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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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 ...
4 votes
1 answer
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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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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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1 answer
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Why this structure is diastereomers instead of enantiomers

In this diagram optical isomers has divided in to 2 categories, one is diastereomers and enantiomers. Is the example for diastereomers correct? For me its looks like enantiomers
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Of 2-bromobutan-2-ol and trans-1,2-dimethylcyclobutane which is chiral as well as dissymmetric?

In an examination I was asked to determine the molecules which are chiral as well as dissymmetric. There were four options, and among them, two were achiral, as they had an improper axis of symmetry. ...
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Chirality of conformations of butane

I have read that the conformations of butane are as follows: I came across a question about number of chiral conformations of butane. My Attempt : The total or fully eclipsed is achiral because it ...
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Confusion in R/S Nomenclature and Chirality [closed]

I have many confusions regarding optical isomerism: What is the use of the R/S nomenclature? I understand that it is used to distinguish between the different spacial arrangements that are possible ...
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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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Does 1,4-dimethylcyclohexane have a chiral center?

My textbook says that 1,4-dimethylcyclohexane (cis or trans) does not have a chiral centre, since two groups on the tertiary carbon (that are the part of the ring) are identical, and thus the compound ...
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1 vote
1 answer
673 views

Are all chiral carbons sp3 hybridised? [closed]

I had this doubt, whether all asymmetric chiral carbons must necessarily be $\mathrm{sp^3}$ hybridized. For sure, we know that double or triple bonded carbon atoms don't shows such chirality, but is ...
3 votes
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Why does an improper rotation axis preclude chirality?

Can anybody prove that any molecule with an axis of improper rotation is nonchiral? I still do not understand why this is so, any proper mathematical proof or visualisation of a generalised molecule ...
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Why do Enantiomers have different chemical properties with optically active reagents?

As I understand Enantiomers have similiar physical properties but they do show different chemical properties with optically active reagents. This point is something which I am not able to logically ...
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1 answer
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Can bromo(chloro)fluoro(iodo)methane be synthesized? [closed]

Bromo(chloro)fluoro(iodo)methane is supposed to have all of the stable halogens a part of this molecule: fluorine, chlorine, bromine, and iodine. Can it really able to be synthesized and if so could ...
3 votes
1 answer
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How can a compound having a plane of symmetry be Chiral?

The compound( Given in the image below) is treated with $\ce{excess H2 in Pt}$. Here, (a) - The given compound. (b) - What the answer should be according to me. (c) - What the actual answer is: Q1 - ...
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Does the 3D conformation of rings affect chirality?

During the chirality analysis of various molecules containing rings, we assume for convenience that the rings are completely flat/planar and if the molecule has a plane of symmetry, it is achiral. ...
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3 answers
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What exactly is a 'chiral centre' in a carbon compound? [duplicate]

The typical progression (in books, YouTube videos) of explanation of chiral carbons in a compound is as follows: Chiral compounds are non-superimposable by their mirror-image; It is easily seen that ...
1 vote
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In a pair of diastereomers, which of the following is true?

While going through my book, I came across this question and got really confused. Here's what the problem was: In a pair of diastereomers, Both can be laevo-rotatory or both can be dextro-rotatory ...
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1 answer
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Is 2-bromo-3-methylbutane chiral? [closed]

Is 2-bromo-3-methylbutane chiral?
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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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1 answer
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Is 2 ethyl 3 methyl oxirane optically active?

According to me this molecule does not have any any plane of symmetry nor centre of symmetry, but in my textbook it is given that this is optically inactive.
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-1 votes
1 answer
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Why is ephedrine optically active? [closed]

Acyclic amine in which three groups are different with a lone pair of electron is optically inactive and nitrogen is achiral because of the rapid pyramidal inversion. Does similar inversion happen in ...
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1 answer
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How is the central carbon in 3‐bromopentane‐2,4‐diol chiral?

My teacher told us the middle carbon in 3‐bromopentane‐2,4‐diol is chiral: $$\ce{CH3-CH(OH)-\overset{\star}{C}H(Br)-CH(OH)-CH3}$$ Since there are two identical groups around it, I would guess it ...
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1 answer
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What are the criteria for a molecule to be chiral?

What are the criteria for a molecule to be chiral? (We frequently get questions of this type, so this is an attempt to construct a suitable general answer for duping.)
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Chirality and Optical activity

Do all chiral objects rotate the plane of polarization of EM waves? For example my hand is chiral, will it rotate the plane of polarization of EM waves of suitable wavelength?
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6 votes
1 answer
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Is (1R,3aR,4S,6aS)‐1,4‐dibromo‐octahydropentalene chiral or achiral?

Is this molecule on the left chiral or achiral? I believe it is achiral because its mirror image (on the right) is essentially the same molecule. But I was told that it is chiral because it doesn't ...
1 vote
1 answer
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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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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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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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1 vote
1 answer
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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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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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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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1 vote
1 answer
216 views

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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5 votes
0 answers
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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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1 answer
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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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1 answer
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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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1 answer
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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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1 answer
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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 ...
16 votes
4 answers
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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'...
3 votes
0 answers
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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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0 votes
0 answers
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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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1 answer
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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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7 votes
2 answers
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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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2 votes
2 answers
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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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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 ...
17 votes
3 answers
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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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1 answer
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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 votes
1 answer
852 views

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 ...
0 votes
1 answer
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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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