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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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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Are meso compounds also included in optical isomers or are they just stereoisomers
Our teacher has taught us today about optical isomers . And at the end given a formula for finding number of optical isomers of a symmetrical molecule( n is number of chiral atoms and the n is odd for ...
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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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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 ...
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Difficult in grasping "the extent/limit of conformational space of a compound until it change its stereochemistry"
I have heard that a conformational landscape encompasses all conformers that a compound has for a specific stereoisomer. I think it makes sense verbally, because if all conformers of a stereoisomer ...
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Calculating energy difference between two 1-4 dimethylcyclohexane conformers
The following question was asked in a quiz at my college
Draw the most stable and least stable chair conformer for 1,4-dimethylcyclohexane and calculate the
energy difference between these two. Given ...
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Can we always use the planar representation of cycloalkanes instead of their true conformations to study their stereochemistry and chirality?
When I have drawn stereoisomers of substituted cyclohexanes and checked if they are chiral, I typically represent the ring as a planar hexagon and look for symmetry elements. For example, I would use ...
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Is there a formal definition of “identical” molecules?
I was reading about atropisomers and their impacts on drug design, and I started wondering whether we have a formal definition for identical molecules. Atropisomers are not the same molecules because ...
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Racemization at stereogenic centre [closed]
I am getting a bit confused about why the configuration at the optical centre changes from d to l after enolization?
Any stereogenic centre next to a carbonyl group will be destroyed by enolization. ...
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How are non-racemic drugs produced?
In many cases the L- or S- stereoisomer of organic compounds is vastly more bioactive than other enantiomers. So we see pharmaceutical companies producing escitalopram (i.e., S-citalopram), ...
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What is the relationship of the following compounds? [closed]
What is the relationship of these following compounds? My guess is they are constitutional isomers. However, a couple of people said that they are enantiomers of each other. Which one is correct?
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Which one has higher priority in CIP rules -- O or OH?
I know that if the atom is the same, I have to look at the next atom. In the first choice, Oxygen is not connected to any other atom (besides the chiral carbon). It is an anion. Whereas in the second ...
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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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Does norcamphor have enantiomers?
The following two molecular structures have two chiral centers, so in total four chiral centers:
I did the absolute configuration multiple times and I keep getting R,R and S,S, which should be ...
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Does single swap rule apply to in-the-plane bonds?
When forming enantiomers, does the single swap rule (swapping 2 of the atoms directly bonded to a chiral C will give its enantiomer) apply, even when we're switching bonds that are in the plane?
For ...
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Stereochemistry R,S configuration
I'm trying to find the R/S configuration of this molecule right here:
At first I tried to find the rotation and then reverse it (since H is pointing outwards), I got an S configuration (drawn poorly ...
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How can a molecule with a double bond on one side have a plane of symmetry, and thus, be achiral?
Does norbornene have a plane of symmetry? Is norbornene achiral or chiral?
I think norbornene is chiral since there is a double bond on the only one side. Thus, there is no plane of symmetry. The ...
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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 ...
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Converting structures into Fisher projections
I am really struggling with converting pyrano/furanosides into their Fisher projection counterparts. Especially when they are drawn like in the shown projection. When do you know to connect the ...
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Are substituents placed alphabetically in the name of a cycloalkane?
I named this molecule 1,5-diethyl-2-methyl-4-propylcyclohexane. Is this correct? Or should we somehow use the size of the substituents?
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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 ...
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How to determine if the ring compound has optical isomers?
The first column and fourth column of the table below says that the compound has the plane of symmetry and is not optically active. However, I noticed that each side has different arrangement of the H ...
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