Questions tagged [chirality]
Applicable to questions about the ability of a molecule (or class of molecules) to be superimposed on their mirror image(s).
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Are all 'dextrorotatory' sugars in biology actually 'd' or '+' in chirality?
When papers or articles say that all proteinogenic amino acids are 'levorotatory' or 'L', they often make a point of saying that only half of them are truly, optically levorotatory. All of them (...
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1answer
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Why is 1-Ethyl-1-methylcyclohexane achiral? [closed]
I was wondering why the 1-Ethyl-1-methylcyclohexane molecule is achiral.
Thank you in advance.
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Can aldol reaction using Evan's auxiliary yield diastereoselective products for ketone substrates?
Evan's diastereoselective aldol reaction commonly uses aldehyde as a substrate and I have never come across an example that uses ketone yet.
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How come the C1 is above the ring in fructose-6-phosphate and C1 is below the ring in fructose-1,6-bisphosphate?
Does the phosphofructokinase-1 flip the position of the covalent bonds? If I've understood correctly, C2 is a chiral atom, so it would make a difference if C1 goes from above the C2 to below the C2.
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In which of the these structures C-3 carbon is not a chiral centre?
In which of the these structures C-3 carbon is not a chiral centre?
I think that the answer to the above question should be both (b) and (c) as C-3 is attached to same groups and also they have a ...
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1answer
87 views
Example of an achiral molecule without a plane of symmetry or inversion center?
Some websites, such as this textbook, mention how generally a plane of symmetry or inversion center in a molecule is enough to consider it achiral. Nonetheless, this source clarifies
but if these ...
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1answer
183 views
Why does [Ni(gly)2] show optical isomerism despite having no chiral carbon?
For optical isomerism chiral carbon should be present i.e. carbon with four different groups but this compound doesn't have one then why does it show optical isomerism?
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2answers
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Is plane of symmetry a necessary and sufficient condition for optical inactivity in coordination compounds? [closed]
In organic chemistry, we have to check for all three types of symmetry in a compound to check its chirality, ie, plane, alternate axis and centre of symmetry. But in coordination compounds, do we need ...
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Do we need to check for all kinds of symmetry in a compound to declare it achiral?
I know that a compound is achiral if it contains any one of the following kind of symmetry.
1.Plane of symmetry
2.Centre of symmetry
3.Normal axis of symmetry
4.Alternate axis of symmetry
It is ...
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0answers
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Type of chirality in polycyclic compounds
Ignoring whether or not this molecule could exist, is there a name for this type of chirality? This molecule's mirror image cannot be superimposed on itself but there are no chiral centres.
Even ...
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Why can't an “upside down” chiral molecule neutralize the polarized light effect? [duplicate]
Steve Mould did a nice video a few months back called "Why Sugar Always Twists Light To The Right" (link is timestamped at the critical part).
However his explanation was not complete.
He ...
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Why has this molecule a S-chirality? [closed]
Can someone explain to me, why this molecule has an (S)-chirality? I don't get it. I tried to apply the rules, but I get only an (R)-chirality. Is there something special with cyclo-alkanes?
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Number of chiral centers in penicillin V
I have often seen that in many drugs chirality plays a role. So I was trying to analyze the structure of Penicillin V.
What is number of chiral centers in the structure of penicillin V? Is the ...
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1answer
56 views
Which chiral carbon do L and D in L- or D-glucose refer to? [duplicate]
I see and D- and L- glucose are mirror images of each other. and I understand D and L are for chirality. But it is not clear which carbon do D and L refer to. Could anybody let me know? Thanks.
What ...
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1answer
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Do different alkyl groups affect chirality?
I am a bit confused on the definition of a chiral center;
A carbon atom is chiral if it has four different items bonded to it at the same time. source
However I am not sure whether different alkyl ...
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4answers
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Are there reactions where the stirring direction would make a difference?
I'm not a chemist. I don't really do anything with chemistry, so I know little of the subject.
I know a bit about chiral molecules. For example, I know that homochirality can affect light polarity.
I'...
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Can a chiral molecule be optically inactive?
Does there exist a chiral compound with zero optical activity? It seems possible that for some (chiral) arrangement of atoms, the optical activity of one section of the molecule could be exactly ...
