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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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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Number of possible stereoisomers for compound X [closed]
X(C9H14) one mole gives 1 mole ethanal+2 moles glycerol+ 1 moles propanal
Find the no. of stereoisomers possible for compound X
Ethanal has 2 carbons, propanal has 3 carbons and glycerol has 3 carbons ...
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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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Are these methylene protons going to be chemically equivalent for this racemic tocopherol derrivative? Are they diasterotopic?
In this molecule, if I am analyzing a racemate not a pure enantiomer would it be the case that the geminal protons on each methylene group (the two CH2 groups) would be chemically equivalent? I would ...
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Determining d(+)/ l(-) configuration
Is there any general rule to find out whether the compound is d(+) or l(-) from a Fischer projection formula? I can write 12 distinct Fischer projections for lactate. How do I know which ones are d(+) ...
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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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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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How does bis(glycinato) Nickle exhibit optical isomerism?
I'm a medical practitioner but sometimes I find time to discuss few topics of chemistry with my son who has just passed out his 12th standard exams. Regarding optical isomerism I have learned that a ...
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Why are the products of Grignard reaction on an alpha-chiral ketone diastereomers rather than a racemate?
Comment on stereochemistry of products.
This is a Grignard reaction and the product has two chiral carbons. I think it should be a racemic mixture.
However, my teacher says the correct answer is ...
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stable conformation of 2,3-dimethylsuccinic acid
I was researching for answering this question on Kolbe's electrolysis of 2,3-butanedicarboxylic acid (succinic acid). Turns out, this compound is not very well researched in particular, and shows few ...
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Is hydroxylamine monodentate or ambidentate ligand?
What is the total number of geometric isomers of the complex $\ce{[Pt(Cl)(py)(NH3)(NH2OH)]+}$?
If $\ce{NH2OH}$ acts as an ambidentate ligand, then there should be six geometric isomers. Or is it ...
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Does no optical rotation always implies optical inactivity? [duplicate]
This question popped up in my mind in reference to this question,
Is a compound optically active if plane polarised light is deflected by an angle of n*(2π) angles?
Suppose that I give a chemistry ...
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Is a compound optically active if plane polarised light is deflected by an angle of n*(2π) angles? [closed]
Is a compound optically active if plane polarised light is deflected by an angle of n*(2π) angles(like 360°); as there won't be any deflection in the analyser of the polarimeter?
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Does the 3D structure generated with MolView violate the wedge-dash rules of "above/below the plane"?
I've been taught that in a wedge-dash diagram, the wedge represents a bond above the plane of the paper, and the dash represents a bond below the plane.
Accordingly, I expected the structure of this ...
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Why is diequatorial trans-1,2-dimethylcyclohexane more stable than diaxial trans-1,2-dimethylcyclohexane?
Consider diequatorial trans-1,2-dimethylcyclohexane and diaxial trans-1,2-dimethylcyclohexane as shown in the figure below [1, p. 178]. In both compounds, the ring is free of angle strain.
trans-1,2-...
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How does Entropy influence the racemization of an optically active compound?
We were doing the topic "Isomerism" in our Organic Chem class and there's a question in our worksheet whose answer I haven't really understood, the question is as follows:
The racemization ...
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Stereochemistry of nitrosyl chloride addition to an alkene
My book states addition of $\ce{NOCl}$ to propylene results in 2‐chloro‐1‐nitrosopropane:
Would it follow syn or anti addition?
According to Mallya and Nagendrappa [1], the reaction would follow syn ...
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Monochlorination of (R)-2-chlorohexane: Number of possible chiral dichloro products
How many possible chiral dichloro products can be formed when (R)-2-chlorohexane reacted with one equivelent of $\ce{Cl2}$ in the presence of UV radiation (monochlorination only)?
$$\ce{C6H11Cl + Cl2 -...
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Is There a Problem with the Assignment of Stereochemical Descriptors by ChemDraw in Select Examples?
While using ChemDraw Professional 21.0.0.28 to construct some cyclic allenes and rotationally restricted biphenyls, I came across anomalous assignments of stereochemistry. [For the latest version of ...
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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{...
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Why is the 'side' of a double bond defined across the double bond horizontally rather than vertically? [closed]
When we are determining cis-trans isomerism, we seem to refer to a molecule's 'side' in relation to the double bond in a horizontal manner, as if we had drawn a mirror line through it horizontally. ...
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Why 5-member rings prefer being cis-fused?
It always bothers me how whenever I am doing practice problems I never got a proper explanation as to why 5-member rings prefer(thermodynamically) being cis- rather than trans-fused( as opposed to ...
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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 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 ...
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