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 meaning of the thick C-C bond and wedge-shaped C-C bond in the Haas projection of glucopyranose
Please refer to the following for how to write the Haas projection formula（https://chemistry.stackexchange.com/questions/75048/hash-and-wedge-nomenclature）.I don't intend to address the true structure ...
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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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Why the C4 in this 1,3,4,5-substituted Cyclohexanes has a R/S configuration?
(1S,3S,4S,5S)-3,5-dimethoxy-1-phenylcyclohexane-1,4-dithiol.
ChemDraw21 shows the C4 is S configuration. However I think C4 has two same function groups(C3 and C5 are both S configuration; C2-1-6 and ...
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Fischer Projection for Different Compounds
Which of the following Fischer projections is different from the other?
Just by looking at the R-S configuration, figure C is the odd one out. But when I look at D I see that both methyl and hydrogen ...
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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 ...
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9,10-dihydro-9,10-ethanoanthracene derivatives. Stereoisomers or different compounds? What are their chemical names?
What is the relationship between these compounds? Are they stereoisomers or some of them are different compounds? Additionally, what would be their names?
(For position 9, with the methyl substituent)
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How many aldehydes and ketones can be formed from molecular formula C5H10O? [closed]
Question:
What are the possible aldehydes and ketones with molecular formula $\ce{C5H10O$ (including the stereoisomers)?
Answer: 5 aldehydes and 3 ketones
The degree of unsaturation of the compound ...
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why does -CHO hold higher priority over -CH2OH according to CIP rule [closed]
i am unable to find proper resources to learn CIP rule at a high school level withut delving deeper into terms i cant understand and hence the basic confusion.if i am correct one has to first compare ...
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Are the anomeric hydroxy groups of α-maltose and β-maltose, axial or equatorial, respectively?
This Q&A is a continuation from the following Q&A;
What do we get when we joint two α- glucoses via an α1,4 bond?
More straightforwardly, the question may focus on whether the bond represented ...
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What do we get when we joint two α- glucoses via an α1,4 bond?
What do we get when we joint two α- glucoses via an α1,4 bond?
Is it alpha maltose or beta maltose?
In other words, if we cleave amylopectin with amylase (α-amylase or β-amylase), which form of ...
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Doubt in chirality and pseudo chirality
So a carbon atom is chiral if it has 4 different group attached to it, and it is pseudo chiral if it has 3 different groups of atoms attached to it, where the 2 similar groups have different ...
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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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What is the meaning of "proto" in nomenclature?
"Proto" is generally used to describe "first", "foremost" or "earliest form of (something)" indicating something primitive that transforms into something known ...
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Optical activity of (1r,3R,5S)-1-methyl-3,5-dipropylcyclohexane (or other long alkyl groups)
Consider a cyclohexane with a methyl group at C1 position and a propyl group at C3 and C5 position and each of the first bond bonded to the cyclohexane in alkyl groups has wedge bond. I do not think ...
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Why is Carbon marked as 1 acting like a pseudo chiral centre?
Since there is a plane of symmetry passing through the middle of the compound, the C (chiral centres) at 2 and 3 will rotate the light through angles opposite in magnitude, say, +A and -A respectively ...
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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 ...
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Why do diastereomers have different physical and chemical properties?
While going through my book (Organic Chemistry, Paula Bruice) I came across the following line:
We have seen that enantiomers have identical physical properties. They
also have identical chemical ...
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What does it mean when a molecule is described as "optically stable"?
In this question about "Why don't trigonal S and P compounds undergo inversion at room temperature?", phosphines, sulfoniums and sulfoxides are described as "optically stable", ...
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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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Determining the number of stereoisomers of a compound [closed]
I am confused about:
Does stereoisomers include both cis-trans isomers and enantiomers (those with chiral carbons)
If a cyclic compound exhibits cis trans isomerism, is it able to exhibit optical ...
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Differentiating identical and enantiomers [closed]
Why is this example not considered enantiomer but identical?
And as it is identical what would be the enantiomer pair?
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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 ...
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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 ...
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