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Is nitrogen with 3 different substituents and lone pair a chiral center? Does it make the whole compound chiral too? [duplicate]
Is nitrogen considered a chiral centre or stereocenter when it has three different substituents attached to it along with a lone pair.
By definition LG Wade says
An asymmetric carbon atom is the ...
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1answer
464 views
How is plane polarized light rotated by chiral compounds? [duplicate]
There are plenty of questions related to this topic on this site but no proper answer.
Can anyone please explain to me how plane polarized light is rotated by chiral compounds, and why it cannot be ...
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2answers
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Identification of the organic compound
An organic compound A $(\ce{C10H14O})$ exhibits following characteristics.
A) It reacts with metallic sodium to give a colorless odorless gas.
B) It is oxidized by $\ce{KMnO4}$ to benzoic acid.
C) It ...
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2answers
121 views
Is chirality absolute or relative?
While going through some questions on chirality and optical isomerism, I came across this compound:
Note that I have marked 3 carbons as $C_1,C_2,C_3$
Its obvious that $C_1,C_3$ are chiral carbons.
$...
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0answers
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Chiral carbons in glucose
In the open chain structure of glucose, one can identify 4 chiral carbon atoms but some sources consider the ring structure and then say that glucose has 5 chiral carbon atoms. If asked to state the ...
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3answers
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Can geometrical isomers be enantiomers?
I have just been pondering upon the question above. I have found this example and I am sure they are enantiomers, but do they also count as geometrical isomers?
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How do i determine R,S configuration for a pseudo-chiral carbon atom?
I recently saw a question on drawing meso forms of this compound. I understand that C4 is a pseudo chiral carbon atom because it is attached to two of the same groups. Then how do i determine the r,s ...
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1answer
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Are the C1 and C3 carbons of cis 1-bromo-3-chloro-cyclobutane chiral?
I have tried to approach this from 2 directions:
The ‘official’ method my textbook gives, which gives the correct answer - They are achiral
It consists of going ‘priority-wise’ from the two carbons ...
3
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1answer
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Total number of isomers formed on monobromination of 2-methylbutane
What is the total number of isomers formed on monobromination of 2-methylbutane (including configurational and stereoisomers)?
I tried working it out. However, I found only five:
According to the ...
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1answer
141 views
Optical activity of 3‐chlorobutan‐2‐ol
In the picture that I have uploaded, I have read that the given compound is chiral.
But on drawing the sawhorse structures (for better visualisation), I feel like the compound is symmetric about a ...
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3answers
271 views
SN2 reactions and inversion of configuration in compounds with more than one chiral centre
Suppose I have a compound with 2 chiral centres which are at (S,S). Now, suppose I have an iodine atom attached to the back carbon, and I wish to carry out an $\mathrm{S_N2}$ type substitution in a ...
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2answers
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Nitrogen inversion barriers of trimethylamine and N,N-diisopropylmethylamine [closed]
Which would have a smaller nitrogen inversion barrier: $\ce{NMe3}$ or $\ce{N(i-Pr)2Me}?$
I think that $\ce{NMe3}$ should have a smaller inversion barrier as it is less bulky, but data shows otherwise....
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2answers
207 views
How to check which compound will show optical isomerism?
So my teacher told that those compounds which have one or more chiral carbon present in them it will definitely show optical isomerism because it has an optically active stereoisomer, but there are ...
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2answers
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In the reaction mentioned what percentage of reaction proceeds via SN1 mechanism?
2-iodo butane (having radioactive iodine) reacts with KI (having non radioactive iodine). Rate of loss of optical activity was 1.96 times the rate of loss of radioactivity. What percentage of reaction ...
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2answers
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Find the number of geometrical and optical isomers of 1,2,3,6-tetramethyl cyclohex-1,4-diene
The compound given to me is 1,2,3,6-tetramethyl cyclohex-1,4-diene.
The geometrical isomers for the following compounds are:
The isomer on the right can also be an optical isomer with its enantiomer....
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1answer
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R-S configuration or Cahn-Ingold-Prelog configuration [closed]
How to assign R and S configurations in alkenes and more complicated structures ?
I know that the groups attached to the sp3 hybridized carbon is first prioritized by atomic number then we see the ...
