a chiral carbon, are there specific examples where the ranking cannot be definie under the CIP ...
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Is this formula for number of optical isomers correct?
For a symmetric molecule with an even number of chiral centres (for acyclic molecules with chiral centres only, not considering $\pi$ bonds or rings), the formulae (also mentioned in this question) ...
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Stereochemical relationship of molecules including double bond configuration and absolute configuration
Are (S,E)-4-isopropoxypent-3-en-2-ol and (R,Z)-4-isopropoxypent-3-en-2-ol both enantiomers and diastereomers? I am a bit confused because they would be diastereomers when only looking at the ...
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Systematic method to determine D/L notation of substances other than amino acids and glyceraldehyde
The fundamental rules of D/L notation, as I understand it, are as follows;
In D/L notation, a molecule is named by mapping it to glyceraldehyde.
The D/L notation is based on the stereo configuration ...
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Does a chiral allene have stereogenic centres?
This a picture of what my professor taught in class.
According the the definition of a stereogenic centre, allene should have two of them. So I don't understand what I am interpreting wrong.
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Do conformations arise from vibrations?
I was wondering how a molecule transforms from one conformation to another. Surely, since the conformations are separated by a potential barrier, some activation energy must be required. The energies ...
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Which enantiomer of 3-Chloro-2-pentanol is this?
I think that there is a chiral centers at $C_2$ and at $C_3$ (Numbering starting such that the carbon with hydroxy attached is number 2.
Then, for $C_2$:
Priority would be: OH > $C_3$ > $C_1$ &...
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Explain the mechanism of the following reaction, which involves a 1,2-alkyl migration with double inversion of configuration
I came across the following reaction, whose mechanism is said to involve a 1,2-alkyl migration with a double inversion in configuration. The reagents used were nitrous acid (generated in situ) ...
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What determines the higher priority in CIP rules, if both groups have the same atoms?
Which of the following groups has the highest priority in the Cahn-Ingold-Prelog sequence rules?
a) CH2CH3
b) CH=CH2
c) C≡CH
d) C(CH3)3
I narrowed it down to either C or D. The carbon in answer C is ...
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Confusion on enantiomers and meso compounds
Question: Are these compounds enantiomers?
Attempt: The compounds given are mirror images. But if I rotated the three bonds in the third carbon (configuration will not change), I will get a meso ...
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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?
