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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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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Chiral molecule loses its optical activity when dissolved in polar solvent [closed]

(R)-3-Bromo-3-methylhexane loses its optical activity when dissolved in nitromethane, a highly polar but non-nucleophilic solvent. Explain this observation and what it tells you about the mechanism of ...
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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 ...
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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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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 ...
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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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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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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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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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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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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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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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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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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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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
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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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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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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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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 ...
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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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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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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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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 ...
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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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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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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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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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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 ...
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1answer
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Cahn–Ingold–Prelog Rules, cyclic structures, and breaking ties

(3S,5R)-3-ethyl-5-methylcyclohex-1-ene Does anyone know how one reaches the conclusion that the 5C is R? I tried using the Cahn–Ingold–Prelog priority rules but kept getting confused. From chem....
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Chirality with tautomers

This molecule has 6 peaks in its proton NMR. I think this is due to the following tautomerisation: However, I am unsure as to whether this molecule would be chiral, as it can freely interconvert ...
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Does a non-chiral substrate (2-bromo-2-methylpropane) also form two products via an SN1 mechanism?

If I have an alkyl halide, in which its tertiary carbon is non-chiral (for example 2-bromobutane), which reacts via an SN1 mechanism does it also produce 2 products? I am asking because I know that ...
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Chiral carbon in carvone molecules

This is the structure of carvone, with the chiral carbon noted by *. I don't understand why this is a chiral carbon, to my understanding a chiral carbon is a carbon with 4 different chemical groups ...
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How are these two molecules identical?

I can see that these compounds are identical as we have basically just done a 180 degree rotation of the molecules. But if we go by the concepts of chirality, the carbons 2 and 4 are chiral centers ...
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Is the existence of chirality center equivalent to chiral?

To make my question more clear, I want to ask two questions: Is it possible for molecule to be achiral even though molecule has chirality center? Is it possible for molecule to be chiral even though ...
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Why are carbons of Inositol chiral centers?

I was asked to draw all possible stereoisomers of inositol (1,2,3,4,5,6-cyclohexanehexol). To obtain the answer I had to assume that all six carbons of the molecule are asymmetric, which (bearing in ...
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Can we rotate a mirror image by any angle to check if it is superimposable? [closed]

A molecule is chiral when it is different from its mirror image, and achiral if it is identical to its mirror image. To check if the mirror image is identical to the original object, we have to check ...
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How would I know that a compound and its isomers are enantiomers? [closed]

How would I know that a compound and its isomers are enantiomers? Considering the chiral carbons Consider the compound is 2-bromo-2-chlorobutanedioic acid.
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Can sp2 hybridised carbon show chirality?

I know that any carbon to show chirality has to be bonded to 4 different atoms (groups of atoms). So a double bond is considered as that the carbon is achiral. I learnt from my lecturer that ...
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Constraints on rate coefficients in chiral catalytic system

Consider some reversible chemical reaction in a closed system: $$\ce{A <=> B + D} \tag{1}$$ where $\ce{A}$ is some input reagent and $\ce{B}$, $\ce{D}$ are some output reagents. Let's denote ...
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Use of axis of symmetry

Does an axis of symmetry determine chiralty? Is axis of symmetry considered a true symmetry? From the above two links, I read that a compound having axis /alternating axis of symmetry is NOT ...
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X-ray structure analysis mirrored coordinates?

How to ensure, that X-ray crystallography structure analysis was done right to provide correct, non-mirrored atomic coordinates? Example: Following Wikipedia image, is generated from data taken from ...
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What compound has the strongest optical rotation of polarised light?

A question recently asked here whether compounds know to be chiral can have non-measurable optical rotations: Are there chiral compounds that don't rotate plane-polarized light?. Apparently they ...
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Are there chiral compounds that don't rotate plane-polarized light?

I know that meso compounds have chiral centers but don't rotate plane-polarized light, and I know that there can be non-traditionally chiral compounds (e.g. ones with large substituents that prohibit ...
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1answer
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Assign stereodiscriptor to 4th carbon of 3-ethyl-2,4-dimethly-5-(propan-2-yl)heptane-1,7-diol

Here is the molecule. Clearly the 4th carbon is chiral. I have drawn the diagraph for it, but the exploratory pathways of the left and right chains are the same. So, the problem is that the two chains ...
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3answers
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Can two lone pairs in different orbitals make a chiral centre?

Is it possible that if the two lone pairs in a molecule occupy different orbitals, then could this make the molecule chiral? What I mean is, suppose a carbon atom is attached to two different atoms ...
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How do we determine molecule chirality in these examples?

I understand that in the first example, the molecule is chiral as there is no symmetry. For the second and third example, I see no symmetry in the 3d conformation after twisting the right hand side. ...

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