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0answers
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How can randomly oriented molecules in a liquid solution create a certain polarization pattern (d or l)? [duplicate]
How can a large number of moving, randomly-oriented chiral molecules in a watery solution twist light only to the left or only to the right?
Wouldn't a levorotary molecule become dextrorotary if I ...
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Enantiomers and Flipping chiral centres [closed]
Hello,
Normally, it seems like enantiomers have inverted R/S configuration at every chiral centre. However, in the pair below which are clearly enantiomers (note the methyl and benzyl groups are ...
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2answers
269 views
Do isotopic groups cause optical activity?
I understood the simplified reason for optical activity of a compound based on the difference in the angular velocities of counter-rotating circularly polarized light. The difference is due to the ...
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1answer
85 views
Are there optically active molecules in which all atoms lie in the same plane?
I've learnt that when a molecule is non-superposable on its mirror image, it exists as a pair of enantiomers and is optically active. Absence of plane of symmetry is given to be one of the properties ...
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0answers
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Is there an anisotropy factor (g factor) for TDDFT Abs and CD calculations?
Experimentally, anisotropy factor is calculated by dividing the CD spectra by the absorbance spectra multiplying by a factor of 32980 (in order to get a nondimensional quantity)
Theoretical ...
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1answer
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The number of optical isomers of 3,4-dichlorobutan-2-ol
The number of optical isomers possible for the given organic molecule is?
$\ce{CH_3-C^*H(OH)-CHCl-CH_2Cl}$ (the configuration is fixed at $\ce{C^*}$)
The given answer is 2.
The carbon marked with an ...
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2answers
518 views
Why is the name 'propylene oxide' preferred for epoxypropane?
This is the molecule I know as epoxypropane:
In my neck of the woods (example), this molecule is used as one of the standard examples of small chiral molecules. The name 'epoxypropane' makes a heck ...
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0answers
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What makes this molecule achiral?
I don't understand why this molecule is achiral:
I've circled what I think is the sole chiral center in red. I thought that any molecule with exactly one chiral center is chiral without exception. I ...
0
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1answer
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R/S chirality question
Consider [(1S,2S,4S)-bicyclo[2.2.1]hept-5-en-2-yl]acetic acid:
(Source: http://www.chemspider.com/Chemical-Structure.22823922.html)
According to the chemspider nomenclature, this has three S ...
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2answers
375 views
Link between centrosymmetry, dipole moment and chirality
What is the relationship between the three concepts in the title?
I know all centrosymmetric molecules are achiral, but not all achiral molecules are centrosymmetric. Thus, there are no molecules ...
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2answers
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Is chirality a property of only molecules with exactly 1 chiral centre? [closed]
I have seen chirality being defined in a number of ways in terms of a molecule not being superimposable with its mirror image.
My syllabus has a statement: "know that optical isomerism is a result of ...
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2answers
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d-Menthol vs dl-menthol: Does an enantiomer and its racemic mixture have different melting points?
I am checking out Wikipedia and it shows a different melting point (m.p.) for l-menthol $(\pu{42 ^\circ C}$ to $\pu{45 ^\circ C})$ vs dl-menthol $(\pu{36 ^\circ C}$ to $\pu{38 ^\circ C}).$
How is ...
5
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1answer
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QM9 dataset with chirality
I am trying to find chiral centers of molecules in QM9 dataset. Browsing their SMILES representation, I noticed SMILES yield using
datasets.get_qm9(GGNNPreprocessor(), return_smiles=True)
don't ...
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0answers
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Chirality as atom feature
I have been reading some literature on molecular energy prediction using machine learning techniques and I have noticed that one of the input parameters in many of the available models is "chirality". ...
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0answers
314 views
Chirality in carbocations
The following compound is a carbocation.
Clearly, the given compound does not have any element of symmetry. The compound is non planar due to the presence of ethyl group. Thus it must be chiral. But ...
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0answers
44 views
Stereochemistry of C as non-chiral centre
When a C of a molecule is not a chiral centre, the spatial orientation of its substituent group doesn't affect its stereochemical specification, does it?
Ex:
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1answer
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Priority of carbons attached to chiral group, one with double bonded oxygen, one with two oxygens [closed]
I have a chiral carbon. Two of the atoms attached to the carbon are other carbon atoms. One of those carbons has a double bonded oxygen and a methyl group attached. The other has two oxygens and a ...
